| In the scope of materials-related fields, the composite materials based on graphene, gold nanomaterials, platinum nanomaterials, liposome, ionic liquids (IL) and Bismuth were synthesized and applied in electrochemistry, especially in electrochemical biosensing. As the electrochemical process is related to the surface properties of electrode materials, current response can be improved and detection sensitivity extended when the composite materials modified electrodes are employed. The resulting electrochemical biosensors showed good performances and exhibited potential application in bioanalysis.This thesis comprises four parts, as follows:1. A simple, inexpensive, one-step synthesis of graphene/PAA-Au nanocomposites was achieved by using polyallylamine (PAA) as a reducing and stabilizing agent. The synthetic process was carried out only in aqueous solution, which is versatile and environmentally friendly. The resulting nanocomposites could be dispersed into water stably without any additional protection by polymeric or surfactant stabilizers. The products were characterized by UV-visible absorption spectroscopy, transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and photoelectron spectroscopy (XPS). The resulting graphene/PAA-Au nanocomposites film exhibited good electrocatalytical activity towards reduction of both H2O2and O2, which showed potential application in electrochemical sensors.2. The electrochemical behavior of ionic liquids (IL) doped supported bilayer lipid membrane (s-BLM) on glassy carbon electrode (GCE) was studied by cyclic voltammetry (CV). The assembled supported bilayer lipid membrane/ionic liquids [(s-BLM)/IL] films exhibited good electrochemical performance. The direct electron transfer of immobilized laccase was observed through the electrocatalytical ability toward the reduction of oxygen with2,2’-azinobis-(3-ethylbenzthiazoline-6-sulphonate)(ABTS) as electron mediator. In addition, the supported phospholipid layers incorporated with ionic liquids (IL) could be come true in the direct electron transfer. Potential electroanalytical applications and the development of biosensors will be explored in the future.3. It is firstly reported that Bismuth was dispersed well in HNO3and had good electrochemical redox towards L-cysteine (L-cys). At the same time, bismuth exhibited low response towards homocysteine (Hcy) and glutathione (GSH), which shows that the interference of bismuth is very less. But so far it is not found a very good quantitative method, which needed further study.4. This study describes the use of catechol for the simultaneous detection of cysteine (Cys), homocysteine (Hcy) and glutathione (GSH) using electrochemical detection, requiring no use of separation techniques. It was found that the current response of Cys/Hcy/GSH-induced aggregation of catechol strongly depends on the pH value of acetic acid buffer solution. At a pH of6.24, the Hcy-induced aggregation kinetics of catechol was much faster than that induced by Cys and GSH. So Hcy is used as the model thiol-containing compound for the study. The highest response for Hcy was obtained around pH5.29by using the Square wave voltammetry(SWV) as the analytical technique. As a result, the catechol exhibited good amperometric response to Hcy with linear range from1to25μM (R=0.995) at0.15V, also, the present approach is simple, high selective and provides high reproducibility, and has a great potentiality in disease diagnosis. |
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