The Studies On Novel Electrochemical Sensors

Electrochemical sensors are active and promising in the analytical chemistry fields. In the theses, we focused our studies on silver nanoparticles (Ag NPs) electrodeposited on type-Ⅰcollagen-modified electrode, Ag NPs electrodeposited on DNA modified electrode and PFS/DNA-modified electrode and developed the corresponding electrochemical sensors. This work mainly covered the following areas.1. The first part was about a novel hydrogen peroxide (H2O2) sensor based on Ag NPs electrodeposited on DNA-networks modified glassy carbon electrode (GCE). In this part, we have exploited Ag NPs electrodeposited on three-dimensional DNA networks that were directly dropped on the surface of glassy carbon electrode as an electrocatalyst to fabricate a H2O2 sensor. The Ag NPs electrodeposited on three-dimensional DNA networks showed very good catalytic ability for the reduction of H2O2. The well catalytic activity of the electrode was ascribed to the DNA networks that caused the formation of small Ag NPs and the homogenous distribution of Ag NPs.2. The second part was concentrated on electrodeposition of Ag NPs on type ? collagen modified GCE and their applications as a H2O2 sensor. Atomic force microscopy (AFM) images showed that many small Ag NPs formed and uniformly distributed on type ? collagen/GCE. We found that the type ? collagen network film could control the growth of Ag NPs and the Ag NPs were well-distributed. Meanwhile, the electrochemical experiments proved that the Ag NPs had an excellent catalytic ability to reduction of H2O2, suggesting that they could be used as a sensor to determinate H2O2. The catalytic activity of Ag NPs was ascribed to type ? collagen that resulted in the homogenous distribution of many small Ag NPs and accordingly depended on the type ? collagen concentration and electrodeposition time.3. The third part focused on studying electrochemical behaviors of poly (ferrocenylsilane)/DNA (PFS/DNA) modified GCE and as an ascorbic acid (AA) sensor. The embedded PFS in DNA film had a good electrocatalytic activity for AA. This behavior suggested that the electro-oxidation of AA could be catalyzed by FC/FC+ couple of PFS as a mediator. The PFS/DNA/GCE showed two reversible waves, which had a lower oxidation potential, smallerΔEp value, and larger ip values as compared with PFS/GCE. The concentration of DNA, PFS and PBS, and temperature influenced the electrochemical behaviors of PFS/DNA/GCE. DNA played an important role as an intermediate for the absorption of PFS and electron transfer.