27 results on '"Zhang, Zhongping"'
Search Results
2. Long-Lived Phosphorescent Carbon Dots as Photosensitizers for Total Antioxidant Capacity Assay.
- Author
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Zheng, Yu, Li, Xinyi, Wei, Caixia, Gao, Yawen, Han, Guangmei, Zhao, Jun, Zhang, Cheng, Zhang, Kui, and Zhang, Zhongping
- Published
- 2023
- Full Text
- View/download PDF
3. Ligand replacement-induced fluorescence switch of quantum dots for ultrasensitive detection of organophosphorothioate pesticides
- Author
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Zhang, Kui, Mei, Qingsong, Guan, Guijian, Liu, Bianhua, Wang, Suhua, and Zhang, Zhongping
- Subjects
Fluorescence -- Research ,Pesticides -- Chemical properties ,Pesticides -- Identification and classification ,Pesticides -- Composition ,Ligands -- Chemical properties ,Semiconductors -- Chemical properties ,Semiconductors -- Usage ,Chemistry - Abstract
The development of a simple and on-site assay for the detection of organophosphorus pesticed residues is very important for food safety and exosystem protection. This paper reports the surface coordination-originated fluorescence resonance energy transfer (FRET) of CdTe quantum dots (QDs) and a simple ligand-replacement turn-on mechanism for the highly sensitive and selective detection of organophosphorothioate pesticides. It has been demonstrated that coordination of dithizone at the surface of CdTe QDs in basic media can strongly quench the green emission of CdTe QDs by a FRET mechanism. Upon the addition of organophosphorothioate pesticides, the dithizone ligands at the CdTe QD surface are replaced by the hydrolyzate of the organophosphorothioate, and hence the fluorescence is turned on. The fluorescence turn on is immediate, and the limit of detection for chlorpyrifos is as low as ~0.1 nM. Two consecutive linear ranges allow a wide determination of chlorpyrifos concentrations from 0.1 nM to 10 [micro]M. Importantly, the fluorescence turn-on chemosensor can directly detect chlorpyrifos residues in apples at a limit of 5.5 ppb, which is under the maximum residue limit allowed by the U.S. Environmental Protection Agency. The very simple strategy reported here should facilitate the development of fluorescence turn-on chemesensors for chemo/biedetection. 10.1021/ac102531z
- Published
- 2010
4. Surface molecular self-assembly for organophosphate pesticide imprinting in electropolymerized poly(p-aminothiophenol) membranes on a gold nanoparticle modified glassy carbon electrode
- Author
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Xie, Chenggen, Li, Huaifen, Li, Shanqi, Wu, Ju, and Zhang, Zhongping
- Subjects
Pesticides -- Analysis ,Nanoparticles -- Usage ,Electrochemical reactions -- Analysis ,Chemistry - Abstract
This paper reports a surface molecular self-assembly strategy for molecular imprinting in electropolymerized polyaminothiophenol (PATP) membranes at the surface of gold nanoparticles (AuNPs) modified glassy carbon (gc) electrode for the electrochemical detection of pesticide chlorpyrifos (CPF). Electropolmedzable p-aminothiophenol (ATP) was first assembled on the AuNPs at the gc electrode surface by the formation of Au--S bonds, and subsequently, the CPF template was further assembled onto the monolayer of ATP through the hydrogen-bonding interaction between amino group and CPF. A conductive hybrid membrane was fabricated at the assembled gc electrode by the electropolymerization in a mixing solution containing additional ATP and CPF templates, and meanwhile, the CPF was spontaneously imprinted into the PATP/AuNP film. The amount of imprinted sites at the PATP/AuNP film was significantly increased due to the additional replenishment of CPF templates. The cyclic voltammetric response of the imprinted PATP-AuNP-gc sensor to CPF is about 3.2-fold as compared with the imprinted PATP-Au sensor, and the detection limit for CPF is about 2 orders of magnitude lower than that by the imprinted PATP-Au sensor. An excellent electrochemical selectivity for CPF over other pesticides was also achieved. The combination of surface molecular self-ssembly with electropolymerized molecular imprinting on a larger surface area of a AuNP-medified electrode produces a high ratio of imprinted sites and, thus, provides an ultrasensitive electrochemical detection of organophosphate pesticide. 10.1021/ac901860t
- Published
- 2010
5. Resonance energy transfer-amplifying fluorescence quenching at the surface of silica nanoparticles toward ultrasensitive detection of TNT
- Author
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Gao, Daming, Wang, Zhenyang, Liu, Bianhua, Ni, Lin, Wu, Minghong, and Zhang, Zhongping
- Subjects
Fluorescence -- Research ,Nanoparticles -- Properties ,Nanoparticles -- Usage ,Resonance -- Research ,Energy transformation -- Research ,Bomb detectors -- Research ,Silica -- Properties ,Chemistry - Abstract
This paper reports a resonance energy transfer-amplifying fluorescence quenching at the surface of silica nanoparticles for the ultrasensitive detection of 2,4,6-trinitrotoluene (TNT) in solution and vapor environments. Fluorescence dye and organic amine were covalently modified onto the surface of silica nanoparticles to form a hybrid monolayer of dye fluorophores and amine ligands. The fluorescent silica particles can specifically bind TNT species by the charge-transfer complexing interaction between electron-rich amine ligands and electron-deficient aromatic rings. The resultant TNT--amine complexes bound at the silica surface can strongly suppress the fluorescence emission of the chosen dye by the fluorescence resonance energy transfer (FRET) from dye donor to the irradiative TNT--amine acceptor through intermolecular polar--polar interactions at spatial proximity. The quenching efficiency of the hybrid nanoparticles with TNT is greatly amplified by at least 10-fold that of the corresponding pure dye. The nanoparticle-assembled arrays on silicon wafer can sensitively detect down to ~ 1 nM TNT with the use of only 10 [micro]L of solution (~2 pg TNT) and several ppb of TNT vapor in air. The simple FRET-based nanoparticle sensors reported here exhibit a high and stable fluorescence brightness, strong analyte affinity, and good assembly flexibility and can thus find many applications in the detection of ultratrace analytes.
- Published
- 2008
6. Amine-capped ZnS-[Mn.sup.2+] nanocrystals for fluorescence detection of trace TNT explosive
- Author
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Tu, Renyong, Liu, Bianhua, Wang, Zhenyang, Gao, Daming, Wang, Feng, Fang, Qunling, and Zhang, Zhongping
- Subjects
Sulfides -- Chemical properties ,Nanotechnology -- Methods ,Manganese -- Chemical properties ,Trace analysis -- Methods ,Zinc compounds -- Chemical properties ,Chemistry - Abstract
[Mn.sup.2+]-doped ZnS nanocrystals with an amine-capping layer have been synthesized and used for the fluorescence detection of ultratrace 2,4,6-trinitrotoluene (TNT) by quenching the strong orange [Mn.sup.2+] photoluminescence. The organic amine-capped nanocrystals can bind TNT species from solution and atmosphere by the acid base pairing interaction between electron-rich amino ligands and electron-deficient aromatic rings. The resultant TNT anions bound onto the amino monolayer can efficiently quench the [Mn.sup.2+] photoluminescence through the electron transfer from the conductive band of ZnS to the lowest unoccupied molecular orbital (LUMO) of TNT anions. The amino ligands provide an amplified response to the binding events of nitroaromatic compounds by the 2- to ~5-fold increase in quenching constants. Moreover, a large difference in quenching efficiency was observed for different types of nitroaromatic analytes, dependent on the affinity of nitro analytes to the amino monolayer and their electron-acceptlng abilities. The amine-capped nanocrystals can sensitively detect down to 1 nM TNT in solution or several parts-per-billion of TNT vapor in atmosphere. The ion-doped nanocrystal sensors reported here show a remarkable air/solution stability, high quantum yield, and strong analyte affinity and, therefore, are well-suited for detecting the ultratrace TNT and distinguishing different nitro compounds.
- Published
- 2008
7. Molecular imprinting at walls of silica nanotubes for TNT recognition
- Author
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Xie, Chenggen, Liu, Bianhua, Wang, Zhenyang, Gao, Daming, Guan, Guijian, and Zhang, Zhongping
- Subjects
Nanotubes -- Properties ,Nanotubes -- Design and construction ,Bomb detectors -- Design and construction ,Bomb detectors -- Properties ,Chemistry - Abstract
This paper reports the molecular imprinting at the walls of highly uniform silica nanotubes for the recognition of 2,4,6-trinitrotoluene (TNT). It has been demonstrated that TNT templates were efficiently imprinted into the matrix of silica through the strong acid-base pairing interaction between TNT and 3-aminopropyltriethoxysilane (APTS). TNT-imprinted silica nanotubes were synthesized by the gelation reaction between APTS and tetraethylorthosilicate (TEOS), selectively occurring at the porous walls of APTS-modified alumina membranes. The removal of the original TNT templates leaves the imprinted cavities with covalently anchored amine groups at the cavity walls. A high density of recognition sites with molecular selectivity to the TNT analyte was created at the wall of silica nanotubes. Furthermore, most of these recognition sites are situated at the inside and outside surfaces of tubular walls and in the proximity of the two surfaces due to the ultrathin wall thickness of only 15 nm, providing a better site accessibility and lower mass-transfer resistance. Therefore, greater capacity and faster kinetics of uptaking target species were achieved. The silica nanotube reported herein is an ideal form of material for imprinting various organic or biological molecules toward applications in chemical/biological sensors and bioassay.
- Published
- 2008
8. Surface molecular self-assembly strategy for TNT imprinting of polymer nanowire/nanotube arrays
- Author
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Xie, Chenggen, Zhang, Zhongping, Wang, Dapeng, Guan, Guijian, Gao, Daming, and Liu, Jinhuai
- Subjects
Nanotubes -- Research ,Polymers -- Chemical properties ,Chemistry - Abstract
This paper reports the finding of an investigation of a surface molecular self-assembly strategy for molecular imprinting of polymer nanowires/nanotubes. It has been demonstrated that 2,4,6-trinitrotoluene (TNT) templates were spontaneously assembled onto aminopropyl group-modified alumina pore walls by a strong charge-transfer complexing interaction between amino groups and electron-deficient nitroaromatics, forming a novel basis of surface molecular imprinting. While an additional amount of TNT templates was further replenished into a precursor mixture, a stepwise progressive polymerization was designed toward the controllable preparation of TNT-imprinted polymer nanowire/nanotube arrays in an alumina membrane. The imprinted nanowires/nanotubes with a high density of surface-imprinted sites and regular interior sites exhibit the high capacity of binding TNT molecules, which is nearly 2.5-3.0-fold that of normal imprinted particles. Moreover, the imprinted nanotubes and nanowires have ~6- and 4-fold increase in the rate of binding TNT molecules, respectively. The combination of surface molecular assembly with nanostructures in the imprinting technique can create more effective recognition sites than the only use of porogens in traditional approaches. This novel, facile strategy reported herein can be further expected to fabricate various molecular recognition nanoarrays for sensing or analytic applications.
- Published
- 2006
9. Revealing Sulfur Dioxide Regulation to Nucleophagy in Embryo Development by an Adaptive Coloration Probe.
- Author
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Li, Dandan, Tian, Xiaohe, Liu, Zhengjie, Liu, Jiejie, Han, Guangmei, Liu, Bianhua, Zhao, Jun, Zhang, Ruilong, Tian, Yupeng, and Zhang, Zhongping
- Published
- 2021
- Full Text
- View/download PDF
10. Design and Synthesis of Nanosensor Based on Unsaturated Double Bond Functional Carbon Dots for Phenylephrine Detection Using Bromine As a Bridge.
- Author
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Zhang, Cheng, Li, Xiangcao, Li, Taotao, Liu, Meilin, Zhang, Kui, Zheng, Yu, Lan, Minhuan, Zhang, Jian, and Zhang, Zhongping
- Published
- 2021
- Full Text
- View/download PDF
11. Conformationally Induced Off–On Two-Photon Fluorescent Bioprobes for Dynamically Tracking the Interactions among Multiple Organelles.
- Author
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Zhang, Huihui, Zhu, Xiaojiao, Liu, Gang, Ding, Xinzhi, Wang, Junjun, Yang, Mingdi, Zhang, Ruilong, Zhang, Zhongping, Tian, Yupeng, and Zhou, Hongping
- Published
- 2019
- Full Text
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12. Coumarin-Based Fluorescent Probes for Super-resolution and Dynamic Tracking of Lipid Droplets.
- Author
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Xu, Hongkang, Zhang, Huihui, Liu, Gang, Kong, Lin, Zhu, Xiaojiao, Tian, Xiaohe, Zhang, Zhongping, Zhang, Ruilong, Wu, Zhichao, Tian, Yupeng, and Zhou, Hongping
- Published
- 2019
- Full Text
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13. Surface Molecular Self-Assembly Strategy for TNT Imprinting of Polymer Nanowire/Nanotube Arrays.
- Author
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Chenggen Xie, Zhang, Zhongping, Wang, Dapeng, Guan, Guijian, Gao, Darning, and Liu, Jinhuai
- Subjects
- *
MOLECULAR self-assembly , *TNT (Chemical) , *MOLECULAR imprinting , *NANOWIRES , *POLYMERIZATION , *NANOTUBES , *CHARGE transfer , *AMINO group , *ANALYTICAL chemistry - Abstract
This paper reports the finding of an investigation of a surface molecular self-assembly strategy for molecular imprinting of polymer nanowires/nanotubes. It has been demonstrated that 2,4,6-trinitrotoluene (TNT) templates were spontaneously assembled onto aminopropyl group-modified alumina pore walls by a strong charge-transfer complexing interaction between amino groups and electron-deficient nitroaromatics, forming a novel basis of surface molecular imprinting. While an additional amount of TNT templates was further replenished into a precursor mixture, a stepwise progressive polymerization was designed toward the controllable preparation of TNT-imprinted polymer nanowire/nanotube arrays in an alumina membrane. The imprinted nanowires/nanotubes with a high density of surface-imprinted sites and regular interior sites exhibit the high capacity of binding TNT molecules, which is nearly 2.5-3.0-fold that of normal imprinted particles. Moreover, the imprinted nanotubes and nanowires have ~6- and 4-fold increase in the rate of binding TNT molecules, respectively. The combination of surface molecular assembly with nanostructures in the imprinting technique can create more effective recognition sites than the only use of porogens in traditional approaches. This novel, facile strategy reported herein can be further expected to fabricate various molecular recognition nanoarrays for sensing or analytic applications. [ABSTRACT FROM AUTHOR]
- Published
- 2006
- Full Text
- View/download PDF
14. Recovery Mechanism of Endoplasmic Reticulum Revealed by Fluorescence Lifetime Imaging in Live Cells.
- Author
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Chen J, Han G, Liu Z, Wang H, Wang D, Zhao J, Liu B, Zhang R, and Zhang Z
- Subjects
- Autophagy, Endoplasmic Reticulum Stress, Fluorescent Dyes metabolism, Triglycerides metabolism, Endoplasmic Reticulum metabolism, Optical Imaging methods
- Abstract
Endoplasmic reticulum (ER) is an important organelle of a membranous tubule network in cells for the synthesis, assembly, and modification of peptides, proteins, and enzymes. Autophagy and destruction of ER commonly occur during normal cellular activities. These processes have been studied extensively, but the spontaneous ER regeneration process is poorly understood because of the lack of molecular tools capable of distinguishing the intact, damaged, autophagic, and regenerative ER in live cells. Herein, we report a dual-localizing, environment-responsive, and lifetime-sensitive fluorescent probe for real-time monitoring ER autophagy and regeneration in live cells. Using this tool, the fluorescence lifetime imaging can quantitatively determine the degrees of ER destruction and spontaneous recovery. Significantly, we show that triglycerides supplied in lipid droplets can efficiently repair ER via the two critical pathways: (i) supplying materials for ER repair by converting triglycerides into fatty acids and diglycerides and (ii) partially inhibiting autophagy for stressed ER.
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- 2022
- Full Text
- View/download PDF
15. Light-Up Lipid Droplets Dynamic Behaviors Using a Red-Emitting Fluorogenic Probe.
- Author
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Zhang X, Yuan L, Jiang J, Hu J, du Rietz A, Cao H, Zhang R, Tian X, Zhang F, Ma Y, Zhang Z, Uvdal K, and Hu Z
- Subjects
- Animals, Biological Transport, Color, Electron Transport, Fluorescent Dyes metabolism, HeLa Cells, Hep G2 Cells, Humans, Lipid Droplets metabolism, Molecular Imaging, Zebrafish, Fluorescent Dyes chemistry, Light, Lipid Droplets chemistry
- Abstract
Intracellular lipid metabolism occurs in lipid droplets (LDs), which is critical to the survival of cells. Imaging LDs is an intuitive way to understand their physiology in live cells. However, this is limited by the availability of specific probes that can properly visualize LDs in vivo. Here, an LDs-specific red-emitting probe is proposed to address this need, which is not merely with an ultrahigh signal-to-noise (S/N) ratio and a large Stokes shift (up to 214 nm) but also with superior resistance to photobleaching. The probe has been successfully applied to real-time tracking of intracellular LDs behaviors, including fusion, migration, and lipophagy processes. We deem that the proposed probe here offers a new possibility for deeper understanding of LDs-associated behaviors, elucidation of their roles and mechanisms in cellular metabolism, and determination of the transition between adaptive lipid storage and lipotoxicity as well.
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- 2020
- Full Text
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16. Ehrlich Reaction Evoked Multiple Spectral Resonances and Gold Nanoparticle Hotspots for Raman Detection of Plant Hormone.
- Author
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Wang F, Gu X, Zheng C, Dong F, Zhang L, Cai Y, You Z, You J, Du S, and Zhang Z
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- Benzaldehydes chemistry, Indoles analysis, Indoles chemistry, Limit of Detection, Plant Growth Regulators chemistry, Vigna metabolism, Gold chemistry, Metal Nanoparticles chemistry, Plant Growth Regulators analysis, Spectrum Analysis, Raman
- Abstract
Surface-enhanced Raman scattering (SERS) by use of noble metal nanoparticles has become a powerful tool to determine a low-concentration target by unique spectral fingerprints, but it is still limited to the Raman-inactive and nonresonant biomolecules such as amine acids, proteins, and hormones. Here, we report an Ehrlich reaction based derivative strategy in combination with gold nanoparticles (Au NPs) hotspots for the selective detection of indole-like plant hormones by SERS spectroscopy. Ehrlich reaction of p-(dimethylamino)benzaldehyde (PDAB) with the indole ring chemically transformed plant hormone indole-3-butyric acid (IBA) into a Raman-active and resonant derivative with an extended π-conjugated system in the form of a cation, which produced a new absorption band at 626 nm. On the other hand, cationic IBA-PDAB highly evoked the aggregation of Au NPs with negative citrate ligands to form the effective Raman hotspots and gave rise to the new absorption ranging from 600 to 800 nm. Significantly, the spectral overlap among IBA-PDAB, aggregated Au NPs, and the exciting laser initiated the multiple optical resonances to generate the ultrahigh Raman scattering with a sensitive limit of 2.0 nM IBA. The IBA in the whole sprouts and various parts of pea, mungbean, soybean, and black bean has been identified and quantified. The reported method opens a novel avenue for the SERS detection of Raman-inactive analyte by a proper derivation.
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- 2017
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17. Color-Multiplexing-Based Fluorescent Test Paper: Dosage-Sensitive Visualization of Arsenic(III) with Discernable Scale as Low as 5 ppb.
- Author
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Zhou Y, Huang X, Liu C, Zhang R, Gu X, Guan G, Jiang C, Zhang L, Du S, Liu B, Han MY, and Zhang Z
- Abstract
Fluorescent colorimetry test papers are promising for the assays of environments, medicines, and foods by the observation of the naked eye on the variations of fluorescence brightness and color. Unlike dye-absorption-based pH test paper, however, the fluorescent test papers with wide color-emissive variations with target dosages for accurate quantification remain unsuccessful even if the multicolorful fluorescent probes are used. Here, we report the dosage-sensitive fluorescent colorimetry test paper with a very wide/consecutive "from red to cyan" response to the presence and amount of arsenic ions, As(III). Red quantum dots (QDs) were modified with glutathione and dithiothreitol to obtain the supersensitivity to As(III) by the quenching of red fluorescence through the formation of dispersive QDs aggregates. A small amount of cyan carbon dots (CDs) with spectral blue-green components as the photostable internal standard were mixed into the QDs solution to produce a composited red fluorescence. Upon the addition of As(III) into the sensory solution, the fluorescence color could gradually be reversed from red to cyan with a detection limit of 1.7 ppb As(III). When the sensory solution was printed onto a piece of filter paper, surprisingly a serial of color evolution from peach to pink to orange to khaki to yellowish to yellow-green to final cyan with the addition of As(III) was displayed and clearly discerned the dosage scale as low as 5 ppb. The methodology reported here opens a novel pathway toward the real applications of fluorescent test papers.
- Published
- 2016
- Full Text
- View/download PDF
18. Ligand Replacement Approach to Raman-Responded Molecularly Imprinted Monolayer for Rapid Determination of Penicilloic Acid in Penicillin.
- Author
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Zhang L, Jin Y, Huang X, Zhou Y, Du S, and Zhang Z
- Subjects
- Ligands, Penicillanic Acid analysis, Spectrum Analysis, Raman, Surface Properties, Time Factors, Molecular Imprinting, Penicillanic Acid analogs & derivatives, Penicillins chemistry
- Abstract
Penicilloic acid (PA) is a degraded byproduct of penicillin and often causes fatal allergies to humans, but its rapid detection in penicillin drugs remains a challenge due to its similarity to the mother structure of penicillin. Here, we reported a ligand-replaced molecularly imprinted monolayer strategy on a surface-enhanced Raman scattering (SERS) substrate for the specific recognition and rapid detection of Raman-inactive PA in penicillin. The bis(phenylenediamine)-Cu(2+)-PA complex was first synthesized and stabilized onto the surface of silver nanoparticle film that was fabricated by a bromide ion-added silver mirror reaction. A molecularly imprinted monolayer was formed by the further modification of alkanethiol around the stabilized complex on the Ag film substrate, and the imprinted recognition site was then created by the replacement of the complex template with Raman-active probe molecule p-aminothiophenol. When PA rebound into the imprinted site in the alkanethiol monolayer, the SERS signal of p-aminothiophenol exhibited remarkable enhancement with a detection limit of 0.10 nM. The imprinted monolayer can efficiently exclude the interference of penicillin and thus provides a selective determination of 0.10‰ (w/w) PA in penicillin, which is about 1 order of magnitude lower than the prescribed residual amount of 1.0‰. The strategy reported here is simple, rapid and inexpensive compared to the traditional chromatography-based methods.
- Published
- 2015
- Full Text
- View/download PDF
19. Label-free surface-enhanced Raman scattering imaging to monitor the metabolism of antitumor drug 6-mercaptopurine in living cells.
- Author
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Han G, Liu R, Han MY, Jiang C, Wang J, Du S, Liu B, and Zhang Z
- Subjects
- Cell Line, Tumor, Gold chemistry, Humans, Metal Nanoparticles chemistry, Molecular Structure, Silver chemistry, Surface Properties, Mercaptopurine analysis, Mercaptopurine metabolism, Spectrum Analysis, Raman
- Abstract
The molecular processes of drugs from cellular uptake to intracellular distribution as well as the intracellular interaction with the target molecule are critically important for the development of new antitumor drugs. In this work, we have successfully developed a label-free surface-enhanced Raman scattering (SERS) technique to monitor and visualize the metabolism of antitumor drug 6-mercaptopurine in living cells. It has been clearly demonstrated that Au@Ag NPs exhibit an excellent Raman enhancement effect to both 6-mercaptopurine and its metabolic product 6-mercaptopurine-ribose. Their different ways to absorb at the surface of Au@Ag NPs lead to the obvious spectral difference for distinguishing the antitumor drug and its metabolite by SERS spectra. The Au@Ag NPs can easily pass through cell membranes in a large amount and sensitively respond to the biological conversion of 6-mercaptopurine in tumor cells. The Raman imaging can visualize the real-time distribution of 6-mercaptopurine and its biotransformation with the concentrations in tumor cells. The SERS-based method reported here is simple and efficient for the assessments of drug efficacy and the understanding of the molecular therapeutic mechanism of antitumor drugs at the cellular level.
- Published
- 2014
- Full Text
- View/download PDF
20. Selective fluorescence turn-on and ratiometric detection of organophosphate using dual-emitting Mn-doped ZnS nanocrystal probe.
- Author
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Zhang K, Yu T, Liu F, Sun M, Yu H, Liu B, Zhang Z, Jiang H, and Wang S
- Subjects
- Molecular Structure, Fluorescence, Fluorescent Dyes chemistry, Manganese chemistry, Nanoparticles chemistry, Organophosphates analysis, Sulfides chemistry, Zinc Compounds chemistry
- Abstract
Semiconductor nanocrystals (NCs) possess unique photoluminescent properties which can be used to design fluorescence probes for chemo/biosensing applications. Several have recently emerged that offer excellent turn-on or ratiometric fluorescence chemosensory protocols by sophisticated procedures, but it has been challenging to realize all of these advantages in a single construct. Herein, we develop an intrinsic dual-emitting Mn-doped ZnS nanocrystal-based probe that achieves this goal with turn-on and ratiometric fluorescence response for the determination of organophosphate (diethylphosphorothioate, DEP). The probe relies on the modification of dopamine dithiocarbamate on the surface of NCs and the modulation of dual emission through a photoinduced electron transfer process, which makes use of red fluorescence of Mn(2+) ions doped in the NCs as specific recognition for the target analyte and blue defect emission of the NCs as stable internal reference. In presence of DEP, the red emission of the probe is thus enhanced by switching off the electron transfer pathway, while the blue emission is almost unchanged. With the addition of different amounts DEP, the two emission intensity ratios gradually vary and display color changes from dark-blue to purple to red. Thus, this method generates turn-on and ratiometric fluorescence signals for quantitative and visual detection of the analyte. Significantly, the dual-emitting probe has been used to fabricate paper-based test strips for visual detection of DEP residues, which validate the method for its rapid, on-site, and visual identification.
- Published
- 2014
- Full Text
- View/download PDF
21. Inkjet-printed silver nanoparticle paper detects airborne species from crystalline explosives and their ultratrace residues in open environment.
- Author
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Wang J, Yang L, Liu B, Jiang H, Liu R, Yang J, Han G, Mei Q, and Zhang Z
- Abstract
An electronic nose can detect highly volatile chemicals in foods, drugs, and environments, but it is still very much a challenge to detect the odors from crystalline compounds (e.g., solid explosives) with a low vapor pressure using the present chemosensing techniques in such way as a dog's olfactory system can do. Here, we inkjet printed silver nanoparticles (AgNPs) on cellulose paper and established a Raman spectroscopic approach to detect the odors of explosive trinitrotoluene (TNT) crystals and residues in the open environment. The layer-by-layer printed AgNP paper was modified with p-aminobenzenethiol (PABT) for efficiently collecting airborne TNT via a charge-transfer reaction and for greatly enhancing the Raman scattering of PABT by multiple spectral resonances. Thus, a Raman switch concept by the Raman readout of PABT for the detection of TNT was proposed. The AgNPs paper at different sites exhibited a highly uniform sensitivity to TNT due to the layer-by-layer printing, and the sensitive limit could reach 1.6 × 10(-17) g/cm(2) TNT. Experimentally, upon applying a beam of near-infrared low-energy laser to slightly heat (but not destruct) TNT crystals, the resulting airborne TNT in the open environment was probed at the height of 5 cm, in which the concentration of airborne species was lower than 10 ppt by a theoretical analysis. Similarly, the odors from 1.4 ppm TNT in soil and 7.2, 2.9, and 5.7 ng/cm(2) TNT on clothing, leather, and envelope, respectively, were also quickly sensed for 2 s without destoying these inspected objects.
- Published
- 2014
- Full Text
- View/download PDF
22. Fluorescence "turn on" detection of mercuric ion based on bis(dithiocarbamato)copper(II) complex functionalized carbon nanodots.
- Author
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Yuan C, Liu B, Liu F, Han MY, and Zhang Z
- Abstract
A new "turn on" fluorescence nanosensor for selective Hg(2+) determination is reported based on bis(dithiocarbamato)copper(II) functionalized carbon nanodots (CuDTC2-CDs). The CuDTC2 complex was conjugated to the prepared amine-coated CDs by the condensation of carbon disulfide onto the nitrogen atoms in the surface amine groups, followed by the coordination of copper(II) to the resulting dithiocarbamate groups (DTC) and finally by the additional coordination of ammonium N-(dithicarbaxy) sarcosine (DTCS) to form the CuDTC2-complexing CDs. The CuDTC2 complex at surface strongly quenched the bright-blue fluorescence of the CDs by a combination of electron transfer and energy transfer mechanism. Hg(2+) could immediately switch on the fluorescence of the CuDTC2-CDs by promptly displacing the Cu(2+) in the CuDTC2 complex and thus shutting down the energy transfer pathway, in which the sensitive limit for Hg(2+) as low as 4 ppb was reached. Moreover, a paper-based sensor has been fabricated by printing the CuDTC2-CDs probe ink on a piece of cellulose acetate paper using a commercial inkjet printer. The fluorescence "turn on" on the paper provided the most conveniently visual detection of aqueous Hg(2+) ions by the observation with naked eye. The very simple and effective strategy reported here facilitates the development of portable and reliable fluorescence nanosensors for the determination of Hg(2+) in real samples.
- Published
- 2014
- Full Text
- View/download PDF
23. Surface-enhanced Raman scattering chip for femtomolar detection of mercuric ion (II) by ligand exchange.
- Author
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Du Y, Liu R, Liu B, Wang S, Han MY, and Zhang Z
- Subjects
- Chromatography, Liquid methods, Mercury analysis, Metal Nanoparticles chemistry, Spectrum Analysis, Raman methods
- Abstract
The chemical sensing for the convenient detection of mercuric ion (II) (Hg(2+)) have been widely explored with the use of various sensing materials and techniques. It still remains a challenge to achieve ultrasensitive but simple, rapid, and inexpensive detection to metal ions. Here we report a surface-enhanced Raman scattering (SERS) chip for the femtomolar (fM) detection of Hg(2+) by employing silver-coated gold nanoparticles (Au@Ag NPs) together with an organic ligand. 4,4'-Dipyridyl (Dpy) can control the aggregation of Au@Ag NPs via its dual interacting sites to Ag nanoshells to generate strong Raman hot spots and SERS readouts. However, the presence of Hg(2+) can inhibit the aggregation of Au@Ag NPs by the coordination with Dpy, and as a result the SERS signals of Dpy are quenched. On the basis of these findings, a SERS chip has been fabricated by the assembly of Au@Ag NPs on a piece of silicon wafer and the further modification with Dpy. The exchange of Dpy from the chip into the aqueous Hg(2+) droplet results in the quenching of Raman signals of Dpy, responding to 10 fM Hg(2+) that is about 6 orders of magnitude lower than the limit defined by the U.S. Environmental Protection Agency in drinkable water. Each test using the SERS chip only needs a droplet of 20 μL sample and is accomplished within ∼4 min. The SERS chip has also been applied to the quantification of Hg(2+) in milk, juice, and lake water.
- Published
- 2013
- Full Text
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24. Highly selective and sensitive detection of mercuric ion based on a visual fluorescence method.
- Author
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Yuan C, Zhang K, Zhang Z, and Wang S
- Subjects
- Color, Ditiocarb analogs & derivatives, Ditiocarb chemistry, Limit of Detection, Mercury chemistry, Paper, Quantum Dots, Spectrometry, Fluorescence, Ultraviolet Rays, Water chemistry, Mercury analysis
- Abstract
The instant and on-site detection of trace aqueous mercuric ion still remains a challenge for environmental monitoring and protection. This work demonstrates a new analytical method and its utility for visual detection of aqueous Hg(2+) on the basis of a novel water-soluble CdSe-ZnS quantum dots (QDs) functionalized with a bidentate ligand of 2-hydroxyethyldithiocarbamate (HDTC). The fluorescence of the aqueous HDTC modified QDs (HDTC-QDs) could be selectively and efficiently quenched by Hg(2+) through a surface chelating reaction between HDTC and Hg(2+), and the detection limit was measured to be 1 ppb. Most interestingly, the orange fluorescence of the HDTC-QDs gradually changes to red upon the increasing amount of Hg(2+) added besides the decreasing of the fluorescence intensity. By taking advantage of this optical phenomenon, a paper-based sensor for aqueous Hg(2+) detection has been developed by immobilizing the HDTC-QDs on cellulose acetate paper which has low background fluorescence in the wavelength range. The paper-based sensor showed high sensitivity and selectivity for Hg(2+) visual detection. When Hg(2+) was dropped onto the paper-sensor, an obviously distinguishable fluorescence color evolution (from orange to red) could be clearly observed depending on the concentration of Hg(2+). The limit of detection of the visual method for aqueous Hg(2+) detection was as low as 0.2 ppm. The very simple and effective strategy reported here should facilitate the development of portable and reliable fluorescence chemosensors for mercuric pollution control.
- Published
- 2012
- Full Text
- View/download PDF
25. Chemiluminescence switching on peroxidase-like Fe3O4 nanoparticles for selective detection and simultaneous determination of various pesticides.
- Author
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Guan G, Yang L, Mei Q, Zhang K, Zhang Z, and Han MY
- Subjects
- Free Radical Scavengers chemistry, Magnetic Phenomena, Models, Molecular, Molecular Conformation, Pesticides chemistry, Time Factors, Biomimetic Materials chemistry, Luminescent Measurements, Magnetite Nanoparticles chemistry, Peroxidase metabolism, Pesticides analysis
- Abstract
To achieve selectivity in direct chemiluminescence (CL) detection is very significant and a great challenge as well. Here, we report a novel concept of developing intrinsically selective CL switching at the surface of Fe(3)O(4) nanoparticles for the sensitive detection and simultaneous determination of various pesticides. Fe(3)O(4) nanoparticles have peroxidase-like catalytic activity and catalyze the decomposition of dissolved oxygen to generate superoxide anions, so that the CL intensity of luminol was amplified by at least 20 times. The CL signals can be quenched by the addition of ethanol because ethanol readily reacts with superoxide anions as a radical scavenger. However, the quenching effect can be inhibited through the specific binding of target molecules on Fe(3)O(4) nanoparticles, leading to CL "turn-on" in the presence of ethanol. The novel CL "switching-on" concept demonstrated unique advantages in the detection of pesticide residues. Using the surface coordinative reactions, nonredox pesticide ethoprophos were sensitively detected with a detection limit of 0.1 nM and had a very wide detection range of 0.1 nM to 100 μM. More importantly, the selectivity of CL switching is tunable through the special surface modification of Fe(3)O(4) nanoparticles, and these Fe(3)O(4) nanoparticles with different surface groups can generate unique CL response pattern for the simultaneous determination of various pesticides. Meanwhile, the superparamagnetic properties of Fe(3)O(4) nanoparticles provide a simple magnetic separation approach to attain interference-free measurement for real detection. The very facile and versatile strategy reported here should open a new window to exploration of selective CL molecular switching and application of magnetic nanoparticles for chemo/biodetection.
- Published
- 2012
- Full Text
- View/download PDF
26. Shell thickness-dependent Raman enhancement for rapid identification and detection of pesticide residues at fruit peels.
- Author
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Liu B, Han G, Zhang Z, Liu R, Jiang C, Wang S, and Han MY
- Subjects
- Gold chemistry, Metal Nanoparticles, Microscopy, Electron, Scanning, Silver chemistry, Fruit chemistry, Pesticide Residues analysis, Spectrum Analysis, Raman methods
- Abstract
Here, we report the shell thickness-dependent Raman enhancement of silver-coated gold nanoparticles (Au@Ag NPs) for the identification and detection of pesticide residues at various fruit peels. The Raman enhancement of Au@Ag NPs to a large family of sulfur-containing pesticides is ~2 orders of magnitude stronger than those of bare Au and Ag NPs, and there is a strong dependence of the Raman enhancement on the Ag shell thickness. It has been shown for the first time that the huge Raman enhancement is contributed by individual Au@Ag NPs rather than aggregated Au@Ag NPs with "hot spots" among the neighboring NPs. Therefore, the Au@Ag NPs with excellent individual-particle enhancement can be exploited as stand-alone-particle Raman amplifiers for the surface identification and detection of pesticide residues at various peels of fruits, such as apple, grape, mango, pear, and peach. By casting the particle sensors onto fruit peels, several types of pesticide residues (e.g., thiocarbamate and organophosphorous compounds) have been reliably/rapidly detected, for example, 1.5 nanograms of thiram per square centimeter at apple peel under the current unoptimized condition. The surface-lifting spectroscopic technique offers great practical potentials for the on-site assessment and identification of pesticide residues in agricultural products., (© 2011 American Chemical Society)
- Published
- 2012
- Full Text
- View/download PDF
27. Trinitrotoluene explosive lights up ultrahigh Raman scattering of nonresonant molecule on a top-closed silver nanotube array.
- Author
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Zhou H, Zhang Z, Jiang C, Guan G, Zhang K, Mei Q, Liu R, and Wang S
- Abstract
The highest Raman enhancement factors are obtained in a double resonance: molecular electronic resonance and plasmon resonance with a "hot spot" in surface-enhanced Raman scattering (SERS). However, for most molecules of interest the double resonance is not realized with the excitation frequencies normally used in Raman. The latter may limit the practical applications of SERS for trace analysis. Here, we report that Raman-inactive trinitrotoluene (TNT) lights up the ultrahigh Raman scattering of off-resonated p-aminobenzenethiol (PABT) through the formation of charge-transfer TNT-PABT complex on the top-closed flexible silver nanotube array. Raman hot spots can spontaneously form in a reversible way by the self-approaching of flexible nanotubes driven through the capillary force of solvent evaporation. Meanwhile, the PABT-TNT-PABT bridges between self-approaching silver nanotubes possibly form by the specific complexing and zwitterion interactions, and the resultant chromophores can absorb the visible light that matches with the incident laser and the localized surface plasmon of a silver nanotube array. The multiple spectral resonances lead to the huge enhancement of Raman signals of PABT molecules due to the presence of ultratrace TNT. The enhancement effect is repeatedly renewable by the reconstruction of molecular bridges and can selectively detect TNT with a limit of 1.5 × 10(-17) M. The results in this report provide the simple and supersensitive approach to the detection of TNT explosives and the possibility of building a robust Raman-based assay platform.
- Published
- 2011
- Full Text
- View/download PDF
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