Co-reporter:Yaoping Hu, Jing Yang, Jiangwei Tian and Jun-Sheng Yu
Journal of Materials Chemistry A 2015 vol. 3(Issue 27) pp:5608-5614
Publication Date(Web):09 Jun 2015
DOI:10.1039/C5TB01005E
A bottom-up method, using monoethanolamine (MEA) as both a passivation agent and a solvent, has been developed for rapid and massive synthesis of nitrogen-doped carbon dots (N-C-dots) from citric acid under heating conditions. This method requires a relatively mild temperature (170 °C) without special equipment, and affords one-pot large-scale production (39.96 g) of high-quality N-C-dots (quantum yield of 40.3%) in a few minutes (10 minutes). Significantly, an interesting formation process of N-C-dots, for the first time, has been monitored by transmission electron microscopy, ultraviolet-visible absorbance spectroscopy, photoluminescence spectroscopy, Fourier transformed infrared spectroscopy, and thermogravimetric analysis, and a corresponding formation mechanism, including polymerization, aromatization, nucleation, and growth, is proposed. It is important that the MEA-based synthesis of N-C-dots can be extended to various precursors, such as glucose, ascorbic acid, cysteine, and glutathione, which show general universality. Furthermore, the N-C-dots with strong fluorescence, excellent optical stability, and low cytotoxicity are successfully applied as fluorescent probes for bioimaging.
Co-reporter:Jing Yang, Yaoping Hu, Jiangwei Tan, Li Jia, Yu-Hua Zhu and Jun-Sheng Yu
Journal of Materials Chemistry A 2015 vol. 3(Issue 34) pp:6928-6938
Publication Date(Web):04 Aug 2015
DOI:10.1039/C5TB01034A
Near-infrared (NIR)-emitting nanocrystals have enormous potential as an enabling technology for applications ranging from tunable infrared lasers to biological labels. Mercury chalcogenide NCs are one of the attractive NCs with NIR emission; however, the potential toxicity of Hg restricts their diverse applications. Herein, we synthesized low-toxic, highly luminescent and stable GSH-capped HgS/ZnS core/shell NCs by an aqueous route for the first time. The core/shell structure was characterized by using TEM, XRD and XPS, which provide evidence for the shell growth. After the successful growth of an appropriate ZnS shell around HgS NCs, poorly luminescent HgS NCs converted into ultra-bright HgS/ZnS NCs, substantially increasing photoluminescence quantum yield up to 43.8% at room temperature. The fluorescence peak of HgS/ZnS NCs was successfully tuned in a wide NIR window ranging from 785 nm to 1060 nm with high emission efficiency by controlling the synthetic pH values. Significantly, an in vitro cytotoxicity study clearly demonstrated that the HgS/ZnS NCs exhibited good biocompatibility as evidenced by the cell viability retained above 80% at a dose of HgS/ZnS NCs up to 150 μg mL−1. More importantly, the low-toxic NIR-emitting HgS/ZnS NCs have proved to be an effective fluorescent label in in vitro and in vivo imaging. The penetration depth reached 2 cm in a nude mouse with distinct separation of autofluorescence and NCs' fluorescence, giving excellent contrast at all depths. The novel highly-luminescent NIR-emitting HgS/ZnS NCs open up new possibilities for highly-sensitive, highly spectrally resolved and multicolor imaging in biomedical applications.
Co-reporter:Li Jia, Lin Ding, Jiangwei Tian, Lei Bao, Yaoping Hu, Huangxian Ju and Jun-Sheng Yu
Nanoscale 2015 vol. 7(Issue 38) pp:15953-15961
Publication Date(Web):18 May 2015
DOI:10.1039/C5NR02224J
In this work we designed a MoS2 nanoplate-based nanoprobe for fluorescence imaging of intracellular ATP and photodynamic therapy (PDT) via ATP-mediated controllable release of 1O2. The nanoprobe was prepared by simply assembling a chlorine e6 (Ce6) labelled ATP aptamer on MoS2 nanoplates, which have favorable biocompatibility, unusual surface-area-to-mass ratio, strong affinity to single-stranded DNA, and can quench the fluorescence of Ce6. After the nanoprobe was internalized into the cells and entered ATP-abundant lysosomes, its recognition to ATP led to the release of the single-stranded aptamer from MoS2 nanoplates and thus recovered the fluorescence of Ce6 at an excitation wavelength of 633 nm, which produced a highly sensitive and selective method for imaging of intracellular ATP. Meanwhile, the ATP-mediated release led to the generation of 1O2 under 660 nm laser irradiation, which could induce tumor cell death with a lysosomal pathway. The controllable PDT provided a model approach for design of multifunctional theranostic nanoprobes. These results also promoted the development and application of MoS2 nanoplate-based platforms in biomedicine.
Co-reporter:Yaoping Hu, Jing Yang, Li Jia, Jun-Sheng Yu
Carbon 2015 Volume 93() pp:999-1007
Publication Date(Web):November 2015
DOI:10.1016/j.carbon.2015.06.018
A novel synthetic strategy has been developed for facile, green and low-cost fabrication of highly photoluminescent carbon dots (C-dots) by hydrothermal treatment of ethanol in aqueous hydrogen peroxide (H2O2) solution. Noticeably, the synthesized C-dots present an unexpectedly large quantum yield of 38.7% without any post-treatments. In contrast to the most amorphous C-dots, the ethanol-derived C-dots possess an essentially crystalline nature as evidenced by the high-resolution transmission electron microscopy and selected-area electron diffraction. It is found that the C-dots can serve as multifunctional fluorescence nanosensors to detect pH, temperature, and the concentration of hypochlorite ion (ClO−). The PL intensity of C-dots decreases dramatically as pH increases from 3 to 11. Based on this feature, a C-dots coated fluorescent paper for visual detection of pH by naked eyes has been successfully prepared. The C-dots reveals a linear and reversible PL response toward the temperature in the range of 10–80 °C, suggesting the great potential for design of temperature-sensitive devices. The selective quantification of ClO− concentration from 0.1 to 10 μM with a detection limit as low as 0.08 μM is achieved by ClO−-induced PL quenching of C-dots. Moreover, the C-dots applied for ClO− assay in real water samples with satisfactory recovery is demonstrated.
Co-reporter:Dawei Deng, Jie Wang and Jun-Sheng Yu
CrystEngComm 2015 vol. 17(Issue 23) pp:4349-4354
Publication Date(Web):21 Apr 2015
DOI:10.1039/C5CE00207A
Selenium (Se) is an important elemental semiconductor. Its intrinsic crystal structure is composed of hexagonally packed, one-dimensional (1D) spiral chains of Se atoms, which easily results in preferential 1D anisotropic growth along the [001] direction. In this study, we observed that planar Se multipod crystals with unusual growth directions (namely, not along the preferential [001] direction), including tripods, tetrapods, pentapods, hexapods, etc. could be formed spontaneously in water, via the oxidation of Na2Se by air and subsequent crystallization of Se monomers under ambient conditions. Here, the controlled synthesis of these Se multipods is achieved by using small molecules containing a carboxyl group to stabilize selectively the (001) facets of hexagonal Se (h-Se) crystals. Furthermore, their growth modes were investigated systematically and revealed, using a combination of scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected-area electron diffraction (SAED) and X-ray powder diffraction (XRD) characterization methods. Lastly, based on the acquired understanding, we consider that by selecting the type of small molecule and(/or) controlling the transformation rate of Se2− → Se, the spontaneous growth of h-Se crystals could be controlled well.
Co-reporter:Dawei Deng and Junsheng Yu
Crystal Growth & Design 2015 Volume 15(Issue 2) pp:602
Publication Date(Web):December 29, 2014
DOI:10.1021/cg5012007
In this report, nonspherical Se crystals were synthesized from the transformation of CdSe nanoparticles (NPs) under ambient conditions, including nanowires (—), microscale or nanoscale rods (−), crossheads, crosses (+), and other unusual highly anisotropic structures. Here, CdSe NPs are used as the starting point of synthesis; the presence of EDTA triggers the decomposition of primary CdSe NPs, and resultant gradual release of Se2– anions into solution; finally, highly pure well-crystallized nonspherical hexagonal Se (h-Se) crystals are formed via the oxidation of the released Se2– anions in air (this redox reaction will stimulate further the release of Se2– anions) and the subsequent spontaneous crystallization of Se monomers. Some key variables such as the concentrations of EDTA and CdSe NPs, and the ligand of primary NPs, were explored systematically. The experimental results show that the ligand nature of the NP precursor influences the transformation rate of CdSe NPs to Se crystals and dominates the shape and aspect ratio of Se product, while the concentrations of EDTA and CdSe NPs only influence the size of the product. Meanwhile, we also investigated intensively the transformation process of CdSe NP precursors to multiarmed Se crystals, aside from the detailed characterizations on their sizes, shapes, and crystal structures.
Co-reporter:Yaoping Hu, Jing Yang, Jiangwei Tian, Li Jia and Jun-Sheng Yu
RSC Advances 2015 vol. 5(Issue 20) pp:15366-15373
Publication Date(Web):26 Jan 2015
DOI:10.1039/C4RA16989A
A novel oxygen-driven method has been developed for low-cost, large-scale, and high-efficiency production of nitrogen-doped carbon dots (N-C-dots) by bubbling pure oxygen into monoethanolamine (MEA) under heating conditions. We find that the addition of pure oxygen significantly increases the reaction rate, and makes feasible one-pot gram scale fabrication (3.36 g) of highly photoluminescent N-C-dots in a couple of hours (2.0 h). With an instantaneous nucleation and gradual growth mechanism, precise control over the particle size of the N-C-dots from 2.0 to 16.1 nm is achieved by simply prolonging the heating time from 0.5 to 4.0 h. The as-prepared N-C-dots contain aromatic CN heterocycles in the core and have plentiful hydrophilic groups on the surface. Practically, the oxygen-driven method can be used to synthesize fluorescent N-C-dots from other alkanolamines such as diethanolamine (DEA) and triethanolamine (TEA), which shows general universality. Due to the strong up-conversion photoluminescence, good aqueous dispersibility, high photostability, excellent biocompatibility, and low cytotoxicity, the N-C-dots are demonstrated to be promising two-photon probes for high contrast bioimaging applications.
Co-reporter:Jing Yang, Yaoping Hu, Jun Luo, Yu-Hua Zhu, and Jun-Sheng Yu
Langmuir 2015 Volume 31(Issue 11) pp:3500-3509
Publication Date(Web):March 5, 2015
DOI:10.1021/la504879m
Bulk HgS itself has proven to be a technologically important material; however, the poor stability and weak emission of HgS nanocrystals have greatly hindered their promising applications. Presently, a critical problem is the uncontrollable growth of HgS NCs and their intrinsic surface states which are susceptible to the local environment. Here, we address the issue by an ion-tuning approach to fabricating stable, highly fluorescent Cd:HgS/CdS NCs for the first time, which efficiently tuned the band-gap level of HgS NCs, pushing their intrinsic states far away from the surface, reducing the strong interaction of the environment with surface states and hence drastically boosting the exciton transition. As compared to bare HgS NCs, the obtained Cd:HgS/CdS NCs exhibited tunable luminescence peaks from 724 to 825 nm with an unprecedentedly high quantum yield up to 40% at room temperature and excellent thermal and photostability. Characterized by TEM, XRD, XPS, and AAS, the resultant Cd:HgS/CdS NCs possessed a zinc-blende structure and was composed of a homogeneous alloyed HgCdS structure coated with a thin-layer CdS shell. The formation mechanism of Cd:HgS/CdS NCs was proposed. These bright, stable HgS-based NCs presented promising applications as fluorescent inks for anticounterfeiting and as excellent light converters when coated onto a blue-light-emitting diode.
Co-reporter:Yaoping Hu, Jing Yang, Jiangwei Tian, Li Jia, Jun-Sheng Yu
Carbon 2014 Volume 77() pp:775-782
Publication Date(Web):October 2014
DOI:10.1016/j.carbon.2014.05.081
Proper disposal of waste frying oil (WFO) is an important waste-management concern. In this paper, we develop a facile method to reuse WFO for one-step synthesis of sulfur-doped carbon dots (S-C-dots) with the assistance of concentrated sulfuric acid. The as-synthesized S-C-dots are uniform in size and show partial disordered graphite-like structure. Different from the doping-free or nitrogen-doped carbon dots, the S-C-dots perform a strong ultraviolet emission at 378 nm due to successful sulfur-doping. Noticeably, the S-C-dots exhibit a distinct pH-sensitive feature and the intensity of photoluminescence increases linearly in the pH range from 3 to 9. Furthermore, possessing fascinating optical properties, high photostability, and low cytotoxicity, the S-C-dots have served as fluorescent probes for cell imaging.
Co-reporter:Yaoping Hu, Jing Yang, Jiangwei Tian, Li Jia and Jun-Sheng Yu
RSC Advances 2014 vol. 4(Issue 88) pp:47169-47176
Publication Date(Web):18 Sep 2014
DOI:10.1039/C4RA08306G
We have developed a facile approach for green and size-controllable synthesis of photoluminescent carbon nanoparticles (CNPs) by hydrothermal treatment of various waste plastic bags (WPBs) in low-concentration H2O2 solutions (≤5.0 wt%). This approach requires no toxic regents, severe synthetic conditions, or complicated procedures. Fine control over the particle size of the CNPs is achieved by simply changing the H2O2 concentration, and higher H2O2 concentration leads to smaller particle size of the CNPs. An interesting formation mechanism of the CNPs derived from WPBs has been proposed including thermo-oxidative degradation, polymerization, carbonization, and passivation. It is found that the CNPs can selectively quantify the concentration of Fe3+ from 10 to 400 μM with a detection limit as low as 2.8 μM. Moreover, the strong photoluminescence, excellent optical stability, low cytotoxicity, and good water-dispersibility of the CNPs make them suitable candidates for cellular imaging. The simple method developed here presents a new way for effective reuse of WPBs and realizes the encouraging “waste-to-treasure” conversion.
Co-reporter:Jiangwei Tian;Dr. Lin Ding; Huangxian Ju;Dr. Yongchao Yang;Xilan Li; Zhen Shen;Dr. Zhi Zhu; Jun-Sheng Yu; Chaoyong James Yang
Angewandte Chemie International Edition 2014 Volume 53( Issue 36) pp:9544-9549
Publication Date(Web):
DOI:10.1002/anie.201405490
Abstract
Simultaneous targeted cancer imaging, therapy and real-time therapeutic monitoring can prevent over- or undertreatment. This work describes the design of a multifunctional nanomicelle for recognition and precise near-infrared (NIR) cancer therapy. The nanomicelle encapsulates a new pH-activatable fluorescent probe and a robust NIR photosensitizer, R16FP, and is functionalized with a newly screened cancer-specific aptamer for targeting viable cancer cells. The fluorescent probe can light up the lysosomes for real-time imaging. Upon NIR irradiation, R16FP-mediated generation of reactive oxygen species causes lysosomal destruction and subsequently trigger lysosomal cell death. Meanwhile the fluorescent probe can reflect the cellular status and in situ visualize the treatment process. This protocol can provide molecular information for precise therapy and therapeutic monitoring.
Co-reporter:Jiangwei Tian ; Lin Ding ; Hai-Jun Xu ; Zhen Shen ; Huangxian Ju ; Li Jia ; Lei Bao
Journal of the American Chemical Society 2013 Volume 135(Issue 50) pp:18850-18858
Publication Date(Web):December 2, 2013
DOI:10.1021/ja408286k
Spatiotemporal control of singlet oxygen (1O2) release is a major challenge for photodynamic therapy (PDT) against cancer with high therapeutic efficacy and minimum side effects. Here a selenium-rubyrin (NMe2Se4N2)-loaded nanoparticle functionalized with folate (FA) was designed and synthesized as an acidic pH-activatable targeted photosensitizer. The nanoparticles could specifically recognize cancer cells via the FA-FA receptor binding and were selectively taken up by cancer cells via receptor-mediated endocytosis to enter lysosomes, in which NMe2Se4N2 was activated to produce 1O2. The pH-controllable release of 1O2 specially damaged the lysosomes and thus killed cancer cells in a lysosome-associated pathway. The introduction of selenium into the rubyrin core enhanced the 1O2 generation efficiency due to the heavy atom effect, and the substitution of dimethylaminophenyl moiety at meso-position led to the pH-controllable activation of NMe2Se4N2. Under near-infrared (NIR) irradiation, NMe2Se4N2 possessed high singlet oxygen quantum yield (ΦΔ) at an acidic pH (ΦΔ = 0.69 at pH 5.0 at 635 nm) and could be deactivated at physiological pH (ΦΔ = 0.06 at pH 7.4 at 635 nm). The subcellular location-confined pH-activatable photosensitization at NIR region and the cancer cell-targeting feature led to excellent capability to selectively kill cancer cells and prevent the damage to normal cells, which greatly lowered the side effects. Through intravenous injection of FA-NMe2Se4N2 nanoparticles in tumor-bearing mice, tumor elimination was observed after NIR irradiation. This work presents a new paradigm for specific PDT against cancer and provides a new avenue for preparation of highly efficient photosensitizers.
Co-reporter:Jing Yang, Da-Wei Deng, Jun-Sheng Yu
Journal of Colloid and Interface Science 2013 Volume 394() pp:55-62
Publication Date(Web):15 March 2013
DOI:10.1016/j.jcis.2012.11.053
A simple and rapid route to water-soluble CdS nanocrystals stabilized by citrate was reported, and the transfer of citrate-stabilized CdS NCs from trap emission to band-edge one was studied systematically for the first time. It was found that heating in air, alkaline activation and illumination, all efficiently manipulated surface states of CdS NCs and controlled the emission states, leading to transferring CdS NCs from a broad trap emission (FWHM ∼125 nm) to their strong, narrow band-gap emission (FWHM ∼25 nm), comparable to that of CdS NCs synthesized by organic routes. Lifetime decay kinetic studies demonstrated that the average lifetimes for CdS NCs before and after transferred were 131.1 and 32.7 ns, respectively. The freshly-synthesized NCs were predominated by trap emission (∼94%), while the transferred CdS NCs with well cubic structure dominated by band-edge emission (up to 91%). The tunable emissions of CdS NCs from violet to green could be achieved by controlling emission states of CdS NCs with different Cd/S molar ratios. The transfer mechanisms of CdS NCs from trap to band-edge emission were proposed to be epitaxial growth of a Cd(OH)2 shell on CdS NCs core. The transition probability of energy states before and after transferred was further investigated.Graphical abstractHighlights► First synthesis of citrate-capped CdS NCs from trap to narrow exciton emission. ► Broad trap emission (94%) to narrow band-edge one (91%) by post-treatments. ► Tunable PL peaks of CdS NCs from violet to visible by controlling emission states.
Co-reporter:Wen-Hao Zhang, Jing Yang and Jun-Sheng Yu
Journal of Materials Chemistry A 2012 vol. 22(Issue 13) pp:6383-6388
Publication Date(Web):22 Feb 2012
DOI:10.1039/C2JM15630J
HgTe/CdS core/shell nanocrystals (NCs) with highly-stable near-infrared (NIR) emissions were synthesized by employing dihydrolipoic acid (DHLA) as a stabilizer. This synthetic route was performed using Te powder as the tellurium source to prepare HgTe NCs, and H2S generated by the reaction of Na2S–H2SO4 as the sulfur source for synthesizing HgTe/CdS core/shell NCs at room temperature. The fluorescence emission peaks of DHLA-capped HgTe/CdS NCs could be facilely tuned from 910 nm to 1200 nm by varying the reflux time at 100 °C, with a maximum photoluminescence quantum yield of 52%. The obtained HgTe/CdS NCs exhibited an NIR stable emission when heated at 75 °C. Correspondingly, these HgTe/CdS core/shell NCs displayed excellent colloidal dispersion stability and long exciton lifetimes that reached up to 47.6 ns in an aqueous medium. The resultant HgTe/CdSe NCs have been successfully used to fabricate NIR emitting thin films on the surface of polymers and to perform fluorescence imaging in a live animal.
Co-reporter:Jing Yang, Wen-Hao Zhang, Yao-Ping Hu, Jun-Sheng Yu
Journal of Colloid and Interface Science 2012 Volume 379(Issue 1) pp:8-13
Publication Date(Web):1 August 2012
DOI:10.1016/j.jcis.2012.04.057
A simple, rapid and green aqueous approach to near-infrared (NIR)-emitting β-HgS nanocrystals (NCs) was demonstrated for the first time by using glutathione (GSH) as the stabilizer at room temperature. The resulting HgS NCs with zinc blend structure exhibited strong quantum size effect, and the emission peak could be tuned in a wide NIR region from ca. 775 to 1041 nm. As compared with early achievements, the emission intensity of GSH-stabilized HgS NCs enhanced, with the maximum quantum yield reaching ∼2.8%. It was also found that the stability of the GSH–HgS NCs was improved noticeably, the PL peak red-shifting only 9 nm and 23 nm after stored at 4 °C for 4 months and 25 °C for 7 days, respectively. The better stability of the HgS NCs was elucidated by FT-IR due to the multiple coordination of GSH molecule to surface Hg of the NCs. The emission range of GSH-stabilized HgS NCs was located between the visible region (500–800 nm) and IR region (1000–1600 nm) of HgS NCs as reported previously, extending the emission region of HgS nanomaterial. Therefore, the continuous emission from visible to IR spectral ranges provided HgS material more potential applications.Graphical abstractHighlights► A simple and green aqueous route to NIR-emitting GSH-stabilized β-HgS NCs. ► The emission peak of β-HgS NCs shifted in a wide NIR region from 775 to 1041 nm. ► Enhanced emission efficiency and improved stability of GSH-capped β-HgS NCs.
Co-reporter:Ying-Fan Liu, Jun-Sheng Yu
Journal of Colloid and Interface Science 2010 Volume 351(Issue 1) pp:1-9
Publication Date(Web):1 November 2010
DOI:10.1016/j.jcis.2010.07.047
This paper focuses on the in situ synthesis of novel CdTe/ZnS core–shell quantum dots (QDs) in aqueous solution. Glutathione (GSH) was used as both capping reagent and sulfur source for in situ growth of ZnS shell on the CdTe core QDs. The maximum emission wavelengths of the prepared CdTe/ZnS QDs can be simply tuned from 569 nm to 630 nm. The PL quantum yield of CdTe/ZnS QDs synthesized is up to 84%, larger than the original CdTe QDs by around 1.7 times. The PL lifetime results reveal a triexponential decay model of exciton and trap radiation behavior. The average exciton lifetime at room temperature is 17.1 ns for CdTe (2.8 nm) and 27.4 ns for CdTe/ZnS (3.7 nm), respectively. When the solution of QDs is dialyzed for 3 h, 1.17 ppm of Cd2+ is released from CdTe QDs and 0.35 ppm is released from CdTe/ZnS. At the dose of 120 μg/ml QDs, 9.5% of hemolysis was induced by CdTe QDs and 3.9% was induced by CdTe/ZnS QDs. These results indicate that the synthesized glutathione-capped CdTe/ZnS QDs are of less toxicity and better biocompatibility, so that are attractive for use in biological detection and related fields.Graphical abstractThe photoluminescence spectra of aqueous CdTe (a) and size-dependent GSH-capped CdTe/ZnS core–shell quantum dots (b–g) with high quantum yields.Research highlights► A novel strategy of in situ synthesizing CdTe/ZnS QDs was reported. ► The optimum PL QY of GSH-capped CdTe/ZnS QDs reaches as high as 84%. ► The GSH-capped CdTe/ZnS QDs are less toxic and better biocompatible than CdTe QDs.
Co-reporter:Ying-Fan Liu, Jun-Sheng Yu
Journal of Colloid and Interface Science 2009 Volume 333(Issue 2) pp:690-698
Publication Date(Web):15 May 2009
DOI:10.1016/j.jcis.2009.01.008
This paper describes the selective syntheses of high luminescence CdTe and core–shell CdTe/CdS quantum dots (QDs) in aqueous solution by simple heating refluxing at 100 °C. CdTe QDs are prepared by using three kinds of ligands (thioglycolic acid—TGA, tiopronin—TP, and glutathione—GSH) as stabilizer, respectively. The results of refluxing for 10 min to several hours indicate that GSH-capped CdTe QDs have higher photoluminescence quantum yields (QY 54%) than TGA (QY 41%)- and TP (QY 24%)-stabilized CdTe QDs. Further, using TP-CdTe as core template and GSH as stabilizer and sulfur source, high luminescence GSH-capped CdTe/CdS core–shell QDs have been successfully synthesized in aqueous solution by simple refluxing at 100 °C. The GSH-CdTe/CdS QDs exhibit high fluorescence QYs about 55% over a broad spectral range of 530–588 nm, with the best QY of 83%. TP-stabilized CdTe/CdS QDs are also synthesized with TP as stabilizer and thioacetamide (TAA) as sulfur source, and with the best QY of 80%. GSH-stabilized CdTe and CdTe/CdS QDs are highly biocompatible, monodispersed, and stable under physiological conditions. The method of QDs prepared using GSH is simple and environmentally friendly, and it can be easily extended to the large-scale, aqueous-phase production of QDs.The photoluminescence spectra of CdTe (a) and size-dependent GSH-capped CdTe/CdS core–shell quantum dots (b–g) with high quantum yields obtained in aqueous solution at 100 °C.
Co-reporter:Da-Wei Deng;Yi Pan
European Journal of Inorganic Chemistry 2008 Volume 2008( Issue 7) pp:1129-1134
Publication Date(Web):
DOI:10.1002/ejic.200701091
Abstract
The spontaneous growth of rose-like Se crystals in aqueous solutions at room temperature is reported. The formation of rose-like Se crystals is based on the oxidation of Na2Se in the presence of thioglycerol solution at pH = 11 in a dark ambient atmosphere. In alkaline solutions, the growth evolution of rose-like Se crystals with aging time was followed by scanning electron microscopy (SEM), and an interesting formation process from initial Se monomers to amorphous Se (a-Se) spheres, and to the final rose-like complex structures of Se crystals was observed. Seven kinds of small molecules with different structures, including 1-thioglycerol (TG), mercaptamine (MA), L-cysteine (L-cys), 3-mercaptopropionic acid (MPA), thioglycolic acid (TGA), glycerol (GLY), and L-serine (L-ser), were used to manipulate the growth of Se crystals. The experimental results show that the structures of the small molecules play a key role in the growth of the Se crystals. The presence of thiols in the structure of the small molecules is favorable for the formation of the aggregates of Se crystals, and other termini, such as –NH2, –OH, or –COO–, will determine whether the aggregates of Se crystals are made up of Se slices or Se prisms. These observations suggest that the ligand molecules have a crucial effect on the nucleation, monomers, and growth of nanocrystals. The selection of ligands can be extended to other important materials for further preparation of nanocrystals with desired shapes. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Co-reporter:Yaoping Hu, Jing Yang, Jiangwei Tian and Jun-Sheng Yu
Journal of Materials Chemistry A 2015 - vol. 3(Issue 27) pp:NaN5614-5614
Publication Date(Web):2015/06/09
DOI:10.1039/C5TB01005E
A bottom-up method, using monoethanolamine (MEA) as both a passivation agent and a solvent, has been developed for rapid and massive synthesis of nitrogen-doped carbon dots (N-C-dots) from citric acid under heating conditions. This method requires a relatively mild temperature (170 °C) without special equipment, and affords one-pot large-scale production (39.96 g) of high-quality N-C-dots (quantum yield of 40.3%) in a few minutes (10 minutes). Significantly, an interesting formation process of N-C-dots, for the first time, has been monitored by transmission electron microscopy, ultraviolet-visible absorbance spectroscopy, photoluminescence spectroscopy, Fourier transformed infrared spectroscopy, and thermogravimetric analysis, and a corresponding formation mechanism, including polymerization, aromatization, nucleation, and growth, is proposed. It is important that the MEA-based synthesis of N-C-dots can be extended to various precursors, such as glucose, ascorbic acid, cysteine, and glutathione, which show general universality. Furthermore, the N-C-dots with strong fluorescence, excellent optical stability, and low cytotoxicity are successfully applied as fluorescent probes for bioimaging.
Co-reporter:Jing Yang, Yaoping Hu, Jiangwei Tan, Li Jia, Yu-Hua Zhu and Jun-Sheng Yu
Journal of Materials Chemistry A 2015 - vol. 3(Issue 34) pp:NaN6938-6938
Publication Date(Web):2015/08/04
DOI:10.1039/C5TB01034A
Near-infrared (NIR)-emitting nanocrystals have enormous potential as an enabling technology for applications ranging from tunable infrared lasers to biological labels. Mercury chalcogenide NCs are one of the attractive NCs with NIR emission; however, the potential toxicity of Hg restricts their diverse applications. Herein, we synthesized low-toxic, highly luminescent and stable GSH-capped HgS/ZnS core/shell NCs by an aqueous route for the first time. The core/shell structure was characterized by using TEM, XRD and XPS, which provide evidence for the shell growth. After the successful growth of an appropriate ZnS shell around HgS NCs, poorly luminescent HgS NCs converted into ultra-bright HgS/ZnS NCs, substantially increasing photoluminescence quantum yield up to 43.8% at room temperature. The fluorescence peak of HgS/ZnS NCs was successfully tuned in a wide NIR window ranging from 785 nm to 1060 nm with high emission efficiency by controlling the synthetic pH values. Significantly, an in vitro cytotoxicity study clearly demonstrated that the HgS/ZnS NCs exhibited good biocompatibility as evidenced by the cell viability retained above 80% at a dose of HgS/ZnS NCs up to 150 μg mL−1. More importantly, the low-toxic NIR-emitting HgS/ZnS NCs have proved to be an effective fluorescent label in in vitro and in vivo imaging. The penetration depth reached 2 cm in a nude mouse with distinct separation of autofluorescence and NCs' fluorescence, giving excellent contrast at all depths. The novel highly-luminescent NIR-emitting HgS/ZnS NCs open up new possibilities for highly-sensitive, highly spectrally resolved and multicolor imaging in biomedical applications.
Co-reporter:Wen-Hao Zhang, Jing Yang and Jun-Sheng Yu
Journal of Materials Chemistry A 2012 - vol. 22(Issue 13) pp:NaN6388-6388
Publication Date(Web):2012/02/22
DOI:10.1039/C2JM15630J
HgTe/CdS core/shell nanocrystals (NCs) with highly-stable near-infrared (NIR) emissions were synthesized by employing dihydrolipoic acid (DHLA) as a stabilizer. This synthetic route was performed using Te powder as the tellurium source to prepare HgTe NCs, and H2S generated by the reaction of Na2S–H2SO4 as the sulfur source for synthesizing HgTe/CdS core/shell NCs at room temperature. The fluorescence emission peaks of DHLA-capped HgTe/CdS NCs could be facilely tuned from 910 nm to 1200 nm by varying the reflux time at 100 °C, with a maximum photoluminescence quantum yield of 52%. The obtained HgTe/CdS NCs exhibited an NIR stable emission when heated at 75 °C. Correspondingly, these HgTe/CdS core/shell NCs displayed excellent colloidal dispersion stability and long exciton lifetimes that reached up to 47.6 ns in an aqueous medium. The resultant HgTe/CdSe NCs have been successfully used to fabricate NIR emitting thin films on the surface of polymers and to perform fluorescence imaging in a live animal.
