Chip surface charge switch for studying histone-DNA interaction by surface plasmon resonance biosensor.
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Adsorption↗
Biomedical subjects
Xiurong Yang
Publications and source records attributed to Xiurong Yang.
Morphology study of gold-chitosan nanocomposites.
Gold nanoparticles were prepared in the presence of chitosan via reduction of HAuCl4 with sodium borohydride. The gold-chitosan nanocomposite was formed by adsorbing chitosan molecules onto the gold nanoparticle surfaces. The resulting gold nanoparticles were characterized by transmission electron microscopy and UV-vis spectroscopy. Morphology of gold-chitosan nanocomposite films was investigated by polarized optical microscopy. The morphology of chitosan crystal cast from the prepared nanocomposite was much different from that cast from chitosan solution due to the possible nucleation of gold nanoparticles. A branched-like structure or a cross-linked needle-like structure could be formed in nanocomposite films with different casting volumes.
Adsorption↗
A sensitive method for the detection of proteins by high-efficiency fluorescence quenching.
A successful method for the detection of electron transfer proteins such as cytochrome c, hemoglobin and myoglobin has been developed based on the fluorescence quenching of semiconductor nanocrystals. High sensitivity and a good linear relationship are obtained.
Animals↗
Simultaneous electrochemical and electrochemiluminescence detection for microchip and conventional capillary electrophoresis.
A simultaneous electrochemical (EC) and electrochemiluminescence (ECL) detection scheme was introduced to both microchip and conventional capillary electrophoresis (CE). In this dual detection scheme, tris(2,2'-bipyridyl)ruthenium(II) (Ru(bpy)3(2+)) was used as an ECL reagent as well as a catalyst (in the formation of Ru(bpy)3(3+)) for the EC detection. In the Ru(bpy)3(2+)-ECL process, Ru(bpy)3(3+) was generated and then reacted with analytes resulting in an ECL emission and a great current enhancement in EC detection due to the catalysis of Ru(bpy)3(3+). The current response and ECL signals were monitored simultaneously. In the experiments, dopamine and three kinds of pharmaceuticals, anisodamine, ofloxacin, and lidocaine, were selected to validate this dual detection strategy. Typically, for the EC detection of dopamine with the presence of Ru(bpy)3(2+), a approximately 5 times higher signal-to-noise ratio (S/N) can be achieved than that without Ru(bpy)3(2+), during the simultaneous EC and ECL detection of a mixture of dopamine and lidocaine using CE separation. The results indicated that this dual EC and ECL detection strategy could provide a simple and convenient detection method for analysis of more kinds of analytes in CE separation than the single EC or ECL detection alone, and more information of analytes could be achieved in analytical applications simultaneously.
Electrochemistry↗
Electrochemiluminescence quenching as an indirect method for detection of dopamine and epinephrine with capillary electrophoresis.
An electrochemiluminescence (ECL) inhibition method was developed as an indirect detection method for the determination of dopamine and epinephrine separated by capillary electrophoresis (CE). When the concentration of Ru(bpy)(3) (2+) was 50 muM diluted by 50 mM phosphate (pH 8.5) in the cell and 0.5 M tripropylamine (TPA) was added to the running buffer (10 mM phosphate, pH 9.0), an inhibition of ECL of the Ru(bpy)(3) (2+)/TPA system by the analytes was observed. Under the optimized conditions, the relative standard deviations of migration time and negative peak area were less than 1% and 3%, respectively, for 1 microM dopamine or 1 microM epinephrine (n = 10). Linear ranges of 0.1-10 microM for both analytes and the detection limits (signal-to-noise ratio S/N = 3) of 10 nM for dopamine and 30 nM for epinephrine were obtained.
Dopamine↗
Electrogenerated chemiluminescence on microfluidic chips.
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Journal Article↗
Preparation and characterization of metal-chitosan nanocomposites.
Various metal-chitosan nanocomposites were synthesized, including silver (Ag), gold (Au), platinum (Pt), and palladium (Pd) in aqueous solutions. Metal nanoparticles were formed by reduction of corresponding metal salts with NaBH4 in the presence of chitosan. And chitosan molecules adsorbing onto the surface of as-prepared metal nanoparticles formed the corresponding metal-chitosan nanocomposites. Transmission electron microscopy (TEM) images and UV-vis spectra of the nanocomposites revealed the presence of metal nanoparticles. Comparison of all the resulting particles size, it shows that silver nanoparticles are much larger than others (Au, Pt and Pd). In addition, the difference in particles size leads to develop different morphologies in the films cast from prepared metal-chitosan nanocomposites. Polarized optical microscopy (POM) images show a batonet-like structure for Ag-chitosan nanocomposites film, while for the films cast from other metal (Au, Pt, and Pd)-chitosan nanocomposites, some branched-like structures with a few differences among them were observed under POM observation.
Biocompatible Materials↗
Short-capillary electrophoresis with electrochemiluminescence detection using porous etched joint for fast analysis of lidocaine and ofloxacin.
Fast analysis of ofloxacin and lidocaine, as bactericide and analgesic or anesthetics, is of clinic importance for understanding the patient's medical process. This paper presented a high throughput, simple analysis method of lidocaine and ofloxacin by capillary electrophoresis coupled with electrochemiluminescence (ECL) using porous etched joint. To shorten the analysis time and to improve the analytical performance, a capillary with 10 cm in length was used as the separation channel. The cyclic voltammograms of Ru(bpy)3(2+) with different capillary length at same field strength showed that the porous etched joint eliminated the effect of electrophoretic current on the ECL detection. Following micro total analysis systems (microTAS), some advantages of which this approach has, the fabrication of channel in chip was not needed. Compared with capillary electrophoresis with 40-cm-long capillary, the high sample throughput and low zone broadening may be the main advantage of the present system. Under optimal condition, the detection limits of lidocaine and ofloxacin based on peak height were 3.0 x 10(-8) and 5.0 x 10(-7) molL(-1) and a 60 h(-1) of sampling frequency was obtained. The precision (R.S.D.) of the migration time and the peak height for five replicate injections of a mixture of lidocaine (1.0 x 10(-6) molL(-1)) and ofloxacin (4.0 x 10(-6) molL(-1)) were 3.2-3.9% and 4.7-5.3%, respectively.
Electrophoresis, Capillary↗
Interaction of echinomycin with guanine: electrochemistry and spectroscopy studies.
The interaction of antitumor antibiotic, echinomycin (Echi) with guanine (Gua) was thoroughly investigated by adsorptive transfer stripping cyclic voltammetry, ultraviolet and visible adsorption spectra (UV/Vis) and Fourier-transform infrared spectroscopy (FTIR). Electrochemistry provided a simple tool for verifying the occurrence of interaction between Echi and Gua. Echi could be accumulated from the solution and give well-defined electrochemical signals in 0.1 M phosphate buffer solution (pH 7.0) only when Gua was present on the surface of the electrochemically pretreated glass carbon electrode (GCE), suggesting a strong binding of Echi to Gua. All the acquired spectral data showed that a new adduct between Echi and Gua was formed, and two pairs of adjacent intermolecular hydrogen bonds between the Ala backbone atoms in Echi and Gua (Ala-NH to Gua-N3 and Gua-NH2 to Ala-CO) played a dominating role in the interaction. Electrochemistry coupled with spectroscopy techniques could provide a relatively easy way to obtain useful insights into the molecular mechanism of drug-DNA interactions, which should be important in the development of new anticancer drugs with specific base recognition.
Adsorption↗
Synthesis of polysaccharide-stabilized gold and silver nanoparticles: a green method.
A simple, green method was developed for the synthesis of gold and silver nanoparticles by using polysaccharides as reducing/stabilizing agents. The obtained positively charged chitosan-stabilized gold nanoparticles and negatively charged heparin-stabilized silver nanoparticles were characterized with UV-vis spectroscopy and transmission electron microscopy. The results illustrated the formation of gold and silver nanoparticles inside the nanoscopic polysaccharide templates. Moreover, the morphology and size distribution of prepared gold and silver nanoparticles varied with the concentration of both the polysaccharides and the precursor metal salts.
Chitosan↗
Electrochemiluminescence detection with integrated indium tin oxide electrode on electrophoretic microchip for direct bioanalysis of lincomycin in the urine.
In this article, an antibiotic, lincomycin was determined in the urine sample by microchip capillary electrophoresis (CE) with integrated indium tin oxide (ITO) working electrode based on electrochemiluminescence (ECL) detection. This microchip CE-ECL system can be used for the rapid analysis of lincomycin within 40s. Under the optimized conditions, the linear range was obtained from 5 to 100 microM with correlation coefficient of 0.998. The limit of detection (LOD) of 3.1 microM was obtained for lincomycin in the standard solution. We also applied this method to analyzing lincomycin in the urine matrix. The limit of detection of 9.0 microM was obtained. This method can determine lincomycin in the urine sample without pretreatment, which demonstrated that it is a promising method of detection of lincomycin in clinical and pharmaceutical area.
Anti-Bacterial Agents↗
Drug-human serum albumin binding studied by capillary electrophoresis with electrochemiluminescence detection.
A new technique for investigating drug-protein binding was developed employing capillary electrophoresis (CE) coupled with tris(2,2'-bipyridyl) ruthenium(II) [Ru(bpy)(3) (2+)] electrochemiluminescence (ECL) (CE-ECL) detection after equilibrium dialysis. Three basic drugs, namely pridinol, procyclidine and its analogue trihexyphenidyl, were successfully separated by capillary zone electrophoresis with end-column Ru(bpy)(3) (2+) ECL detection. The relative drug binding to human serum albumin (HSA) for each single drug as well as for the three drugs binding simultaneously was calculated. It was found that the three antiparkinsonian drugs compete for the same binding site on HSA. This work demonstrated that Ru(bpy)(3) (2+) CE-ECL can be a suitable technique for studying drug-protein binding.
Antiparkinson Agents↗
Electrochemical detector based on sol-gel-derived carbon composite material for capillary electrophoresis microchips.
An on-chip disk electrode based on sol-gel-derived carbon composite material could be easily and reproducibly fabricated. Unlike other carbon-based electrodes reported previously, this detector is rigid, convenient to fabricate, and amenable to chemical modifications. Based on the stable and reproducible characters of this detector, a copper particle-modified detector was developed for the detection of carbohydrates which extends the application of the carbon-based electrode. In our experiments, the performance of the new integrated detector for rapid on-chip measurement of epinephrine and glucose was illustrated. Experimental procedures including the fabrication of this detector, the configuration of separation channel outlet and electrode verge, and the performance characteristics of this new electrochemical detector were investigated.
Carbon↗
A strategy for constructing a hybrid bilayer membrane based on a carbon substrate.
We construct a hybrid bilayer membrane (HBM) on a new substrate-carbon electrode. It is an extension of HBM based on other substrates. Primary alkylamine was chemically modified onto the surface of a carbon electrode by electrochemical scans; thus, a monolayer was formed on the electrode. Because the alkane chains section is toward the outside, a hydrophobic surface was constructed. Then a lipid monolayer was spread on the hydrophobic surface of the carbon electrode. The formed HBM was characterized by electrochemical and ATR-FT-IR methods. From ATR-FT-IR results, the lipid order parameter (S) of 0.73 was obtained. This kind of hybrid membrane has the advantages of a lipid/alkanethiol HBM. A potential application of this HBM as a biosensor (detecting K+) was given.
Journal Article↗
Preparation of poly(thionine) modified screen-printed carbon electrode and its application to determine NADH in flow injection analysis system.
A poly(thionine) modified screen-printed carbon electrode has been prepared by an electrooxidative polymerization of thionine in neutral phosphate buffer. The modified electrodes are found to give stable and reproducible electrocatlytic responses to NADH and exhibit good stability. Several techniques, including cyclic voltammetry, X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM), have been employed to characterize the poly(thionine) film. Further, the modified screen-printed carbon electrode was found to be promising as an amperometric detector for the flow injection analysis (FIA) of NADH, typically with a dynamic range of 5-100 microM.
Biosensing Techniques↗
Layer-by-layer electrodeposition of redox polymers and enzymes on screen-printed carbon electrodes for the preparation of reagentless biosensors.
Layer-by-layer electrodeposition of redox polymer/enzyme composition films on screen-printed carbon electrodes for fabrication of reagentless enzyme biosensors has been proposed and the resulting films were found to be very stable and rigid.
Biosensing Techniques↗
Fabrication of integrated microelectrodes for electrochemical detection on electrophoresis microchip by electroless deposition and micromolding in capillary technique.
A new method for the fabrication of an integrated microelectrode for electrochemical detection (ECD) on an electrophoresis microchip is described. The pattern of the microelectrode was directly made on the surface of a microscope slide through an electroless deposition procedure. The surface of the slide was first selectively coated with a thin layer of sodium silicate through a micromolding in capillary technique provided by a poly(dimethylsiloxane) (PDMS) microchannel; this left a rough patterned area for the anchoring of catalytic particles. A metal layer was deposited on the pattern guided by these catalytic particles and was used as the working electrode. Factors influencing the fabrication procedure were discussed. The whole chip was built by reversibly sealing the slide to another PDMS layer with electrophoresis microchannels at room temperature. This approach eliminates the need of clean room facilities and expensive apparatus such as for vacuum deposition or sputtering and makes it possible to produce patterned electrodes suitable for ECD on microchip under ordinary chemistry laboratory conditions. Also once the micropattern is ready, it allows the researchers to rebuild the electrode in a short period of time when an electrode failure occurs. Copper and gold microelectrodes were fabricated by this technique. Glucose, dopamine, and catechol as model analytes were tested.
Journal Article↗
Microchip capillary electrophoresis with an integrated indium tin oxide electrode-based electrochemiluminescence detector.
This paper describes an indium tin oxide (ITO) electrode-based Ru(bpy)3(2+) electrochemiluminecence (ECL) detector for a microchip capillary electrophoresis (CE). The microchip CE-ECL system described in this article consists of a poly(dimethylsiloxane) (PDMS) layer containing separation and injection channels and an electrode plate with an ITO electrode fabricated by a photolithographic method. The PDMS layer was reversibly bound to the ITO electrode plate, which greatly simplified the alignment of the separation channel with the working electrode and enhanced the photon-capturing efficiency. In our study, the high separation electric field had no significant influence on the ECL detector, and decouplers for isolating the separation electric field were not needed in the microchip CE-ECL system. The ITO electrodes employed in the experiments displayed good durability and stability in the analytical procedures. Proline was selected to perform the microchip device with a limit of detection of 1.2 microM (S/N = 3) and a linear range from 5 to 600 microM.
Journal Article↗