Base On Carbon Nanotube-chitosan Modified Electrodes And Its Application

For the past dozen years, carbon nanotube modified electrode (CNTME) has been developed a kinds of new type chemical modified electrodes. The CNTME is attractive because of properties such as porous structure, high surface area and more functional group, which has some special electrochemical performance. CNTME has been widely used in analysis, environmental and biological sciences. Besides, chitosan has excellent biological compatibility, and has been extensively used as modifier. In this work, the principal research is the preparation of carbon nanotube-chitosan modified electrode and its application in electroanalytical and electrocatalysis.The primary research work is as follows:1. Electrochemical determination of serotonin based on multiwalled carbon nanotube-chitosan modified glassy carbon electrodeA new chemically modified electrode is based on multiwalled carbon nanotube-chitosan modified glassy carbon electrode (MWCNT-CS/GCE) is described for determination of serotonin (5-HT). The multiwalled carbon nanotube-chitosan (MWCNT-CS) film coated GCE exhibits a marked enhancement effect on the current response of serotonin. The measurements were carried out by application of differential pulse voltammetry (DPV), cyclic voltammetry (CV) methods. The linear relationship between oxidation peak current and concentration of serotonin were0.4to IOO.OuM, and the limit of detection is0.1u.M. The modified electrode has been successfully applied for the assay of serotonin in human blood serum.2. Electrochemical detection of serotonin in the presence of dopamine based on Fe3CO4-carbon nanotube-chitosan/poly-(bromocresol green) modified glassy carbon electrodeA novel nanocomposite material based on the magnetic nanoparticles Fe3O4, multiwalled carbon nanotube (MWCNT), chitosan (CS) and poly-bromocresol green (PBCG) modified glassy carbon electrode (GCE) was successfully prepared. When used in electrochemical detection of serotonin, the modified electrode exhibited a marked enhancement effect on the current response of serotonin and a mass diffusion-controlled process. The linear relationship of serotonin was0.5to IOO.OuM in the interference of IO.OuM dopamine and the limit of detection is0.06uM. The results indicate that the nanocomposite film has a versatile platform for the fabrication of electrochemical sensors. 3. Direct electrochemistry and electrocatalysis of a nanobiocomposite film containing hematin and carbon nanotube-chitosan on poly-(acridine red) modifie glassy carbon electrodeA novel biocomposite material based on the poly-acridine red (PAR), multiwalled carbon nanotube (MWCNT) and chitosan (CS) was used to incorporate hematin onto the surface of glassy carbon electrode for studying the direct electron transfer and electrocatalytic activity of hematin. A pair of well denned and quasi-reversible redox peaks, corresponding to the hematin Fe (III)/Fe (II) redox couple, appeared at about-0.272V(vs. Ag/AgCl). The electron transfer rate constant was estimated to be5.06s-1. The results indicated that MWCNT-CS and PAR composite film enhanced the electron transfer process of hematin. Hematin exhibited its bioelectrocatalysis activity towards the reduction of H2O2from1.0to IO.OuM, and the detection limit was0.6luM (S/N=3). The results indicate that the composite film has a versatile platform for the fabrication of electrochemical biosensors.4. Direct electrochemistry and electrocatalysis behavior of hematin entrapped in carbon nanotube-chitosan/poly-(vinylpyrrolidone)-prussian blue nanocomposite modified glassy carbon electrodeA novel nanocomposite material based on the poly-(vinylpyrrolidone)-prussian blue (PVP-PB), multiwalled carbon nanotube (MWCNT) and chitosan (CS) was used to incorporate hematin onto the surface of glassy carbon electrode for studying the direct electron transfer and electrocatalytic activity of hematin. The immobilized Hb retains its biological activity and shows high catalytic activity to the reduction of hydrogen peroxide. The electron transfer rate constant was estimated to be1.55s"1. The results indicated that MWCNT-CS and PVP-PB composite film enhanced the electron transfer process of hematin. Hematin exhibited its bioelectrocatalytic activity towards the reduction of H2O2from5.0to60.0uM, and the detection limit was0.73uM (S/N=3). The results indicate that the composite film has a versatile platform for the fabrication of electrochemical biosensors. Moreover, the composite film can be easily extended to immobilize and obtain the direct electrochemistry of other redox enzymes or proteins.