Co-reporter:Shuai Chen, Fu Tang, Liangzhen Tang, and Lidong Li
ACS Applied Materials & Interfaces June 21, 2017 Volume 9(Issue 24) pp:20895-20895
Publication Date(Web):June 1, 2017
DOI:10.1021/acsami.7b04956
Copper (Cu) nanoparticles possess unusual electrical, thermal, and optical properties. However, applications of these materials are often limited by their tendency to oxidize. We prepared Cu nanoparticles by a simple polyol method, with a good control over the particle size. The reaction required no inert atmosphere or surfactant agents. The as-prepared Cu nanoparticles showed good resistance to oxidation in solution. These Cu nanoparticles were then incorporated into a biocompatible polysaccharide hydrogel, which further stabilized the nanoparticles. The hybrid hydrogel exhibited a rapid self-healing ability. Because of the excellent photothermal conversion properties of the embedded Cu nanoparticles, the hybrid hydrogel showed rapid temperature elevation under laser irradiation. The hybrid hydrogel showed limited cytotoxicity; however, under laser irradiation the hydrogel displayed antibacterial properties owing to the heating effects. This study demonstrates that our hybrid hydrogel may have applications in biomedical fields and photothermal therapy.Keywords: antibacterial; hydrogel; nanoparticles; photothermal effect; self-healing;
Co-reporter:Shijie Zhang, Ronghua Liu, Qianling Cui, Yu Yang, Qian Cao, Wenqiang Xu, and Lidong Li
ACS Applied Materials & Interfaces December 20, 2017 Volume 9(Issue 50) pp:44134-44134
Publication Date(Web):November 29, 2017
DOI:10.1021/acsami.7b15612
Fluorescent micro- and nanosized particles have a broad range of applications in biology, medicine, and engineering. For these uses, the materials should have high emission efficiency and good photostability. However, many organic fluorophores suffer from aggregation-induced quenching effects and photobleaching. Here, we used a simple method based on covalently blending a fluorescent conjugated oligomer with silica nanoparticles to achieve emission quantum yields as high as 97%. The resulting system also showed excellent stability under continuous light illumination, in a range of pH values and temperatures, and in common solvents. This fluorescent material showed outstanding properties, including highly efficient blue emission, low cost, low toxicity, and easy synthesis. Furthermore, its effectiveness for latent fingerprint detection was demonstrated as a proof of concept on various substrates. The obtained emissive fingerprint powder gave good optical/fluorescent images with high contrast and resolution between the ridges and spaces.Keywords: conjugated oligomer; fluorescence; high quantum yield; latent fingerprints; silica nanoparticles;
Co-reporter:Xiaoyu Wang, Lu Liu, Shuxian Zhu, Lidong Li
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2017 Volume 520(Volume 520) pp:
Publication Date(Web):5 May 2017
DOI:10.1016/j.colsurfa.2017.01.072
•Organic fluorescent nanocomposites were prepared by a facile reprecipitation method.•The nanocomposites offer a ratiometric fluorescence signal based on fluorescence resonance energy transfer mechanism.•The fluorescence signal of nanocomposites shows a good response to different DNA.In this work, we report a novel organic fluorescent nanocomposite for DNA detection. Through a reprecipitation method, π-conjugated oligomers 4,7-(9,9′-bis(6-adenine hexyl)fluorenyl)-2,1,3-benzothiadiazole (OFBT-A) incorporated Texas Red labeled oligonucleotides (named TR-P5) within their matrices to form OFBT-A/TR-P5 nanocomposites. Efficient fluorescence resonance energy transfer (FRET) was observed between OFBT-A and TR-P5. Introduction of DNA with different lengths has changed the aggregation structures of nanocomposites and thus altered the FRET efficiency. Based on the fluorescence signal responses of the OFBT-A/TR-P5 nanocomposites to different DNA, DNA elongation and cleavage processes were successfully monitored by simply observing the change of FRET efficiency of the nanocomposites solutions. This research provides a facile, fast and highly efficient manner for DNA analysis, which shows great potential in the study of DNA-related biological processes.Download high-res image (84KB)Download full-size image
Co-reporter:Jingxian Li;Qingxi Duan;Teng Zhang;Minghui Yin;Xinhao Sun;Yimao Cai;Yuchao Yang;Ru Huang
RSC Advances (2011-Present) 2017 vol. 7(Issue 68) pp:43132-43140
Publication Date(Web):2017/09/04
DOI:10.1039/C7RA07522G
Memristive devices with analog resistive switching characteristics are widely investigated nowadays for electronic synapses that facilitate memory and learning in neuromorphic computing hardware. It is therefore essential to understand and optimize the incremental switching behavior of the cells in order to enhance the functionality of memristive neural networks. Here we report a systematic study on the analog switching of bilayer oxide based memristive synapses and show that transition metal oxides with rich intermediate phases, such as WOx, are able to provide larger number of conductance states compared with oxides with few intermediate phases such as TaOx and HfOx. This could be attributed to the intrinsically different electrical properties of the intermediate phases that jointly contribute to the change of device conductance, in addition to that caused by the varied geometry of filaments during programming. Controlled studies adopting different materials, compositions and sequences of oxide bilayers reveal that the analog switching is mainly dominated by the switching layer, thus providing clues to the optimization of memristive devices for future neuromorphic applications.
Co-reporter:Rongqin Ye;Qianling Cui;Chuang Yao;Ronghua Liu
Physical Chemistry Chemical Physics 2017 vol. 19(Issue 46) pp:31306-31315
Publication Date(Web):2017/11/29
DOI:10.1039/C7CP06434A
In this work, we developed a supramolecular fluorescent system based on host–guest interactions between a fluorene derivative carrying two bispyridinium units (FPy) and cucurbit[8]uril (CB[8]). In aqueous solution, the system showed outstanding tunable emission properties. After being encapsulated into the rigid hydrophobic cavity of the CB[8] host, the fluorescence emission of fluorene had an obvious red-shift with enhanced quantum yield. Interestingly, the emission behavior of the FPy/CB[8] complex showed a two-step self-assembly process when the molar ratio of FPy to CB[8] changed from 1 : 1 to 1 : 2. Besides, the influence of several factors on the emission properties of the FPy/CB[8] complex was also investigated, like pH value, salt concentration, and temperature. Finally, the fluorescent FPy/CB[8] complexes displayed a good performance for detection of adenosine-5′-triphosphate (ATP), which can cause aggregation-induced quenching of the complexes via electrostatic attraction.
Co-reporter:Ronghua Liu, Qianling CuiChun Wang, Xiaoyu Wang, Yu Yang, Lidong Li
ACS Applied Materials & Interfaces 2017 Volume 9(Issue 3) pp:
Publication Date(Web):January 4, 2017
DOI:10.1021/acsami.6b14320
Fluorescent conjugated polymer nanoparticles have attracted great interest for applications in biological imaging owing to their excellent optical properties and low cytotoxicity; however, a lack of effective targeting limits their use. In this work, we design and synthesize a fluorescent conjugated polymer modified with a phenylboronic acid group, which can covalently bind with cis-diol-containing compounds, such as sialic acid (SA), by forming a cyclic ester. However, the obtained conjugated polymer nanoparticles failed to discriminate between cancer cells, with or without SA overexpressed surfaces (such as DU 145 and HeLa cells, respectively). To address this problem, we introduced SA template molecules into the polymer nanoparticles during the reprecipitation process and then removed the template by adjusting the solution pH. The SA-imprinted nanoparticles showed a uniform size around 30 nm and enhanced fluorescence intensity compared with unmodified polymer nanoparticles. The SA-imprinted nanoparticles exhibited selective staining for DU 145 cancer cells and did not enter HeLa cells even after long incubation times. Thus, we present a facile method to prepare fluorescent nanoparticles for applications in targeted cancer cell imaging.Keywords: cellular imaging; conjugated polymer; fluorescence; phenylboronic acid; sialic acid;
Co-reporter:Xiaoyu Wang;Lu Liu;Shuxian Zhu;Jinghong Peng
RSC Advances (2011-Present) 2017 vol. 7(Issue 65) pp:40842-40848
Publication Date(Web):2017/08/18
DOI:10.1039/C7RA08142A
In this paper, we report a novel organic fluorescent nanoparticle based on exciplexes for cell imaging. Through a reprecipitation method, we used a combination of 1,1-bis((di-4-tolylamino)phenyl)cyclohexane (TAPC) and 2,7-bis(diphenylphosphoryl)-9,9′-spirobi[fluorene] (SPPO13) to form nanoparticles. In the aggregated structures, TAPC and SPPO13 were forced into proximity that led to the corresponding exciplex formation. A red-shifted fluorescence emission with considerably longer fluorescence lifetimes ascribed to exciplex emission can be achieved. Along with the good stability and low cytotoxicity of organic nanoparticles, the prepared TAPC/SPPO13 exciplex nanoparticles were successfully applied in live cell imaging. These properties make TAPC/SPPO13 exciplex nanoparticles good candidates for cellular labeling and imaging materials.
Co-reporter:Xiaoyu Wang, Xiaofeng Jiang, Shuxian Zhu, Lu Liu, Junhan Xia, Lidong Li
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2017 Volume 535(Volume 535) pp:
Publication Date(Web):20 December 2017
DOI:10.1016/j.colsurfa.2017.09.026
In this work, an optical functional composite film was prepared through self-assembly technique for specific protein detection. The Au nanostructures with metal enhanced fluorescence (MEF) effect were prepared via the in situ reduction of Au ions in a filter paper. Then, a multilayer film was prepared on the Au nanostructures by layer-by-layer adsorption of poly-(ethylenimine), poly-(glycolic acid) and biotinylated poly(l-lysine)-graft-poly(ethylene glycol) (PLL-g-PEG-biotin). Through adjusting the structure of multilayer film, an optimum interaction distance between Au nanostructures and fluorophores for the MEF effect was achieved. Meanwhile, the surface PLL-g-PEG-biotin layer allows the film to capture specific streptavidin through biotin-streptavidin interaction. Owing to the MEF effect of Au nanostructures, a significant enhancement in the fluorescence of fluorescein isothiocyanate (FITC) that labeled streptavidin was successfully obtained. This optical functional composite film with enhanced fluorescence could be used to recognize specific protein in a facile and efficient way.Download high-res image (164KB)Download full-size image
Co-reporter:Qian Cao, Xiaoyu Wang, Qianling Cui, Yu Yang, Lidong Li
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2017 Volume 514(Volume 514) pp:
Publication Date(Web):5 February 2017
DOI:10.1016/j.colsurfa.2016.11.057
•A bifunctional gold/gelatin nanocomposite was fabricated with core-shell structure.•Enhanced fluorescence and Raman scattering signals were observed in this particle.•It shows good performance for fluorescence and SERS imaging of HeLa cells.In recent decades, the preparation of multi-functional nanoplatforms that integrate two or more abilities into a single nanocomposite has attracted increasing interest and potential applications in many fields. Here, we report a novel hybrid core-shell structured nanocomposite integrating the capabilities of metal-enhanced fluorescence (MEF) and surface-enhanced Raman scattering (SERS). The nanocomposite consists of porous gold nanoparticle as a magnifying material for both MEF and SERS, 4-aminothiophenol (ATP) molecule as Raman probe, gold nanocluster as the fluorescent emitter, and gelatin as the protecting outer shell. In this nanocomposite, the fluorescence intensity of the gold nanoclusters was enhanced by about four times, while the Raman signal of the ATP molecules was increased by 4 orders of magnitude. Additionally, the nanocomposite shows low cytotoxicity and good performance for fluorescence and SERS imaging of HeLa cells.Download high-res image (138KB)Download full-size image
Co-reporter:Qianling Cui, Xiaoyu Wang, Yu Yang, Shengliang Li, Lidong Li, and Shu Wang
Chemistry of Materials 2016 Volume 28(Issue 13) pp:4661
Publication Date(Web):June 10, 2016
DOI:10.1021/acs.chemmater.6b01424
Binding of biomolecules or probes to the plasma membrane is of great importance for investigations of cell morphology and various biological processes. Herein, a water-soluble conjugated polymer is designed as a membrane probe. The probe shows a strong affinity toward lipid membranes owing to the high charge density from abundant imidazolium moieties together with the moderate rigidity and hydrophobicity derived from the conjugated backbone. Upon binding with a membrane, the interchain FRET of the probe was substantially enhanced, which resulted in the emission of both blue and red fluorescence. This is favorable for dual-color imaging. Finally, cellular experiments demonstrate the excellent performance of this macromolecular probe on stable binding with cell membranes without the appearance of cell endocytocysis even after a long retention time.
Co-reporter:Jianfeng Zhang, Xinjun Xu, Chuang Yao and Lidong Li
Journal of Materials Chemistry A 2016 vol. 4(Issue 5) pp:944-950
Publication Date(Web):06 Jan 2016
DOI:10.1039/C5TC03719K
Organic nano/micro one-dimensional (1D) materials are generally considered as promising materials for flexible, portable optoelectronic devices due to their well-known distinctive feature. Over the past few years, numerous organic nano/micro 1D photosensitive resistors have been developed; however, as one of the important photoelectronic components for fabricating organic nano/microelectronic circuits, organic nano/micro 1D photodiodes have not been reported yet. Herein, on the basis of our previous work about an organic photosensitive radial heterostructure microwire, we tried to prepare another kind of radial heterostructure microwire and explore its photodiode properties. Excitingly, the organic radial heterostructure microwire using aluminum tris(8-hydroxyquinoline) as the core and poly(3-hexyl thiophene) as the shell, which was prepared by a solution-based method, showed excellent performance with a large rectification ratio, a high on/off ratio and a good photoresponsivity under ambient conditions. Our work has developed a convenient method to prepare microwire photodiodes based on an all-organic heterojunction.
Co-reporter:Jianfeng Zhang, Xinjun Xu, Chuang Yao, Jinghong Peng, Manping Jia and Lidong Li
Journal of Materials Chemistry A 2016 vol. 4(Issue 20) pp:4505-4511
Publication Date(Web):07 Apr 2016
DOI:10.1039/C6TC00214E
We fabricated a unique ternary organic hybrid microwire radial heterojunction by a facile method. First, 4,4′,4′′-tri(N-carbazolyl)triphenylamine (TCTA) microwires were prepared by solvent-evaporation-assisted self-assembly. Then, [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) nanoparticles were adsorbed onto the surface of the TCTA microwires, forming interesting corncob-like binary hybrid microwires. Finally, (4s,6s)-2,4,5,6-tetra(9H-carbazol-9-yl)isophthalonitrile (4CzIPN) was adsorbed on the surface of the binary hybrid microwires to form ternary hybrid microwire radial heterojunctions. The thermally activated delayed fluorescence (TADF) material 4CzIPN was introduced into the donor–acceptor (D–A) system to form the ternary hybrid microwire radial heterojunction for the first time. The morphology has been confirmed by fluorescence microscopy, SEM and TEM. Interestingly, we found that this ternary hybrid microwire exhibited efficient photoconductivity by fabricating a bottom contact device; the photocurrent increased by more than 3 times compared with the reference device without 4CzIPN. By examining some reference devices, it can be inferred that the enhancement of the photoconductivity originates from the reversed intersystem crossing (RISC) process in 4CzIPN. This process can promote the formation of triplet excitons, thereby increasing the charge carrier concentration in the conductive channel of the microwire radial heterojunction. These high photoconductivity ternary microwires provide an efficient approach to improve the performance of photovoltaic devices and show promise for applications in organic integrated optoelectronics.
Co-reporter:Yu Yang, Xiaoyu Wang, Qianling Cui, Qian Cao, and Lidong Li
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 11) pp:7440
Publication Date(Web):March 7, 2016
DOI:10.1021/acsami.6b00065
Fluorescent organic nanoparticles have attracted increasing attentions for chemical or biological sensing and imaging due to their low-toxicity, facile fabrication and surface functionalization. In this work, we report novel fluorescent organic nanoparticles via facile self-assembly method in aqueous solution. First, the designed water-soluble fluorophore shows a weak and negligible intrinsic fluorescence in water. Upon binding with adenosine-5′-triphosphate (ATP), fluorescent nanoparticles were formed immediately with strongly enhanced fluorescence. These fluorescent nanoparticles exhibit high sensitivity and selectivity toward Fe3+ sensing with detection limit of 0.1 nM. In addition, after incubation with HeLa cells, the fluorophore shows excellent imaging performance by interaction with entogenous ATP in cells. Finally, this fluorescent system is also demonstrated to be capable of Fe3+ sensing via fluorescence quenching in cellular environment.Keywords: cellular imaging; Fe3+ sensing; fluorescence; organic nanoparticles; self-assembly;
Co-reporter:Chun Wang, Qianling Cui, Xiaoyu Wang, and Lidong Li
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 42) pp:29101
Publication Date(Web):October 4, 2016
DOI:10.1021/acsami.6b12487
In this work, we report a photosensitizer-loaded hybrid nanostructure that shows high antibacterial efficiency after surface interaction with a lectin protein. Gold nanoparticles were generated on the polymer nanoparticle surface through an in situ reduction method and behaved as a plasmonic amplifier. After conjugation of the photosensitizer rose bengal onto the hybrid nanoparticles, higher phosphorescence intensity and generation of reactive oxygen species (ROS) were observed. The nanocomposites showed high antibacterial efficiency toward Gram-negative Escherichia coli treated with a lectin protein concanavalin A, which caused self-assembly of the bacteria and nanoparticles. Therefore, the as-prepared nanostructure considerably improved the effectiveness of ROS toward bacteria and provides an alternative strategy for controlled antibacterial assays.Keywords: antibacterial; gold nanoparticles; nanocomposite; phosphorescence; polymer; self-assembly
Co-reporter:Fu Tang, Xiaoyu Wang, Chuang Yao, Shuai Chen and Lidong Li
RSC Advances 2016 vol. 6(Issue 81) pp:77745-77751
Publication Date(Web):11 Aug 2016
DOI:10.1039/C6RA13965E
A novel fluorescent organic small molecule, 4,4′-((1E,1′E)-(2-(3-aminopropoxy)pyrimidine-4,6-diyl)bis(ethene-2,1-diyl))bis(N,N-diethylaniline) (PPBEN), was designed and synthesized. When PPBEN was dissolved in aqueous solution, its emission maximum showed a large blue shift compared with that in organic solution. The emission spectra of PPBEN could be finely tuned by controlling the water content in organic/water mixed solutions, resulting in a sequential color change of its fluorescence as a function of water fraction. Theoretical calculations illustrated that protonation of the tertiary amine groups of PPBEN was the main reason for this phenomenon. A pH-responsive study showed that an acidic aqueous environment increased the emission intensity of PPBEN, further proving that protonation affected its emission properties. Cell assays showed that PPBEN is suitable for cellular imaging. Colocalization analysis of PPBEN with a commercial lysosome dye demonstrated its potential application in specific lysosome imaging.
Co-reporter:Jinghong Peng, Fu Tang, Xinjun Xu, Manping Jia and Lidong Li
RSC Advances 2016 vol. 6(Issue 44) pp:38148-38152
Publication Date(Web):11 Apr 2016
DOI:10.1039/C6RA05247A
Core–shell gold nanoparticles have been doped into the solution-processed electron-transporting layer (ETL) of polymer light-emitting diodes (PLEDs). By using this doping strategy, metal-enhanced fluorescence was realized in the device. The doped device has obtained enhanced luminance, enhanced luminous efficiency and a reduced turn-on voltage compared with that using the non-doped ETL.
Co-reporter:Jianfeng Zhang, Xinjun Xu, Chuang Yao and Lidong Li
RSC Advances 2016 vol. 6(Issue 58) pp:52878-52883
Publication Date(Web):26 May 2016
DOI:10.1039/C6RA09053B
Herein, we report a facile self-assembly strategy to prepare a novel 1D organic semiconductor/graphene microribbon heterojunction by coating a layer of graphene sheets on the organic semiconductor microribbon. The organic semiconductor microribbon composed of a p-type small molecule 3,7-bis(5-(2-ethylhexyl)thiophen-2-yl)dithieno[2,3-b:2′,3′-e]pyrazine (BEHT-DTP) was prepared by evaporation-induced self-assembly. Subsequently the graphene nanosheets, as an electron acceptor, were self-assembled onto the surface of a BEHT-DTP microribbon in aqueous solution to form a 1D p–n junction. The device based on the single microribbon heterojunction demonstrated enhanced photoconductivity properties. This preliminary work points out a new path to fabricate 1D organic nano/micro-heterojunctions, avoiding complex molecular design and equipment.
Co-reporter:Qianling Cui, Yu Yang, Chuang Yao, Ronghua Liu, and Lidong Li
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 51) pp:
Publication Date(Web):December 1, 2016
DOI:10.1021/acsami.6b12525
Water-soluble conjugated polymers are attractive fluorescent materials for applications in chemical and biological sensing. The molecular wire effect of such polymers amplifies changes in the fluorescence signal, which can be used for detecting various analytes with high sensitivity. In this work, we report an efficient ratiometric fluorescent probe based on a water-soluble conjugated polymer that showed high sensitivity and selectivity toward adenosine 5′-triphosphate (ATP). The macromolecular probe consisted of a polyfluorene backbone doped with 5 mol % 1,4-dithienylbenzothiadiazole (DBT) modified by bis-imidazolium and oligo(ethylene glycol) moieties. Solutions of the polymer emitted purple fluorescence, which changed to red upon addition of ATP molecules. The addition of ATP caused the polymer to aggregate, which enhanced fluorescence resonance energy transfer efficiency from the fluorene segments to DBT units, leading to an increase in red emission. The ratio of the fluorescence at these different wavelengths (I655/I423) showed a strong dependence on the ATP concentration. PF-DBT-BIMEG also exhibited high selectivity for ATP sensing over other representative anions and discriminated it from adenosine 5′-diphosphate (ADP) and adenosine 5′-monophosphate (AMP). This can be explained by the much stronger electrostatic interactions between the polymer and ATP than the interactions between the polymer and ADP or AMP, as confirmed through molecular dynamics simulations.Keywords: ATP sensing; fluorescence; fluorescence enhancement; FRET; water-soluble conjugated polymer;
Co-reporter:Yu Yang, Qianling Cui, Qian Cao, Lidong Li
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2016 Volume 503() pp:28-33
Publication Date(Web):20 August 2016
DOI:10.1016/j.colsurfa.2016.05.026
•Imidazolium derivates were used to stable and functionalize gold nanoparticles.•The interaction between ATP and imidazolium causes self-assmbly of gold nanoparticles.•The modified gold nanoparticles are efficient colorimetric probe for ATP sensing.Gold nanoparticles (AuNPs) have attracted intensive interests due to their promising applications in sensing, catalysis, optical and electric fields. Herein, we present a novel colorimetric adenosine-5′-triphosphate (ATP) sensor based on AuNPs modified with bis-imidazolium moieties. The positive charges with high density on bis-imidazolium groups show a strong affinity towards the triphosphate part of ATP, leading to subsequent aggregation of neighboring nanoparticles. By changing the ATP concentration, the aggregation extent of AuNPs can be easily controlled. At the same time, a readily detectable colorimetric shift from red to blue is also displayed, which is favorable for ATP sensing. It is found that triphosphate are more effective than di- or mono-phosphate groups in the aggregation formation process, which can easily distinguish ATP from ADP and AMP. Moreover, this ATP detection by Au@BIMEG is less interfered by other representative anions and cations. We provide a facile, efficient and cost-effective strategy to colorimetric ATP sensing via controllable assembly of AuNPs.
Co-reporter:Chun Wang, Fu Tang, Xiaoyu Wang, Lidong Li
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2016 Volume 506() pp:425-430
Publication Date(Web):5 October 2016
DOI:10.1016/j.colsurfa.2016.07.014
Biocompatible fluorescent hybrid nanoparticles were prepared via a green method.Fluorescence enhancement can be observed due to the structure of the nanoparticles.These nanoparticles exhibit targeted integrin detection property.In this work, green synthesis of a kind of fluorescent core-shell nanoparticles via a facile one-pot method was reported. We chose tryptophan, a common amino acid, to serve as the green reducing agent of the gold core. And a biomacromolecule, poly-(l-lysine), was then employed to assemble and cross-link onto gold nanoparticle surfaces serving as the biocompatible shell. Fluorescence enhancement was observed after a cyanine dye was conjugated onto the nanoparticle surfaces. Then, peptides with arginine-glycine-aspartic acid sequence were bound to the shell as targeting ligand. Cell imaging assay demonstrated that the prepared nanoparticles are efficient in target sensing of integrin-positive cells. Moreover, they possess high biocompatibility because of the green synthetic method. Thus, the prepared nanoparticles show great potential in cellular imaging and targeted integrin detection.Download high-res image (113KB)Download full-size image
Co-reporter:Fu Tang, Chun Wang, Lidong Li
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2016 Volume 494() pp:95-100
Publication Date(Web):5 April 2016
DOI:10.1016/j.colsurfa.2016.01.007
•Polymer shell/gold nanocomposites were synthesized by a facile method.•The polymer shell thickness could be easily adjusted by varying the reaction condition.•Fluorescence enhancement was observed due to the structure of the nanocomposites.Here, we report a facile strategy for the preparation of polymer shell/gold nanocomposites with enhanced fluorescence. The nanocomposites were synthesized using two main steps. First, gold nanoparticles were prepared via a butenoic acid reduction method, which directly functionalized the nanoparticle surfaces with vinyl groups. The gold nanoparticle surfaces were then encapsulated with polymer shells via a simple free radical polymerization of acrylic acid monomer. The polymer shell thickness could be controlled by varying the amount of acrylic acid used in the polymerization. An enhancement in fluorescence was observed when a fluorescent conjugated polymer was assembled on the shell surfaces. Interestingly, this fluorescence enhancement effect was pH-dependent, because of the swelling of the polymer shells that occurred as the pH was increased.
Co-reporter:Xiaoyu Wang;Shengliang Li;Pengbo Zhang;Fengting Lv;Libing Liu;Shu Wang
Advanced Materials 2015 Volume 27( Issue 39) pp:6040-6045
Publication Date(Web):
DOI:10.1002/adma.201502880
Co-reporter:Chuang Yao, Qianling Cui, Jinghong Peng, Xinjun Xu, Ronghua Liu, Jinshan Wang, Yuan Tian and Lidong Li
Journal of Materials Chemistry A 2015 vol. 3(Issue 19) pp:5017-5025
Publication Date(Web):14 Apr 2015
DOI:10.1039/C5TC00612K
Two kinds of host materials, 4,4′-(diphenylgermanediyl)bis(N,N-diphenylaniline) and bis(4-(9H-carbazol-9-yl)phenyl)diphenylgermane (DCzGe), for blue phosphorescent organic light emitting diodes (PhOLEDs) were designed by incorporating electron donating groups (carbazole and triphenylamine) into tetraphenylgermane, which is a new type of core moiety that has never been studied for use in this field. This molecular structure endows the compounds with a wide energy bandgap, high thermal/morphological stability and good solution processability. Based on the theoretic calculations, DCzGe was selected and synthesized as a host material which demonstrates a wide bandgap (Eg: 3.56 eV) and a high triplet energy (ET: 3.02 eV). It also exhibits a high glass transition temperature (110 °C), which is beneficial for resisting the Joule heat in devices. All solution processed, blue emitting PhOLEDs were fabricated by using a mixed host combining DCzGe and an electron-transporting material, with a maximum luminance of 10000 cd m−2 and a maximum current efficiency of 15.2 cd A−1. Furthermore, the devices showed a very low current efficiency roll-off, which remained as high as 15.2 cd A−1 at the luminance of 1000 cd m−2, and the roll-off is only 2.6% even at the higher luminance of 2000 cd m−2.
Co-reporter:Jianfeng Zhang, Jinshan Wang, Xinjun Xu, Shiyan Chen, Qinglin Zhang, Chuang Yao, Xiujuan Zhuang, Anlian Pan and Lidong Li
Journal of Materials Chemistry A 2015 vol. 3(Issue 23) pp:5933-5939
Publication Date(Web):05 May 2015
DOI:10.1039/C5TC01050K
Organic semiconductor materials with one-dimensional (1D) radial (core–shell) heterojunction structures are highly desired for their expected excellent optoelectronic properties. However, currently, such structures are still in a fledgling period for optoelectronic applications due to the absence of both good materials and suitable preparation methods. Here we have synthesized a p-type organic semiconductor based on a new electron-donating unit (dithienopyrazine) and utilized it as a shell material to construct organic 1D radial p–n heterojunctions. This p-type compound shows a higher oxidation potential and is more resistant to photooxidation in air than its analogs with the commonly-used benzodithiophene unit. Moreover, we prepared organic microwires with radial heterojunctions via a solution-processed method by self-assembly of our p-type material on the surface of n-type cores. Thus, photoconductive devices based on an individual microwire with the radial heterojunction can be fabricated and demonstrate a high photoconductivity. Our work provides a path for preparing 1D radial heterojunctions suitable for optoelectronic applications.
Co-reporter:Jinshan Wang, Xinjun Xu, Yuan Tian, Chuang Yao, Ronghua Liu and Lidong Li
Journal of Materials Chemistry A 2015 vol. 3(Issue 12) pp:2856-2864
Publication Date(Web):02 Feb 2015
DOI:10.1039/C4TC02899F
Two blue-emitting fluorescent polymers PTPATPPO and PTPATPP with small singlet–triplet splitting comprising triphenylamine and triphenylphosphine/triphenylphosphine oxide moieties have been designed and synthesized. An appropriate overlap between the HOMO and the LUMO in these compounds was realized. This design strategy endows the two blue-emitting polymers with a high triplet energy of 2.45 and 2.46 eV, a shallow HOMO level of −5.21 and −5.23 eV, and a bipolar feature to act as good host materials. Monochromic organic light-emitting devices (OLEDs) using these polymers as emitters show sky-blue emissions with Commission Internationale de l'Eclairage (CIE) coordinates of (0.24, 0.32) and (0.24, 0.31) together with a maximum current efficiency of 3.63 cd A−1. Moreover, the single-emitting-layer two-element fluorescent–phosphorescent (F–P) hybrid white OLEDs based on PTPATPPO or PTPATPP as both hosts and blue-emitting fluorophores were fabricated by a solution process. Among the two polymers, PTPATPPO-based F–P hybrid white OLEDs show better performance with a maximum current efficiency of 10.5 cd A−1, a maximum external quantum efficiency of 6.1%, CIE coordinates of (0.40, 0.34), and a maximum luminance of 11962 cd m−2.
Co-reporter:Chuang Yao, Jingxian Li, Jinshan Wang, Xinjun Xu, Ronghua Liu and Lidong Li
Journal of Materials Chemistry A 2015 vol. 3(Issue 33) pp:8675-8683
Publication Date(Web):20 Jul 2015
DOI:10.1039/C5TC01544H
Being incompatible with host materials in a physically blended emitting layer, phosphorescent dyes are prone to form aggregates induced by Joule heat in devices under work. In this work, a new and efficient blue phosphorescent dye Cz-C8-FIrpic was designed and synthesised by incorporating 9-phenyl-9H-carbazole into a commonly used blue emissive iridium complex bis(4,6-(difluorophenyl)pyridine-N,C2′)picolinate (FIrpic) via an alkyl chain linkage. This phosphorescent dye exhibits similar photophysical properties to the units of FIrpic and 9-phenyl-9H-carbazole in solutions. In solid films of Cz-C8-FIrpic, the energy transfer from 9-phenyl-9H-carbazole to FIrpic units is effective. The Cz-C8-FIrpic doped emissive layer was investigated by AFM, STEM-EDS, transient photoluminescence decay curves and molecular dynamics simulations. The results show that in the Cz-C8-FIrpic doped film the phase aggregation of FIrpic units is less severe than that in the typically used FIrpic film. In addition, the optimized Cz-C8-FIrpic based device achieved a maximum luminance of 25142 cd m−2, a maximum EQE of 8.5% and a maximum current efficiency of 22.5 cd A−1 which is about 15% higher than that of the control device based on FIrpic. We conclude that grafting a typically used dye to functional groups with alkyl chains is useful to restrict phase separation in physically blended emitting layers, and thus can achieve high electroluminescence performances.
Co-reporter:Xin Jiang Feng, Jinghong Peng, Zheng Xu, Renren Fang, Hua-rong Zhang, Xinjun Xu, Lidong Li, Jianhua Gao, and Man Shing Wong
ACS Applied Materials & Interfaces 2015 Volume 7(Issue 51) pp:28156
Publication Date(Web):December 8, 2015
DOI:10.1021/acsami.5b10786
A series of fluorene derivatives end-capped with diphenylamino and oxadiazolyl were synthesized, and their photophysical and electrochemical properties are reported. Aggregation-induced emission (AIE) effects were observed for the materials, and bipolar characteristics of the molecules are favored with measurement of carrier mobility and calculation of molecular orbitals using density functional theory (DFT). Using the fluorene derivatives as emitting-layer, nondoped organic light-emitting devices (OLEDs) have been fabricated by spin-coating in the configuration ITO/PEDOT:PSS(35 nm)/PVK(15 nm)/PhN-OF(n)-Oxa(80 nm)/SPPO13(30 nm)/Ca(8 nm)/Al(100 nm) (n = 2–4). The best device with PhN-OF(2)-Oxa exhibits a maximum luminance of 14 747 cd/m2, a maximum current efficiency of 4.61 cd/A, and an external quantum efficiency (EQE) of 3.09% in the blue region. Investigation of the correlation between structures and properties indicates that there is no intramolecular charge transfer (ICT) increase in these molecules with the increase of conjugation length. The device using material of the shortest conjugation length as emitting-layer gives the best electroluminescent (EL) performances in this series of oligofluorenes.Keywords: AIE-active; blue; fluorene; nondoped; organic light-emitting devices
Co-reporter:Fu Tang, Chun Wang, Xiaoyu Wang, and Lidong Li
ACS Applied Materials & Interfaces 2015 Volume 7(Issue 45) pp:25077
Publication Date(Web):November 2, 2015
DOI:10.1021/acsami.5b08907
In this work, we report the facile synthesis of functional core–shell structured nanoparticles with fluorescence enhancement, which show specific targeting of cancer cells. Biopolymer poly-l-lysine was used to coat the silver core with various shell thicknesses. Then, the nanoparticles were functionalized with folic acid as a targeting agent for folic acid receptor. The metal-enhanced fluorescence effect was observed when the fluorophore (5-(and-6)-carboxyfluorescein-succinimidyl ester) was conjugated to the modified nanoparticle surface. Cellular imaging assay of the nanoparticles in folic acid receptor-positive cancer cells showed their excellent biocompatibility and selectivity. The as-prepared functional nanoparticles demonstrate the efficiency of the metal-enhanced fluorescence effect and provide an alternative approach for the cellular imaging and targeting of cancer cells.Keywords: cellular imaging; core−shell nanoparticles; fluorescence; fluorescence enhancement; polymer
Co-reporter:Xi Zhu, Xiaoyu Wang, Fang He, Fu Tang, and Lidong Li
ACS Applied Materials & Interfaces 2015 Volume 7(Issue 2) pp:1334
Publication Date(Web):December 25, 2014
DOI:10.1021/am507772e
In this study, a simple and environmentally friendly, silver nanocomposite film was prepared via the in situ reduction of silver ions in self-assembled chitosan (CS)/sodium alginate film matrixes. Negatively charged DNA containing the fluorescent intercalator acriflavine (Acf) was assembled on the surface of the silver nanocomposite film, to facilitate the detection of DNA. A tunable fluorescence enhancement was achieved for the Acf in the silver nanocomposite film simply by changing the thickness of the interlayer between the DNA and the silver nanocomposite film. Using the interlayer prepared by an assembly of poly(acrylic acid) and CS, a significant enhancement in the fluorescence of Acf was obtained. Owing to the ability of Acf to intercalate into DNA, this hybrid system with an enhanced Acf fluorescence could be used to monitor the template-independent DNA elongation process in a facile, high-efficiency, label-free fashion.Keywords: DNA detection; fluorescence; multilayers; nanocomposite; polyelectrolytes; self-assembly
Co-reporter:Xinjun Xu, Ronghua Liu and Lidong Li
Chemical Communications 2015 vol. 51(Issue 94) pp:16733-16749
Publication Date(Web):22 Sep 2015
DOI:10.1039/C5CC06439B
Semiconducting organic nanoparticles have recently attracted increasing attention in the chemical and biomedical fields. Such nanoparticles are mainly composed of π-conjugated compounds. They possess the properties of easy synthesis, facile tuning, less toxicity and more biocompatibility relative to the existing inorganic nanoparticles. In addition, they show advantages such as brighter fluorescence, higher photostability and higher biocompatibility, compared with classical fluorescent organic dyes. In this review, we summarize the latest advances in the development of organic nanoparticles made of π-conjugated compounds, including preparation methods, material design, nanoparticle fabrication and surface functionalization for chemical and biological applications. Especially, we focus on the applications of semiconducting organic nanoparticles in chemical and biological sensing by monitoring the fluorescence signal, as nanocarriers for drug/gene delivery, in photothermal and photodynamic therapy, and in photoacoustic imaging. Finally, the challenges and perspectives for the future development of organic nanoparticles based on π-conjugated compounds are also discussed.
Co-reporter:Meng Wu, Xinjun Xu, Jinshan Wang, and Lidong Li
ACS Applied Materials & Interfaces 2015 Volume 7(Issue 15) pp:8243
Publication Date(Web):March 31, 2015
DOI:10.1021/acsami.5b01338
Fluorescent organic nanoparticles have a much better photostability than molecule-based probes. Here, we report a simple strategy to detect chemicals and biomolecules by a binary nanoparticle system based on fluorescence resonance energy transfer (FRET). Poly(9,9-di-n-octylfluorenyl-2,7-diyl) (PFO, energy donor) and poly [2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV, energy acceptor) are utilized to prepare the binary nanoparticle system through a reprecipitation method. Since the FRET process is strongly distance-dependent, a change in the interparticle distance between the two kinds of nanoparticles after introduction of analytes will alter the FRET efficiency. The response of the binary nanoparticle system to cationic polyelectrolytes was investigated by monitoring the FRET efficiency from PFO to MEH-PPV nanoparticles and the fluorescence color of the nanoparticle solutions. Furthermore, the cationic polyelectrolyte pretreated binary nanoparticle system can be used to detect DNA by desorption of nanoparticles from the polyelectrolyte’s chains and the detection concentration can go down to 10–14 M. Thus, the binary nanoparticle system shows great promise for applications in chemical sensing or biosensing.Keywords: conjugated polymer; fluorescence; fluorescence resonance energy transfer; organic nanoparticles; polyelectrolyte; reprecipitation;
Co-reporter:Chun Wang, Fu Tang, Xiaoyu Wang, and Lidong Li
ACS Applied Materials & Interfaces 2015 Volume 7(Issue 24) pp:13653
Publication Date(Web):June 2, 2015
DOI:10.1021/acsami.5b03440
In this work, a fluorescent hybrid core–shell nanoparticle was prepared by coating a functional polymer shell onto silver nanoparticles via a facile one-pot method. The biomolecule poly-l-lysine (PLL) was chosen as the polymer shell and assembled onto the silver core via the amine-reactive cross-linker, 3,3′-dithiobis(sulfosuccinimidylpropionate). The fluorescent anticancer drug, doxorubicin, was incorporated into the PLL shell through the same linkage. As the cross-linker possesses a thiol-cleavable disulfide bond, disassembly of the PLL shell was observed in the presence of glutathione, leading to controllable doxorubicin release. The silver core there provided an easily modified surface to facilitate the shell coating and ensures the efficient separation of as-prepared nanoparticles from their reaction mixture through centrifugation. Cell assays show that the prepared hybrid fluorescent nanoparticles can internalize into cells possessing excellent biocompatibility prior to the release of doxorubicin, terminating cancer cells efficiently as the doxorubicin is released at the intracellular glutathione level. Such properties are important for designing smart containers for target drug delivery and cellular imaging.Keywords: cellular imaging; core−shell nanoparticles; disassembly; fluorescence; polymer; self-assembly;
Co-reporter:Yuan Tian, Jinghong Peng, Xinjun Xu and Lidong Li
RSC Advances 2015 vol. 5(Issue 119) pp:98075-98079
Publication Date(Web):11 Nov 2015
DOI:10.1039/C5RA23371B
The small-molecule hole-blocking material SPPO13 has been doped with a non-conjugated polymer to act as the hole-blocking layer in solution-processed OLEDs. Such a doping strategy can significantly improve the electron injection in devices, resulting in an enhanced luminous efficiency and a reduced turn-on voltage.
Co-reporter:Fu Tang, Jinghong Peng, Ronghua Liu, Chuang Yao, Xinjun Xu and Lidong Li
RSC Advances 2015 vol. 5(Issue 87) pp:71419-71424
Publication Date(Web):17 Aug 2015
DOI:10.1039/C5RA14362D
Fluorescent molecule 9,9-bis(4-bromobutyl)-2,7-bis(4-(1,2,2-triphenylvinyl)phenyl)-9H-fluorene, TPEF, comprising a fluorene unit and two tetraphenylethene moieties, has been utilized to serve as a sky-blue emitter in a solution-processed non-doped organic light-emitting diode (OLED), and its optical and electrical properties are investigated. The TPEF is an aggregation-induced emission (AIE)-active molecule. It is nearly non-emissive when dissolved in solution while emits strong fluorescence in solid state, indicating that it could be a promising candidate for electrofluorescence use. The solution-processed TPEF-based OLED with a simple non-doped structure exhibits sky-blue fluorescence emission, showing a maximum luminance of 2618 cd m−2, a maximum current efficiency of 4.55 cd A−1, and a maximum external quantum efficiency (EQE) of 2.17%.
Co-reporter:Ronghua Liu, Xinjun Xu, Jinghong Peng, Chuang Yao, Jinshan Wang and Lidong Li
RSC Advances 2015 vol. 5(Issue 46) pp:36568-36574
Publication Date(Web):16 Apr 2015
DOI:10.1039/C5RA04599A
A novel alcohol-soluble electron-transporting small-molecule material comprising oxadiazole and arylphosphine oxide moieties, ((1,3,4-oxadiazole-2,5-diyl)bis(4,1-phenylene))bis(diphenylphosphine oxide) (OXDPPO), has been synthesized and characterized. Its single crystal structure, together with the photophysical, electrochemical and thermal properties, has been investigated. This material not only possesses a wide bandgap with a low HOMO level but also exhibits a strong π–π stacking with a distance of 3.35 Å. Moreover, this compound shows excellent thermal stability with a high glass transition temperature of 104 °C and a decomposition temperature of 384 °C. The unique solubility in 2-propanol makes it a good candidate for fabricating fully solution-processed multilayer organic light-emitting diodes (OLEDs). Efficient solution-processed white OLEDs have been fabricated with this compound as an electron-transporting layer (ETL). It was found that this ETL can greatly balance the electrons and holes in devices with the high work-function metal cathode (Al) and an increase in luminous efficiency of ∼70-fold can be achieved. The maximum luminous efficiency of devices with an ETL/Al configuration is even higher than that of devices using a Ca cathode.
Co-reporter:Qianling Cui, Bihua Xia, Steffen Mitzscherling, Admir Masic, Lidong Li, Matias Bargheer, Helmuth Möhwald
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2015 Volume 465() pp:20-25
Publication Date(Web):20 January 2015
DOI:10.1016/j.colsurfa.2014.10.028
•Gold nanostars show catalytic and surface-enhanced Raman scattering (SERS) activity.•They can catalyze the reduction of 4-nitrophenol and 4-nitroaniline efficiently.•The different molecular orientations at surface were proved by SERS spectroscopy.In this work, gold nanostars (AuNSs) with size around 90 nm were prepared through an easy one-step method. They show excellent catalytic activity and large surface-enhanced Raman scattering (SERS) activity at the same time. Surprisingly, they exhibited different catalytic performance on the reduction of aromatic nitro compounds with different substituents on the para position. To understand such a difference, the SERS spectra were recorded, showing that the molecular orientation of reactants on the gold surface were different. We anticipate that this research will help to understand the relationship of the molecular orientation with the catalytic activity of gold nanoparticles.
Co-reporter:Qianling Cui, Fang He, Lidong Li, Helmuth Möhwald
Advances in Colloid and Interface Science 2014 Volume 207() pp:164-177
Publication Date(Web):May 2014
DOI:10.1016/j.cis.2013.10.011
Highlights
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We review the construction of systems based on metal-enhanced fluorescence.
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Various kinds of materials serve as spacer to separate metal and fluorophores.
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The fluorophores show enhanced intensity, photostability and other desirable effects.
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The MEF can be exploited to improve the potential of present fluorescence-based techniques.
Co-reporter:Jinshan Wang, Xinjun Xu, Yuan Tian, Chuang Yao and Lidong Li
Journal of Materials Chemistry A 2014 vol. 2(Issue 25) pp:5036-5045
Publication Date(Web):02 May 2014
DOI:10.1039/C4TC00052H
By attaching two electron-withdrawing trifluoromethyl (CF3) groups to the 2-phenylbenzothiazole cyclo-metalated ligand, a bis-trifluoromethyl-functionalized orange-emitting phosphorescent iridium(III) complex bis-(6-(trifluoromethyl)-2-(4-(trifluoromethyl)phenylbenzothiozolato))iridium(acetylacetonate) [(F3BT-CF3P)2Ir(acac)] was successfully synthesized. The optical, electrochemical and electroluminescence (EL) properties of this new complex were studied. The experimental results support the theoretical expectation that incorporating electron-withdrawing trifluoromethyl groups at the 4-site of the phenyl ring directly bonded to the metal center, and at the 6-site of 2-phenylbenzothiazole, cause a bathochromic shift in the emission peak and bring the emission color much closer to long-wavelength orange light. Moreover, such trifluoromethyl substituents can hinder the π–π stacking or self-polarization effect occurring from the aggregation of the molecules. The new iridium complex gives an unchanged luminescence spectrum, regardless of whether it is in solution, in untreated film or in film doped at different concentrations. Using this iridium complex as a dopant emitter, solution-processed single emissive layer orange and two-element white OLEDs with good performance can be obtained. Highly efficient orange electroluminescence was obtained with a maximum efficiency of 10.5 cd A−1 and CIE coordinates (0.48, 0.51). When combined with a commercial sky-blue phosphorescent emitter, (CF3BT–CF3P)2Ir(acac) can be utilized to achieve two-element white OLEDs that exhibited a high efficiency of 28.3 cd A−1. Such OLEDs retain high efficiency at a luminance suitable for lighting (e.g. 5000 cd m−2).
Co-reporter:Qianling Cui, Guizhi Shen, Xuehai Yan, Lidong Li, Helmuth Möhwald, and Matias Bargheer
ACS Applied Materials & Interfaces 2014 Volume 6(Issue 19) pp:17075
Publication Date(Web):September 12, 2014
DOI:10.1021/am504709a
Here, we present an Au@Pt core–shell multibranched nanoparticle as a new substrate capable of in situ surface-enhanced Raman scattering (SERS), thereby enabling monitoring of the catalytic reaction on the active surface. By careful control of the amount of Pt deposited bimetallic Au@Pt, nanoparticles with moderate performance both for SERS and catalytic activity were obtained. The Pt-catalyzed reduction of 4-nitrothiophenol by borohydride was chosen as the model reaction. The intermediate during the reaction was captured and clearly identified via SERS spectroscopy. We established in situ SERS spectroscopy as a promising and powerful technique to investigate in situ reactions taking place in heterogeneous catalysis.Keywords: bimetallic nanoparticles; core−shell nanostructure; gold; heterogeneous catalysis; nanoparticles; surface-enhanced Raman scattering
Co-reporter:Yuan Tian, Xinjun Xu, Jinshan Wang, Chuang Yao, and Lidong Li
ACS Applied Materials & Interfaces 2014 Volume 6(Issue 11) pp:8631
Publication Date(Web):April 25, 2014
DOI:10.1021/am501466y
Solution-processed white organic light emitting diodes (WOLEDs) with quaternary ammonium salt doped water/alcohol soluble conjugated polyelectrolyte, poly[(9,9-bis(3′-((N,N-dimethyl)-N-ethylammonium)-propyl)-2,7-fluorene)-alt-2,7-(9,9-dioctylfluoren)] dibromide (PFNBr), as electron transport material has been fabricated. Compared with the undoped devices, the performances of such devices with a doped electron transport layer have been dramatically improved to be nearly twice high in luminous efficiency and nearly one-third in response time when the weight ratio of PFNBr to tetraethylammonium bromide (TEAB) was 10:3. Four kinds of quaternary ammonium salts have been investigated to be dopants in the conjugated polyelectrolyte electron transport layer. It has been shown that both the anions and the cations of quaternary ammonium salts can influence the device performance. The dopant who has both a smaller anion and a smaller cation size can exhibit a better device performance. In addition, ultraviolet photoelectron spectroscopy measurement and single-carrier device testing have been employed to investigate the reason why such quaternary ammonium salt dopants can make an obvious improvement in the device performance of WOLEDs. These findings will be beneficial to the progress in design and fabrication of solution-processed WOLEDs suitable for lighting.Keywords: conjugated polyelectrolyte; dopant; electron transport material; quaternary ammonium salt; solution-processing; white organic light-emitting diodes;
Co-reporter:Fu Tang, Chun Wang, Jinshan Wang, Xiaoyu Wang, and Lidong Li
ACS Applied Materials & Interfaces 2014 Volume 6(Issue 20) pp:18337
Publication Date(Web):October 2, 2014
DOI:10.1021/am505776a
We report a simple strategy to prepare organic biocompatible fluorescent nanoparticles with enhanced fluorescence. A significant fluorescence enhancement was realized by designing a fluorescent small molecule, 4,4′-(2,7-bis[4-{1,2,2-triphenylvinyl}phenyl]-9H-fluorene-9,9-diyl)bis(N,N,N-trimethylbutan-1-aminum)bromide (TPEFN), with aggregation-induced emission enhancement (AIEE) effect. Nanoparticles of TPEFN can be formed through molecular self-aggregation by gradually increasing the water fraction in TPEFN mixed solution (methanol/water). Fluorescence enhancement by about 120-fold was observed after nanoparticle formation. By addition of the biomolecule adenosine triphosphate (ATP), larger nanoparticles of TPEFN are formed and further fluorescence enhancement can be achieved, yielding a total fluorescence enhancement of 420-fold compared with the TPEFN molecular solution. Both of these nanoparticles show very good biocompatibility. Ultrabright spots present in the confocal laser scanning microscopy image again proved the formation of nanoparticles. Positively charged side chains of TPEFN endow these nanoparticles cationic surfaces. The size of the prepared TPEFN nanoparticles and their cationic surface allow them to be rapidly internalized into cells. Cell viability assays prove that the TPEFN nanoparticles have high biocompatibility. These organic fluorescent nanoparticles show great promise for applications in cellular imaging or biotechnology.Keywords: cellular imaging; enhanced fluorescence; fluorescence; nanoparticle; quenching; self-aggregation
Co-reporter:Qianling Cui, Alexey Yashchenok, Lu Zhang, Lidong Li, Admir Masic, Gabriele Wienskol, Helmuth Möhwald, and Matias Bargheer
ACS Applied Materials & Interfaces 2014 Volume 6(Issue 3) pp:1999
Publication Date(Web):January 9, 2014
DOI:10.1021/am5000068
Herein, a facile method is presented to integrate large gold nanoflowers (∼80 nm) and small gold nanoparticles (2–4 nm) into a single entity, exhibiting both surface-enhanced Raman scattering (SERS) and catalytic activity. The as-prepared gold nanoflowers were coated by a gelatin layer, in which the gold precursor was adsorbed and in situ reduced into small gold nanoparticles. The thickness of the gelatin shell is controlled to less than 10 nm, ensuring that the small gold nanoparticles are still in a SERS-active range of the inner Au core. Therefore, the reaction catalyzed by these nanocomposites can be monitored in situ using label-free SERS spectroscopy. In addition, these bifunctional nanocomposites are also attractive candidates for application in SERS monitoring of bioreactions because of their excellent biocompatibility.Keywords: core−shell nanostructure; gelatin; gold; hybrid material; nanoparticles; surface-enhanced Raman scattering;
Co-reporter:Mingchao Ma, Xinjun Xu, Leilei Shi and Lidong Li
RSC Advances 2014 vol. 4(Issue 102) pp:58720-58723
Publication Date(Web):23 Oct 2014
DOI:10.1039/C4RA11833B
Solution-processed organic field-effect transistors (OFETs) were fabricated based on a hygroscopic biomaterial, egg-white albumin, as the gate dielectric and poly(3-hexylthiophene) as the semiconductor. With increasing humidity, such OFETs can show improved performance exhibiting a very low driving voltage, together with enhanced carrier mobility and suppressed off-state current.
Co-reporter:Jinshan Wang, Xinjun Xu, Yuan Tian, Chuang Yao, Lidong Li
Synthetic Metals 2014 Volume 197() pp:90-98
Publication Date(Web):November 2014
DOI:10.1016/j.synthmet.2014.08.015
•An orange–red iridium(III) complex (CF3BT-N)2Ir(acac) for single emissive layer monochromatic and white OLEDs by solution processing was synthesized.•(CF3BT-N)2Ir(acac) exhibit unchanged EL emission under different doping concentrations in monochromatic OLEDs.•A high luminous efficiency of 14.6 cd A−1 together with good CIE coordinates were obtained for WOLEDs.A novel iridium(III) complex bis(2-(naphthalen-1-yl)-6-(trifluoromethyl)benzothiazole)iridium(acetylacetonate) (CF3BT-N)2Ir(acac) with an orange–red emission was synthesized. The incorporation of CF3 and naphthalene groups into benzimidazole to act as a new ligand causes a significant change of both HOMO and LUMO energy levels of the iridium complex compared with the yellow emissive parent compound comprising the 2-phenylbenzimidazole ligand. As a result, a bathochromic shift by as much as 50 nm of the phosphorescence emission peak can be achieved. Electronic properties of (CF3BT-N)2Ir(acac) were examined by time-dependent density functional theory (TD-DFT) calculations. The influence of such substituent groups on the photophysical, electrochemical and electroluminescent properties of iridium complex was studied. Furthermore, two- and three-element solution-processed white organic light-emitting diodes (WOLEDs) with high performance can be realized by using this kind of orange–red phosphorescent emitter in conjunction with other phosphors in a single emissive layer. A maximum luminous efficiency of 10.9 cd A−1 with CIE coordinates of (0.27, 0.37) was obtained for the two-element WOLEDs. For the three-element WOLED, a maximum luminance of 22716 cd m−1 and a maximum luminous efficiency of 14.6 cd A−1 with CIE coordinates of (0.33, 0.42) can be achieved.
Co-reporter:Jindong Wang;Fangxia Shen;Zhenxing Wang;Gen He;Jinwen Qin;Nongyi Cheng; Maosheng Yao; Lidong Li; Xuefeng Guo
Angewandte Chemie International Edition 2014 Volume 53( Issue 20) pp:5038-5043
Publication Date(Web):
DOI:10.1002/anie.201309438
Abstract
Probing interactions of biological systems at the molecular level is of great importance to fundamental biology, diagnosis, and drug discovery. A rational bioassay design of lithographically integrating individual point scattering sites into electrical circuits is capable of realizing real-time, label-free biodetection of influenza H1N1 viruses with single-molecule sensitivity and high selectivity by using silicon nanowires as local reporters in combination with microfluidics. This nanocircuit-based architecture is complementary to more conventional optical techniques, but has the advantages of no bleaching problems and no fluorescent labeling. These advantages offer a promising platform for exploring dynamics of stochastic processes in biological systems and gaining information from genomics to proteomics to improve accurate molecular and even point-of-care clinical diagnosis.
Co-reporter:Bihua Xia, Xiaoyu Wang, Lidong Li
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2014 Volume 461() pp:92-97
Publication Date(Web):5 November 2014
DOI:10.1016/j.colsurfa.2014.07.025
•Hybrid thin film was prepared by in situ reduction and self-assembly technique.•The hybrid film showed good antibacterial activity.•The hybrid film exhibited metal-enhanced fluorescence effect.Hybrid thin biomacromolecular films were fabricated by combining the in situ formation of silver nanoparticles (Ag NPs) in gelatin and self-assembly of carboxymethyl chitosan (CCHI). The hybrid films exhibited excellent antibacterial activity toward Escherichia Coli. When the fluorescent dye 4,7-(9,9ʹ-bis(6-adenine hexyl)fluorenyl)-2,1,3-benzothiadiazole modified with nucleotide adenine and quaternary ammonium groups (OFBT-AA) was adsorbed onto the surface of the hybrid films, metal-enhanced fluorescence resulted in a maximum 5.3-fold increase in the fluorescence of OFBT-AA.
Co-reporter:Bihua Xia, Fang He, Lidong Li
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2014 Volume 444() pp:9-14
Publication Date(Web):5 March 2014
DOI:10.1016/j.colsurfa.2013.12.029
•Ag microcomposite was prepared by self-assembly between Ag nanoparticles and cationic polyacrylamide (PAM) in solution.•The fluorescence intensity of the fluorophore can be increased significantly due to MEF effect.•This method for preparing this system was simple and novel.A simple strategy to prepare aggregated Ag nanoparticle composites in solution by self-assembly is developed. Sodium citrate is used as the reduction agent to produce negatively charged Ag nanoparticles which are then aggregated using cationic polyacrylamide (PAM) to form self-assembled Ag-PAM microcomposites. In these microcomposites, the degree of aggregation of Ag nanoparticles can be controlled by changing the Ag/PAM ratio. This special structural feature can be applied in the study of metal-enhanced fluorescence. Confocal laser scanning microscopy and time-resolved fluorescence measurements are used to examine the fluorescence enhancement phenomenon of the Ag-PAM microcomposites. The microcomposites considerably enhanced the fluorescence intensity of fluorescein isothiocyanate isomer (FITC).
Co-reporter:Jindong Wang;Fangxia Shen;Zhenxing Wang;Gen He;Jinwen Qin;Nongyi Cheng; Maosheng Yao; Lidong Li; Xuefeng Guo
Angewandte Chemie International Edition 2014 Volume 53( Issue 20) pp:
Publication Date(Web):
DOI:10.1002/anie.201482071
Co-reporter:Jindong Wang, Gen He, Jinwen Qin, Lidong Li, Xuefeng Guo
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2014 450() pp: 156-160
Publication Date(Web):
DOI:10.1016/j.colsurfa.2014.03.028
Co-reporter:Hui Wang, Fang He, Rongjian Yan, Xiaoyu Wang, Xi Zhu, and Lidong Li
ACS Applied Materials & Interfaces 2013 Volume 5(Issue 16) pp:8254
Publication Date(Web):July 23, 2013
DOI:10.1021/am402438v
This work shows the sodium citrate induced efficient interpolymer π-stacking aggregation of the planar cationic conjugated polyelectrolyte poly[{9,9-bis[6′-(N,N-trimethylamino)hexyl]-2,7-fluorenyleneethynylene}-alt-co-(1,4-phenylene)] dibromide (PFE) in aqueous solution, which results in the self-quenching of fluorescence. Using the citrate-induced aggregation properties of PFE and the strong chelation ability of citrate with aluminum ions (Al3+), a sensitive and selective Al3+-ion detection assay in aqueous solution was developed through monitoring of the fluorescence recovery of PFE. The fluorescence intensity recovery of PFE depends on the concentration of Al3+ ions, and linear fluorescence recovery was observed in the range of 0.5–9 μM. The limit of detection of this assay is 0.37 μM. Its simplicity and rapidity mean this assay shows promise for the real-time detection of Al3+.Keywords: aggregation; chelation; citrate; conjugated polymer; fluorescence; ion detection;
Co-reporter:Jinshan Wang, Xinjun Xu, Leilei Shi, and Lidong Li
ACS Applied Materials & Interfaces 2013 Volume 5(Issue 8) pp:3392
Publication Date(Web):March 27, 2013
DOI:10.1021/am4004396
Fluorescent organic nanoparticles (FONs) as a new class of nanomaterials can provide more advantages than molecule based probes. However, their applications in specific metal ion detection have rarely been exploited. We design and synthesize a branched small-molecule compound with triazole as a core and benzothiadiazole derivative as branches. By a facile reprecipitation method, nanoparticles (NPs) of this compound can be prepared in aqueous solutions, which can show high selectivity and sensitivity to Fe(III) ions based on fluorescence quenching. In addition, the fluorescence intensity of these NPs is resistant to pH changes in solutions. Such characters of this kind of NPs can be utilized in Fe3+ impurity detection in a promising cathode material (LiFePO4) for lithium ion batteries. When exposed to Fe3+, both the triazole and benzothiadiazole groups contribute to the fluorescence quenching of NPs, but the former one plays a more important role in Fe3+ impurity detection. The sensing mechanism has also been investigated which indicates that a Fe-organic complex formation may be responsible for such sensing behavior. Our findings demonstrate that specific metal ion detection can be realized by FONs and have extended the application field of FONs for chemical sensing in aqueous solutions.Keywords: branched small molecule; fluorescence; ion detection; lithium iron(II) phosphate; lithium-ion battery; organic nanoparticles;
Co-reporter:Chuang Yao, Xinjun Xu, Jinshan Wang, Leilei Shi, and Lidong Li
ACS Applied Materials & Interfaces 2013 Volume 5(Issue 3) pp:1100
Publication Date(Web):January 18, 2013
DOI:10.1021/am302878m
A new method is reported for preparing solution-processed molybdenum oxide (MoO3) hole selective layer (HSL). Via combustion processing at low annealing temperatures, the obtained MoO3 HSL exhibits a high charge-transporting performance similar to poly(ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) but overcoming its defect to device stability. The combustion precursor solution using ammonium heptamolybdate as the metal source, acetylacetone as a ‘fuel’, and nitric acid as an oxidizer can largely reduce the temperature for transformation of the polyoxomolybdate to α-phase MoO3. Furthermore, when a small amount of PEDOT:PSS has been introduced into the combustion precursor solution to improve the film morphology, the derived film can exhibit a flat and continuous surface morphology with coexistence of α- and β-MoO3 after being annealed at a low temperature (150 °C). The simplicity, rapidness, and effectiveness of our method together with the low annealing temperature needed make it promising for the roll-to-roll manufacture of polymer solar cells.Keywords: device stabilities; hole selective layers; polymer; polymer solar cells; polyoxomolybdates; solution-processing;
Co-reporter:Qianling Cui, Fang He, Xiaoyu Wang, Bihua Xia, and Lidong Li
ACS Applied Materials & Interfaces 2013 Volume 5(Issue 1) pp:213
Publication Date(Web):December 13, 2012
DOI:10.1021/am302589g
In the present work, a facile one-pot method is designed to fabricate a core–shell fluorescent nanoparticle (NP) for cellular imaging based on a new cationic conjugated polymer, poly[9,9′-bis(6,6′-(N,N,N-trimethylaminium)fluorene-2,7-ylenevinylene-co-alt-2,5-dicyano-1,4-phenylene] (PFVCN). Gold nanoflowers (AuNFs) are prepared by a seedless method, in which a gelatin layer formed through a sol–gel phase transition is deposited on the surface of each AuNF. The cationic PFVCN self-assembles onto the negative surface of the resultant (AuNF@Gelatin NPs) driven by electrostatic attraction. An obvious enhancement of fluorescence intensity is observed. The AuNF@Gelatin/PFVCN NPs exhibit excellent cytocompatibility, and their cellular imaging ability is demonstrated when cocultured with HeLa cells. AuNF@Gelatin/PFVCN hybrid NPs are expected to be a desirable material in the field of cellular imaging and biosensing.Keywords: cellular imaging; conjugated polymers; core−shell nanoparticles; fluorescence; gold nanoflowers; self-assembly;
Co-reporter:Xiaoyu Wang, Fang He, Lingling Li, Hui Wang, Rongjian Yan, and Lidong Li
ACS Applied Materials & Interfaces 2013 Volume 5(Issue 12) pp:5700
Publication Date(Web):May 30, 2013
DOI:10.1021/am401118r
Oligonucleotides such as siRNA and plasmid DNA (pDNA) have great potential for gene therapies. Multifunctional, environment-resistant carriers with imaging capabilities are required to track the assembly and disassembly of oligonucleotides, monitor the delivery processes, and develop new delivery systems. Conjugated polymers and oligomers can potentially be used as novel materials for functional nanocarriers with both delivery and imaging abilities. In this work, a novel π-conjugated oligomer 4,7-(9,9′-bis(6-adenine hexyl)fluorenyl)-2,1,3-benzothiadiazole (OFBT-A) modified with nucleotide adenine (A) groups in its side chains is synthesized and characterized. Fluorescent nanoparticles based on the π-conjugated oligomers OFBT-A are developed as novel functional nanocarriers for oligonucleotides. Single-stranded DNA (ssDNA) TR-T5 labeled with Texas Red (TR) fluorescent dye is selected as a model payload oligonucleotide. The capture abilities and stability of OFBT-A are investigated by monitoring the fluorescence resonance energy transfer (FRET) efficiency between the OFBT-A nanoparticles and TR labels in solution. The OFBT-A/TR-T5 composites are stable in solution at high ionic strengths (0–500 mM) and have a wide working pH range, from 3.0 to 9.5. The in vitro profile demonstrates that the release of the TR-DNA is induced by the ssDNA A43, which has a high charge density. The release process is monitored by measuring the changes in FRET efficiency and fluorescence color for the OFBT-A/TR-T5 composites. Using this carrier, the uptake of TR-DNA by A549 lung cancer cells is observed. Both the OFBT-A nanoparticles and the OFBT-A/TR-T5 composites show high cytocompatibility. We anticipate that these novel functional nanocarriers will provide a safe strategy for monitoring the gene delivery process.Keywords: conjugated oligomers; delivery; fluorescence; fluorescence resonance energy transfer; nanocarrier; nanoparticles;
Co-reporter:Bihua Xia, Fang He, and Lidong Li
Langmuir 2013 Volume 29(Issue 15) pp:4901-4907
Publication Date(Web):March 21, 2013
DOI:10.1021/la400355u
A straightforward, economically viable, and green approach for the synthesis of well-stabilized Au/Ag bimetallic nanoparticles is described; this method uses nontoxic and renewable degraded pueraria starch (DPS) as a matrix and mild reaction conditions. The DPS acted as both a reducing agent and a capping agent for the bimetallic nanoparticles. Au/Ag bimetallic nanoparticles were successfully grown within the DPS matrixes, and the bimetallic structures were characterized using various methods, including high-resolution transmission electron microscopy, energy-dispersive X-ray, and X-ray diffraction. Moreover, it was shown that these DPS-capped Au/Ag bimetallic nanoparticles could function as catalysts for the reduction of 4-nitrophenol in the presence of NaBH4 and were more effective than Au or Ag monometallic nanoparticles.
Co-reporter:Jindong Wang;Zhenxing Wang;Qiaochu Li;Lin Gan;Xinjun Xu; Lidong Li; Xuefeng Guo
Angewandte Chemie International Edition 2013 Volume 52( Issue 12) pp:3369-3373
Publication Date(Web):
DOI:10.1002/anie.201209816
Co-reporter:Jindong Wang;Zhenxing Wang;Qiaochu Li;Lin Gan;Xinjun Xu; Lidong Li; Xuefeng Guo
Angewandte Chemie 2013 Volume 125( Issue 12) pp:3453-3457
Publication Date(Web):
DOI:10.1002/ange.201209816
Co-reporter:Xinjun Xu;Bo Liu;Yingping Zou;Yunlong Guo;Yunqi Liu
Advanced Functional Materials 2012 Volume 22( Issue 19) pp:4139-4148
Publication Date(Web):
DOI:10.1002/adfm.201200316
Abstract
The interface between the organic semiconductor and dielectric plays an important role in determining the device performance of organic field-effect transistors (OFETs). Although self-assembled monolayers (SAMs) made from organosilanes have been widely used for dielectric modification to improve the device performance of OFETs, they suffer from incontinuous and lack uniform coverage of the dielectric layer. Here, it is reported that by introduction of a solution-processed organozinc compound as a dielectric modification layer between the dielectric and the silane SAM, improved surface morphology and reduced surface polarity can be achieved. The organozinc compound originates from the reaction between diethylzinc and the cyclohexanone solvent, which leads to formation of zinc carboxylates. Being annealed at different temperatures, organozinc compound exists in various forms in the solid films. With organozinc modification, p-type polymer FETs show a high charge carrier mobility that is about two-fold larger than a control device that does not contain the organozinc compound, both for devices with a positive threshold voltage and for those with a negative one. After organozinc compound modification, the threshold voltage of polymer FETs can either be altered to approach zero or remain unchanged depending on positive or negative threshold voltage they have.
Co-reporter:Xiaoyu Wang, Fang He, Fu Tang and Lidong Li
Journal of Materials Chemistry A 2012 vol. 22(Issue 30) pp:15303-15308
Publication Date(Web):01 Jun 2012
DOI:10.1039/C2JM32534A
A new label-free heterogeneous DNA detection method was developed using the fluorescent conjugated polyelectrolyte poly[9,9′-bis(6′′-(N,N,N-trimethylammonium)-hexyl)fluorene-2,7-ylenevinylene-co-alt-1,4-phenylene dibromide] (PFV). In this assay, Layer-by-Layer (LbL) assembly was used to form a polyelectrolyte multilayer thin film on a substrate, and enhance the adsorption ability and stability of PFV. A cationic poly-(allylamine hydrochloride) (PAH) buffer layer was deposited to increase deposition of DNA. DNA detection was studied using a platform with the double-stranded DNA (dsDNA) intercalator ethidium bromide (EB). The thickness of the PAH layer was controlled by pH to obtain an optimum distance between PFV and EB for efficient fluorescence resonance energy transfer (FRET). Because of the different interactions of dsDNA and single-stranded DNA (ssDNA) with EB, DNA hybridization was selectively detected by monitoring the FRET efficiency.
Co-reporter:Lingyun Tong, Ning Ma, Fu Tang, Dengli Qiu, Qianling Cui and Lidong Li
Journal of Materials Chemistry A 2012 vol. 22(Issue 18) pp:8988-8993
Publication Date(Web):06 Mar 2012
DOI:10.1039/C2JM30579H
In this paper, Ag nanoparticles were prepared by the in situ growth of Ag seeds in polyelectrolytes multilayered film matrixes to form Ag nanoparticle-containing hybrid multilayered films. The hybrid films can realize a controllable MEF effect of adsorbed indocyanine green (ICG) fluorophores with pH- and thermoresponsive PAA/PNIPAM interlayer films. According to the interaction distance dependent nature, the nanocomposite films exhibited different MEF behaviours with the PAA/PNIPAM films of different layer numbers. Moreover, the MEF behaviour can be well tuned by varying the temperature or the pH of the external environments due to the unique responsive swelling-shrinking properties of PAA/PNIPAM interlayer films. We obtained an increase of up to 28 times for the weak fluorescence of ICG fluorophores. It is anticipated that this nanocomposite film with controllable MEF effects can be applied for responsive fluorescence detection and imaging.
Co-reporter:Lingling Li, Fang He, Xiaoyu Wang, Ning Ma, and Lidong Li
ACS Applied Materials & Interfaces 2012 Volume 4(Issue 9) pp:4927
Publication Date(Web):September 6, 2012
DOI:10.1021/am301286q
A novel water-soluble conjugated polymer poly{(4,4′-azobenzene)-2,7-[9,9-bis(6′-N,N,N,-trimethylammonium)hexyl fluorene]dibromide} (PFAB) has been designed and synthesized via Suzuki cross-coupling the fluorene units and azobenzene units. Through simple photoreduction, the azo group of the nonfluorescent PFAB to hydrazine group using UV light, polyfluorene PFAB-L with turn-on fluorescence in aqueous solution is obtained. The optical measurements illustrate that the generation of the flexible hydrazine group induces face-to-face arrangement of phenyl–fluorene–phenyl moieties. Therefore, the excimer formation of phenyl–fluorene–phenyl moieties was induced in PFAB-L. And the fluorescence of PFAB-L can be controlled through modulating the protonation of the −NH–NH– group in solution with different pH. The pH-responsive property is reversible. Moreover, the Fe3+ ions can selectively quench the fluorescence of the PFAB-L. This new polymer PFAB-L could be used for selective and sensitive sensing Fe3+ ions in aqueous solution.Keywords: excimer; fluorescence; ion detection; pH-responsive; photoreduction; polyfluorene;
Co-reporter:Bihua Xia, Xiaoyu Wang, Fang He, Qianling Cui, and Lidong Li
ACS Applied Materials & Interfaces 2012 Volume 4(Issue 11) pp:6332
Publication Date(Web):October 26, 2012
DOI:10.1021/am301945k
A new kind of hybrid core–shell nanosphere was fabricated by combining the in situ formation of Au nanoparticles and covalent cross-linking of biocompatible carboxymethyl starch dialdehyde (CMSD) and chitosan (CTS). When the fluorescent dye poly[9,9′-bis(6″-(N,N,N-trimethylammonium)-hexyl)fluorene-2,7-ylenevinylene-co-alt-1,4-phenylene dibromide] (PFV) was assembled on the surface of the hybrid nanospheres through electrostatic attraction, these biocompatible hybrid nanospheres exhibited metal-enhanced fluorescence effects. The fluorescence intensity of (CTS–Au)@CMSD/PFV hybrid nanosphere is 1.43 times that of CTS–CMSD/PFV hybrid nanospheres lacking Au nanoparticle. In addition, the (CTS–Au)@CMSD/PFV hybrid nanospheres exhibit excellent biodegradability upon exposure to enzymatic aqueous solution and good biocompatibility when cocultured with HeLa cervical carcinoma cells; these advantages make them attractive for cellular imaging and biological analysis and detection.Keywords: biocompatibility; cellular imaging; conjugated polymer; fluorescence; hybrid nanosphere; self-assembly;
Co-reporter:Jianfeng Zhang, Ning Ma, Fu Tang, Qianling Cui, Fang He, and Lidong Li
ACS Applied Materials & Interfaces 2012 Volume 4(Issue 3) pp:1747
Publication Date(Web):February 10, 2012
DOI:10.1021/am201858u
In this paper, a novel core–shell hybrid nanoparticle with a silver core and cross-linked poly(3-acrylamidephenylboronic acid-co-acrylic acid) shell (Ag@PAPBA-PAA) was reported. The prepared hybrid nanoparticles can exhibit good responsiveness to the glucose concentration and pH of the environment and exhibit a responsive swelling and shrinking behavior. Tuned by the glucose concentration or pH, a swelling of up to 15.0 nm thickness of the hybrid nanoparticle shell can be observed. These unique responsive properties can be employed to tune the metal-enhanced fluorescence (MEF) effects of the incorporated Ag cores. The fluorescence of adsorbed positively charged porphyrin molecules (Por4+) shows good sensitivity to the glucose concentration and pH with an enhancement of up to about 1.8-fold. These functional hybrid nanoparticles with tunable MEF effects show a great potential application in the fields of responsive fluorescent sensing and detection.Keywords: fluorescence; metal-enhanced fluorescence; nanoparticles; self-assembly; stimuli-responsive;
Co-reporter:Bihua Xia, Qianling Cui, Fang He, and Lidong Li
Langmuir 2012 Volume 28(Issue 30) pp:11188-11194
Publication Date(Web):July 6, 2012
DOI:10.1021/la302011x
In this Article, large and uniform Ag nanoparticle-containing hybrid hydrogels were prepared by in situ reduction of Ag ions in cross-linked tapioca dialdehyde starch (DAS)–chitosan hydrogels. In the hybrid hydrogels, chitosan was chosen as a macromolecular cross-linker because of its abundant source and good biocompatibility. The hybrid hydrogel showed good water-swelling properties, which could be controlled by varying the ratio of chitosan to tapioca DAS in the hydrogel. The reductive aldehyde groups in the cross-linked hydrogels could be used to reduce Ag ions to Ag nanoparticles without any additional chemical reductants. Interestingly, by controlling the reduction conditions such as the tapioca DAS concentration, aqueous AgNO3 concentration, reaction time, and aqueous ammonium concentration, Ag nanoparticles with different sizes and morphologies were obtained. Because of their biocompatibility, degradable constituents, mild reaction conditions, and controlled preparation of Ag nanoparticles, these tapioca DAS–chitosan/Ag nanoparticle hybrid hydrogels show promise as functional hydrogels.
Co-reporter:Fu Tang, Ning Ma, Lingyun Tong, Fang He, and Lidong Li
Langmuir 2012 Volume 28(Issue 1) pp:883-888
Publication Date(Web):November 8, 2011
DOI:10.1021/la203704j
In this paper, we report on the Ag nanoparticle-containing hybrid poly(N-isopropylacrylamide-co-acrylic acid) (PNIPAM-co-PAA) microgels with pH- and thermoresponsive metal-enhanced fluorescence (MEF). The hybrid microgels were prepared by in situ reducing Ag salts to Ag nanoparticles in the PNIPAM-co-PAA microgels. According to the interaction distance-dependent nature of MEF effects, we can realize a controllable MEF effect by adjusting the average interaction distance between fluorophores and Ag nanoparticles due to the good stimuli-responsive swelling–shrinking behavior of the hybrid microgels. The results show that MEF effect can be well tuned in the pH region 2–12 as well as the temperature region of 20–50 °C. By this method, an enhanced fluorescence detection can possibly be manipulated by adjusting external stimuli such as pH and temperature.
Co-reporter:Fang He;Libing Liu
Advanced Functional Materials 2011 Volume 21( Issue 16) pp:3143-3149
Publication Date(Web):
DOI:10.1002/adfm.201100216
Abstract
A series of water-soluble polyfluorene derivatives containing diketopyrrolopyrrole derivative units are synthesized and characterized. These copolymers, poly[9,9'-bis(6”-N,N,N-trimethyl ammonium) hexylfluorene-co-alt-2,5-bis (6”-N,N,N-trimethylammonium)hexylpyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione] (PFDPN), demonstrate intramolecular energy transfer from the fluorene units to the diketopyrrolopyrrole derivative units, and show red-shifted emissions in aqueous solution. The PFDPN polymers can combine with Cy5-labeled ssDNA by electrostatic interactions and efficiently amplify the fluorescence signal of red Cy5 dye through fluorescence resonance energy transfer. Moreover, based on DNA replacement method, this amplification system can be used to monitor the template-independent DNA elongation process catalyzed by terminal deoxynucleotidyl transferase.
Co-reporter:Qing Wang, Xuefeng Guo, Lichao Cai, Yang Cao, Lin Gan, Song Liu, Zhenxing Wang, Hongtao Zhang and Lidong Li
Chemical Science 2011 vol. 2(Issue 9) pp:1860-1864
Publication Date(Web):21 Jul 2011
DOI:10.1039/C1SC00344E
We detail a facile fabrication and testing method of functionalizing single-layer graphenes (SLGs) by photoactive TiO2 thin films as test-beds for building efficient multifunctional optoelectronic devices. Interestingly, tuning the photoactivity of TiO2 enables us to realize fast and significant photoswitching effects in TiO2-graphene devices. More importantly, using the hybrid devices as solid-state gas sensors, we have demonstrated a reversible and linear electrical sensitivity towards oxygen gas in the full concentration range (5–100%) at room temperature and ambient pressure, with a calculated minimum detection limit (MDL) of 0.01% oxygen. The unique oxygen sensitivity of the devices is attributed to the synergetic effect of the photoactivity of TiO2 and the environmental ultrasensitivity of SLGs. These results form the basis for new types of future ultrasensitive multifunctional integrated devices for a variety of possible detection and/or sensing applications.
Co-reporter:Jinshan Wang, Xinjun Xu, Yuwei Zhao, Changchun Zheng and Lidong Li
Journal of Materials Chemistry A 2011 vol. 21(Issue 46) pp:18696-18703
Publication Date(Web):26 Oct 2011
DOI:10.1039/C1JM13145A
Two classical conjugated polymers, poly(9,9-di-n-octylfluorenyl-2,7-diyl) (PFO) and poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV), commonly used in organic optoelectronic devices are endowed with a new function for radical sensing. The synergetic effect between MEH-PPV and PFO nanoparticles (NPs) plays an important role in the detection of hydroxyl radicals and sulfate anion radicals. When exposed to free radicals, MEH-PPV NPs are subjected to attack by the radicals and undergo molecular structure changes. Thus, a strong-polarity shell can be formed on the radical treated MEH-PPV NPs. When such radical treated MEH-PPV NPs come into close contact with PFO NPs, a new phenomenon whereby PFO alters its fluorescence emission intensity of the 0–2 transition relative to the 0–0 transition band is observed. The relative intensity ratio of these two transition bands can serve as an index for the hydroxyl radical concentration. Therefore, radical detection can be realized by measuring the solid state fluorescence, which is highly desired in off-site laboratory determination since solid samples are more convenient for storage and transport than solutions. Our results can open a way for the application of conjugated polymer nanoparticles in chemical/biological sensing.
Co-reporter:Fu Tang, Ning Ma, Xiaoyu Wang, Fang He and Lidong Li
Journal of Materials Chemistry A 2011 vol. 21(Issue 42) pp:16943-16948
Publication Date(Web):23 Jun 2011
DOI:10.1039/C1JM11395J
Hybrid nanoparticles with core–shell structures have shown brilliant potential application in many research fields. In this paper, a novel core–shell Ag@PNIPAM nanocomposite particle which combines the thermoresponsive property of poly(N-isopropylacrylamide) (PNIPAM) and the metal-enhanced fluorescence (MEF) effect of Ag colloids is demonstrated. The cationic conjugated polymer poly[9,9′-bis(6′′-(N,N,N-trimethylammonium)-hexyl)fluorene-2,7-ylenevinylene-co-alt-1,4-phenylene dibromide] (PFV) is then assembled onto the surface of these core–shell nanoparticles by the self-assembly technique. The fluorescence intensity of the prepared PFV/Ag@PNIPAM nanoparticles shows excellent thermostability in the temperature region from 20 °C to 50 °C, and the thermoquenching of PFV is greatly inhibited due to the MEF effects of Ag nanoparticles. Compared with the PFV solution without adding Ag@PNIPAM nanoparticles, a 1.6-fold and 3.1-fold enhancement can be observed when the temperature of the PFV/Ag@PNIPAM dispersion was 20 °C and 50 °C, respectively. In addition, the PFV/Ag@PNIPAM nanoparticles can exhibit excellent cytocompatibility, as well as strong and stable fluorescence when co-cultured with A549 lung cancer cells. These unique properties make these PFV/Ag@PNIPAM core–shell nanoparticles a desirable material especially in the field of efficient cellular imaging and biosensing.
Co-reporter:Xinjun Xu, Chang He, Lidong Li, Ning Ma and Yongfang Li
Journal of Materials Chemistry A 2011 vol. 21(Issue 26) pp:9626-9633
Publication Date(Web):31 May 2011
DOI:10.1039/C0JM04296J
Low-dimensional nanomaterials have brilliant potential applications in a lot of fields. The surface of nanomaterials plays an important role in their applications. Under many circumstances, surface modification of nanomaterials is needed to endow them with novel or improved properties. Although the surface modification of inorganic one-dimensional nanomaterials by organic molecules can be easily achieved, decoration on the surface of organic semiconductor one-dimensional nanomaterials by organic molecules has not been reported yet. The harsh reaction conditions such as high temperature, acid or alkaline catalysis for the surface modification of inorganic materials will do harm to organic semiconductors and are not suitable. So the surface modification of organic semiconductor one-dimensional nanomaterials is still a big challenge. We report here the surface treatment of polymer semiconductor nanowires by alkylsilanes with different end groups. By selection of the appropriate alkylsilane, we can either modify the surface of polymer semiconductor nanowires with a self-assembled monolayer or adjust the shape of the nanowires to nanoparticles. The surface-modified polymer semiconductor nanowires show improved device performance when used in organic optoelectronic devices. Consequently, our results will open a way for the surface modification and shape adjustment of organic semiconductor one-dimensional nanomaterials, which is highly desired for their future applications in catalysis or nanodevices.
Co-reporter:Ning Ma;Fu Tang;Xiaoyu Wang;Fang He
Macromolecular Rapid Communications 2011 Volume 32( Issue 7) pp:587-592
Publication Date(Web):
DOI:10.1002/marc.201000733
Co-reporter:Xiaoyu Wang, Fang He, Fu Tang, Ning Ma, Lidong Li
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2011 Volume 392(Issue 1) pp:103-109
Publication Date(Web):5 December 2011
DOI:10.1016/j.colsurfa.2011.09.040
A unique fluorescent–magnetic hybrid bimodal nanocomposite was prepared by the layer-by-layer self-assembly (LbL) technique fabrication of water-soluble conjugated polymers (CPs) onto the CoFe2O4@SiO2 core–shell nanoparticles (NPs). First, magnetic CoFe2O4 nanoparticles were prepared as the magnetic core and coated with a SiO2 shell to obtain a good dispersion in aqueous solution. Then the polyelectrolytes and cationic conjugated polymer PFV was assembled onto the surface of core–shell nanoparticles by the LbL technique. The prepared nanocomposites were magnetically responsive and fluorescent, simultaneously. Finally, the biomacromolecule heparin sodium (HS) was then assembled on the outer layer of the nanocomposite to provide a cytocompatible surface. The nanocomposites show monodispersity, good fluorescence and good biocompatibility that are useful for efficient cellular imaging. Moreover, the colloidal stability and the cellular uptake ability of the nanocomposition with HS layer were efficiently improved.Graphical abstractHighlights► Hybrid fluorescent–magnetic nanocomposite was prepared by self-assembly technique. ► The nanocomposites with a cytocompatible surface show monodispersity, good fluorescence and good biocompatibility. ► The colloidal stability and the cellular uptake ability of the nanocomposition were efficiently improved.
Co-reporter:Fu Tang, Xiaoyu Wang, Xinjun Xu, Lidong Li
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2010 Volume 369(1–3) pp:101-105
Publication Date(Web):20 October 2010
DOI:10.1016/j.colsurfa.2010.08.013
In this paper, an environmentally friendly metal corrosion inhibitor, phytic acid, was assembled into the walls of silica nanoparticles via layer-by-layer self-assembly technique (LbL) with poly(allylamine hydrochloride). Such functionalized nanoparticles were uniformly distributed into sol–gel films for metal anticorrosion. The films showed very pronounced and lasting protective efficiency in concentrated salt aqueous solutions as indicated by electrochemical impedance spectroscopy (EIS) measurement. These results may provide a new route for the preparation of environment-friendly anticorrosion coatings.
Co-reporter:Fu Tang, Fang He, Huicong Cheng and Lidong Li
Langmuir 2010 Volume 26(Issue 14) pp:11774-11778
Publication Date(Web):June 15, 2010
DOI:10.1021/la101714q
A novel fluorescent nanoparticle was prepared via a simple self-assembly technique based on water-soluble conjugated polymers (CPs) and Ag@SiO2 core−shell nanoparticles. Core−shell nanoparticles with silver NPs core show a unique property referred to as metal-enhanced fluorescence (MEF). In the present work, the cationic conjugated polymer poly[9,9′-bis(6′′-(N,N,N-trimethylammonium)-hexyl) fluorene-2,7-ylenevinylene-co-alt-1,4−phenylene dibromide] (PFV) was hybridized with Ag@SiO2 NPs via simple self-assembly procedure, and given high stability, monodispersity. The fluorescence intensity of PFV after assembling on Ag@SiO2 core−shell NPs is enhanced 1.3-fold compared with the fluorescence intensity of PFV assembled on silica NPs without silver cores for the MEF property of the Ag@SiO2 nanostructure. Nanocomposite with bright fluorescence was obtained. Moreover, the nanocomposition exhibits good monodispersity and low cytotoxicity, which promote their application in cellular imaging. Furthermore, fluorescent nanoparticles with amendable peripheral surfaces can also be potentially obtained because of the easy modification property of CPs and give potential application in selective biological sensing and imaging.
Co-reporter:Changchun Zheng, Xinjun Xu, Fang He, Lidong Li, Bin Wu, Gui Yu, and Yunqi Liu
Langmuir 2010 Volume 26(Issue 22) pp:16730-16736
Publication Date(Web):October 13, 2010
DOI:10.1021/la103449q
Organic semiconductor nanoparticles are expected to be used in organic optical and electronic devices due to their unique optical and electrical properties. However, no method has been reported for the preparation of high-quality organic nanoparticle films without remaining additives and being capable of dealing with binary nanoparticle blends. We developed a simple approach to fabricate high-quality organic semiconductor nanoparticle films from their aqueous solutions by solvent-evaporation-induced self-assembly. Only volatile solvents are employed in the nanoparticle solutions, so the self-assembled nanoparticle films are free of additives. Moreover, this method is also suitable for fabricating thin films containing binary nanoparticles. Therefore, it paves the way for potential applications of organic semiconductor nanoparticles in nanoscale optical and electronic devices.
Co-reporter:Shujing Li, Lidong Li, Feipeng Wu, Erjian Wang
Journal of Photochemistry and Photobiology A: Chemistry 2009 Volume 203(2–3) pp:211-215
Publication Date(Web):15 April 2009
DOI:10.1016/j.jphotochem.2009.02.007
An effective two-photon photopolymerization in an aqueous environment was done using a new water-soluble two-photon photopolymerization (TPP) initiation system. This system comprised a photosensitizer dye and the photoinitiator 4,4′-dimethyl diphenyliodonium hexafluorophosphate (DMDPI) encapsulated by methylated-β-cyclodextrin (Me-β-CD). Photochemical properties of the complex were studied in film. We proved that the complex can be used as an effective TPP photoinitiator for two-photon photopolymerization in an aqueous system. Three-dimensional microstructure was successfully fabricated by TPP.
Co-reporter:Xinjun Xu, Shiyan Chen, Lidong Li, Gui Yu, Chong'an Di and Yunqi Liu
Journal of Materials Chemistry A 2008 vol. 18(Issue 22) pp:2555-2561
Publication Date(Web):08 Apr 2008
DOI:10.1039/B801984C
Abnormal photoluminescent properties of polyphenylphenyl compounds 6,7-dicyano-2,3-di-[4-(2,3,4,5-tetraphenylphenyl)phenyl]quinoxaline (CPQ) and 6,7-dimethyl-2,3-di-(4-(2,3,4,5-tetraphenylphenyl)phenyl)quinoxaline (MPQ) in aqueous solutions have been investigated. Photoluminescent emissions of CPQ and MPQ in tetrahydrofuran (THF)–water mixtures do not change monotonously with increasing their effective concentration in solution. This phenomenon is different from both aggregation-induced emission quenching and aggregation-induced emission enhancement, and can be ascribed to the results of combinational effects of intramolecular rotation, intermolecular hydrogen bonds, and solvent viscosity and hydration. We also observed that organic nanoparticles of CPQ and MPQ are formed in the aqueous solutions. Based on detection of the fluorescence of CPQ nanoparticles in aqueous solutions when introducing nucleobases, we report for the first time the application of organic nanoparticles for nucleobase sensing and found that CPQ nanoparticles can recognize the nucleobases with a sensitivity of guanine > adenine > thymine ≥ cytosine. These findings elucidate the photoluminescent behavior of polyphenylphenyl compounds in aqueous solutions and provide an approach to apply fluorescent organic nanoparticles for biosensing instead of metal and inorganic nanoparticles.
Co-reporter:Xinjun Xu, Chang He, Lidong Li, Ning Ma and Yongfang Li
Journal of Materials Chemistry A 2011 - vol. 21(Issue 26) pp:NaN9633-9633
Publication Date(Web):2011/05/31
DOI:10.1039/C0JM04296J
Low-dimensional nanomaterials have brilliant potential applications in a lot of fields. The surface of nanomaterials plays an important role in their applications. Under many circumstances, surface modification of nanomaterials is needed to endow them with novel or improved properties. Although the surface modification of inorganic one-dimensional nanomaterials by organic molecules can be easily achieved, decoration on the surface of organic semiconductor one-dimensional nanomaterials by organic molecules has not been reported yet. The harsh reaction conditions such as high temperature, acid or alkaline catalysis for the surface modification of inorganic materials will do harm to organic semiconductors and are not suitable. So the surface modification of organic semiconductor one-dimensional nanomaterials is still a big challenge. We report here the surface treatment of polymer semiconductor nanowires by alkylsilanes with different end groups. By selection of the appropriate alkylsilane, we can either modify the surface of polymer semiconductor nanowires with a self-assembled monolayer or adjust the shape of the nanowires to nanoparticles. The surface-modified polymer semiconductor nanowires show improved device performance when used in organic optoelectronic devices. Consequently, our results will open a way for the surface modification and shape adjustment of organic semiconductor one-dimensional nanomaterials, which is highly desired for their future applications in catalysis or nanodevices.
Co-reporter:Xinjun Xu, Shiyan Chen, Lidong Li, Gui Yu, Chong'an Di and Yunqi Liu
Journal of Materials Chemistry A 2008 - vol. 18(Issue 22) pp:NaN2561-2561
Publication Date(Web):2008/04/08
DOI:10.1039/B801984C
Abnormal photoluminescent properties of polyphenylphenyl compounds 6,7-dicyano-2,3-di-[4-(2,3,4,5-tetraphenylphenyl)phenyl]quinoxaline (CPQ) and 6,7-dimethyl-2,3-di-(4-(2,3,4,5-tetraphenylphenyl)phenyl)quinoxaline (MPQ) in aqueous solutions have been investigated. Photoluminescent emissions of CPQ and MPQ in tetrahydrofuran (THF)–water mixtures do not change monotonously with increasing their effective concentration in solution. This phenomenon is different from both aggregation-induced emission quenching and aggregation-induced emission enhancement, and can be ascribed to the results of combinational effects of intramolecular rotation, intermolecular hydrogen bonds, and solvent viscosity and hydration. We also observed that organic nanoparticles of CPQ and MPQ are formed in the aqueous solutions. Based on detection of the fluorescence of CPQ nanoparticles in aqueous solutions when introducing nucleobases, we report for the first time the application of organic nanoparticles for nucleobase sensing and found that CPQ nanoparticles can recognize the nucleobases with a sensitivity of guanine > adenine > thymine ≥ cytosine. These findings elucidate the photoluminescent behavior of polyphenylphenyl compounds in aqueous solutions and provide an approach to apply fluorescent organic nanoparticles for biosensing instead of metal and inorganic nanoparticles.
Co-reporter:Jinshan Wang, Xinjun Xu, Yuwei Zhao, Changchun Zheng and Lidong Li
Journal of Materials Chemistry A 2011 - vol. 21(Issue 46) pp:NaN18703-18703
Publication Date(Web):2011/10/26
DOI:10.1039/C1JM13145A
Two classical conjugated polymers, poly(9,9-di-n-octylfluorenyl-2,7-diyl) (PFO) and poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV), commonly used in organic optoelectronic devices are endowed with a new function for radical sensing. The synergetic effect between MEH-PPV and PFO nanoparticles (NPs) plays an important role in the detection of hydroxyl radicals and sulfate anion radicals. When exposed to free radicals, MEH-PPV NPs are subjected to attack by the radicals and undergo molecular structure changes. Thus, a strong-polarity shell can be formed on the radical treated MEH-PPV NPs. When such radical treated MEH-PPV NPs come into close contact with PFO NPs, a new phenomenon whereby PFO alters its fluorescence emission intensity of the 0–2 transition relative to the 0–0 transition band is observed. The relative intensity ratio of these two transition bands can serve as an index for the hydroxyl radical concentration. Therefore, radical detection can be realized by measuring the solid state fluorescence, which is highly desired in off-site laboratory determination since solid samples are more convenient for storage and transport than solutions. Our results can open a way for the application of conjugated polymer nanoparticles in chemical/biological sensing.
Co-reporter:Fu Tang, Ning Ma, Xiaoyu Wang, Fang He and Lidong Li
Journal of Materials Chemistry A 2011 - vol. 21(Issue 42) pp:NaN16948-16948
Publication Date(Web):2011/06/23
DOI:10.1039/C1JM11395J
Hybrid nanoparticles with core–shell structures have shown brilliant potential application in many research fields. In this paper, a novel core–shell Ag@PNIPAM nanocomposite particle which combines the thermoresponsive property of poly(N-isopropylacrylamide) (PNIPAM) and the metal-enhanced fluorescence (MEF) effect of Ag colloids is demonstrated. The cationic conjugated polymer poly[9,9′-bis(6′′-(N,N,N-trimethylammonium)-hexyl)fluorene-2,7-ylenevinylene-co-alt-1,4-phenylene dibromide] (PFV) is then assembled onto the surface of these core–shell nanoparticles by the self-assembly technique. The fluorescence intensity of the prepared PFV/Ag@PNIPAM nanoparticles shows excellent thermostability in the temperature region from 20 °C to 50 °C, and the thermoquenching of PFV is greatly inhibited due to the MEF effects of Ag nanoparticles. Compared with the PFV solution without adding Ag@PNIPAM nanoparticles, a 1.6-fold and 3.1-fold enhancement can be observed when the temperature of the PFV/Ag@PNIPAM dispersion was 20 °C and 50 °C, respectively. In addition, the PFV/Ag@PNIPAM nanoparticles can exhibit excellent cytocompatibility, as well as strong and stable fluorescence when co-cultured with A549 lung cancer cells. These unique properties make these PFV/Ag@PNIPAM core–shell nanoparticles a desirable material especially in the field of efficient cellular imaging and biosensing.
Co-reporter:Xiaoyu Wang, Fang He, Fu Tang and Lidong Li
Journal of Materials Chemistry A 2012 - vol. 22(Issue 30) pp:NaN15308-15308
Publication Date(Web):2012/06/01
DOI:10.1039/C2JM32534A
A new label-free heterogeneous DNA detection method was developed using the fluorescent conjugated polyelectrolyte poly[9,9′-bis(6′′-(N,N,N-trimethylammonium)-hexyl)fluorene-2,7-ylenevinylene-co-alt-1,4-phenylene dibromide] (PFV). In this assay, Layer-by-Layer (LbL) assembly was used to form a polyelectrolyte multilayer thin film on a substrate, and enhance the adsorption ability and stability of PFV. A cationic poly-(allylamine hydrochloride) (PAH) buffer layer was deposited to increase deposition of DNA. DNA detection was studied using a platform with the double-stranded DNA (dsDNA) intercalator ethidium bromide (EB). The thickness of the PAH layer was controlled by pH to obtain an optimum distance between PFV and EB for efficient fluorescence resonance energy transfer (FRET). Because of the different interactions of dsDNA and single-stranded DNA (ssDNA) with EB, DNA hybridization was selectively detected by monitoring the FRET efficiency.
Co-reporter:Lingyun Tong, Ning Ma, Fu Tang, Dengli Qiu, Qianling Cui and Lidong Li
Journal of Materials Chemistry A 2012 - vol. 22(Issue 18) pp:
Publication Date(Web):
DOI:10.1039/C2JM30579H
Co-reporter:Jianfeng Zhang, Xinjun Xu, Chuang Yao and Lidong Li
Journal of Materials Chemistry A 2016 - vol. 4(Issue 5) pp:NaN950-950
Publication Date(Web):2016/01/06
DOI:10.1039/C5TC03719K
Organic nano/micro one-dimensional (1D) materials are generally considered as promising materials for flexible, portable optoelectronic devices due to their well-known distinctive feature. Over the past few years, numerous organic nano/micro 1D photosensitive resistors have been developed; however, as one of the important photoelectronic components for fabricating organic nano/microelectronic circuits, organic nano/micro 1D photodiodes have not been reported yet. Herein, on the basis of our previous work about an organic photosensitive radial heterostructure microwire, we tried to prepare another kind of radial heterostructure microwire and explore its photodiode properties. Excitingly, the organic radial heterostructure microwire using aluminum tris(8-hydroxyquinoline) as the core and poly(3-hexyl thiophene) as the shell, which was prepared by a solution-based method, showed excellent performance with a large rectification ratio, a high on/off ratio and a good photoresponsivity under ambient conditions. Our work has developed a convenient method to prepare microwire photodiodes based on an all-organic heterojunction.
Co-reporter:Jianfeng Zhang, Xinjun Xu, Chuang Yao, Jinghong Peng, Manping Jia and Lidong Li
Journal of Materials Chemistry A 2016 - vol. 4(Issue 20) pp:NaN4511-4511
Publication Date(Web):2016/04/07
DOI:10.1039/C6TC00214E
We fabricated a unique ternary organic hybrid microwire radial heterojunction by a facile method. First, 4,4′,4′′-tri(N-carbazolyl)triphenylamine (TCTA) microwires were prepared by solvent-evaporation-assisted self-assembly. Then, [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) nanoparticles were adsorbed onto the surface of the TCTA microwires, forming interesting corncob-like binary hybrid microwires. Finally, (4s,6s)-2,4,5,6-tetra(9H-carbazol-9-yl)isophthalonitrile (4CzIPN) was adsorbed on the surface of the binary hybrid microwires to form ternary hybrid microwire radial heterojunctions. The thermally activated delayed fluorescence (TADF) material 4CzIPN was introduced into the donor–acceptor (D–A) system to form the ternary hybrid microwire radial heterojunction for the first time. The morphology has been confirmed by fluorescence microscopy, SEM and TEM. Interestingly, we found that this ternary hybrid microwire exhibited efficient photoconductivity by fabricating a bottom contact device; the photocurrent increased by more than 3 times compared with the reference device without 4CzIPN. By examining some reference devices, it can be inferred that the enhancement of the photoconductivity originates from the reversed intersystem crossing (RISC) process in 4CzIPN. This process can promote the formation of triplet excitons, thereby increasing the charge carrier concentration in the conductive channel of the microwire radial heterojunction. These high photoconductivity ternary microwires provide an efficient approach to improve the performance of photovoltaic devices and show promise for applications in organic integrated optoelectronics.
Co-reporter:Xinjun Xu, Ronghua Liu and Lidong Li
Chemical Communications 2015 - vol. 51(Issue 94) pp:NaN16749-16749
Publication Date(Web):2015/09/22
DOI:10.1039/C5CC06439B
Semiconducting organic nanoparticles have recently attracted increasing attention in the chemical and biomedical fields. Such nanoparticles are mainly composed of π-conjugated compounds. They possess the properties of easy synthesis, facile tuning, less toxicity and more biocompatibility relative to the existing inorganic nanoparticles. In addition, they show advantages such as brighter fluorescence, higher photostability and higher biocompatibility, compared with classical fluorescent organic dyes. In this review, we summarize the latest advances in the development of organic nanoparticles made of π-conjugated compounds, including preparation methods, material design, nanoparticle fabrication and surface functionalization for chemical and biological applications. Especially, we focus on the applications of semiconducting organic nanoparticles in chemical and biological sensing by monitoring the fluorescence signal, as nanocarriers for drug/gene delivery, in photothermal and photodynamic therapy, and in photoacoustic imaging. Finally, the challenges and perspectives for the future development of organic nanoparticles based on π-conjugated compounds are also discussed.
Co-reporter:Qing Wang, Xuefeng Guo, Lichao Cai, Yang Cao, Lin Gan, Song Liu, Zhenxing Wang, Hongtao Zhang and Lidong Li
Chemical Science (2010-Present) 2011 - vol. 2(Issue 9) pp:NaN1864-1864
Publication Date(Web):2011/07/21
DOI:10.1039/C1SC00344E
We detail a facile fabrication and testing method of functionalizing single-layer graphenes (SLGs) by photoactive TiO2 thin films as test-beds for building efficient multifunctional optoelectronic devices. Interestingly, tuning the photoactivity of TiO2 enables us to realize fast and significant photoswitching effects in TiO2-graphene devices. More importantly, using the hybrid devices as solid-state gas sensors, we have demonstrated a reversible and linear electrical sensitivity towards oxygen gas in the full concentration range (5–100%) at room temperature and ambient pressure, with a calculated minimum detection limit (MDL) of 0.01% oxygen. The unique oxygen sensitivity of the devices is attributed to the synergetic effect of the photoactivity of TiO2 and the environmental ultrasensitivity of SLGs. These results form the basis for new types of future ultrasensitive multifunctional integrated devices for a variety of possible detection and/or sensing applications.
Co-reporter:Chuang Yao, Jingxian Li, Jinshan Wang, Xinjun Xu, Ronghua Liu and Lidong Li
Journal of Materials Chemistry A 2015 - vol. 3(Issue 33) pp:NaN8683-8683
Publication Date(Web):2015/07/20
DOI:10.1039/C5TC01544H
Being incompatible with host materials in a physically blended emitting layer, phosphorescent dyes are prone to form aggregates induced by Joule heat in devices under work. In this work, a new and efficient blue phosphorescent dye Cz-C8-FIrpic was designed and synthesised by incorporating 9-phenyl-9H-carbazole into a commonly used blue emissive iridium complex bis(4,6-(difluorophenyl)pyridine-N,C2′)picolinate (FIrpic) via an alkyl chain linkage. This phosphorescent dye exhibits similar photophysical properties to the units of FIrpic and 9-phenyl-9H-carbazole in solutions. In solid films of Cz-C8-FIrpic, the energy transfer from 9-phenyl-9H-carbazole to FIrpic units is effective. The Cz-C8-FIrpic doped emissive layer was investigated by AFM, STEM-EDS, transient photoluminescence decay curves and molecular dynamics simulations. The results show that in the Cz-C8-FIrpic doped film the phase aggregation of FIrpic units is less severe than that in the typically used FIrpic film. In addition, the optimized Cz-C8-FIrpic based device achieved a maximum luminance of 25142 cd m−2, a maximum EQE of 8.5% and a maximum current efficiency of 22.5 cd A−1 which is about 15% higher than that of the control device based on FIrpic. We conclude that grafting a typically used dye to functional groups with alkyl chains is useful to restrict phase separation in physically blended emitting layers, and thus can achieve high electroluminescence performances.
Co-reporter:Jinshan Wang, Xinjun Xu, Yuan Tian, Chuang Yao, Ronghua Liu and Lidong Li
Journal of Materials Chemistry A 2015 - vol. 3(Issue 12) pp:NaN2864-2864
Publication Date(Web):2015/02/02
DOI:10.1039/C4TC02899F
Two blue-emitting fluorescent polymers PTPATPPO and PTPATPP with small singlet–triplet splitting comprising triphenylamine and triphenylphosphine/triphenylphosphine oxide moieties have been designed and synthesized. An appropriate overlap between the HOMO and the LUMO in these compounds was realized. This design strategy endows the two blue-emitting polymers with a high triplet energy of 2.45 and 2.46 eV, a shallow HOMO level of −5.21 and −5.23 eV, and a bipolar feature to act as good host materials. Monochromic organic light-emitting devices (OLEDs) using these polymers as emitters show sky-blue emissions with Commission Internationale de l'Eclairage (CIE) coordinates of (0.24, 0.32) and (0.24, 0.31) together with a maximum current efficiency of 3.63 cd A−1. Moreover, the single-emitting-layer two-element fluorescent–phosphorescent (F–P) hybrid white OLEDs based on PTPATPPO or PTPATPP as both hosts and blue-emitting fluorophores were fabricated by a solution process. Among the two polymers, PTPATPPO-based F–P hybrid white OLEDs show better performance with a maximum current efficiency of 10.5 cd A−1, a maximum external quantum efficiency of 6.1%, CIE coordinates of (0.40, 0.34), and a maximum luminance of 11962 cd m−2.
Co-reporter:Chuang Yao, Qianling Cui, Jinghong Peng, Xinjun Xu, Ronghua Liu, Jinshan Wang, Yuan Tian and Lidong Li
Journal of Materials Chemistry A 2015 - vol. 3(Issue 19) pp:NaN5025-5025
Publication Date(Web):2015/04/14
DOI:10.1039/C5TC00612K
Two kinds of host materials, 4,4′-(diphenylgermanediyl)bis(N,N-diphenylaniline) and bis(4-(9H-carbazol-9-yl)phenyl)diphenylgermane (DCzGe), for blue phosphorescent organic light emitting diodes (PhOLEDs) were designed by incorporating electron donating groups (carbazole and triphenylamine) into tetraphenylgermane, which is a new type of core moiety that has never been studied for use in this field. This molecular structure endows the compounds with a wide energy bandgap, high thermal/morphological stability and good solution processability. Based on the theoretic calculations, DCzGe was selected and synthesized as a host material which demonstrates a wide bandgap (Eg: 3.56 eV) and a high triplet energy (ET: 3.02 eV). It also exhibits a high glass transition temperature (110 °C), which is beneficial for resisting the Joule heat in devices. All solution processed, blue emitting PhOLEDs were fabricated by using a mixed host combining DCzGe and an electron-transporting material, with a maximum luminance of 10000 cd m−2 and a maximum current efficiency of 15.2 cd A−1. Furthermore, the devices showed a very low current efficiency roll-off, which remained as high as 15.2 cd A−1 at the luminance of 1000 cd m−2, and the roll-off is only 2.6% even at the higher luminance of 2000 cd m−2.
Co-reporter:Jianfeng Zhang, Jinshan Wang, Xinjun Xu, Shiyan Chen, Qinglin Zhang, Chuang Yao, Xiujuan Zhuang, Anlian Pan and Lidong Li
Journal of Materials Chemistry A 2015 - vol. 3(Issue 23) pp:NaN5939-5939
Publication Date(Web):2015/05/05
DOI:10.1039/C5TC01050K
Organic semiconductor materials with one-dimensional (1D) radial (core–shell) heterojunction structures are highly desired for their expected excellent optoelectronic properties. However, currently, such structures are still in a fledgling period for optoelectronic applications due to the absence of both good materials and suitable preparation methods. Here we have synthesized a p-type organic semiconductor based on a new electron-donating unit (dithienopyrazine) and utilized it as a shell material to construct organic 1D radial p–n heterojunctions. This p-type compound shows a higher oxidation potential and is more resistant to photooxidation in air than its analogs with the commonly-used benzodithiophene unit. Moreover, we prepared organic microwires with radial heterojunctions via a solution-processed method by self-assembly of our p-type material on the surface of n-type cores. Thus, photoconductive devices based on an individual microwire with the radial heterojunction can be fabricated and demonstrate a high photoconductivity. Our work provides a path for preparing 1D radial heterojunctions suitable for optoelectronic applications.
Co-reporter:Jinshan Wang, Xinjun Xu, Yuan Tian, Chuang Yao and Lidong Li
Journal of Materials Chemistry A 2014 - vol. 2(Issue 25) pp:NaN5045-5045
Publication Date(Web):2014/05/02
DOI:10.1039/C4TC00052H
By attaching two electron-withdrawing trifluoromethyl (CF3) groups to the 2-phenylbenzothiazole cyclo-metalated ligand, a bis-trifluoromethyl-functionalized orange-emitting phosphorescent iridium(III) complex bis-(6-(trifluoromethyl)-2-(4-(trifluoromethyl)phenylbenzothiozolato))iridium(acetylacetonate) [(F3BT-CF3P)2Ir(acac)] was successfully synthesized. The optical, electrochemical and electroluminescence (EL) properties of this new complex were studied. The experimental results support the theoretical expectation that incorporating electron-withdrawing trifluoromethyl groups at the 4-site of the phenyl ring directly bonded to the metal center, and at the 6-site of 2-phenylbenzothiazole, cause a bathochromic shift in the emission peak and bring the emission color much closer to long-wavelength orange light. Moreover, such trifluoromethyl substituents can hinder the π–π stacking or self-polarization effect occurring from the aggregation of the molecules. The new iridium complex gives an unchanged luminescence spectrum, regardless of whether it is in solution, in untreated film or in film doped at different concentrations. Using this iridium complex as a dopant emitter, solution-processed single emissive layer orange and two-element white OLEDs with good performance can be obtained. Highly efficient orange electroluminescence was obtained with a maximum efficiency of 10.5 cd A−1 and CIE coordinates (0.48, 0.51). When combined with a commercial sky-blue phosphorescent emitter, (CF3BT–CF3P)2Ir(acac) can be utilized to achieve two-element white OLEDs that exhibited a high efficiency of 28.3 cd A−1. Such OLEDs retain high efficiency at a luminance suitable for lighting (e.g. 5000 cd m−2).
![Phenol, 4-[bis(4-bromophenyl)amino]-](/data/chemimg/104600/336619-79-5.png)
![Phenol, 4-[bis(4-bromophenyl)amino]-](/data/chemimg/104600/336619-79-5_b.png)
![Poly[(9,9-dioctylfluorenyl-2,7-diyl)-alt-(benzo[2,1,3]thiadiazol-4,7-diyl)]](/data/chemimg/107700/210347-52-7.png)
![Poly[(9,9-dioctylfluorenyl-2,7-diyl)-alt-(benzo[2,1,3]thiadiazol-4,7-diyl)]](/data/chemimg/107700/210347-52-7_b.png)
![Sodium 2,3-dihydroxypropyl [(2r)-2,3-di(tetradecanoyloxy)propyl] Phosphate](http://img.cochemist.com/ccimg/200900/200880-40-6.png)
![Sodium 2,3-dihydroxypropyl [(2r)-2,3-di(tetradecanoyloxy)propyl] Phosphate](http://img.cochemist.com/ccimg/200900/200880-40-6_b.png)
![Poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene]](http://img.cochemist.com/ccimg/138200/138184-36-8.png)
![Poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene]](http://img.cochemist.com/ccimg/138200/138184-36-8_b.png)
![[4-(4-bromobutoxy)phenyl]-phenylmethanone](http://img.cochemist.com/ccimg/101400/101308-54-7.png)
![[4-(4-bromobutoxy)phenyl]-phenylmethanone](http://img.cochemist.com/ccimg/101400/101308-54-7_b.png)
](http://img.cochemist.com/ccimg/27000/26913-06-4.png)
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