The direct electrochemistry of hemoglobin (Hb) immobilized on a hexagonal mesoporous silica (HMS)-modified glassy carbon electrode was described. The interaction between Hb and the HMS was investigated using UV-Vis spectroscopy, FT-IR, and electrochemical methods. The direct electron transfer of the immobilized Hb exhibited two couples of redox peaks with the formal potentials of ?0.037 and ?0.232V in 0.1M (pH 7.0) PBS, respectively, which corresponded to its two immobilized states. The electrode reactions showed a surface-controlled process with a single proton transfer at the scan rate range from 20 to 200mV/s. The immobilized Hb retained its biological activity well and displayed an excellent response to the reduction of both hydrogen peroxide (H2O2) and nitrate (NO2-). Its apparent Michaelis-Menten constants for H2O2 and NO2-were 12.3 and 49.3μM, respectively, showing a good affinity. Based on the immobilization of Hb on the HMS and its direct electrochemistry, two novel biosensors for H2O2 and NO2-were presented. Under optimal conditions, the sensors could be used for the determination of H2O2 ranging from 0.4 to 6.0μM and NO2-ranging from 0.2 to 3.8μM. The detection limits were 1.86×10-9M and 6.11×10-7M at 3σ, respectively. HMS provided a good matrix for protein immobilization and biosensor preparation.

Serum vascular endothelial growth factor (VEGF) and endostatin levels were detected in 59 patients with breast cancer before surgery and at 3 weeks after surgery. Pre-operatively, their levels were significantly elevated and correlated with each other. Post-operatively, VEGF level decreased significantly and endostatin remained at a high level. Patients with both normalized VEGF and elevated endostatin following surgery had a lower risk of relapse than patients whose VEGF failed to normalize. Univariate and multivariate analyses showed a correlation between elevated VEGF level and short free-relapse survival. These findings suggest a new angiogenesis balance is formed in the patients after surgery and such a resultant balance may be beneficial for the prognosis of breast cancer, which deserves more extensive study.

0.1 to 9.7 μmol dm-3 and a detection limit of 0.06 μmol dm-3 at 3σ. The amperometric determination of high concentrations of NO2-based on the irreversible reduction of NO could be performed at pH 4.0 with a linear range from 0.1 to 1.2 mmol dm-3. The surface of biosensor could be renewed quickly and reproducibly by a simple polish step. The biosensor has been used satisfactorily for nitrite determination in native water samples.

We describe a novel electrochemical immunosensor for carbohydrate antigen 19-9 (CA19-9) based on the immobilization of CA19-9 with titania sol-gel on a graphite electrode (GE) by vapor deposition. The CA19-9 membrane was characterized using scanning electron microscopy and proved to be chemically clean, porous and homogeneous. The incubation of the immunosensor in a solution containing horseradish peroxidase (HRP)-labeled CA19-9 antibody led to the binding of HRP-labeled antibody with the immobilized antigen. The immobilized HRP catalyzed the oxidation of catechol by H2O2 and this provided a competitive method for the measurement of serum CA19-9. The response current decreased with increasing CA19-9 concentration in the incubation solution. The effects of pH, amount of HRP-labeled antibody, incubation time and temperature were explored to provide optimum analytical performance. Under optimal conditions, the current decrease of the immunosensor was proportional to CA19-9 concentrations in the range of 3-20 U/ml with a detection limit of 2.68 U/ml at a current decrease of 10%. The detection of CA19-9 in two serum samples obtained from clinically diagnosed patients with pancreatic carcinoma showed acceptable accuracy. The proposed immunosensor provides a new promising tool for the clinical immunoassay of CA19-9.

A novel amperometric phenol sensor was constructed by immobilizing tyrosinase in a titania sol-gel matrix. The tyrosinase entrapped sol-gel film was obtained with a vapor deposition method, which simplified the traditional sol-gel process and avoided the shrinkage and cracking of conventional sol-gel-derived glasses. This matrix provided a microenvironment for retaining the native structure and activity of the entrapped enzyme and a very low mass transport barrier to the enzyme substrates. Phenol could be oxidized by dissolving oxygen in presence of immobilized tyrosinase to form a detectable product, which was determined at-150 mV without any mediator. The phenol sensor exhibited a fast response (less than 5 s) and sensitivity as high as 103μA/mM, which resulted from the porous structure and high enzyme loading of the sol-gel matrix. The linear range for phenol determination was from 1.2×10-7 to 2.6×10-4 M with a detection limit of 1.0×10-7M. The apparent Michaelis-Menten constant of the encapsulated tyrosinase was calculated to be (0.299±0.02) mM. The stability of the biosensor was also evaluated.