A reagentless uric acid (UA) biosensor based on uricase immobilized on ZnO nanorods was developed. Direct electrochemistry and thermal stability of immobilized uricase were studied. The ZnO nanorods derived electrode retained the enzyme bioactivity and could enhance the electron transfer between the enzyme and the electrode. This sensor showed a high thermal stability up to 85℃ and an electrocatalytic activity to the oxidation of uric acid without the presence of an electron mediator. The electrocatalytic response showed a linear dependence on the uric acid concentration ranging from 5.0×10-6 to 1.0×10-3mol L-1 with a detection limit of 2.0×10-6mol L−1 at 3σ. The apparent KappM value for the uric acid sensor was estimated to be 0.238mM, showing a high affinity.

Microdialysis sampling was combined with flow-injection analysis-electrochemical detection (FIA-ECD) to determine the interactions between streptomycini sulfas (STS) and bovine serum albumin (BSA). In the mobile phase of NaOH (pH=13), a Ni-Ti alloy electrode was used as working electrode. At this electrode good electrocatalytical oxidation of streptomycini sulfas occurs with a detection limit of 8.0×10-7mol/l and a linear concentration range 1.0×10-6-1.0×103mol/l at+500meV (vs. Ag/AgCl). Microdialysis is an excellent complement to directly monitor chemical events in different organs in vivo. This method has been widely used for many fields. We applied microdialysis to determine the interactions of drug-protein.Streptomycini sulfas and BSA were mixed at different molar ratios and incubated at 37℃ in a water-bath. The microdialysis probe was then used to sample the mixed STS-BSA solution at a perfusion rate of 1.0μl/min. The concentration of unbound streptomycini sulfas in the microdialysate was determined by FIA-ECD. Relative recovery (R) of streptomycini sulfas, determined in vitro under similar conditions, was approximately 16.0% at 1.0μl/min. The estimated association constant (K) and the number of the binding sites (n) on one molecule of BSA were 5.45×103 (mol/l)-1 and 1.21, respectively. The method provided a fast and simple technique for the study of drug-protein interactions.

A novel superoxide (O2-) ultramicrosensor based on copper/platinum microparticles and electropolymerized pyrrole was fabricated for the measurement of extracellular myocardial superoxide. The Cu/Pt-PPy modified ultramicrosensors were evaluated, for the first time, as superoxide sensor. The amperometric response to superoxide was monitored at the potential of 0.45meV (versus saturated calomel electrode (SCE)) in Hank's balanced salt solution (HBSS). The sensor proved were proved to have a high sensitivity, selectivity and short response time. The detection limit is 24 (DL) of the sensors is 24mol/l (S/N of 3). The life period (at least 1 month) of sensors is longer than that of enzyme electrodes. The potential interference from some endogenous electroactive substances in biological tissues, such as hydrogen peroxide (H2O2), uric acid (UA), neurotransmitters and their metabolites, at the concentrations higher than those in biological systems, could be eliminated by further coating the Cu/Pt modified electrode with a polymer film. The method was applied to the measurement of superoxide production in a biologically relevant model system and in rat myocardial cells (MCs).

This paper summarizes the results of a degradation test of bromopyrogallol red (BPR) and textile dye wastewater (TDW) with a conventional three-electrode potentiostatic system in the presence of cobalt ions (electro Co2+-H2O2 system). H2O2, produced by the two-electron reduction of O2 at the cathode, would react with Co2+ ions, leading to the generation of hydroxyl radicals (

A new type of chemically modified electrode (CME) was fabricated by electrodeposition of palladium (Ⅱ)-substituted Dawson type heptadecatungstodiphosphate, K8 [P2W17O61Pd(H2O)] (abbreviated as P2W17Pd in the following), onto a carbon fiber microelectrode (CFME). A pair of waves was observed on the P2W17Pd CFME, which is ascribed to the redox process of the palladium center in the heteropolytungstate. After continuous potential scanning for 30 min in a pH 4.0 buffer, 92% of the original electrode response remained for the P2W17Pd CFME. The P2W17Pd CFME had high electrocatalytic activity for nitrite reduction and exhibited good reproducibility and stability. The catalytic peak current was found to be linear with the nitrite concentration in the range of 1.0×10-7～1.2×10-3mol l-1 (at25℃) with a correlation coefficient of 0.9886. The detection limit (signal: noise 3) was found to be 2.0×10-8mol l-1. The response time of the microsensor for nitrite measurement was less than 15s. For 10 parallel measurements of 1.0×10-5 mol l-1 nitrite, the relative standard deviation (RSD) was found to be 4.5%. The sensitivity of the microsensor was 0.57nA (μmol l-1)-1. The P2W17Pd CME was applied successfully as an electrochemical detector (ECD) to determine the nitrite level in rat brain by flow injection analysis (FIA) coupled with microdialysis sampling. The linear range was over three orders of magnitude and the detection limit was 3.0 pmol for nitrite determination. The mechanism of the catalytic reaction was also addressed.