Study On The Application Of Nanomaterials And Amino Acid Modified Electrodes In Drug Analysis

The chemically modified electrodes have been one of the most burgeoning andflourish research areas in the electrochemistry areas and electroanalytic chemistry sincethey were developed in the middle of1970's．It has been widely applied in many areassuch as material science, life science, analytic science and environmental science.The mediators modified on the electrode could be used to catalyse the electrochemicalreaction f and acilitate the electron transfer,which couldn't be realized easily, like theelectrocatalysis of organic compounds,biomolecules and inorganic jons．Differentmethods and materials have been used for the modification of electrodes in this workand the appllication of the electrodes prepared is also evaluated.The main works we have done in this thesis include:1. Acetylene black nanoparticles were homogeneously dispersed into water in thepresence of hydrophobic surfactant and then used to modify the surface of a glassycarbon electrode. An examination of the electrochemistry of rutin showed that thismodification of the electrodes resulted in a considerable enhancement of the surface,thus remarkably increasing the signal for rutin. As a result, a sensitive and convenientelectrochemical method was developed for the determination of rutin. The linear rangeis from20μg L^-1to5mg L^-1, and the limit of detection is10μg L^-1. The method wassuccessfully employed to the determination of rutin in traditional Chinese medicines.2. The graphite oxide (GO) was prepared via the chemical oxidation of naturalgraphite powder, and then used to modify the surface of glassy carbon electrode (GCE).The electrochemical behavior of acetaminophen was examined. In0.01mol L^-1HCl, anirreversible oxidation peak is observed for acetaminophen, and the peak currentremarkably increases at the GO film-modified GCE. The influences of supportingelectrolyte, amount of GO suspension, accumulation potential and time were studied onthe oxidation peak current of acetaminophen. As a result, a new electrochemical methodwas developed for the detection of acetaminophen. The linear range is from25μg L^-1to4mg L^-1, and the limit of detection is6μg L^-1based on three signal-noise ratio. Finally,it was successfully used to detect acetaminophen in tablets.3. A mesoporous SiO₂was synthesized according to the published work, and thenused to modify the carbon paste electrode (CPE). The electrochemical behaviors of5-hydroxytryptamine (5-HT) at the bare CPE and the mesoporous SiO₂modified CPE were compared. Owing to the huge surface area, unique mesopores and strongadsorptive ability, the oxidation signal of5-HT at the mesoporous SiO₂modified CPEgreatly increased, compared with that at the bare CPE. This clearly suggests that themesoporous SiO₂modified electrode shows efficient and remarkable enhancementeffect towards5-HT. Based on this, a sensitive, rapid and convenient electrochemicalmethod was developed for the determination of5-HT after optimizing the experimentalparameters such as supporting electrolyte, content of mesoporous SiO₂as well asaccumulation time. The linear range is from2.0x10^-7to1.5x10^-5mol/l, and the limitof detection is as low as8.0x10^-8mol/l after2-min accumulation. The relative standarddeviation (RSD) for10mesoporous SiO₂modified CPEs is evaluated to be6.7%.Finally, this novel method was successfully used to determine5-HT in human bloodserums.4. A thin film of poly(L-serine) was prepared via electropolymerization for thedetermination of trace levels of estradiol. In pH5.0phosphate buffer, L-serine wasoxidized during the cyclic potential sweeps between-0.60and2.0V, forming a thin filmat the electrode surface. The electrochemical behavior of estradiol was investigated. Theoxidation peak potential of estradiol shifts negatively at the poly(L-serine) film-coatedglassy carbon electrode (GCE) compared with that at the bare GCE. Otherwise, theoxidation peak current greatly increases at the poly(L-serine) film-modified GCE. Thesephenomena suggest that the poly(L-serine) film exhibits catalytic activity towards theelectrochemical oxidation of estradiol. Based on this, a sensitive, rapid and simpleelectrochemical method was proposed for the determination of estradiol. The limit ofdetection is evaluated to be2.0x10^-8mol L^-1. Finally, this method was successfullyused to determine estradiol in blood serum.