Gold nanoparticles-based colorimetric assay possesses several unique advantages, and has been applied for a wide range of targets, varying from nucleic acids to different metal ions. However, due to the lack of proper coordinating ligand, gold nanoparticles-based colorimetric sensing system for Au has not been developed so far. It is well-known that Au could induce the oxidation transition of thiol compounds to disulfide compounds. In this article, for the first time we converted such thiol masking reaction into colorimetric sensing system for label-free detection of Au via a target-controlled aggregation of nanoparticles strategy. In the new proposed sensing system, fluorosurfactant-capped gold nanoparticles were chosen as signal reporter units, while an Au-triggered oxidation of cysteine (Cys), which inhibited the aggregation of gold nanoparticles, acted as the recognition unit. By varying the amount of Cys, a tunable response range accompanied with different windows of color change could be obtained for Au, illustrating the universality of the sensing system for Au samples with different sensitivity requirements. Under optimized condition, the proposed sensing system exhibits a high sensitivity towards Au with a detection limit of 50nM, which is lower than previously reported spectroscopic methods. It has also been applied for detection of Au in practical water samples with satisfactory result. © 2013 Elsevier B.V.

Yang Bin    Xiaobing Zhang    Liu Wei-Na    Rong Hu    谭蔚泓     沈国励    俞汝勤   

Biosensors and Bioelectronics

2013

Taking advantage of the super-quenching effect of the cationic perylene derivative on adjacent fluorophores, we for the first time reported a DNAzyme-perylene complex-based strategy for constructing fluorescence catalytic biosensors with improved sensitivity. © 2013 The Royal Society of Chemistry.

Ting Fu    Xuhua Zhao    Bai Huarong    Zilong Zhao    Rong Hu    Rongmei Kong    Xiaobing Zhang    谭蔚泓     俞汝勤   

Chemical Communications

2013

HS is the third endogenously generated gaseous signaling compound and has also been known to involve a variety of physiological processes. To better understand its physiological and pathological functions, efficient methods for monitoring of HS in living systems are desired. Although quite a few one photon fluorescence probes have been reported for HS, two-photon (TP) probes are more favorable for intracellular imaging. In this work, by employing a donor-π-acceptor-structured naphthalene derivative as the two-photon fluorophore and an azide group as the recognition unit, we reported a new two-photon bioimaging probe 6-(benzo[d]thiazol-2′- yl)-2-azidonaphthalene (NHS1) for HS with improved sensitivity. The probe shows very low background fluorescence in the absence of HS. In the presence of HS, however, a significant enhancement for both one photon and TP excited fluorescence were observed, resulting in a high sensitivity to HS in aqueous solutions with a detection limit of 20 nM observed, much lower than the previously reported TP probe. The probe also exhibits a wide linear response concentration range (0-5 μM) to H S with high selectivity. All these features are favorable for direct monitoring of HS in complex biological samples. It was then applied for direct TP imaging of HS in living cells with satisfactory sensitivity, demonstrating its value of practical application in biological systems. © 2013 American Chemical Society.

Guojiang Mao    Wei Tian-Tian    Wang Xu-Xiang    Huan Shuangyan    Lu Dan-Qing    Jing Zhang    Xiaobing Zhang    谭蔚泓     沈国励    俞汝勤   

Analytical Chemistry

2013

Heavy metal ion pollution poses severe risks in human health and the environment. Driven by the need to detect trace amounts of mercury, this article demonstrates, for the first time, that silver/mercury amalgamation, combining with DNA-protected silver nanoparticles (AgNPs), can be used for rapid, easy and reliable screening of Hg ions with high sensitivity and selectivity over competing analytes. In our proposed approach, Hg detection is achieved by reducing the mercury species to elemental mercury, silver atoms were chosen as the mercury atoms' acceptors by forming Ag/Hg amalgam. To signal fluorescently this silver amalgamation event, a FAM-labeled ssDNA was employed as the signal reporter. AgNPs were grown on the DNA strand that resulted in greatly quenching the FAM fluorescence. Formation of Ag/Hg amalgam suppresses AgNPs growth on the DNA, leading to fluorescence signal increase relative to the fluorescence without Hg ions, as well as marked by fluorescence quenching. This FAM fluorescence enhancement can be used for detection of Hg at the a few nanomolar level. Moreover, due to excellent specificity of silver amalgamation with mercury, the sensing system is highly selective for Hg and does not respond to other metal ions with up to millimolar concentration levels. This sensor is successfully applied to determination of Hg in tap water, spring water and river water samples. The results shown herein have important implications in the development of new fluorescent sensors for the fast, easy, and selective detection and quantification of Hg in environmental and biological samples. © 2013 American Chemical Society.

Deng Li    Ouyang Xiangyuan    Jianyu Jin    Ma Cheng    Jiang Ying    Jing Zheng    Jishan Li    Yinhui Li    谭蔚泓     Ronghua Yang   

Analytical Chemistry

2013

In this work, atomic force microscopy (AFM) was employed to characterize the elastic properties of a living suspension of Nicotiana tabacum L. cv. Bright Yellow (BY-2) cells and to investigate the changes in plant-cell elasticity that were induced by water-soluble C fullerene derivatives. The results revealed different effects of the three fullerene derivatives that had different numbers of carboxylic groups on the cell elasticity. BY-2 cells that were repressed by dimalonic-acid-modified C fullerenes (DiF ) and trimalonic-acid-modified C fullerenes (TriF ) showed a clear decrease in their Young's modulus. However, the Young's modulus of cells that were treated with tetramalonic-acid-modified C fullerenes (TetraF) increased. Disruption of the actin cytoskeleton arrangement was observed following treatment with DiF and TriF, but not with TetraF Moreover, the fullerene-induced cell-elasticity change was consistent with the change in cell-proliferation rate. This work provides a new approach and valuable information for the study of the biological effect of nanomaterials on plant cells. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Zhang Xuejie    Qiaoling Liu    Xia Tie    Nan Li    He Kangmin    Chunru Wang    谭蔚泓     Fang Xiaohong   

Chemistry - An Asian Journal

2013

Hugh Fan    谭蔚泓    

Nanomedicine

2013

Aptamer-based fluorescence anisotropy (FA) assays have attracted great interest in recent years. However, a key factor that determines FA value is molar mass, thus limiting the utility of this assay for the detection of small molecules. To solve this problem, streptavidin, as a molar mass amplifier, was used in a hybridization chain reaction (HCR) to construct a target-triggered cyclic assembly of DNA-protein hybrid nanowires for highly sensitive detection of small molecules by fluorescence anisotropy. In this assay, one blocking DNA strand is released by target-aptamer recognition. The DNA then serves as an initiator to trigger enzyme-free autonomous cross-opening of hairpin probes via HCR to form a DNA nanowire for further assembly of streptavidin. Using adenosine triphosphate (ATP) as the small molecule target, this novel dual-amplified, aptamer-based FA assay affords high sensitivity with a detection limit of 100 nM. This limit of detection (LOD) is much lower than that of the disassembly approach without HCR amplification or the assembly strategy without streptavidin. In contrast to the previous turn-off disassembly approaches based on nonspecific interactions between the aptamer probe and amplification moieties, the proposed aptamer-based FA assay method exhibits a turn-on response to ATP, which can increase sensing reliability and reduce the risk of false hits. Moreover, because of its resistance to environmental interferences, this FA assay has been successfully applied for direct detection of 0.5 μM ATP in complex biological samples, including cell media, human urine, and human serum, demonstrating its practicality in real complex biological systems. © 2013 American Chemical Society.

Yang Bin    Xiaobing Zhang    Kang Li-Ping    沈国励    俞汝勤    谭蔚泓    

Analytical Chemistry

2013

Aggregation-induced emission (AIE) dyes show different emission mechanism from traditional dyes, which were found to be nonluminescent in the solution state and emissive in the aggregate state, and have been well employed to design turn-on fluorescent probes for various targets. In this paper, we report for the first time a tetraphenylethylene-based AIE probe 1 for Al, which employed two diethylenetriamine units as the recognition ligand for Al. In the presence of Al, a large fluorescence enhancement was achieved for probe 1, which together with the low background fluorescence of free probe 1 allow for high sensitivity for Al, with a dynamic range from 2.0 × 10 to 1.1 × 10 M observed, and a detection limit of 5 × 10 M for Al. The proposed probe shows high selectivity to Al . UV-vis absorption spectra experiments and dynamic light scattering measurements were performed to verify the AIE sensing mechanism of probe 1. Moreover, a 1:1 stoichiometry was estimated for the 1-Al complex via fluorescence Job's method. © 2013 The Royal Society of Chemistry.

Wei Tian-Tian    Jing Zhang    Guojiang Mao    Xiaobing Zhang    Ran Zhao-Jin    谭蔚泓     俞汝勤   

Analytical Methods

2013

This paper described the optimized design, synthesis and application of a novel rhodamine thiospirolactam derivative as an 'off-on' fluorescent probe for the detection of Hg in aqueous samples. The 'off-on' fluorescence and color signal change of the probe is based on an Hg -triggered domino reaction which brings on the opened-ring form of the rhodamine spirolactam to regain the conjugated system of the rhodamine skeleton. In the well designed probe, the thiospirolactam serves as both Hg binding unit and electron-defect carbon centre, a phenolic hydroxyl with very strong nucleophilicity after deprotonation is chosen as the attacking unit, and a benzene ring is introduced on the linker to afford steric effects, which benefits an efficient nucleophilic reaction, with a high sensitivity towards Hg . It exhibits a stable response for Hg from 1.0 × 10 to 1.0 × 10 M, with a detection limit of 3.0 × 10 M. The response of the probe to Hg is highly selective and pH-insensitive, with a fast response time. All these unique features make it particularly favorable for cellular Hg imaging applications. It has been preliminarily used for highly sensitive monitoring of Hg levels in living cells with satisfying resolution. © The Royal Society of Chemistry 2012.

Gong Yi-Jun    Xiaobing Zhang    陈卓    袁媛    Jin Zhen    Mei Lei    Jing Zhang    谭蔚泓     沈国励    俞汝勤   

Analyst

2012

The need to decipher various biological events has led to the elucidation of the molecular mechanisms underlying a number of disease processes. Consequently, the detection and simultaneous monitoring of chemical interactions between biological targets has become indispensable in medical diagnosis, targeted therapeutics, and molecular biology. Multiplexed applications employing nanomaterials, which represent the integration of nanotechnology and biology, have changed the bioanalytical outlook and provided various promising tools. Among these nanomaterials, fluorescent dye-doped silica nanoparticles have demonstrated excellent potential for use in advanced bioanalysis to facilitate deeper understanding of biology and medicine at the molecular level. In particular, silica nanoparticles have been applied to diagnostics and therapeutic applications in cancer and gene/drug delivery. This feature article summarizes recent developments in the synthesis, biocompatibility, and bioapplications of fluorescent dye-doped silica nanoparticles. © The Royal Society of Chemistry.

Bae Se Won    谭蔚泓     Hong Jong In   

Chemical Communications

2012