| In this dissertation, the structure-function relationship of boron-doped diamond thin-film electrodes was studied. This includes assessing the factors that influence the properties of boron-doped diamond thin-film electrodes as well as investigating the electrical and electrochemical mechanism of these electrodes. In addition, the application of boron-doped diamond microelectrode for in vitro amperometric measurements was also studied.;The electrical and electrochemical properties of boron-doped diamond thin-film are influenced by many factors such as growth conditions, grain size, doping level, impurities (e.g., grain defects, sp2 carbon and adsorbed hydrogen) and surface chemistry. Growth condition is the primary determinant of the surface morphology of BDD thin-film, although both microcrystalline and nanocrystalline diamond thin-film can be deposited in similar hydrogen-rich gas mixtures. Microcrystalline BDD thin-film has different Raman spectrum and carrier mobility from nanocrystalline film but their electrochemical properties are very similar in macroscopic level. Using CP-AFM and SECM, we found that the electrical conductivity and electrochemical activity for microcrystalline BDD thin-film are different from those for nanocrystalline film. Microcrystalline BDD thin-film possesses lower fraction of active regions but more active individual sites compared with nanocrystalline BDD thin-film.;Doping level influences the surface morphology of BDD thin-film. More importantly, CP-AFM and SECM measurements illustrated that both the fraction of electrically conductive regions and the fraction of electrochemically active regions increase as the doping level increases and this is true for both microcrystalline and nanocrystalline BDD films.;Surface termination has a significant influence on the properties of CVD diamond. For example, the fastest electron-transfer kinetics for Fe(CN) 63-/4- has been recorded at hydrogen-terminated BDD electrode but very sluggish reaction has been recorded at oxygen-terminated BDD electrode. Electrochemical measurements show that O-terminated BDD electrode has a little larger background current that H-terminated BDD electrode. The reason for this might be the O-terminated surface is more hydrophilic and this may increase the dielectric constant of H2O at the surface. CP-AFM and SECM studies show that both the fraction of electrically-active regions and the fraction of electrochemically-active regions are greater for H-terminated than for O-terminated BDD films.;As a preclusive work, the BDD microelectrode has been used to study the denervation of capsaicin on mesenteric blood vessels by monitoring the release of norepinephrine. The distribution of sensory and sympathetic nerves was visualized using glyoxylic acid fluorescence histochemistry and anti-TH, anti-substance P and anti-CGRP immunohistochemistry. The effects of 7 neuro-phamarceutical drugs on the determination of norepinephrine were also studied. We failed to show any evidence for the local communication between the sensory and sympathetic nerves by using exogenous substance P. |
