Wenjiang Li

Fabrication of multilayer films containing horseradish peroxidase and polycation-bearing Os complex by means of electrostatic layer-by-layer adsorption and its application as a hydrogen peroxide sensor

Abstract Layer-by-layer (LBL) assembled multilayer films were obtained on the surface of quartz slides and gold electrode by alternating deposition of negatively charged horseradish peroxidase (HRP) and quaternized poly(4-vinylpyridine) complexed of (Os(bpy) 2 Cl) +/2+ (PVP–Os). The assembly process was monitored by UV–VIS spectroscopy. The electrochemical behavior of the enzyme electrode showed that multilayer films containing the enzyme and the redox polymer were highly stable. Mediator PVP–Os in the multilayer films as electron shuttle was able to transfer electrons successfully between the active center of the immobilized HRP and the electrode surface. The enzyme electrode of multilayer films was sensitive for the electrocatalytic reduction of hydrogen peroxide and can be used as amperometric sensors for hydrogen peroxide.

Fabrication of Carbon Paste Electrode Containing 1:12 Phosphomolybdic Anions Encapsulated in Modified Mesoporous Molecular Sieve MCM‐41 and Its Electrochemistry

Carbon paste electrode modified with H3(PMo12O40). X H2O (PMo12) which was encapsulated in the channel surface of MCM-41 modified with 3-aminopropyltriethoxysilane was prepared and characterized. The chemical interaction between PMo12 and the support was stronger on the modified MCM-41 than on unmodified MCM-41. The large specific surface area and porous structure of the modified MCM-41 particle result in high heteropolyacid loading, and the PMo12 entrapped in this matrix is stable. FT-IR spectra and XRD were employed to give insight into the intermolecular interaction between the substrate and PMo12. The electrochemical behavior of the modified electrode was studied in detail, including pH-dependence, stability and so on. Experimental results show that the modified electrode not only maintains the electrochemical activity of PMo12, but also has good stability and sensibility. At the same time, the electrocatalytic behavior toward the reduction of ClO and BrO is also reported. It has been demostrated that PMo12 encapsulated in the modified MCM-41 is a stable catalyst for reduction of ClO and BrO.

12-tungstophosphoric heteropolyacid anions encapsulated in chemically modified mesoporous silica FSM-16 and its electrocatalytic reduction for nitrite

Abstract 12-Tungstophosphoric heteropolyacid anions (denoted PW 12 ) have been successfully immobilised on chemically modified mesoporous silica FSM-16 (denoted FSM-16 (m) ). The complex PW 12 /FSM-16 (m) was characterized by IR, XRD, spectrum NMR and CV. The results show the framework of FSM-16 is retained upon inserting the guest compound and the composite is an active electrocatalyst for the reduction of NO 2 − .

Alternate deposition of horseradish peroxidase and bipolar pyridine salt on the solid surface to prepare electrocatalytically active enzyme thin film

Abstract Horseradish peroxidase (HRP)-containing multilayer films have been fabricated by alternate deposition with bipolar pyridine salt (PyC6BPC6Py) on the surface of gold electrode derivatized by 3-mercapto-1-proponesulfonate monolayer. The driving force of forming the multilayer structures is the electrostatic interaction between the negatively charged HRP and the positively charged PyC6BPC6Py. The assembly process was monitored by ultraviolet-visible spectroscopy on quartz slides. The electrochemical behavior of the enzyme electrode showed that the multilayer film was stable and electroactive. The diffusing mediator, methylene green in solution as an electron shuttle, was able to transfer electrons successfully between the active center of the immobilized HRP and the electrode surface. Its potential application as amperometric sensor for hydrogen peroxide is anticipated.

Preparation of stable mesoporous silica FSM-16 from water glass in the presence of cetylpyridium bromide

The synthesis and characterization of the mesoporous materials FSM-16 (folded sheets mesoporous materials) with highly ordered structure in open-vessel by using cetylpyridium bromide (CPBr) and the single-layered polysilica Kanemite as new template and silicon source, respectively, has been investigated systematically. The hexagonal arrangements of uniformly size pores were characterized by FTIR. XRD. nitrogen adsorption. TG-DTA. SEM and TEM. Especially, the porous products with higher surface areas show remarkable thermal stability up to 1000 C. The potential application as carrier of catalysts or host-guest materials is anticipated

Preparation of catalytically active enzyme thin film by alternate deposition of horseradish peroxidase and bipolar quaternary ammonium on solid surface

Abstract Multilayered assemblies of horseradish peroxidase (HRP) and bipolar quaternary ammonium salt (NC6BPC6N) were fabricated successfully by alternate deposition technique on the surface of quartz slides and gold electrode. The assembly process was monitored by ultraviolet–visible spectra on quartz slides. Cyclic voltammetry indicated that the gold electrode fabricated in this way had the function of reduction of hydrogen peroxide, in which methylene green transferred electrons successfully between the immobilized HRP and the electrode surface.