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ABSTRACT: For the first time, hen egg white coagulum was utilized as a surface modification agent for biomimetic multilevel structured nanomaterials (BMSN). By using a straightforward thermal control process, hen egg white can be coagulated in a precisely tailored manner, which is specifically adapted to the morphology of BMSN. Consequently, the structural stability, hydrophobicity and biocompatibility of BMSN can be improved significantly and simultaneously within one hour. Meanwhile, their initial structure-related function can be maintained with higher reliability. These advantages offer an incentive to use egg white coagulum as a facile, precise, quick and much cost-effective alternative to the conventional stabilization materials, such as hot melt adhesive, chitosan and polydopamine.
Scientific Reports 03/2013; 3:1464.
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ABSTRACT: Contamination of food and drinking water by dangerous levels of nitrite has always been of strong concern and toxicity of this inorganic anion calls for convenient detection methods. Although some visible approaches were developed to deal with this problem, using environmentally incompatible organic reagents or functionalized nanoparticles may greatly limit their wide applications. In this article, we report a method to visibly detect nitrite in less than 1 min at room temperature. The efficacy of the method relies on a specific reaction of HNO2 with H2O2 to produce peroxynitrous acid (HOONO), which oxidizes colorless 3,3',5,5'-tetramethylbenzidine (TMB) to its golden yellow diimine product in seconds, with the regeneration of HNO2. Therefore, HNO2 can be regarded as a catalyst for the oxidation of TMB by H2O2. Because color visualization of the TMB-H2O2 system (system I) is dependent upon the concentration of HNO2, it offers a unique avenue for the determination of nitrite. With this method, 1 μM of nitrite could be detected by the perception of yellow color in solution and less than 0.5 μM of nitrite be quantified with a spectrophotometer. The limit of detection (LOD) was 0.1 μM (S/N = 3). More interestingly, we found that the TMB-HNO2 system (system II) could be reversibly designed to detect H2O2 and then glucose with the help of glucose oxidase. We evaluated the applicability of the TMB-HOONO platform in the determination of nitrite in drinking water and urinary glucose, obtaining satisfactory results. Being sensitive, selective, time-efficient, and cost-effective, the two methods derived from the three-component reaction platform are feasible for quantification of nitrite and glucose in routine laboratory practice or rapid assay outside the laboratory.
The Analyst 03/2013; · 4.23 Impact Factor
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ABSTRACT: We have developed a Boolean NAND logic gate for the fluorescent detection of nitrite ions by using bovine serum albumin (BSA) functionalized gold nanoclusters.
Chemical Communications 03/2013; 49(26):2691-3. · 6.17 Impact Factor
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ABSTRACT: High-quality cysteamine-coated CdTe quantum dots (CA-CdTe QDs) were successfully synthesized in aqueous phase by a facile one-pot method. Through hydroxylamine hydrochloride-promoted kinetic growth strategy, water-soluble CA-CdTe QDs could be obtained conveniently in a conical flask by a stepwise addition of raw materials. The photoluminescence quantum yield (PL QY) of the obtained QDs reached 9.2% at the emission peak of 520nm. The optical property and the morphology of the QDs were characterized by UV-vis absorption spectra, photoluminescence spectra (PL) and transmission electron microscopy (TEM) respectively. Furthermore, the fluorescence of the resultant QDs was quenched by copper (II) (Cu(2+)) and mercury (II) (Hg(2+)) meanwhile. It is worthy of note that to separately detect Hg(2+), cyanide ion could be used to eliminate the interference of Cu(2+). Under the optimal conditions, the response was linearly proportional to the logarithm of Hg(2+) concentration over the range of 0.08-3.33μM with a limit of detection (LOD) of 0.07μM.
Analytica chimica acta 12/2012; 757:63-8. · 4.31 Impact Factor
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ABSTRACT: We present a method for the rapid visible assay of bromate and hypochlorite in drinking water within 5 min. The assay utilizes a commercially common reagent and allows the determination of bromate and hypochlorite at several ppb levels with remarkably high selectivity over other ions.
The Analyst 11/2012; · 4.23 Impact Factor
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ABSTRACT: Poly(o-phenylenediamine) (POPD)-derived functional carbon materials with excellent capacitive performance are successfully synthesized by means of an integrated one-step process, in which FeCl(3) not only oxidizes the polymerization of the organic monomers but also activates the carbonization. Furthermore, extensive research has proved that this strategy to discover novel carbons is useful not only for capacitors but also for other energy storage/conversion devices.
Advanced Materials 10/2012; · 13.88 Impact Factor
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ABSTRACT: In this work, we explored a novel fabrication method to construct Au and Ag electrodes on chip, utilizing the different solubility of gold and silver in different etching solutions. KI-I(2) etching solution and 50% HNO(3) were chosen to dissolve the metal layers alternatively. Planar electrodes with gold and silver could be simultaneously and accurately patterned on chip using photolithographic technique. The as-prepared electrode could be directly served as integrated three-electrode system for electrochemical measurement. Based on it, a sensing strategy has been carried out using home-made electrochemical sensing (ECS) chip, which depended on the competition of double strand DNA and Hg(II)-mediated T-T base pairs (T-Hg(II)-T). Actually, a mercury specific oligonucleotide (MSO) was immobilized onto the thus-fabricated gold working electrode and employed as the sensing element. Chronocoulometry (CC) was chosen to monitor the differences of surface charge volume and quantify the concentrations of Hg(II) ions with a low detection limit down to 1nM. Therefore, a facile method to fabricate Au and Ag electrodes has been demonstrated to simplify the production of ECS chip. The ECS chip was finally used for constructing an effective sensing platform for sensitive Hg(II) determination, which held promising potential for designing ECS chip in lab-on-a-chip device or point-of-care diagnosis.
Analytica chimica acta 08/2012; 738:45-50. · 4.31 Impact Factor
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ABSTRACT: A colorimetric sensor for nitrite ion with high selectivity and sensitivity by unmodified citrate-capped gold nanoparticles (Au NPs) is presented. Recognition of nitrite is developed on the basis of a highly specific diazo reaction between nitrite and phenylenediamine (PDA). PDA caused the Au NPs to aggregate owing to the strong covalent NH-Au bond, with a clear color change of solution from red to blue being visualized. In the presence of phosphoric acid and nitrite, the amines of PDA would readily be converted to diazo bonds, and a red solution was observed after the subsequent addition of Au suspension due to the much less strength of electrostatic interaction between the positive diazo groups and the negative citrate-capped Au NPs. With this colorimetric "light-up" method, <1 ppm of nitrite can be easily detected within 5 min at room temperature without instrumentation. Since the diazo reaction and the colorimetric response are separate, this approach features the use of pristine Au NPs in an assay where acidic environment is a necessity, making it a more convenient and cost-effective method for the sensing of nitrite when compared with those utilizing chemically modified Au NPs.
The Analyst 06/2012; 137(14):3286-92. · 4.23 Impact Factor
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ABSTRACT: Colorimetric recognition and sensing of sulfite by melamine-modified gold nanoparticle is reported, using Tris-HCl as the operating buffer. Furthermore, indirect determination of hypochlorite is accomplished by its oxidation of sulfite.
The Analyst 06/2012; 137(15):3437-40. · 4.23 Impact Factor
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ABSTRACT: A selected region functionalized strategy was proposed and realized here to combine the advantages of nanotechnology and living fungi activities.
Nanoscale 05/2012; 4(12):3629-34. · 5.91 Impact Factor
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ABSTRACT: In this article, we report a colorimetric approach for the determination of hypochlorite (OCl(-)) with gold nanoparticles (Au NPs). The test proceeds as two individual steps and selectivity is developed based on the strong oxidizing ability of hypochlorite. In concentrated phosphate buffer (PB), the red solution of citrate-capped Au NPs could be stabilized by the chemisorption of 11-mercaptoundecanoic acid (MUA), without which the colloidal suspension turned blue because of salt-induced particles aggregation. However, by its oxidizing power, OCl(-) converted the alkanethiol to a sulfonate derivative, which could not protect Au NPs from aggregation, thereby a blue solution was observed after the subsequent addition of Au suspension. With this method and under the optimal conditions (28 nm Au NP, 50 mM PB, pH 7.0, and 10 min for the colorimetric response), 1.5 μM of OCl(-) can be easily visualized by the naked eye. This sensitive and selective colorimetric assay opens up a fresh insight of facile, rapid, and reliable detection of OCl(-), and may find its future application in the monitoring of OCl(-)/HOCl in waters sanitized by chlorine or hypochlorite compounds.
The Analyst 05/2012; 137(12):2806-12. · 4.23 Impact Factor
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ABSTRACT: A sensor for hydrogen peroxide is described that is based on an indium tin oxide electrode modified with Fe3O4 magnetic nanoparticles which act as a mimic for the enzyme peroxidase and greatly improve the analytical performance of the
sensor. The amperometric current is linearly related to the concentration of H2O2 in the range from 0.2mM to 2mM, the regression equation is y = -0.5–1.82x, the correlation coefficient is 0.998 (n = 3), and the detection limit is 0.01mM (S/N = 3). The sensor exhibits favorable selectivity and excellent stability.
FigureUsing the peroxidase mimic property of Fe3O4 magnetic nanoparticles (MNPs), a sensitive electrochemical method with favorable analytical performance for the determination
of hydrogen peroxide (H2O2) was developed.
KeywordsFe3O4 magnetic nanoparticle–Peroxidase mimic–Hydrogen peroxide–Amperometric
Microchimica Acta 04/2012; 174(1):183-189. · 3.03 Impact Factor
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ABSTRACT: Deoxyribonucleic acid (DNA) can form G-quadruplexes in the presence of certain metal ions. These play a functional role in
a variety of biological process. A DNA 17-mer (PW17) was previously reported to bind hemin in the presence of excess potassium
ion. The resulting stabilized G-quadruplex-hemin complex exhibits peroxidase-like activity. However, this activity is lost
in the presence of one equivalent of Pb2+ ion. We exploit this property in a method for spectrophotometric detection of Pb2+. Inhibition by Pb2+ ion is reflected by a change in the Soret band of hemin and a sharp reduction in the catalytic activity towards hydrogen
peroxide-mediated chromogenic oxidation of 2,2′-azino-bis(3-ethylbenzothiazoline)-6-sulfonate. The new method enables Pb2+ to be detected in the concentration range from 0.05 to 1.2μM, with a detection limit of 27nM. The assay shows high selectivity
over other metal ions. It was successfully used to determine Pb2+ in water samples.
KeywordsLead(II) ion-Potassium ion-Peroxidase-like DNAzyme-Spectrophotometry
Microchimica Acta 04/2012; 171(1):195-201. · 3.03 Impact Factor
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ABSTRACT: This work attempts to calculate the binding-site number using fluorescence spectroscopic method with bovine serum albumin
(BSA) and Indo-1 as protein and ligand models, respectively. The method for calculating the binding-site number in BSA for
Indo-1 was developed based on the relationships between changes in Indo-1 fluorescence intensity and the analytical concentration
of BSA. The interaction between BSA with Indo-1 was investigated comprehensively using fluorescence techniques as well as
fluorescence resonance energy transfer, and the thermodynamic parameters were calculated according to the effect of enthalpy
on temperature. Three binding sites in BSA for Indo-1 were revealed, and the distances from Trp212 in BSA to the three binding
sites were 2.93, 2.57 and 2.40 nm, respectively. It was also proven that Indo-1 embedded into the three hydrophobic cavities
of BSA by hydrophobic association. This paper provides a reference on calculating the binding-site number in proteins for
ligands and studying their interactions by fluorescence spectroscopic methods. In fluorescent quenching experiments, fluorescence
changes were automatically recorded in real time by combining the Microlab 500 Series Dispenser and PTI fluorescence apparatus.
Frontiers of Chemistry in China 04/2012; 3(1):105-111.
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ABSTRACT: This communication describes a new type of alloyed Cd-In-S quantum dots (CdIS QDs) with ultra small particle size and broadly tunable fluorescence emission from 450 to 700 nm. The band gap of CdIS QDs was mainly controlled by their composition rather than their particle size. The CdIS-ZnS core-shell nanocrystals exhibited significantly improved optical properties and chemical stabilities, with the PL quantum yield (QY) of up to 60%.
Chemical Communications 04/2012; 48(44):5452-4. · 6.17 Impact Factor
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ABSTRACT: A colorimetric method for the determination of thiocyanate (SCN(-)) ion with a cystamine-modified gold nanoparticle (Au NP) probe is presented. In this method, recognition is based on electrostatic attraction and directional hydrogen bonding between thiocyanate and cystamine on the surface of an Au NP. In phosphate buffer solution (PBS, pH 5.2, 10 mM), the cystamine-modified Au NPs readily aggregated upon incubation with N,N-dimethyl-1-naphthylamine (denoted "2N"), and a visible change in the color of the solution from red to blue was observed. When present, thiocyanate interacted with the gold nanoparticle probe more prominently than 2N, thereby protecting the gold nanoparticles and attenuating the degree of aggregation. The solution was observed (by the naked eye) to change in color from blue to purple and then back to red as a function of thiocyanate concentration (<10 μM). Iodide was noted to be a significant interferent; however, the optical absorption spectrum in the presence of iodide was fortunately easily distinguished from that for thiocyanate, thereby making it possible to discriminate iodide from thiocyanate. It was possible to determine thiocyanate in human urine samples using this method. This colorimetric method opens up a new avenue for assaying thiocyanate considering its rapid readout and simple implementation, which makes it convenient to determine thiocyanate in biological samples, especially at levels below 100 μM.
Analytical and Bioanalytical Chemistry 04/2012; 403(7):1971-81. · 3.78 Impact Factor
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ABSTRACT: A real-time, label-free dual polarisation interferometry technique was used to investigate the interaction of Hg(2+) with a 21-mer T-rich oligonucleotide and further construct a Hg(2+) biosensor based on thymine-Hg(2+)-thymine coordination chemistry.
Chemical Communications 03/2012; 48(23):2873-5. · 6.17 Impact Factor
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ABSTRACT: Here we report a facile immunoassay for detecting a synthetic peptide fragment of neurogenin3 (amino acid sequence: SKQRRSRRKKANDRERNRMH) by harnessing the aggregation-dependent fluorescence property of antibody-conjugated CdTe quantum dots in the presence of the target.
The Analyst 03/2012; 137(8):1775-8. · 4.23 Impact Factor
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ABSTRACT: Colorimetric recognition and sensing of sulfide with high selectivity by virtue of glutathione-modified gold nanoparticle (GSH-AuNP) is presented. The assay is developed based on a specific anion-for-molecule ligand exchange reaction, through which sulfide replaces glutathione self-assembled on the AuNP. The unique feature of the GSH-AuNP probe makes it a novel colorimetric sensor for sulfide.
The Analyst 03/2012; 137(7):1556-8. · 4.23 Impact Factor
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ABSTRACT: We report an aptasensor for biosensing of Ochratoxin A (OTA) using aptamer-DNAzyme hairpin as biorecognition element. The structure of this engineered nucleic acid includes the horseradish peroxidase (HRP)-mimicking DNAzyme and the OTA specific aptamer sequences. A blocking tail captures a part of these sequences in the stem region of the hairpin. In the presence of OTA, the hairpin is opened due to the formation of the aptamer-analyte complex. As a result, self-assembly of the active HRP-mimicking DNAzyme occurs. The activity of this DNAzyme is linearly correlated with OTA concentration up to 10 nM, showing a limit of detection of 2.5 nM.
Biosensors & bioelectronics 02/2012; 32(1):208-12. · 5.43 Impact Factor
