Sensitive measurement of polyols in urine by capillary zone electrophoresis coupled with amperometric detection using on-column complexation with borate.

Little is known about human polyol metabolism, but recent studies indicate that abnormal polyol concentrations in body fluids are related to several diseases. In this study, a rapid and sensitive method for the determination of seven major polyols in urine including two groups of polyol isomers, C5-polyols (Rib+Arb+Xyl) and C6-polyols (Sor+Gal+Man), was developed using capillary zone electrophoresis coupled with amperometric detection (CZE-AD). The effects of the working electrode potential, pH, running buffer components and concentrations, separation voltage and injection times were investigated. Under the optimised conditions, seven types of polyols could be perfectly separated via the formation of anionic polyol-borate complexes in a borate buffer solution. Highly linear current responses to the polyol concentrations were obtained with good correlation (0.9984

Ultrasensitive detection of bacteria by microchip electrophoresis based on multiple-concentration approaches combining chitosan sweeping, field-amplified sample stacking, and reversed-field stacking.

In this paper we describe an on-chip multiple-concentration method combining chitosan (CS) sweeping, reversed-field stacking, and field-amplified sample stacking for highly efficient detection of bacteria. Escherichia coli was selected as a model bacterium to investigate the efficiency of this multiple-concentration method. CS was the most suitable sweeping agent for microchip electrophoresis, replacing the usually used cetyltrimethylammonium bromide for capillary electrophoresis. The additive taurine had a synergistic effect by enhancing the interaction between CS and the surface of the bacteria, thus improving the analysis sensitivity. All steps of the concentration method and related mechanisms are described and discussed in detail. A concentration enhancement factor of approximately 6000 was obtained using this concentration method under optimal conditions as compared to using no concentration step, and the detection limit of E. coli was 145 CFU/mL. The multiple-concentration methodology was also applied for the quantification of bacteria in surface water, and satisfactory results were achieved. The application of this methodology showed that the concentration enhancement of bacteria clearly conferred advantageous sensitivity, speed, and sample volume compared to established methods.

Microchip electrophoresis of bacteria using lipid-based liquid crystalline nanoparticles.

The aggregation and adhesion of bacterial cells is a serious disadvantage for electrophoretic separations of bacteria. In this study, lipid-based liquid crystalline nanoparticles were used as a pseudostationary phase to minimise the bacterial aggregation and adsorption to the inner walls of microchannels. Lactobacillus delbrueckii subsp. bulgaricus, Streptococcus thermophilus and Lactobacillus rhamnosus were selected as analytes and were separated by microchip electrophoresis (MCE) with laser-induced fluorescence (LIF) detection using 4.5 mM tris(hydroxymethyl) aminomethane (TRIS)-4.5 mM boric acid-0.1 mM ethylenediaminetetraacetate (EDTA) (TBE) containing poly(ethylene oxide) (PEO) and lipid-based nanoparticles as the running buffer. The mechanism of lipid-based nanoparticles affecting bacterial adhesion and aggregation was discussed and supported by zeta potential experiments. Under the optimal conditions, the three species of bacteria were identified with patterned peaks. This proposed MCE method using lipid-based nanoparticles as running buffer additives was also used to analyse a real yogurt sample, and valuable bacterial information was obtained by the electropherograms.

Study on acetylcholinesterase inhibition induced by endogenous neurotoxin with an enzyme-semiconductor photoelectrochemical system.

The integration of Au-doped TiO(2) nanotubes with biomolecule acetylcholinesterase (AChE) yields a novel AChE-Au-TiO(2) hybrid system, which provides a new rapid and valid photoelectrochemical approach to the determination of AChE inhibition induced by endogenous neurotoxin.