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ABSTRACT: Determining and monitoring toxicity of chemicals in water are very important for human health and country security. Electrochemical measurement of respiratory chain activity is a rapid and reliable screening of the toxicity towards microorganisms. Here, we report a rapid and sensitive toxicity bioassay using p-benzoquinone as the artificial electron mediator and Escherichia coli as the test organism. Four heavy metal ions, Cu(2+), Ag(+), Hg(2+) and Co(2+), are tested as the model toxicants, and the corresponding 50% respiration inhibition concentrations (IC50) are determined to be 0.95, 8.14, 11.69 and 42.76 mg L(-1), respectively. Based on the IC50 values, the descending order of toxicity is: Cu(2+) > Ag(+) > Hg(2+) > Co(2+). The presented bioassay not only provides a good foundation for further toxicity tests using E. coli, but also the potential for expanding the technique to utilize other bacteria with complementary toxicity responses, thereby allowing use of the bioassay in a wide range of applications.
The Analyst 04/2013; · 4.23 Impact Factor
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ABSTRACT: This work presents a new colorimetric microorganism biosensor for monitoring and detecting acute toxicity in water, where prussian blue (PB) is used as the colorimetric indicator and E. coli as the model bacterial. In this biosensor, the electron mediator, ferricyanide, accepts electrons from E. coli during respiration to produce ferrocyanide, which subsequently reacts with ferric ions to yield PB, a famous material with a blue color. Since toxicants can inhibit the respiratory activity of E. coli and then reduce the ferrocyanide and consequent PB production, toxicity can be easily detected by measuring the decrease in the production of PB induced by toxicants. Three important toxicants, 3,5-dichlorophenol (DCP), As(3+), Cr(6+) are tested and the detection limits are 3.2, 25, and 3.2 ppm, respectively. Moreover, we could identify the yellow green to dark green color change by naked eye even at concentrations as low as 12.5 ppm for both DCP and Cr(6+). Subsequently, the acute toxicities of groundwater and south lake water are successfully determined by this sensor. This biosensor is rapid, sensitive and cost-effective, and can thus be regarded as a promising biosensor for giving an early warning of acute water toxicity.
The Analyst 11/2012; · 4.23 Impact Factor
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ABSTRACT: We demonstrated a facile and green approach to synthesize bifunctional fluorescent carbon nanodots via soy milk, which not only showed favorable photoluminescent properties, but also exhibited good electrocatalytic activity towards oxygen reduction reaction.
Chemical Communications 08/2012; 48(75):9367-9. · 6.17 Impact Factor
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ABSTRACT: In this letter, we report on the preparation of supramolecular hexagonal disk-like microparticles via a simple solution ionic
self-assembly approach. The formation of the microdisks occurs in a single process, carried out by mixing aqueous Ru(NH3)6Cl3 and K4Fe(CN)6 solution at room temperature. The morphology and size were examined by scanning electron microscopy and the chemical composition
of such microdisks was further determined by both energy-dispersed spectrum and X-ray maps. The influence of both molar ratio
and concentration of reactants on the particle formation was also investigated and they are found to play an important role
in the formation of microdisks.
Inorganic Materials 04/2012; 46(5):472-475. · 0.41 Impact Factor
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ABSTRACT: In this communication, the application of coordination polymer nanobelts (CPNs) assembled from H(2)PtCl(6) and 3,3',5,5'-tetramethylbenzidine (TMB) are explored as an effective fluorescent sensing platform for nucleic acid detection for the first time. The suggested method has a high selectivity down to single-base mismatch. DNA detection is accomplished by the following two steps: (1) CPN binds fluorecent dye-labeled single-stranded DNA (ssDNA) probe via both electrostatic attraction and π-π stacking interactions between unpaired DNA bases and CPN. As a result, the fluorescent dye is brought into close proximity to CPN and substantial fluorescence quenching occurs due to photoinduced electron transfer from the nitrogen atom in CPN to the excited fluorophore. (2) The hybridization of adsorbed ssDNA probe with its target generates a double stranded DNA (dsDNA). The duplex cannot be adsorbed by CPN due to its rigid conformation and the absence of unpaired DNA bases, leading to an obvious fluorescence enhancement.
Macromolecular Rapid Communications 06/2011; 32(12):899-904. · 4.60 Impact Factor
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ABSTRACT: In this article, carbon nanoparticles (CNPs) were used as a novel fluorescent sensing platform for highly sensitive and selective Hg(2+) detection. To the best of our knowledge, this is the first example of CNPs obtained from candle soot used in this type of sensor. The general concept used in this approach is based on that adsorption of the fluorescently labeled single-stranded DNA (ssDNA) probe by CNP via π-π stacking interactions between DNA bases and CNP leads to substantial dye fluorescence quenching; however, in the presence of Hg(2+), T-Hg(2+)-T induced hairpin structure does not adsorb on CNP and thus retains the dye fluorescence. A detection limit as low as 10nM was achieved. The present CNP-based biosensor for Hg(2+) detection exhibits remarkable specificity against other possible metal ions. Furthermore, superior selectivity performance was observed when Hg(2+) detection was carried out in the presence of a large amount of other interference ions. Finally, in order to evaluate its potential practical application, Hg(2+) detection was conducted with the use of lake water other than pure buffer and it is believed that it holds great promise for real sample analysis upon further development.
Biosensors & bioelectronics 04/2011; 26(12):4656-60. · 5.43 Impact Factor
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ABSTRACT: The present communication demonstrates the use of water-soluble nano-C(60) as a novel, effective fluorescent sensing platform for Hg(2+) detection for the first time. This sensing system achieves a detection limit as low as 500 pM and exhibits excellent selectivity.
Nanoscale 04/2011; 3(5):2155-7. · 5.91 Impact Factor
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ABSTRACT: Herein, we develop a novel single fluorophore-labeled double-stranded oligonucleotide (OND) probe for rapid fluorescence-enhanced K(+) detection, based on an inherent quenching ability of guanine bases and G-rich OND conformation transition from duplex to G-quadruplex. This probe presents high sensitivity and good selectivity for the detection of K(+), and the assay process is simple and fast.
Journal of Fluorescence 04/2011; 21(5):1841-6. · 2.11 Impact Factor
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ABSTRACT: In this communication, we demonstrate for the first time that titanium silicalite-1 zeolite microparticles (TSZMs) can effectively catalyze the reduction of H(2)O(2), leading to an enzymeless H(2)O(2) sensor with a linear detection range from 100 μM to 40 mM (r = 0.994) and a detection limit of 0.5 μM at a signal-to-noise ratio of 3.
The Analyst 03/2011; 136(10):2037-9. · 4.23 Impact Factor
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ABSTRACT: In this Letter, we demonstrate the first use of carbon nanoparticles (CNPs) obtained from carbon soot by lighting a candle as a cheap, effective fluorescent sensing platform for Ag(+) detection with a detection limit as low as 500 pM and high selectivity. We further demonstrate its practical application to detect Ag(+) in a real sample.
Langmuir 03/2011; 27(8):4305-8. · 4.19 Impact Factor
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ABSTRACT: In this Communication, we report water-soluble nano-C(60) in the first use as an effective fluorescent sensing platform for the highly sensitive and selective detection of Ag(+). The general concept used in this approach is based on a fluorescently labeled single-stranded DNA (ssDNA) probe that adsorbs on nano-C(60), leading to substantial dye fluorescence quenching; however, in the presence of Ag(+), C-Ag(+)-C coordination induces the probe to fold into a hairpin structure, which does not adsorb on nano-C(60) and thus retains the dye fluorescence. This sensing system exhibits a detection limit as low as 1 nM and has a high selectivity against other metal ions. Finally and most importantly, we demonstrate its performance in real sample analysis.
The Analyst 03/2011; 136(10):2040-3. · 4.23 Impact Factor
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ABSTRACT: In this Communication, we report on the first preparation of conjugation polymer poly(2,3-diaminonaphthalene) (PDAN) microspheres via chemical oxidation polymerization of 2,3-diaminonaphthalene (DAN) monomers by ammonium persulfate (APS) at room temperature. We further demonstrate the use of PDAN microspheres as a novel quencher for fluorescence-enhanced nucleic acid detection.
The Analyst 03/2011; 136(11):2221-4. · 4.23 Impact Factor
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ABSTRACT: In this paper, we report on the large-scale formation of supramolecular rhombus microparticles (SRMs) driven by electrostatic assembly, carried out by direct mixing of an aqueous HAuCl(4) solution and an ethanol solution of 4,4'-bipyridine at room temperature. We further demonstrate their use as an effective fluorescent sensing platform for nucleic acid detection with a high selectivity down to single-base mismatch. The general concept used in this approach is based on adsorption of the fluorescently labeled single-stranded DNA (ssDNA) probe by SRM, which is accompanied by substantial fluorescence quenching. In the following assay, specific hybridization with its target to form double-stranded DNA (dsDNA) results in desorption of ssDNA from SRM surface and subsequent fluorescence recovery.
PLoS ONE 01/2011; 6(4):e18958. · 4.09 Impact Factor
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ABSTRACT: In this study, we reported on the construction of a stable single-chamber ethanol/O(2) biofuel cell harvesting energy from the ethanol and alcoholic beverage. We prepared a composite film which consisted of partially sulfonated (3-mercaptopropyl)-trimethoxysilane sol-gel (PSSG) and chitosan (CHI). The combination of ion-exchange capacity sol-gel and biopolymer chitosan not only provided the attached sites for mediator MDB and AuNPs to facilitate the electron transfer along the substrate reaction, but also gave the suitable microenvironment to retain the enzyme activity in long term. The ethanol bioanode was constructed with the film coimmobilized dehydrogenase (ADH), Meldola's blue (MDB) and gold nanoparticles (AuNPs). The MDB/AuNPs/PSSG-CHI-ADH composite modified electrode showed prominent electrocatalytic activity towards the oxidation of ethanol. The oxygen biocathode consisted of laccase and AuNPs immobilized on the PSSG-CHI composite membrane. The AuNPs/PSSG-CHI-laccase modified electrode catalyzed four-electron reduction of O(2) to water, without any mediator. The assembled single-chamber biofuel cell exhibited good stability and power output towards ethanol. The open-circuit voltage of this biofuel cell was 860 mV. The maximum power density of the biofuel cell was 1.56 mWcm(-2) at 550 mV. Most interestingly, this biofuel cell showed the similar performance when the alcoholic beverage acted as the fuel. When this biofuel cell ran with wine as the fuel, the maximum power output density was 3.21 mAcm(-2) and the maximum power density was 1.78 mWcm(-2) at 680 mV of the cell voltage. Our system exhibited stable and high power output in the multi-component substrate condition. This cell has great potential for the development and practical application of bioethanol fuel cell.
Biosensors & bioelectronics 09/2010; 26(1):70-3. · 5.43 Impact Factor
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ABSTRACT: Chain-like and ring-like CoPt hollow nanoparticles were facilely obtained via a one-pot synthesis process, and we found that temperature played an important role in the assembly morphology.
Chemical Communications 03/2010; 46(9):1500-2. · 6.17 Impact Factor
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ABSTRACT: The change of the photoluminescence (PL) property of CdTe quantum dot (QD) assembled multilayers along with applied potential has been investigated in aqueous solution. By using the in situ fluorescence spectroelectrochemistry technique, we examined the PL property of QDs upon applying potentials under different atmosphere media, in air and in nitrogen. It was found that when the sample was under nitrogen or exposed to air, the luminescence of QDs bear quenching by adding positive potentials. On the contrary, while applying negative potentials, the luminescence of QD was weakened only in the air condition. It seemed that the luminescence of CdTe QDs was hardly affected by the potentials under nitrogen. On the basis of the phenomena, electrochemistry and X-ray photoelectron spectroscopy (XPS) measurements were then performed to explain the possible origins of PL changes. The results clearly indicated that the variation of surface structure of QDs affected the PL property of CdTe QDs significantly.
12/2009;
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ABSTRACT: A new synthesis strategy has been developed for the preparation of bimetallic gold-silver (Au-Ag) alloy nanoparticles by the virtue of polyelectrolyte multilayer (PEM) nanoreactors. By controlling the assembly conditions, gold and silver ions can be effectively loaded onto the PEM composed of polyethylenimine (PEI) and poly(acrylic acid) (PAA) simultaneously. Upon further thermal treatment, Au-Ag alloy nanoparticles with sizes of ca. 3.8 nm formed in the PEM, which were characterized in detail by UV-vis absorption spectroscopy, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and energy-dispersive X-ray (EDX) analysis. Appearance of a single plasmon band in the visible region and lack of apparent core-shell structures in the TEM images confirm the formation of homogeneous Au-Ag alloy nanoparticles. In addition, the surface plasmon absorption band of the Au-Ag alloy nanoparticles shows linear blue-shift with increasing Ag content, which also supported the formation of alloy nanoparticles. Several key parameters of the present strategy have been investigated, which showed that pH of both the assembly solution and gold salt solution and the choice of polymers for constructing PEM, as well as the reduction approach, all played an important role in successfully synthesizing bimetallic Au-Ag nanoparticles. The formation mechanism of alloy nanoparticles has also been discussed based on the spectral evolution during the thermal reduction.
Langmuir 12/2009; 26(9):6713-9. · 4.19 Impact Factor
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ABSTRACT: Prussian blue/carbon nanotube (PB/CNT) hybrids with excellent dispersibility in aqueous solutions were synthesized by adding CNTs to an acidic solution of Fe3+, [Fe(CN)6]3− and KCl. Fourier transform infrared spectroscopy, UV-vis absorption spectroscopy and scanning electron microscopy were employed to confirm the formation of PB/CNT hybrids. The PB nanoparticles formed on the CNT surfaces exhibit a narrow size distribution and an average size of 40 nm. The present results demonstrate that the selective reduction of Fe3+ to Fe2+ by CNTs is the key step for PB/CNT hybrid formation. The subsequent fabrication of the PB/CNT hybrid films was achieved by layer-by-layer technique. The thus-prepared PB/CNT hybrid films exhibit electrocatalytic activity towards H2O2 reduction.
Electroanalysis 09/2009; 21(20):2207 - 2212. · 2.87 Impact Factor
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ABSTRACT: We report here a facile method to obtain folic acid (FA)-protected gold nanoparticles (Au NPs) by heating an aqueous solution of HAuCl(4)/FA in which FA acts as both the reducing and stabilizing agent. The successful formation of FA-protected Au NPs is demonstrated by UV/Vis spectroscopy, transmission electron microscopy (TEM), selected-area electron diffraction (SAED), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FTIR). The intracellular uptake of these nanoparticles is facilitated by HeLa cells overexpressing the folate reporter, which itself is significantly inhibited by free FA in a competitive assay as quantified by inductively coupled plasma mass spectroscopy (ICP-MS). This simple one-step approach affords a new perspective for creating functional nanomaterials, and the resulting biocompatible, functional Au NPs may find some prospective applications in various biomedical fields.
Chemistry 09/2009; 15(38):9868-73. · 5.93 Impact Factor
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ABSTRACT: An easy surface-modified method has been developed to link −NH2 groups to the TiO2 colloidal spheres with nanoporous surface (f-TiO2). It was found that the as-prepared f-TiO2 is positively charged in neutral conditions and could act as an electrostatic anchor for nanosructures with opposite charge. Furthermore, platinum nanoparticles (Pt NPs) are successfully assembled on the f-TiO2 mainly via electrostatic interaction to fabricate a new kind of Pt NPs/TiO2 hybrid nanomaterial (f-TiO2−Pt NPs). The morphology, structure, and composition of the hybrids were characterized by the means of diverse techniques such as transmission electron microscopy, scanning electron microscopy, X-ray powder diffraction, and Raman spectra. Electrochemical experiments indicate the electrode modified with f-TiO2−Pt NPs shows prominent electrocatalytic activity toward the oxidation of hydrogen peroxide. In particular, as an example, a glucose biosensor fabricated by casting on additional glucose oxidase containing a biocompatible polymer, chitosan on the f-TiO2−Pt NPs film exhibits great promise for sensitive and fast detection of glucose.
07/2009;
