Guangming Wen

Application of hydrophobic palladium nanoparticles for the development of electrochemical glucose biosensor.

An amperometric glucose biosensor based on an n-alkylamine-stabilized palladium nanoparticles (PdNPs)-glucose oxidase (GOx) modified glassy carbon (GC) electrode has been successfully fabricated. PdNPs were initially synthesized by a biphase mixture of water and toluene method using n-alkylamines (dodecylamine, C₁₂-NH₂ and octadecylamine, C₁₈-NH₂) as stabilizing ligands. The performance of the PdNPs-GOx/GC biosensor was studied by cyclic voltammetry. The optimum working potential for amperometric measurement of glucose in pH 7.0 phosphate buffer solution is -0.02 V (vs. Ag/AgCl). The analytical performance of the biosensor prepared from C₁₈-PdNPs-GOx is better than that of C₁₂-PdNPs-GOx. The C₁₈-PdNPs-GOx/GC biosensor exhibits a fast response time of ca. 3s, a detection limit of 3.0 μM (S/N=3) and a linear range of 3.0 μM-8.0 mM. The linear dependence of current density with glucose concentration is 70.8 μA cm⁻² mM⁻¹. The biosensor shows good stability, repeatability and reproducibility. It has been successfully applied to determine the glucose content in human blood serum samples.

Spectral study on the interaction of cryptophane-A and neutral molecules CHnCl4 − n (n = 0, 1, 2)

Cryptophane-A was synthesized from vanillin by a three-step method and its spectroscopic properties in different organic solvents were determined. Two absorption bands at about 240-250 and 280-290 nm were observed for cryptophane-A. A fluorescence emission peak was obtained at 320-330 nm using a solution of approximately 10(-5)M cryptophane-A. The interaction of cryptophane-A with chlorinated compounds CH(n)Cl(4 - n) (n=0, 1, 2) in dioxane and ethyl acetate solvents were studied in detail by fluorescence spectroscopy, respectively. The results show that cryptophane-A is well suited for inclusion of CH(2)Cl(2) to form a stable 1:1 complex and the binding constant was estimated to be 19+/-2M(-1). These results were also confirmed by (1)H NMR and CPK models. Larger similar molecules such as CHCl(3) and CCl(4) are unable to enter the cavity of cryptophane-A because of their bigger sizes. However, the fluorescence emission of cryptophane-A can be efficiently quenched by CHCl(3) and CCl(4), following the Stern-Volmer relationship.

Biosensors for Determination of Galactose with Galactose Oxidase Immobilized on Eggshell Membrane

Abstract A galactose biosensor was first fabricated using a galactose oxidase‐immobilized eggshell membrane and an oxygen electrode. The detection scheme was based on the depletion of dissolved oxygen content upon exposure to galactose solution, and the decrease in oxygen level was monitored and related to the galactose concentration. The effects of pH, buffer compositions, phosphate buffer concentration, and temperature on the biosensor were investigated. The linear range is 0.1 to 8.5 mM with relative standard deviation (RSD) is 3.74% and the response time is 100 s. Some possible interferents such as L‐ascorbic acid, ethanol, sucrose, glucose, maltose, and fructose did not give significant interference and retained 83.6% of initial enzyme activity after 3 months when stored in a pH 7.0 phosphate buffer solution at 4°C. The proposed biosensor was applied to the determination of galactose added to plasma samples with the recoveries of galactose is 94%–110%.

Characterization of a methane‐utilizing strain and its application for monitoring methane

Aims:  To explore new resources of methane‐utilizing micro‐organism and develop a microbial biosensing system for monitoring methane released from natural and semi‐natural ecosystems.

Assembly and disassembly activity of two AIEE model compounds and its potential application

Aggregation-induced emission (AIE) has received great attention. In this paper, Cu2+ induced self-assembly and H2S induced disassembly of two aggregation-induced emission enhancement (AIEE) compounds were reported in this paper. Two salicylaldehyde azine Schiff base were synthesized and characterized. It is found that 1 and 2 are AIEE active molecular both in aqueous solution and crystal state with strong yellow fluorescence. Theirs fluorescence can be selectively quenched in the presence of Cu2+ ions with the formation of self-assembly system [1-Cu2+]n. The interaction mechanism has been researched by multiple means. Depending on this reaction, energy changes (ΔG) from 1 to [1-Cu2+]n was also estimated by Scatchard formula. Moreover, the quenching fluorescence was further restored by H2S both in tube and live cells along with the releasing of AIEE molecular 1. That is, a reversible process between AIEE, self-assembly and disaggregation can be found in the model compound.