Co-reporter:Liming Shen, Meiling Chen, Linlin Hu, Xuwei Chen, and Jianhua Wang
Langmuir December 31, 2013 Volume 29(Issue 52) pp:16135-16140
Publication Date(Web):December 31, 2013
DOI:10.1021/la404270w
Carbon dots (C-dots) have been proven to show the capability for direct reduction of Ag+ to elemental silver (Ag0) without additional reducing agent or external photoirradiation by incubating Ag+ with C-dots for 5 min in a water bath at 50 °C. Silver nanoparticles (Ag-NPs) are simultaneously formed with an average size of 3.1 ± 1.5 nm and grew on carbon dots. This process involves the oxidation of amine or phenol hydroxyl groups on the aromatic ring of C-dots. Meanwhile C-dots protect and stabilize the Ag-NPs from aggregation in aqueous medium; that is, the Ag-NPs are stable at least for 45 days in aqueous medium. The formed Ag-NPs cause significant resonance light scattering (RLS), which correlates closely with the concentration of silver cation, and this facilitates quantitative detection of silver in aqueous medium.
Co-reporter:Qing Chen, Xue Hu, Dan-Dan Zhang, Xu-Wei Chen, and Jian-Hua Wang
Bioconjugate Chemistry December 20, 2017 Volume 28(Issue 12) pp:2976-2976
Publication Date(Web):November 21, 2017
DOI:10.1021/acs.bioconjchem.7b00597
The bioconjugation of a polyoxometalate (POMs), i.e., dodecavanadate (V12O32), to DNA strands produces a functional labeled DNA primer, V12O32-DNA. The grafting of DNA primer onto streptavidin-coated magnetic nanoparticles (SVM) produces a novel composite, V12O32-DNA@SVM. The high binding-affinity of V12O32 with the ATP binding site in myosin subfragment-1 (S1) facilitates favorable adsorption of myosin, with an efficiency of 99.4% when processing 0.1 mL myosin solution (100 μg mL–1) using 0.1 mg composite. Myosin adsorption fits the Langmuir model, corresponding to a theoretical adsorption capacity of 613.5 mg g–1. The retained myosin is readily recovered by 1% SDS (m/m), giving rise to a recovery of 58.7%. No conformational change is observed for myosin after eliminating SDS by ultrafiltration. For practical use, high-purity myosin S1 is obtained by separation of myosin from the rough protein extract from porcine left ventricle, followed by digestion with α-chymotryptic and further isolation of S1 subfragment. The purified myosin S1 is identified with matrix-assisted laser desorption/ionization time-of-flight/mass spectrometry, giving rise to a sequence coverage of 38%.
Co-reporter:Yong Tian, Xiaomin Zhang, Huiyan Shen, Aifeng Liu, Zongshan Zhao, Ming-Li Chen, and Xu-Wei Chen
Analytical Chemistry December 19, 2017 Volume 89(Issue 24) pp:13064-13064
Publication Date(Web):November 14, 2017
DOI:10.1021/acs.analchem.7b03578
High time-resolution monitoring of nitrogen dioxide (NO2) is of great importance for studying the formation mechanism of aerosols and improving air quality. Based on the Griess–Saltzman (GS) reaction, a portable NO2 optical sensor was developed by employing a porous polypropylene membrane tube (PPMT) integrated gas permeation collector and detector. The PPMT was filled with GS reagents and covered with a coaxial jacket tube for gas collection. Its two ends were respectively fixed with a yellowish-green light-emitting diode and a photodiode for optic signal reception. NO2 was automatically introduced through the collector by two air pumps cooperating with a homemade gas injector. Under the optimized conditions, the device presented good performance for monitoring NO2, such as a limit of detection of 5.1 ppbv (parts per billion by volume), an intraday precision of 4.1% (RSD, relative standard deviation, n = 11, c = 100 ppbv), an interday precision of 5.7% (RSD, n = 2–3 per day for 5 days, c = 100 ppbv), an analysis time of 4.0 min, and a linearity range extended to 700 ppbv. The developed device was successfully applied to analyzing outdoor air with a comparable precision to that of the standard method of China. The high time-resolution characteristic that includes sampling 15 times per hour and a good stability for 10 days of urban air analysis had also been evaluated.
Co-reporter:Lili Song, Jiaquan Xu, Konstantin Chingin, Tenggao Zhu, Yue Zhang, Yong Tian, Huanwen Chen, and Xuwei Chen
Journal of Agricultural and Food Chemistry August 16, 2017 Volume 65(Issue 32) pp:7006-7006
Publication Date(Web):July 24, 2017
DOI:10.1021/acs.jafc.7b01715
Hemoglobin (Hb) present in the blood and meat juice samples was selectively adsorbed by graphene oxide (GO) particles functionalized with amylopectin (AP) and was sensitively detected by direct internal extractive electrospray ionization mass spectrometry (iEESI-MS) analysis for the identification of meat type. Various samples including the whole blood samples of chicken, duck, sheep, mouse, pigeon, turtledove, and meat juice mixtures were successfully identified based on the difference in molecular composition of Hb reflected in MS. The adulteration of sheep blood with only 2% chicken blood could be detected, which demonstrated the high chemical specificity of the approach. The established method is featured by the high speed of analysis (4 min per sample, including the analyte extraction and sample loading), high sensitivity, minimal sample preparation, and low sample consumption (0.9 μL of whole blood or 300 mg of raw meat). In perspective, the reported method can be extended for the sensitive detection of trace analytes in complex matrices in broad molecular range by using the selective enrichment on functionalized graphene oxide particles followed by iEESI-MS analysis.Keywords: functionalized graphene oxide; hemoglobin; Internal extractive electrospray ionization; mass spectrometry; meat species;
Co-reporter:Yue Zhang;Yuting Zhuang;Huiyan Shen;Xuwei Chen;Jianhua Wang
Microchimica Acta 2017 Volume 184( Issue 4) pp:1037-1044
Publication Date(Web):2017 April
DOI:10.1007/s00604-017-2100-z
The authors have prepared a super-hydrophilic polymer consisting of a poly-polyhedral oligomeric silsesquioxane (POSS)-formaldehyde (PPF) composite. The polymerization process does not require a catalyst and results in a material with excellent hydrophilic properties and abundant functional groups. The PFF composite, even if not chemically modified, can selectively bind glycoproteins due to strong hydrophilic interactions. It is shown that glycoproteins can be selectively captured by the composite that has a binding capacity as large as 542 mg g−1 for the model protein ovalbumin. The PPF was applied to the selective capture and isolation of ovalbumin from complex biological samples.
Co-reporter:Yue Zhang, Hui-Yan Shen, Xin Hai, Xu-Wei Chen, and Jian-Hua Wang
Analytical Chemistry 2017 Volume 89(Issue 2) pp:
Publication Date(Web):December 12, 2016
DOI:10.1021/acs.analchem.6b04407
The rapid and accurate detection of hydrogen sulfide is of great concern due to its unique role on environmental pollution and signal transmission in physiological systems. Herein, we report a smart colorimetric probe for the selective detection of H2S. The probe is prepared via a surfactant-free route with cross-linked polyhedral oligomeric silsesquioxane (POSS) polymer cage as capping ligand and reducing agent under microwave irradiation, called poly-POSS-formaldehyde polymer (PPF) cage-AgNPs or PPF-AgNPs for short. The caged silver nanoparticles are well-dispersed with narrow size distribution within 6.0–8.4 nm. Chloride ions and aldehyde groups in PPF make the nucleation and growth of Ag nanoparticles accomplished within a very short time of 1 min. The positively charged PPF-AgNPs exhibit excellent selectivity to H2S against other anionic species and thiols due to the specific Ag–H2S interaction, where the favorable protection effect of PPF polymer cage from the nanoparticle aggregation is demonstrated. The colorimetric probe presents a quick response to H2S (<3 min) and favorable sensitivity within a linear range of 0.7–10 μM along with a detection limit of 0.2 μM. The probe is well demonstrated by analysis of H2S in various water and biological samples.
Co-reporter:Chang Xia, Xin Hai, Xu-Wei Chen, Jian-Hua Wang
Talanta 2017 Volume 168(Volume 168) pp:
Publication Date(Web):1 June 2017
DOI:10.1016/j.talanta.2017.03.040
•Bi-morphological N, S-GQDs are simultaneously fabricated via a fast, facile and eco-friendly procedure.•The doping of N, S brings the free N, S-GQDs high fluorescence quantum yield and improves the affinity of GQDs with Fe3+.•The cross-linking among L-cysteine molecules and graphene nucleus prevent the aggregation of GQDs efficiently.A facile one-step solvent-free synthesis approach is proposed for the simultaneous fabrication of free and solidified N, S-doped graphene quantum dots (N, S-GQDs) by using citric acid as precursor and L-cysteine as dopant. Graphene nucleus is firstly formed via the intermolecular dehydration of citric acid. N and S are then incorporated into the graphene structure by attacking the margin of graphene nucleus. The cross-linking among the graphene nucleus via the intermolecular condensation leads to the generation of free N, S-GQDs, while the intermolecular amidation between L-cysteine molecules and graphene nucleuses contributes to the solid-state fluorescence graphene quantum dots (SSF-GQDs). The free N, S-GQDs exhibit favorable photoluminescence behaviors such as high fluorescent quantum yield of 74.5%, stable photoluminescence within a wide range of pH and high tolerance to external ionic strength of up to 1.0 mol L−1 NaCl, making it excellent fluorescence probe for the sensitive detection of Fe3+ with a linear range of 0.01–3 μM and a detection limit of 3.3 nM. The solidification of GQDs prevents the aggregation of GQDs efficiently and offers the solidified N, S-GQDs yellow-green fluorescence, with a fluorescence quantum yield of 10.6%. This proposed protocol provides a novel avenue to fabricate diverse fluorescent graphene materials for different practical applications.The simultaneous fabrication of free N, S-doped GQDs and solidified N, S-doped GQDs are achieved via the intermolecular dehydration and intermolecular amidation; the obtained GQDS can be used as excellent fluorescence probes for sensitive detection of Fe3+ and fingermarks.Download high-res image (292KB)Download full-size image
Co-reporter:Li Zhang, Xin Hai, Chang Xia, Xu-Wei Chen, Jian-Hua Wang
Sensors and Actuators B: Chemical 2017 Volume 248(Volume 248) pp:
Publication Date(Web):1 September 2017
DOI:10.1016/j.snb.2017.04.011
•GQDs/CuO nanocomposites are facilely fabricated by the growth of CuO nanoparticles on GQDs.•GQDs/CuO nanocomposites could be used as effective peroxidase mimics for the detection of H2O2 and glucose.•Detection limit of GQDs/CuO nanocomposites for glucose is down to 0.59 μM.Graphene quantum dots-copper oxide nanocomposites (GQDs/CuO) are facilely fabricated by the growth of CuO nanoneedles on graphene quantum dots under mild conditions. The as-prepared GQDs/CuO nanocomposites could be used as an effective peroxidase mimics to catalyze the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) in the presence of H2O2 to produce a blue-colored solution. Investigations on the mechanism indicate that the nature of peroxidase-like activity of GQDs/CuO nanocomposites originates from OH radical generation. The increase of absorbance at 652 nm induced by the catalytic effect of GQDs/CuO nanocomposites offers accurate detection of H2O2 in the range of 0.5–10 μM, along with a detection limit of 0.17 μM. A colorimetric method for serum glucose detection is also proposed by combining the GQDs/CuO catalytic reaction and the enzymatic oxidation of glucose with glucose oxidase. This method is simple, sensitive and selective for glucose detection with a linear range from 2 to 100 μM with a detection limit of 0.59 μM.
Co-reporter:Yue Zhang, Zhiyong Guo, Lu Han, Yang Zhang, Xuwei Chen, Jianhua Wang
Carbon 2017 Volume 122(Volume 122) pp:
Publication Date(Web):1 October 2017
DOI:10.1016/j.carbon.2017.06.051
We report the self-assembly of monolayer polyhedral oligomeric silsesquioxane (POSS) on graphene oxide (GO), where GO acts as a directing template along with the assembly of POSS into a three-dimensional porous framework structure, shortly termed as PPG. The PPG framework contains ultrathin nanopetals with a thickness of ca. 1.95 nm, giving rise to reduced restacking and high surface area. The PPG framework exhibits a high adsorption capacity of up to 1570.3 mg g−1 towards β-lactoglobulin, in addition to a favorable selectivity against other protein species with similar isoelectric points to that of β-lactoglobulin. This might be attributed to the specific hydrogen-bonding donor-acceptor interaction between the calyx structure of β-lactoglobulin and the PPG framework. Satisfactory separation performance of PPG is confirmed by the selective discrimination and isolation of β-lactoglobulin from complex biological sample matrixes, e.g., milk whey. This observation provides a promising approach for the construction of monolayer polymer-modified three-dimensional graphene oxide composites with specific biological application potentials.Download high-res image (262KB)Download full-size image
Co-reporter:Xin Lin, Xin Hai, Ning Wang, Xu-Wei Chen, Jian-Hua Wang
Analytica Chimica Acta 2017 Volume 992(Volume 992) pp:
Publication Date(Web):1 November 2017
DOI:10.1016/j.aca.2017.09.006
•A novel dual-signal model array sensor is developed for sensitive discrimination of proteins.•The protein concentration for complete discrimination is low down to 50 nM.•This dual-signal model array sensor can be applied to sample of complicated matrices.•Discriminations and identifications of microorganisms originated from same species are achieved.The accurate differentiation and identification of proteins play a vital role in many areas. Herein a novel array sensor is developed for sensitive discrimination of proteins, based on the various optical responses of GQDs/AuNPs system towards different protein species. The simultaneously generated distinct variations of fluorescence and absorbance of GQDs/AuNPs system resulted from the interactions between protein species and sensing units contribute to a dual-signal strategy for protein discrimination. The protein concentration for complete discrimination is low down to 50 nM, and accurate discriminations of protein mixture of different concentrations/molar ratio are achieved. The complementary fluorescence and absorbance response makes this dual-signal model array sensor practicable to sample of complicated matrices, demonstrated by the accurate discrimination of protein species in human urine. Moreover, six strains of microorganisms originated from three different species are also successfully discriminated with 100% accuracy (OD600 = 1.0).A dual-signal model array sensor is developed and applied for the highly sensitive discrimination of proteins and microorganisms based on GQDs stabilized AuNPs sensing system.Download high-res image (179KB)Download full-size image
Co-reporter:Dan-Dan Zhang;Peng-Fei Guo;Lin-Lin Hu;Jian-Hua Wang
Journal of Materials Chemistry B 2017 vol. 5(Issue 4) pp:750-756
Publication Date(Web):2017/01/25
DOI:10.1039/C6TB02733D
A novel polyoxometalate (POM)-based hybrid is prepared for the selective adsorption of acidic and/or basic proteins. The solidification of the POM moiety P8W48 is firstly achieved through dehydration condensation between the –OH group on the P8W48 surface and the Si–OH of aminopropyltriethoxysilane (APTS), and thereafter further condensation of the P8W48O184–APTS intermediate with poly(acrylic acid) (PAA) produces a hybrid, by linking carboxyl groups in PAA with –NH2 groups in P8W48O184–APTS via the formation of an amide bond. The P8W48–APTS–PAA hybrid surface is negatively charged due to abundant COO− groups from PAA, which provides electrostatic interactions with positively charged proteins by varying pHs. Meanwhile, the d–p π bond in P8W48 offers strong affinity to other proteins via π–π stacking interaction. The hybrid thus offers potential for achieving selective adsorption of either acidic or basic proteins by simply controlling the adsorption conditions, i.e., pH value or ionic strength of the adsorption medium. With ovalbumin (Ova) and lysozyme (Lys) as the models of acidic and basic proteins, their adsorption behaviors fit the Langmuir model, with adsorption capacities of 367.0 mg g−1 and 74.0 mg g−1, respectively. The retained proteins are readily recovered with 0.01 mol L−1 CTAB, providing recoveries of 89.0% for Ova and 93.0% for Lys. The P8W48–APTS–PAA hybrid is further applied for the isolation of Ova and Lys from real biological samples, egg white.
Co-reporter:Meng-Meng Wang, Qing Chen, Dan-Dan Zhang, Xu-Wei Chen, Ming-Li Chen
Talanta 2017 Volume 171(Volume 171) pp:
Publication Date(Web):15 August 2017
DOI:10.1016/j.talanta.2017.04.079
•A novel nickel substituted polyoxotungsate composite Ni4P2@SiO2 is prepared.•Ni4P2@SiO2 composite exhibits highly adsorption selectivity towards histidine protein.•Isolation of His6-tagged proteins from cell lysate is achieved with Ni4P2@SiO2 composite as an sorbent.By virtue of the flexible structure of polyoxometalates, Ni2+ is encapsulated into trivacant lacunary tungstophosphate ligands by the form of [Ni4] cluster to offer a tetra-nickel substituted polyoxotungsate K6Na4[Ni4(H2O)2(PW9O34)2] (Ni4P2). The Ni4P2 is then immobilized onto the surface of SiO2 nanoparticles by self-assembly under electrostatic interactions to give the product of Ni4P2@SiO2 composites. Due to the specific affinity between substituted Ni2+ in the polyoxotungsate and the histidine residues of protein, Ni4P2@SiO2 composites exhibit highly adsorption selectivity towards histidine protein. This Ni4P2@SiO2 composite is of high stability, and SDS-PAGE assay indicates that it can be used repeatedly as an efficient sorbent for the isolation of His6-tagged proteins from cell lysate with improved performance when compared with commercial NTA-Ni2+ column.Download high-res image (171KB)Download full-size image
Co-reporter:Zhi-Yong Guo, Yue Zhang, Dan-Dan Zhang, Yang Shu, Xu-Wei Chen, and Jian-Hua Wang
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 43) pp:29734
Publication Date(Web):October 12, 2016
DOI:10.1021/acsami.6b11158
A novel strategy for the preparation of magnetic nanospheres encapsulated by mesoporous copper oxide shell, shortly termed as Fe3O4@mCuO, is reported via the calcination of Cu(NH3)4(NO3)2 into continuous mesoporous CuO shell onto the surface of Fe3O4 nanoparticles. The magnetic nanospheres are characterized to possess stable core–shell structure with a crystalline mesoporous CuO layer, exhibiting a CuO loading content of 25.2 ± 1.1% along with a favorable magnetic susceptibility. Fe3O4@mCuO nanospheres exhibit favorable selectivity on the adsorption of hemoglobin with a high adsorption capacity of up to 1162.5 mg g–1. After adsorption, the high magnetic susceptibility allows convenient separation of the nanospheres by an external magnet. The retained hemoglobin could be readily recovered by using 0.5% (m/v) sodium dodecyl sulfate (SDS) as stripping reagent, providing a recovery of 78%. Circular dichroism spectra illustrate virtually no change in the conformation of hemoglobin after the process of adsorption/desorption. Fe3O4@mCuO nanospheres are further applied for the selective isolation of hemoglobin from human whole blood, achieving high-purity hemoglobin as demonstrated by SDS-PAGE (polyacrylamide gel electrophoresis) assays.Keywords: core−shell structure; hemoglobin; isolation; magnetic Fe3O4 nanospheres; mesoporous CuO
Co-reporter:Dan-Dan Zhang, Lin-Lin Hu, Qing Chen, Xu-Wei Chen, Jian-Hua Wang
Talanta 2016 Volume 159() pp:23-28
Publication Date(Web):1 October 2016
DOI:10.1016/j.talanta.2016.06.005
•A novel biocompatible polyoxometalates-based hybrid is developed by solidification of super-lacunary P8W48O18440- polyoxoanions.•The hybrid exhibits favorable adsorption selectivity toward hemoglobin through π-π stacking interaction.•Selective isolation of hemoglobin is achieved from a complex biological sample matrix, human whole blood.A novel polyoxometalate (POM)-based hybrid P8W48-APTS is prepared by the solidification of super-lacunary P8W48O18440- polyoxoanions with APTS in an acidic medium. The oxygen (O−) atoms in P8W48O18440- are bound to silicon atoms in APTS by the formation of Si-O linkage through dehydration condensation. The solidification is confirmed by characterizations with XRD, FT-IR, TGA, SEM and EDXS. Selective isolation of proteins of interest, hemoglobin (Hb) in this case, from complex sample matrices is achieved by using P8W48-APTS hybrid as adsorbent under controlled conditions. 5.0 mg of P8W48-APTS hybrid results in an adsorption efficiency of 93% for 100 mg L−1 hemoglobin in 1.0 mL sample solution at pH 7. The adsorption behavior of Hb onto P8W48-APTS hybrid fits Langmuir adsorption model, corresponding to an adsorption capacity of 355.0 mg g−1. The retained Hb could be readily recovered with either a SDS solution (0.1 mol L−1) or a Na3PO4 (0.1 mol L−1) solution as stripping reagent, providing recoveries of 94.6% or 83.9%, respectively. The biological activity of Hb remains 96.7% after an adsorption/desorption process (with elution by SDS), which illustrates virtually no change on the conformation of hemoglobin. The P8W48-APTS hybrid has been applied for the selective adsorption of Hb from human whole blood, and the results are demonstrated by SDS-PAGE assay.A novel polyoxometalate-based hybrid is developed by solidification of super-lacunary P8W48O18440- polyoxoanions which exhibits favorable selectivity to hemoglobin adsorption.
Co-reporter:Quan-Xing Mao, Lu Han, Yang Shu, Xu-Wei Chen, Jian-Hua Wang
Talanta 2016 Volume 161() pp:54-61
Publication Date(Web):1 December 2016
DOI:10.1016/j.talanta.2016.08.031
•Ionic liquids modified carbon nanodots is prepared at ambient temperature via covalent conjugation interaction.•The biocompatibility of carbon nanodots is significantly improved with the modification of ionic liquid moiety.•The prepared carbon nanodots show potentials in two-color cell imaging.In the practice of in vivo imaging with carbon nanodots (CNDs) as probe, the volume of CNDs solution introduced into living body should be kept at minimum, and a higher concentration is needed to ensure sufficient quantity of the probe for obtaining bright image. Therefore, the improvement on biocompatibility of the CNDs is among the most important and critical issues. We report herein the improvement on the biocompatibility of CNDs with modification by ionic liquid. Amide group functionalization of carbon nanodots is first conducted through microwave irradiation, followed by coupling the ionic liquid 1-carboxymethyl-3-methyl imidazolium bromide on the surface of the Amide-CNDs via covalent conjunction to produce the modified carbon nanodots (IL-CNDs). This modification process significantly improved the biocompatibility of CNDs, as demonstrated by cell imaging at a higher concentration of CNDs. Both Amide-CNDs and IL-CNDs exhibit abundant surface functional groups, resulting in tunable fluorescent emission feature and potential applications in two-color cell imaging.Ionic liquid modified carbon nanodots are prepared via covalent conjugation between carboxyl and amide groups functionalized carbon nanodots which exhibit significant improvement on the biocompatibility.
Co-reporter:Quan-Xing Mao, Shuang E, Jun-Mei Xia, Ru-Sheng Song, Yang Shu, Xu-Wei Chen, and Jian-Hua Wang
Langmuir 2016 Volume 32(Issue 46) pp:12221-12229
Publication Date(Web):November 2, 2016
DOI:10.1021/acs.langmuir.6b03331
Tunable fluorescent emission and applications in both in vitro and in vivo imaging of hydrophobic carbon nanodots (CNDs) with rapid penetration capability are reported. The hydrophobic CNDs are prepared via hydrothermal treatment of ionic liquid 1-ethyl-3-methylimidazolium bromide and exhibit excitation-dependent photoluminescence behavior along with a red-shift in the excitation/emission maxima with concentration. The quantum yields of the as-prepared CNDs are in the range of 2.5–4.8% at an excitation wavelength of 300–600 nm. The rapid penetration behavior (within 1 min) of CNDs into the cell membrane significantly reduces the sample treatment time and avoids potential fluorescence quenching induced by the interaction between CNDs and samples. A co-location study reveals that the hydrophobic CNDs are distributed mainly in the lysosome. The potentials of the hydrophobic CNDs as fluorescent probe in in vitro and in vivo imaging are well demonstrated by the labeling of HeLa cells, MCF-7 cells, A549 cells, and Kunming mice.
Co-reporter:Yang Shu, Mingcen Gao, Xueying Wang, Rusheng Song, Jun Lu, Xuwei Chen
Talanta 2016 Volume 149() pp:6-12
Publication Date(Web):1 March 2016
DOI:10.1016/j.talanta.2015.11.009
•An IL ATPS combined with an in situ DLLME method is developed.•The metathesis reaction of IL triggers the DLLME.•This method was applied to the separation of curcuminoids from Curcumin Longa.An aqueous two-phase extraction system (ATPS) combined with an in situ dispersive liquid-liquid microextraction (DLLME) method using imidazolium ionic liquids (ILs) for the separation of curcuminoids is developed. The influence of structure of IL, the type of metathesis reagents, and the back extraction agents on the extraction efficiency is investigated. 2.0 mg of curcuminoids are extracted by an IL ATPS composed of 0.4 g 1,3-diethylimidazolium iodine (EeimI), 0.6 g potassium hydrogen phosphate, 1.0 g water. Then the bis[(trifluoromethyl)sulfonyl]imide lithium (LiNTf2) aqueous solution is added to the EeimI-rich phase of the ATPS. The water-immiscible ionic liquids, 1,3-diethylimidazole bis[(trifluoromethyl)sulfonyl]imide (EeimNTf2), forms by the metathesis reaction. The in situ DLLME is triggered simultaneously and further purifies the curcuminoids. 92% of EeimI transforms into EeimNTf2 and thus the Eeim+ cation is used for twice in this method. Finally, 0.1 mol/L NaOH aqueous solution is used as the back extraction reagent. The curcuminoids precipitate is achieved with 93% of recovery when the aqueous solution is adjusted to pH 3.0. This ATPS-DLLME method is successfully applied to the separation of curcuminoids from Curcuma Longa (0.96±0.02% of extraction yield, a purity of >51% with respect to the total dry mass of the product).
Co-reporter:Xin Hai, Quan-Xing Mao, Wen-Jing Wang, Xiao-Feng Wang, Xu-Wei Chen and Jian-Hua Wang
Journal of Materials Chemistry A 2015 vol. 3(Issue 47) pp:9109-9114
Publication Date(Web):02 Nov 2015
DOI:10.1039/C5TB01954K
Boron-doped graphene quantum dots (B-GQDs) are prepared via a one-pot acid-free microwave approach with graphene oxide as the carbon source and borax as the boron source. Boron atoms are incorporated into the graphene framework by attacking the defects in the graphene structure, deriving an atomic percentage of 1.44% in the final product. Boron atom doping into the graphene structure and restoration of defects in the graphene structure bring the obtained B-GQDs favorable photoluminescence behaviors. The as-prepared B-GQDs exhibit excitation-independent photoluminescence behaviors with an excitation/emission maximum at 320/430 nm, and a fluorescence quantum yield of 21.1%. Moreover, stable photoluminescence is observed within a wide range of pH 3.0–11.0. A tolerance to an external ionic strength of up to 2.0 mol L−1 KCl along with an excellent anti-photobleaching capability is achieved. The standard MTT assay suggests that the B-GQDs are of low cytotoxicity with favorable biocompatibility, and a cell viability of 87% could be achieved at 4.0 mg mL−1 of B-GQDs. The practical application of B-GQDs in bio-analysis is demonstrated by bio-imaging of HeLa cells.
Co-reporter:Qing Chen, Dan-Dan Zhang, Meng-Meng Wang, Xu-Wei Chen and Jian-Hua Wang
Journal of Materials Chemistry A 2015 vol. 3(Issue 34) pp:6964-6970
Publication Date(Web):28 Jul 2015
DOI:10.1039/C5TB01298H
A novel polyoxometalate (POM)-based organic–inorganic hybrid [C33H24O4]H3PMo12O40, namely, TPPA–PMo12, is prepared via a one-pot hydrothermal reaction between a Keggin POM (H3PMo12O40, PMo12) and a star-like N-donor ligand (tri(4-pyridylphenyl)amine, TPPA). The hybrid polyoxometalate is confirmed by characterization with XRD, FT-IR, TGA, SEM and EDS. It exhibits excellent adsorption performance towards β-lactoglobulin, and thus a solid-phase extraction procedure was established for the efficient and selective isolation of β-lactoglobulin from complex sample matrices. At pH 5.0, an adsorption efficiency of 99.2% is achieved for processing 100 μg mL−1 β-lactoglobulin in 1.0 mL aqueous solution with 0.5 mg TPPA–PMo12 as an adsorbent. The adsorption behavior of β-lactoglobulin fits the Langmuir model, corresponding to a theoretical adsorption capacity of 1428 mg g−1. The retained β-lactoglobulin could be readily recovered by rinsing with 0.05 mol L−1 Tris-HCl buffer, facilitating a recovery of 91.5%. The hybrid polyoxometalate was practically applied to the selective isolation of β-lactoglobulin from milk whey, and SDS-PAGE assay results clearly indicate that β-lactoglobulin of high-purity is obtained.
Co-reporter:Quan-Xing Mao, Wen-Jing Wang, Xin Hai, Yang Shu, Xu-Wei Chen and Jian-Hua Wang
Journal of Materials Chemistry A 2015 vol. 3(Issue 29) pp:6013-6018
Publication Date(Web):22 Jun 2015
DOI:10.1039/C5TB00963D
The regulation of hydrophilicity/hydrophobicity of carbon dots (CDs) at will is most important. One pot simultaneous preparation of hydrophilic and/or hydrophobic CDs is herein reported, via a hydrothermal process with 1-butyl-3-methylimidazolium hexafluorophosphate as the carbon source in a H3PO4–ethanol medium. The hydrophilicity or hydrophobicity of CDs (or their proportions) is simply regulated by varying the H3PO4/ethanol molar ratio. Hydrophilic and hydrophobic CDs are obtained simultaneously with H3PO4/ethanol molar ratios within 0–1.72, while hydrophilic or hydrophobic CDs are the sole product obtained from H3PO4–BmimPF6 or BmimPF6-only systems. The CDs exhibit excitation-dependent maximum fluorescence at 360/440 nm (hydrophilic) and 430/510 nm (hydrophobic), with quantum yields of 17.0% and 7.7%, respectively. Both hydrophilic and hydrophobic CDs obtained by this approach exhibit favorable biocompatibility and offer great potential in bio-imaging as demonstrated for the fluorescent labeling and imaging of live HeLa cells.
Co-reporter:Dan-Dan Zhang, Qing Chen, Lin-Lin Hu, Xu-Wei Chen and Jian-Hua Wang
Journal of Materials Chemistry A 2015 vol. 3(Issue 21) pp:4363-4369
Publication Date(Web):21 Apr 2015
DOI:10.1039/C5TB00544B
A Keggin-type cobalt mono-substituted silicotungstic acid doped with aniline (SiW11Co–PANI composite, where PANI denotes polyaniline) is prepared by a liquid phase method at room temperature. The obtained SiW11Co–PANI composite possesses a porous framework structure and has proven to be a promising adsorbent for the retention of proteins, which exhibits favorable selectivity toward the adsorption of ovalbumin from egg whites. 5.0 mg of SiW11Co–PANI composite gives rise to an adsorption efficiency of >70% for 100 mg L−1 ovalbumin in 1.0 mL of sample solution within a wide pH range of 3–9, and a maximum adsorption efficiency of 92% is achieved at pH 9. The adsorption behavior of ovalbumin onto the SiW11Co–PANI composite fits the Langmuir adsorption model, corresponding to a sorption capacity of 200.0 mg g−1. The retained ovalbumin could be readily recovered by using a 0.1 mol L−1 phosphate buffer at pH 5.6 as a stripping reagent, providing a recovery of 84.4%. Circular dichroism (CD) spectra illustrate virtually no change in the conformation of ovalbumin after the process of adsorption–desorption. The SiW11Co–PANI composite has been applied for the selective adsorption of ovalbumin from the chicken egg white, and SDS-PAGE assay demonstrates that high purity of ovalbumin is obtained.
Co-reporter:Yue Zhang, Jia-Wei Liu, Xu-Wei Chen and Jian-Hua Wang
Journal of Materials Chemistry A 2015 vol. 3(Issue 6) pp:983-989
Publication Date(Web):23 Dec 2014
DOI:10.1039/C4TB01792G
A three-dimensional graphene oxide framework is prepared via a simple and cost-effective one-pot approach through the hydrogen-bonding interaction between amylopectin and graphene oxide in the presence of hydrazine hydrate acting as a reducing reagent. The framework is shortly termed as AP-rGO and it is characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), surface charge analysis and thermogravimetric analysis (TGA). The obtained AP-rGO framework exhibits excellent adsorption performance toward hemoglobin in the presence of other protein species. It provides a maximum adsorption capacity of 1010 mg g−1. In a neutral medium (at pH 7), 70 mg L−1 of Hb in 1.0 mL of aqueous solution could be effectively adsorbed by 1.0 mg of the AP-rGO framework, giving rise to an adsorption efficiency of 92.7%. The practical application of the AP-rGO framework is demonstrated by the removal of a highly abundant protein, i.e., hemoglobin, from complex biological sample matrices, e.g., human whole blood. The removal efficiency is well confirmed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) assay.
Co-reporter:Yang Zhang, Li-Gang Xing, Xu-Wei Chen, and Jian-Hua Wang
ACS Applied Materials & Interfaces 2015 Volume 7(Issue 9) pp:5116
Publication Date(Web):February 18, 2015
DOI:10.1021/am508836m
Assembly of nano-objects with tunable size, morphology and function into integrated nanostructures is critical for the development of a novel nanosystem in adsorption, sensing and drug/gene delivery. We demonstrate herein the fabrication of ordered mesoporous carbon by assembling uniform and highly dispersed copper-oxide (CuxOy) nanoparticles into the mesopores via evaporation of solvent from the mixture of triblock copolymer, carbon source and metal nitrate hydrate. The ordered 2D hexagonal mesoporous carbon composite possesses a large surface area of 580.8 cm2/g, a uniform pore size of 5.4 nm, a large pore volume of 0.64 cm3/g and a high metal content of 3.32 wt %. The mesoporous composite exhibits excellent adsorption selectivity and high adsorption capacity to hemoglobin (Hb) under the synergistic effect of hydrophobic and metal-affinity interactions as well as size exclusion. This facilitates multimode adsorption of hemoglobin fitting Langmuir adsorption model and offers an adsorption capacity of 1666.7 mg g–1 for hemoglobin. The mesoporous composite is used for the isolation of hemoglobin from human whole blood with high purity. It demonstrates the potential of the copper-oxide nanoparticle-embedded mesoporous carbon composite in selective isolation/removal of specific protein species from biological sample matrixes.Keywords: copper-oxide nanoparticles; hemoglobin; mesoporous carbon; multimodal adsorption
Co-reporter:Shuai Chen, Ling Wei, Xu-Wei Chen, and Jian-Hua Wang
Analytical Chemistry 2015 Volume 87(Issue 21) pp:10902
Publication Date(Web):October 1, 2015
DOI:10.1021/acs.analchem.5b02453
It is of great importance to develop novel and sensitive sensing materials for the detection of proteins and microorganisms to fulfill the demand of disease diagnosis. As the selectivity and sensitivity of sensing systems are highly dependent on the receptor, the fluorescent sensor array with imidazolium ionic liquids (ILs) and ionic liquid–quantum dots conjugates as semiselective receptors is developed for protein/bacteria differential sensing or discrimination. The IL sensing system formed by 1,3-dibutylimidazolium chloride (BBimCl), 1,3-diethylimidazolium bromine (EEimBr), 1,3-dibutylimidazolium bromine (BBimBr), 1,3-dihexylimidazolium bromine (HHimBr), and 1,3-dioctylimidazolium bromine (OOimBr) and the IL@QDs/QDs sensing system formed by CdTe, BBimCl@CdTe, EEimBr@CdTe, BBimBr@CdTe, and HHimBr@CdTe are tested, by transferring the interaction binding difference between receptors and proteins to the fluorescent response pattern. The IL sensing system is applied to the identification of 48 samples (8 proteins at 500 nM) with an accuracy of 91.7%. For the IL@QDs/QDs sensing system, 8 proteins are completely distinguished with 100% accuracy at a very low concentration level of 10 nM. Remarkably, 36 training cases (6 strains of bacteria from 3 different species) are discriminated with 100% (OD600 of 0.1).
Co-reporter:Li-Ming Shen, Qing Chen, Zheng-Yue Sun, Xu-Wei Chen, and Jian-Hua Wang
Analytical Chemistry 2014 Volume 86(Issue 10) pp:5002
Publication Date(Web):April 28, 2014
DOI:10.1021/ac500601k
Recently, the development of optical probes for the assay of thiols, e.g., cysteine (Cys), homocysteine (Hcy), and glutathione (GSH), has been an active research area due to their biological significance. We have found that carbon dots (C-dots) exhibit direct reduction of Ag+ to elemental silver (Ag0) and the resulting Ag0 formed a silver nanoparticle (Ag-NP) spontaneously. The excessive C-dots consume free Ag+ in the solution by binding Ag+ with functional groups on the C-dots surface and thus inhibits the growth of Ag-NPs. Biothiols can coordinate with Ag+ through thiol groups, and afterward, the Ag+-biothiol complex gradually releases free Ag+ to ensure its reduction by C-dots and thus facilitates the growth of Ag-NPs on C-dots surface. A colorimetric assay procedure is thus developed for fast detection of biothiols based on Ag-NPs plasmon absorption. The linear calibration range can be regulated by controlling the concentration of Ag+. Two linear ranges were obtained for the biothiols assay at different levels, which offer ultrahigh sensitivity for the assay of an ultratrace amount of biothiols with detection limits of 1.5, 2.6, and 1.2 nM for Cys, Hcy, and GSH, respectively. The precisions for the assay of Cys, Hcy, and GSH at 20 nM are achieved as 3.1%, 3.1%, and 2.4%. In addition, the sensing system exhibits good selectivity toward biothiols in the presence of other amino acids, the major metal cations, and biomolecules in biological fluids. For the assay of 20 nM Cys, 150-fold of coexisting amino acids, 2500-fold of Ca2+, Mg2+, glucose, and ascorbic acid, and 38-fold of HSA are tolerated. In the assay of Cys in human plasma, spiking recoveries of 94% to 108% are obtained at 100 μM.
Co-reporter:Shuai Chen, Xin Hai, Xu-Wei Chen, and Jian-Hua Wang
Analytical Chemistry 2014 Volume 86(Issue 13) pp:6689
Publication Date(Web):May 26, 2014
DOI:10.1021/ac501497d
We report a facile green approach for in situ growth of silver nanoparticles (AgNPs) on the surface of graphene quantum dots (GQDs). GQDs serve as both reducing agent and stabilizer, and no additional reducing agent and stabilizer is necessary. The GQDs/AgNPs hybrid exhibits a superior absorbance fading response toward the reduction of H2O2. A simple colorimetric procedure is thus proposed for ultrasensitive detection of H2O2 without additional chromogenic agent. It provides a record detection limit of 33 nM for the detection of H2O2 by the AgNPs-based sensing system. This colorimetric sensing system is further extended to the detection of glucose in combination with the specific catalytic effect of glucose oxidase for the oxidation of glucose and formation of H2O2, giving rise to a detection limit of 170 nM. The favorable performances of the GQDs/AgNPs hybrid are due to the peroxidase-like activity of GQDs.
Co-reporter:Xiaofeng Wang, Ligang Xing, Yang Shu, Xuwei Chen, Jianhua Wang
Analytica Chimica Acta 2014 Volume 837() pp:64-69
Publication Date(Web):21 July 2014
DOI:10.1016/j.aca.2014.06.002
•Polymeric ionic liquid (PIL) microspheres are adopted for DNA isolation.•Fast adsorption equilibrium of DNA on PIL is achieved within 1 min.•The adsorption capacity of the PIL is much higher than that of the reported adsorbents.A novel polymeric ionic liquid (PIL) microsphere, poly(1-vinyl-3-(2-methoxy-2-oxyl ethyl)imidazolium) hexafluorophosphate, is prepared via W/O emulsion polymerization. Rapid ion-exchange between the anionic moieties of PIL and DNA fragments is demonstrated facilitating the exchange equilibrium to be reached within 1 min. The PIL microspheres exhibit a high capacity of 190.7 μg mg−1 for DNA adsorption. A fast DNA isolation protocol is thus developed with the PIL microspheres as solid phase adsorbent. It is feasible to facilitate DNA adsorption or stripping from the microspheres by simply regulating the concentration of salt. DNA adsorption is facilitated at low salt concentration, while higher concentration of salt entails DNA recovery from the microspheres. In practice, the retained DNA could be readily recovered with 1.0 mol L−1 NaCl as stripping reagent, giving rise to a recovery of ca. 80.7%. The PIL microspheres are used for the adsorption/isolation of plasmid DNA from E. coli cell culture, demonstrating a superior adsorption performance with respect to that achieved by a commercial Plasmid Miniprep Kit.
Co-reporter:Qing Chen;Li-Ming Shen;Jie Xia;Jian-Hua Wang
Journal of Separation Science 2014 Volume 37( Issue 19) pp:2716-2723
Publication Date(Web):
DOI:10.1002/jssc.201400401
Keggin-type phosphomolybdate ((C19H42N)3PMo12O40) is prepared by a one-step solid-state reaction at room temperature and characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, and elemental analysis. The as-prepared phosphomolybdate is demonstrated to be an efficient adsorbent for proteins. In this particular case, the selective adsorption of neutral protein hemoglobin is achieved. While under the same conditions virtually no adsorption of acidic and basic proteins, represented by bovine serum albumin and cytochrome c, are observed. A solid-phase extraction procedure is developed for the selective isolation of hemoglobin. At pH 6, a sorption efficiency of 91.4% is achieved for 100 μg/mL hemoglobin in 1.0 mL solution by using 5.0 mg of the phosphomolybdate. The adsorption behavior of hemoglobin fits well with a Langmuir adsorption model, corresponding to a theoretical adsorption capacity of 55.86 mg/g. The retained hemoglobin could be readily recovered by using a 60 mmol/L imidazole solution at pH 7, giving rise to a recovery of 64.7%. The practical application of phosphomolybdate for protein adsorption is demonstrated by the selective isolation of hemoglobin from human whole blood followed by a sodium dodecyl sulfate polyacrylamide gel electrophoresis assay.
Co-reporter:Ming-Li Chen, Lin-Yu Ma, Xu-Wei Chen
Talanta 2014 Volume 125() pp:78-86
Publication Date(Web):1 July 2014
DOI:10.1016/j.talanta.2014.02.037
•New arsenic speciation procedures in last 5 years are reviewed.•The performances of various sample pretreatment techniques in arsenic speciation are discussed and compared.•Strategies for arsenic speciation are compared.•Challenges and future developments are proposed.Considerable analytical methods have been developed for arsenic speciation in the last 5 years, the details of these new arsenic speciation procedures are thus summarized in present mini review. The performances of various sample pretreatment techniques including solid phase extraction, liquid–liquid extraction, hydride generation, liquid chromatography and capillary electrophoresis, which offer effective preconcentration/separation and eventually contribute greatly to excellent sensitivity and selectivity in arsenic speciation when coupling with suitable detection mode, are discussed and compared thoroughly. High-performance liquid chromatography coupling with inductively coupled plasma mass spectrometry and hydride generation atomic spectrometry are proved to be the most powerful hyphenated methodologies for arsenic speciation in environmental and biological matrices.
Co-reporter:Mei-Ling Chen, Li-Ming Shen, Shuai Chen, Hui Wang, Xu-Wei Chen and Jian-Hua Wang
Journal of Materials Chemistry A 2013 vol. 1(Issue 20) pp:2582-2589
Publication Date(Web):25 Mar 2013
DOI:10.1039/C3TB20234H
β-FeOOH has shown promise as a new contrast agent in magnetic resonance imaging (MRI), however, sensitive and accurate MR imaging is largely limited by its low transverse relaxivity (r2). Herein, for the first time we report in situ growth of β-FeOOH nanorods onto PEGylated graphene oxide (GO) sheets to produce a nanocomposite, e.g., GO-PEG–β-FeOOH. This nanocomposite exhibits a record ultra-high transverse relaxivity (r2) value of 303.81 mM−1 s−1, that is, >60 times higher than those achieved by hitherto reported β-FeOOH based MRI contrast agents. This well facilitates its practical use as a contrast agent for in vivo MR imaging. PEG on the surface of the GO nanocomposite improved the colloidal stability in aqueous medium. In addition, in vitro cell viability tests demonstrated that GO-PEG–β-FeOOH has minimal cellular toxicity. GO-PEG–β-FeOOH has been used for loading doxorubicin hydrochloride (DOX) with a capacity of 1.35 mg mg−1, which exhibits high efficiency in Hela cell apoptosis. These results indicated that GO-PEG–β-FeOOH provides an effective alternative to the existing nanoparticle-based contrast agents for non-invasive in vivo MR imaging and cancer therapy.
Co-reporter:Bo Hu, Li-Pei Zhang, Xu-Wei Chen and Jian-Hua Wang
Nanoscale 2013 vol. 5(Issue 1) pp:246-252
Publication Date(Web):25 Oct 2012
DOI:10.1039/C2NR32457A
A hybrid bactericidal material, gold nanorod-covered kanamycin-loaded hollow SiO2 (HSKAurod) nanocapsules, is constructed. The hybrid material combines the features of a chemical drug with photothermal physical sterilization which decreases the dosage of broad-spectrum antibiotic and the physical damage of biological systems. Hollow SiO2 nanocapsules are used as carriers for drug delivery. The nanocapsules load a model drug, kanamycin, and are covered with gold nanorods to avoid drug leakage and realize photothermal treatment. The sterilizing effect on the bacterial strain is investigated by incubating E. coli BL21 with the hybrid nanocapsules and irradiating under near-infrared light (NIR) for 20 min. A bactericidal effect, i.e., a sterilizing rate of 53.47%, is achieved for the HSKAurod nanocapsules under NIR irradiation, with respect to a net sum sterilizing rate of 34.49% for the individual components of the HSKAurod nanocapsules, e.g., carrier nanocapsules, chemical sterilization of kanamycin and physical sterilization due to the gold nanorods under NIR irradiation. It is demonstrated that the combination of chemical drug and physical sterilization results in an obvious synergistic effect and makes the sterilization more effective. This novel hybrid has great potential as an adjuvant therapeutic alternative material for sterilization or even for the control of disease.
Co-reporter:Jia-Wei Liu, Ting Yang, Shuai Chen, Xu-Wei Chen and Jian-Hua Wang
Journal of Materials Chemistry A 2013 vol. 1(Issue 6) pp:810-818
Publication Date(Web):30 Nov 2012
DOI:10.1039/C2TB00334A
A novel functionalized graphene-based composite is prepared by successive modification of graphene oxide (GO) with epichlorohydrin (ECH), iminodiacetic acid (IDA) and 1-phenylboronic acid (1-PBA) through covalent functionalization and then chelating with nickel ions. Characterizations by FT-IR, XRD, SEM, TGA and ICP-MS demonstrate the successful modification of the graphene surface, resulting in a GO–PBA–IDA–Ni composite with a Ni2+ immobilization amount of 3.01 × 10−3 mol g−1. The composite shows favorable selectivity for the adsorption of lysozyme (Lys). In practice, a homogeneous GO–PBA–IDA–Ni film with a thickness of ca. 1.0 μm is fabricated by filtering the composite through a cellulose membrane with a pore aperture of 1.2 μm. The GO–PBA–IDA–Ni film is subsequently fastened into a rounded membrane cartridge and incorporated into a sequential injection system for on-line selective isolation of Lys. An adsorption efficiency of ca. 96% is achieved for 25 μg ml−1 Lys in 500 μl of sample solution at a loading rate of 5 μl s−1. Metal affinity and electrostatic interactions are the main driving forces for governing the protein adsorption behaviors. The retained Lys is readily recovered by a borate buffer (pH 10) containing 1.0 mol l−1 NaCl and 20 mmol l−1 imidazole, giving rise to a recovery of ca. 90%. The practical applicability of the composites is demonstrated by selective isolation of Lys from chicken egg white, and SDS-PAGE assay indicates that Lys is selectively isolated with high purity from complex matrices.
Co-reporter:Liming Shen, Meiling Chen, Linlin Hu, Xuwei Chen, and Jianhua Wang
Langmuir 2013 Volume 29(Issue 52) pp:16135-16140
Publication Date(Web):2017-2-22
DOI:10.1021/la404270w
Carbon dots (C-dots) have been proven to show the capability for direct reduction of Ag+ to elemental silver (Ag0) without additional reducing agent or external photoirradiation by incubating Ag+ with C-dots for 5 min in a water bath at 50 °C. Silver nanoparticles (Ag-NPs) are simultaneously formed with an average size of 3.1 ± 1.5 nm and grew on carbon dots. This process involves the oxidation of amine or phenol hydroxyl groups on the aromatic ring of C-dots. Meanwhile C-dots protect and stabilize the Ag-NPs from aggregation in aqueous medium; that is, the Ag-NPs are stable at least for 45 days in aqueous medium. The formed Ag-NPs cause significant resonance light scattering (RLS), which correlates closely with the concentration of silver cation, and this facilitates quantitative detection of silver in aqueous medium.
Co-reporter:Dr. Shuai Chen;Xin Hai;Chang Xia;Dr. Xu-Wei Chen;Dr. Jian-Hua Wang
Chemistry - A European Journal 2013 Volume 19( Issue 47) pp:15918-15923
Publication Date(Web):
DOI:10.1002/chem.201302207
Abstract
We report the first pyrrole-ring surface-functionalized graphene quantum dots (p-GQDs) prepared by a two-step hydrothermal approach under microwave irradiation in an ammonia medium. The most distinct feature of the functionalized GQDs is that both the excitation and emission wavelengths fall into the visible-light region. The p-GQDs are excited by visible light at λex 490 nm (2.53 eV) to emit excitation-independent photoluminescence at a maximum wavelength of λem 550 nm. This is thus far the longest emission wavelength reported for GQDs. Stable photoluminescence is achieved at pH 4–10 with an ionic strength of 1.2 mol L−1 KCl. These features make the p-GQDs excellent probes for bio-imaging and bio-labeling, which is demonstrated by imaging live HeLa cells.
Co-reporter:Shuai Chen, Jia-Wei Liu, Mei-Ling Chen, Xu-Wei Chen and Jian-Hua Wang
Chemical Communications 2012 vol. 48(Issue 61) pp:7637-7639
Publication Date(Web):13 Jun 2012
DOI:10.1039/C2CC32984K
Graphene quantum dots prepared by a one-step hydrothermal procedure in a microwave exhibit an unusual emission transformation in strong acidic media and at high concentration, induced by self-assembled J-type aggregation under restrained π–π interactions.
Co-reporter:Li-Pei Zhang, Xiao-Xing Zhang, Bo Hu, Li-Ming Shen, Xu-Wei Chen and Jian-Hua Wang
Analyst 2012 vol. 137(Issue 21) pp:4974-4980
Publication Date(Web):28 Aug 2012
DOI:10.1039/C2AN36049G
A label-free strategy based on the Fenton reaction with DNA-templated silver nanoclusters (DNA-Ag NCs) as a probe is demonstrated for the sequential detection of Cu2+, ascorbic acid (AA) and H2O2. Cu2+ causes a structural change of the DNA template in DNA-Ag NCs to resist the environmental quenching and emit stronger fluorescence. The addition of AA in the presence of Cu2+ results in a further fluorescence increase of the DNA-Ag NCs. Interestingly, an even higher fluorescence enhancement is recorded by introducing Cu2+ into the DNA-Ag NCs–AA probing system. The fluorescence turn-on probe offers detection limits of 3 nM for Cu2+ and 7 nM for AA. Thereafter, the addition of H2O2 generates hydroxyl radicals from the Fenton reaction, which induces cleavage of the DNA template, leading to fluorescence quenching of the DNA-Ag NCs. This facilitates H2O2 detection. Moreover, based on the DNA-templated fluorescent silver nanoclusters and Fenton reaction, a multiple logic gate system, including AND and a three-input logic gate, is constructed, with Cu2+, AA and H2O2 as inputs, and the fluorescence intensity of the DNA-Ag NCs probe as output.
Co-reporter:Mei-Ling Chen, Ye-Ju He, Xu-Wei Chen, and Jian-Hua Wang
Langmuir 2012 Volume 28(Issue 47) pp:16469-16476
Publication Date(Web):November 6, 2012
DOI:10.1021/la303957y
A novel and specific nanoplatform for in vitro simultaneous cancer-targeted optical imaging and magnetically guided drug delivery is developed by conjugating CdTe quantum dots with Fe3O4-filled carbon nanotubes (CNTs) for the first time. Fe3O4 is filled into the interior of the CNTs, which facilitates magnetically guided delivery and improves the synergetic targeting efficiency. In comparison with that immobilized on the external surface of CNTs, the magnetite nanocrystals inside the CNTs protect it from agglomeration, enhance its chemical stability, and improve the drug loading capacity. It also avoids magnetic nanocrystals-induced quenching of fluorescence of the quantum dots. The SiO2-coated quantum dots (HQDs) attached on the surface of CNTs exhibit favorable fluorescence as the hybrid SiO2 shells on the QDs surface prevent its fluorescence quenching caused by the CNTs. In addition, the hybrid SiO2 shells also mitigate the toxicity of the CdTe QDs. By coating transferrin on the surface of the herein modified CNTs, it provides a dual-targeted drug delivery system to transport the doxorubicin hydrochloride (DOX) into Hela cells by means of an external magnetic field. The nanocarrier based on the multifunctional nanoplatform exhibits an excellent drug loading capability of ca. 110%, in addition to cancer-targeted optical imaging as well as magnetically guided drug delivery.
Co-reporter:Yang Shu, Menglin Liu, Shuai Chen, Xuwei Chen, and Jianhua Wang
The Journal of Physical Chemistry B 2011 Volume 115(Issue 42) pp:12306-12314
Publication Date(Web):September 15, 2011
DOI:10.1021/jp2071925
The interactions of imidazolium ionic liquids (ILs), i.e., dibutylimidazolium chloride, 1-butyl-3-methylimidazolium chloride, and 1-butyl-3-methylimidazolium nitrate, with bovine serum albumin (BSA) were studied by monitoring the spectral behaviors of IL–BSA aqueous systems. The intrinsic fluorescence of BSA at 340 nm excited at 230 nm is obviously quenched by these ILs due to complex dynamic collision and their quenching constants are at the order of 102 L mol–1. However, no fluorescence quenching is observed within the same region when excited at 280 nm, which is widely used for probing protein conformations. Thermodynamic investigations reveal that the combination between ILs and BSA is entropy driven by predominantly hydrophobic and electrostatic interactions, leading to the unfolding of polypeptides within BSA. The influence of the ILs on the conformation of BSA follows a sequence of BmimNO3 > BmimCl ≈ BbimCl. Molecular docking shows that cationic imidazolium moieties of ILs enter the subdomains of protein and interact with the hydrophobic residues of domain III. An agreement between fluorescence spectroscopic investigations and molecular docking is reached. It is found that the fluorescence of BSA at λex 230 nm arising from aromatic amino acids Trp and Tyr is almost as sensitive as that achieved at λex 280 nm for elucidating the protein conformational changes, which provides a valid and new probe for the investigation of binding kinetics between molecules/ions and proteins.
Co-reporter:Jia-Wei Liu;Dr. Qian Zhang;Dr. Xu-Wei Chen; Jian-Hua Wang
Chemistry - A European Journal 2011 Volume 17( Issue 17) pp:4864-4870
Publication Date(Web):
DOI:10.1002/chem.201003361
Abstract
Graphene oxide (GO) nanosheets have been immobilized onto SiO2 particles through electrostatic interactions by surface assembly. The surface-assembled composite material was characterized by means of SEM and FTIR and UV/Vis spectroscopy to reveal an assembling ratio of 2.3 % (w/w, GO/SiO2). The GO/SiO2 composites were subsequently used, for the first time, as adsorbents for the adsorption/isolation of proteins. Selective isolation of proteins of interest, namely, hemoglobin (Hb) in this case, from complex sample matrices, for example, human whole blood, could be obtained by carefully manipulating the adsorption/desorption process. At pH 7, an adsorption of 85 % was achieved for Hb (70 mg L−1) in sample solution (1.0 mL) by the GO/SiO2 composites (3.0 mg). The adsorption behavior was consistent with the Langmuir adsorption model, corresponding to a theoretical adsorption capacity of 50.5 mg g−1 for Hb. The retained Hb could be readily recovered by using a Tris-HCl buffer at pH 8.9 to give a recovery of 80 %. Circular dichroism and specific activity investigations indicated that the GO/SiO2 composites exhibited favorable biocompatibility, characterized by virtually no effect on the conformation and activity of Hb after adsorption/desorption. The composites were used for the selective isolation of Hb from human whole blood and achieved satisfactory results by assaying with sodium dodecyl sulfate polyacrylamide gel electrophoresis.
Co-reporter:Li-Ming Shen, Ming-Li Chen, Xu-Wei Chen
Talanta 2011 Volume 85(Issue 3) pp:1285-1290
Publication Date(Web):15 September 2011
DOI:10.1016/j.talanta.2011.06.006
A flow-through fluorescence optosensor with Sephadex G-50 microbeads as solid support is developed for the sensitive determination of tetracycline (TC). The fluorescent TC derivative encapsulated in CTAB micelle structures is retained onto the surface of the microbeads packed into a fluorescent flow cell in a flow system, followed by measurement of the native fluorescence of the TC derivative on the bead surface. The retained TC derivative is easily stripped off with DI water from the bead surface by breaking-down the micelle structure. This offers a convenient and effective way for the regeneration of the used solid support with DI water as a carrier. Under the optimal conditions, a linear calibration graph is obtained within a range of 3–500 μg L−1, along with a detection limit of 1.0 μg L−1. The present solid surface fluorescence optosensor provides a 22-fold improvement on the detection sensitivity for TC in comparison with that derived by fluorescence detection in aqueous medium. The feasibility of this flow-through fluorescence optosensor is evaluated by analyzing TC in a commercial drug tablet and surface water samples.
Co-reporter:Yang Shu, Jun Lu, Quan-Xing Mao, Ru-Sheng Song, Xue-Ying Wang, Xu-Wei Chen, Jian-Hua Wang
Carbon (April 2017) Volume 114() pp:
Publication Date(Web):April 2017
DOI:10.1016/j.carbon.2016.12.038
By taking advantage of the structural tunability of ionic liquids (ILs), a series of imidazolium ILs were employed as precursors to prepare carbon dots (IL-CDs) and as regulators to control their properties. The simultaneous formation of hydrophilic CDs (IL-HCDs) and organophilic CDs (IL-OCDs) is achieved in hydrothermal reaction system by undergoing sulfuric acid carbonization. The quantum yields (QY) of IL-OCDs are closely correlated with both the cationic and anionic moieties of the ionic liquids, i.e., longer side chains of cations in the imidazolium ILs and weakly nucleophilic anions tend to produce highly fluorescent IL-OCDs. Both IL-HCDs and IL-OCDs exhibit low cytotoxicity, and that of IL-HCDs is even lower than IL-OCDs. A drug delivery system is constructed by combining anticancer drug curcumin (Cur) with IL-OCDs via hydrophobic interaction, among which 1,3-dibutylimidazolium nitrate derived IL-OCDs exhibit highest photoluminescence. In addition, it serves as a favorable drug carrier with high drug loading efficiency and facilitates rapid penetration/transportation of Cur into the cell interior, which significantly accelerates the apoptosis of HeLa cells. This process is further visualized by cell imaging.
Co-reporter:Jia-Wei Liu ; Yue Zhang ; Xu-Wei Chen ;Jian-Hua Wang
ACS Applied Materials & Interfaces () pp:
Publication Date(Web):
DOI:10.1021/am503298v
Graphene oxide-La(BTC)(H2O)6 (H3BTC=1,3,5-benzenetricarboxylic acid) metal organic framework composites (LaMOF-GOn, n = 1–6, corresponding to the percentage of GO at 1, 2, 3, 4, 5, and 10%) are prepared through a simple and large-scale method at room temperature. The obtained composites are characterized by ATR-FTIR spectra, SEM, XRD, TGA, and N2 adsorption–desorption isotherm. The presence of GO significantly changes the morphologies of the composites from spindly rectangular rods to irregular thick blocks and increases their surface area from 14.8 cm2 g–1 (LaMOFs) to 26.6 cm2 g–1 (LaMOF-GO3), whereas at the same time, the crystalline structure of La(BTC)(H2O)6 is maintained. As a novel solid-phase adsorbent the LaMOF-GO composite exhibits outstanding adsorption properties for proteins. The strong hydrophobic interaction, especially π–π interaction between protein and the composite, is the main driving force for protein adsorption. In particular, highly selective isolation of hemoglobin (Hb) is achieved by using LaMOF-GO3 composite as sorbent in 4 mM B-R buffer containing 0.05 mol L–1 NaCl at pH 8. The retained Hb could be effectively recovered with a 1 mM B-R buffer at pH 10, giving rise to a recovery of 63%. The practical applicability of the LaMOF-GO3 composite is demonstrated by the selective adsorption of Hb from human whole blood, and SDS-PAGE assays indicate that Hb could be selectively isolated with high purity from biological samples of complex matrixes.
Co-reporter:Dan-Dan Zhang, Peng-Fei Guo, Lin-Lin Hu, Xu-Wei Chen and Jian-Hua Wang
Journal of Materials Chemistry A 2017 - vol. 5(Issue 4) pp:NaN756-756
Publication Date(Web):2016/12/08
DOI:10.1039/C6TB02733D
A novel polyoxometalate (POM)-based hybrid is prepared for the selective adsorption of acidic and/or basic proteins. The solidification of the POM moiety P8W48 is firstly achieved through dehydration condensation between the –OH group on the P8W48 surface and the Si–OH of aminopropyltriethoxysilane (APTS), and thereafter further condensation of the P8W48O184–APTS intermediate with poly(acrylic acid) (PAA) produces a hybrid, by linking carboxyl groups in PAA with –NH2 groups in P8W48O184–APTS via the formation of an amide bond. The P8W48–APTS–PAA hybrid surface is negatively charged due to abundant COO− groups from PAA, which provides electrostatic interactions with positively charged proteins by varying pHs. Meanwhile, the d–p π bond in P8W48 offers strong affinity to other proteins via π–π stacking interaction. The hybrid thus offers potential for achieving selective adsorption of either acidic or basic proteins by simply controlling the adsorption conditions, i.e., pH value or ionic strength of the adsorption medium. With ovalbumin (Ova) and lysozyme (Lys) as the models of acidic and basic proteins, their adsorption behaviors fit the Langmuir model, with adsorption capacities of 367.0 mg g−1 and 74.0 mg g−1, respectively. The retained proteins are readily recovered with 0.01 mol L−1 CTAB, providing recoveries of 89.0% for Ova and 93.0% for Lys. The P8W48–APTS–PAA hybrid is further applied for the isolation of Ova and Lys from real biological samples, egg white.
Co-reporter:Yue Zhang, Jia-Wei Liu, Xu-Wei Chen and Jian-Hua Wang
Journal of Materials Chemistry A 2015 - vol. 3(Issue 6) pp:NaN989-989
Publication Date(Web):2014/12/23
DOI:10.1039/C4TB01792G
A three-dimensional graphene oxide framework is prepared via a simple and cost-effective one-pot approach through the hydrogen-bonding interaction between amylopectin and graphene oxide in the presence of hydrazine hydrate acting as a reducing reagent. The framework is shortly termed as AP-rGO and it is characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), surface charge analysis and thermogravimetric analysis (TGA). The obtained AP-rGO framework exhibits excellent adsorption performance toward hemoglobin in the presence of other protein species. It provides a maximum adsorption capacity of 1010 mg g−1. In a neutral medium (at pH 7), 70 mg L−1 of Hb in 1.0 mL of aqueous solution could be effectively adsorbed by 1.0 mg of the AP-rGO framework, giving rise to an adsorption efficiency of 92.7%. The practical application of the AP-rGO framework is demonstrated by the removal of a highly abundant protein, i.e., hemoglobin, from complex biological sample matrices, e.g., human whole blood. The removal efficiency is well confirmed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) assay.
Co-reporter:Quan-Xing Mao, Wen-Jing Wang, Xin Hai, Yang Shu, Xu-Wei Chen and Jian-Hua Wang
Journal of Materials Chemistry A 2015 - vol. 3(Issue 29) pp:NaN6018-6018
Publication Date(Web):2015/06/22
DOI:10.1039/C5TB00963D
The regulation of hydrophilicity/hydrophobicity of carbon dots (CDs) at will is most important. One pot simultaneous preparation of hydrophilic and/or hydrophobic CDs is herein reported, via a hydrothermal process with 1-butyl-3-methylimidazolium hexafluorophosphate as the carbon source in a H3PO4–ethanol medium. The hydrophilicity or hydrophobicity of CDs (or their proportions) is simply regulated by varying the H3PO4/ethanol molar ratio. Hydrophilic and hydrophobic CDs are obtained simultaneously with H3PO4/ethanol molar ratios within 0–1.72, while hydrophilic or hydrophobic CDs are the sole product obtained from H3PO4–BmimPF6 or BmimPF6-only systems. The CDs exhibit excitation-dependent maximum fluorescence at 360/440 nm (hydrophilic) and 430/510 nm (hydrophobic), with quantum yields of 17.0% and 7.7%, respectively. Both hydrophilic and hydrophobic CDs obtained by this approach exhibit favorable biocompatibility and offer great potential in bio-imaging as demonstrated for the fluorescent labeling and imaging of live HeLa cells.
Co-reporter:Qing Chen, Dan-Dan Zhang, Meng-Meng Wang, Xu-Wei Chen and Jian-Hua Wang
Journal of Materials Chemistry A 2015 - vol. 3(Issue 34) pp:NaN6970-6970
Publication Date(Web):2015/07/28
DOI:10.1039/C5TB01298H
A novel polyoxometalate (POM)-based organic–inorganic hybrid [C33H24O4]H3PMo12O40, namely, TPPA–PMo12, is prepared via a one-pot hydrothermal reaction between a Keggin POM (H3PMo12O40, PMo12) and a star-like N-donor ligand (tri(4-pyridylphenyl)amine, TPPA). The hybrid polyoxometalate is confirmed by characterization with XRD, FT-IR, TGA, SEM and EDS. It exhibits excellent adsorption performance towards β-lactoglobulin, and thus a solid-phase extraction procedure was established for the efficient and selective isolation of β-lactoglobulin from complex sample matrices. At pH 5.0, an adsorption efficiency of 99.2% is achieved for processing 100 μg mL−1 β-lactoglobulin in 1.0 mL aqueous solution with 0.5 mg TPPA–PMo12 as an adsorbent. The adsorption behavior of β-lactoglobulin fits the Langmuir model, corresponding to a theoretical adsorption capacity of 1428 mg g−1. The retained β-lactoglobulin could be readily recovered by rinsing with 0.05 mol L−1 Tris-HCl buffer, facilitating a recovery of 91.5%. The hybrid polyoxometalate was practically applied to the selective isolation of β-lactoglobulin from milk whey, and SDS-PAGE assay results clearly indicate that β-lactoglobulin of high-purity is obtained.
Co-reporter:Jia-Wei Liu, Ting Yang, Shuai Chen, Xu-Wei Chen and Jian-Hua Wang
Journal of Materials Chemistry A 2013 - vol. 1(Issue 6) pp:NaN818-818
Publication Date(Web):2012/11/30
DOI:10.1039/C2TB00334A
A novel functionalized graphene-based composite is prepared by successive modification of graphene oxide (GO) with epichlorohydrin (ECH), iminodiacetic acid (IDA) and 1-phenylboronic acid (1-PBA) through covalent functionalization and then chelating with nickel ions. Characterizations by FT-IR, XRD, SEM, TGA and ICP-MS demonstrate the successful modification of the graphene surface, resulting in a GO–PBA–IDA–Ni composite with a Ni2+ immobilization amount of 3.01 × 10−3 mol g−1. The composite shows favorable selectivity for the adsorption of lysozyme (Lys). In practice, a homogeneous GO–PBA–IDA–Ni film with a thickness of ca. 1.0 μm is fabricated by filtering the composite through a cellulose membrane with a pore aperture of 1.2 μm. The GO–PBA–IDA–Ni film is subsequently fastened into a rounded membrane cartridge and incorporated into a sequential injection system for on-line selective isolation of Lys. An adsorption efficiency of ca. 96% is achieved for 25 μg ml−1 Lys in 500 μl of sample solution at a loading rate of 5 μl s−1. Metal affinity and electrostatic interactions are the main driving forces for governing the protein adsorption behaviors. The retained Lys is readily recovered by a borate buffer (pH 10) containing 1.0 mol l−1 NaCl and 20 mmol l−1 imidazole, giving rise to a recovery of ca. 90%. The practical applicability of the composites is demonstrated by selective isolation of Lys from chicken egg white, and SDS-PAGE assay indicates that Lys is selectively isolated with high purity from complex matrices.
Co-reporter:Mei-Ling Chen, Li-Ming Shen, Shuai Chen, Hui Wang, Xu-Wei Chen and Jian-Hua Wang
Journal of Materials Chemistry A 2013 - vol. 1(Issue 20) pp:NaN2589-2589
Publication Date(Web):2013/03/25
DOI:10.1039/C3TB20234H
β-FeOOH has shown promise as a new contrast agent in magnetic resonance imaging (MRI), however, sensitive and accurate MR imaging is largely limited by its low transverse relaxivity (r2). Herein, for the first time we report in situ growth of β-FeOOH nanorods onto PEGylated graphene oxide (GO) sheets to produce a nanocomposite, e.g., GO-PEG–β-FeOOH. This nanocomposite exhibits a record ultra-high transverse relaxivity (r2) value of 303.81 mM−1 s−1, that is, >60 times higher than those achieved by hitherto reported β-FeOOH based MRI contrast agents. This well facilitates its practical use as a contrast agent for in vivo MR imaging. PEG on the surface of the GO nanocomposite improved the colloidal stability in aqueous medium. In addition, in vitro cell viability tests demonstrated that GO-PEG–β-FeOOH has minimal cellular toxicity. GO-PEG–β-FeOOH has been used for loading doxorubicin hydrochloride (DOX) with a capacity of 1.35 mg mg−1, which exhibits high efficiency in Hela cell apoptosis. These results indicated that GO-PEG–β-FeOOH provides an effective alternative to the existing nanoparticle-based contrast agents for non-invasive in vivo MR imaging and cancer therapy.
Co-reporter:Xin Hai, Quan-Xing Mao, Wen-Jing Wang, Xiao-Feng Wang, Xu-Wei Chen and Jian-Hua Wang
Journal of Materials Chemistry A 2015 - vol. 3(Issue 47) pp:NaN9114-9114
Publication Date(Web):2015/11/02
DOI:10.1039/C5TB01954K
Boron-doped graphene quantum dots (B-GQDs) are prepared via a one-pot acid-free microwave approach with graphene oxide as the carbon source and borax as the boron source. Boron atoms are incorporated into the graphene framework by attacking the defects in the graphene structure, deriving an atomic percentage of 1.44% in the final product. Boron atom doping into the graphene structure and restoration of defects in the graphene structure bring the obtained B-GQDs favorable photoluminescence behaviors. The as-prepared B-GQDs exhibit excitation-independent photoluminescence behaviors with an excitation/emission maximum at 320/430 nm, and a fluorescence quantum yield of 21.1%. Moreover, stable photoluminescence is observed within a wide range of pH 3.0–11.0. A tolerance to an external ionic strength of up to 2.0 mol L−1 KCl along with an excellent anti-photobleaching capability is achieved. The standard MTT assay suggests that the B-GQDs are of low cytotoxicity with favorable biocompatibility, and a cell viability of 87% could be achieved at 4.0 mg mL−1 of B-GQDs. The practical application of B-GQDs in bio-analysis is demonstrated by bio-imaging of HeLa cells.
Co-reporter:Dan-Dan Zhang, Qing Chen, Lin-Lin Hu, Xu-Wei Chen and Jian-Hua Wang
Journal of Materials Chemistry A 2015 - vol. 3(Issue 21) pp:NaN4369-4369
Publication Date(Web):2015/04/21
DOI:10.1039/C5TB00544B
A Keggin-type cobalt mono-substituted silicotungstic acid doped with aniline (SiW11Co–PANI composite, where PANI denotes polyaniline) is prepared by a liquid phase method at room temperature. The obtained SiW11Co–PANI composite possesses a porous framework structure and has proven to be a promising adsorbent for the retention of proteins, which exhibits favorable selectivity toward the adsorption of ovalbumin from egg whites. 5.0 mg of SiW11Co–PANI composite gives rise to an adsorption efficiency of >70% for 100 mg L−1 ovalbumin in 1.0 mL of sample solution within a wide pH range of 3–9, and a maximum adsorption efficiency of 92% is achieved at pH 9. The adsorption behavior of ovalbumin onto the SiW11Co–PANI composite fits the Langmuir adsorption model, corresponding to a sorption capacity of 200.0 mg g−1. The retained ovalbumin could be readily recovered by using a 0.1 mol L−1 phosphate buffer at pH 5.6 as a stripping reagent, providing a recovery of 84.4%. Circular dichroism (CD) spectra illustrate virtually no change in the conformation of ovalbumin after the process of adsorption–desorption. The SiW11Co–PANI composite has been applied for the selective adsorption of ovalbumin from the chicken egg white, and SDS-PAGE assay demonstrates that high purity of ovalbumin is obtained.
Co-reporter:Shuai Chen, Jia-Wei Liu, Mei-Ling Chen, Xu-Wei Chen and Jian-Hua Wang
Chemical Communications 2012 - vol. 48(Issue 61) pp:NaN7639-7639
Publication Date(Web):2012/06/13
DOI:10.1039/C2CC32984K
Graphene quantum dots prepared by a one-step hydrothermal procedure in a microwave exhibit an unusual emission transformation in strong acidic media and at high concentration, induced by self-assembled J-type aggregation under restrained π–π interactions.
