Biomedical subjects

Guangjin Cheng

Publications and source records attributed to Guangjin Cheng.

2 recordsLinked to original sources

PubMed2002

Structural electrochemical study of hemoglobin by in situ circular dichroism thin layer spectroelectrochemistry.

Secondary and tertiary or quaternary structural changes in hemoglobin (HB) during an electroreduction process were studied by in situ circular dichroism (CD) spectroelectrochemistry with a long optical path thin-layer cell. By means of singular value decomposition least-squares analysis, CD spectra in the far-UV region give two similar alpha components with different CD intensity, indicating slight denaturation in the secondary structures due to the electric field effect. CD spectra in the Soret band show a R-->T transition of two quaternary structural components induced by electroreduction of the heme, which changes the redox states of the center ion from Fe3+ to Fe2+ and the co-ordination number from 6 to 5. The double logarithmic analysis shows that electroreduction of hemoglobin follows a chemical reaction with R-->T transition. Some parameters in the electrochemical process were obtained: formal potential, E0'=-0.167 V; electrochemical kinetic overpotential, deltaE0=-0.32 V; standard electrochemical reaction rate constant, k0=1.79 x 10(-5) cm s(-1); product of electron transfer coefficient and electron number, alphan=0.14; and the equilibrium constant of R-->T transition, Kc=9.0.

Circular Dichroism↗

PubMed2002

A method to construct a third-generation horseradish peroxidase biosensor: self-assembling gold nanoparticles to three-dimensional sol-gel network.

A novel method for fabrication of horseradish peroxidase biosensor has been developed by self-assembling gold nanoparticles to a thiol-containing sol-gel network. A cleaned gold electrode was first immersed in a hydrolyzed (3-mercaptopropyl)-trimethoxysilane (MPS) sol-gel solution to assemble three-dimensional silica gel, and then gold nanoparticles were chemisorbed onto the thiol groups of the sol-gel network. Finally, horseradish peroxidase (HRP) was adsorbed onto the surface of the gold nanoparticles. The distribution of gold nanoparticles and HRP was examined by atomic force microscopy (AFM). The immobilized horseradish peroxidase exhibited direct electrochemical behavior toward the reduction of hydrogen peroxide. The performance and factors influencing the performance of the resulting biosensor were studied in detail. The resulting biosensor exhibited fast amperometric response (2.5 s) to H2O2. The detection limit of the biosensor was 2.0 micromol L(-1), and the linear range was from 5.0 micromol L(-1) to 10.0 mmol L(-1). Moreover, the studied biosensor exhibited high sensitivity, good reproducibility, and long-term stability.

Biosensing Techniques↗