Fabrication And Application Of Modified Electrodes By Novel Nanomaterials

At present, the chemically modified electrodes (CMEs) more and more attractmany attentions of researchers, so finding the chemical groups or materials with thespecial functions to modify the surface of electrodea and giving some specificperformance of the CMEs are very important. And to build a simple, cheap, fast andstable chemical sensor of different CMEs is also a hotspot in the research of thescientists. In this dissertation, researches were carried out for the hot spots.1. It described a simple and reliable method for the electrochemical determinationof nitrite based on the immobilization of myoglobin (Mb) on LaF3doped CeO2(LaF3-DP-CeO2) and ionic liquid (IL) composite film. Meantime, ultraviolet visiblespectra (UV-vis), fourier transform infrared spectra (FT-IR) and circular dichroismspectra (CD) were utilized to characterize the composite film. The results demonstratedthat Mb in the composite membrane retained its secondary structure similar to the nativestate. Furthermore, electrochemical examination reveale that the LaF3-DP-CeO2withthe virtues of excellent biocompatibility, conductivity and high sensitivity to the localperturbations can provide a biocompatible microenvironment for protein immobilizationand a suitable electron transfer distance between Mb and electrode surface.Amperometric responses indicate that the amperometric response is rapid, stable andoffered a linear range of nitrite (NO2) concentration from5μM to4650μM with adetection limit of2μM. The low value of Michaelis-Menten constant KM(2.19mM)indicates enhanced protein affinity of Mb to NO2. The attractive features ofLaF3-DP-CeO2provide potential applications in sensor and biosensor design. 2. By microwave method improved the methods for preparation of carbon aerogen(CA). On the basis, the metal nanoparticles Ni and Pd functionalized CA weresynthesized succefully through the chemical precipitation. The inorganic doped CAcomposites as the electrode modified materials for the first time were used toimmobilize myoglobin (Mb) so as to exhibite good electronic conductivity, stability andelectrocatalytical activity towards the reduction of H2O2. Spectroscopic and directelectrochemistry examinations indicated that the two metal nanoparticles doped CAcomposites were biocompatible matrix for immobilizing Mb. These two novel inorganicdoped CA/IL/Mb-CPE could act as sensors toward the detection of H2O2with a lowerdetection limit (1.68μM and1.02μM respectively for Ni-CA/IL/Mb-CPE,Pd-CA/IL/Mb-CPE) and smaller apparent Michaelis-Menten constant KM.3. In the previous section, on the basis of the research content, the conductingpolymer functionalized carbon aerogel (Ppy-CA) composite material was synthesizedsuccefully through chemical redox polymerization. Then Ppy-CA was used to preparaethe Ppy-CA/IL/Mb-CPE modified electrode. Spectroscopic and electrochemicalexaminations revealed that the Ppy-CA/IL composite was biocompatible matrix forimmobilizing Mb with good stability and bioactivity. Compared with the other twoH2O2sensors (Ni-CA/IL/Mb-CPE and Pd-CA/IL/Mb-CPE), the Ppy-CA/IL/Mb-CPEhad the lowest detection limit (0.85μM) and the minimum apparent Michaelis–Mentenconstant KM(0.29mM). So CA and a class of CA-based hybrid materials could be apromising matrix for the fabrication of direct electrochemical sensors in biomedicalanalysis.