Chemically Modified Electrodes For Sensing Bioactive Small Molecules

Chemically modified electrode (CME) is one of the most active research areas in the field of the electroanalytical and electrocatalytical chemistry. It is very widely applied in food, environmental, biological and pharmaceutical analysis. This thesis aims at further application of CMEs in electroanalytical area, monolayer modified electrodes were prepared and used to detect small biological molecule.This thesis is divided into five chapters. The origin, development, application and significance of the CMEs were reviewed in chapter one; In chapter two, in-situ electrochemical reduction method and electrochemical oxidation method were applied for the design of the electrode surface. Among them, the 4-carboxyphenyl,4-sulfophenyl, 4-2,6-dihydroxypyrimidyl, antipyryl,4-pyridyl was covalently successfully modified on GCE via in-situ electrochemical reduction method, meanwhile, the midification of the pyridyl and phenanthrolyl on GCE was achieved by electrochemical oxidation method. The various characterization results showed that the CMEs were superior to the original bulk electrode due its advantage of predominant reusability, wherein pyridyl, phenanthrolyl, 4-2,6-dihydroxypyrimidyl and 4-pyridyl-modified GCE have better performance comparatively. In chapter three, electrospun cobalt acetate and polyvinyl alcohol (PVA) nanofibers were collected on a FTO electrode and then calcined at a high temperature of 600℃. Then the product of metallic oxide nanoparticles and carbon fiber were used to sense ascorbic acid (AA), experimental results showed that metallic oxide and carbon fiber produced enhanced electrochemical signal toward detecting AA. The chapter four further investigate the enhanced effect mentioned in chapter three. In chapter four, electrospun polyvinyl pyrrolidone (PVP), PVP and cobalt acetate, PVP and ammonium ferric citrate on FTO, respectively. The consequence declared that the electrode annealed at high temperature owned a double-singal electrochemical response toward sensing dopamine (DA), the results manifested that the composite modified electrode not only realized enhanced electrochemical signal for sensing DA, but also produced synergy effect. In the last chapter, platinum nanoparticles (PtNPs) and 4-aminobenzioc acid (4-ABA) were applied to alternately modify nitrogen-doped diamond like carbon (N:DLC) film electrode toward sensing hydrazine sulfate to study the relationship between interface structure and electrochemical sensing properties. Results manifested that the optimization of sensing hydrazine sulfate can realize via the modification of the electrodes structure.This study results show that the covalent CME have a limitation in sensing biological small molecules simultaneously; we can use nanofibers mixed with metal to achieve collaborative detection of target molecules;alternate modification also can improve the detection performance of the electrode.