Preparation And Electrochemical Studies Of Calcium Alginate Composite Porous Films

The main purpose of this dissertation is to study the fabrication and optimization of the third-generation electrochemical biosensors by exploring the proper method and novel materials in the fabrication of bioelectrochemical interface and evaluating the resulting biosensors. In this paper, to explore a more stable film in immobilizing myoglobi n(Mb) on electrodes, some new materials were introduced in the porous calcium alginate(CA) film modified electrode. Electrochemical behaviors and their characterization of the resulting modified electrodes were studied. The details are as follows:The porous CA film had been fabricated by combining the advantages of the film-forming properties of sodium alginate(SA) and porogenic properties of polyethylene glycol(PEG) in a previous study. In order to obtain a composite film with better stability and higher water content, polyvinyl alcohol(PVA), glycerin and gelatin were introduced in the porous CA film. The CA’s composite porous film was fabricated. By modifying Mb on the surface of the CA’s composite porous film modified glassy carbon electrodes(GCE), the Mb-CA’s composite porous film modified electrochemical biosensor was fabricated successfully. The resulting composite porous film was characterized by means of scanning electron microscopy(SEM), UV-vis absorption, electrochemical impedance spectra(EIS), cyclic voltammetry(CV), square-wave voltammetry(SWV) and amperometry. UV-vis experiments demonstrated that Mb assembled in the CA’s composite porous film keep their original conformation. EIS data reflects that the addition of PVA, glycerin and gelatin made the charge transfer resistance(Rct) decline obviously. The CV curve showed a pair of reversible cyclic voltammetry preaks at about ﹣0.37 V vs SCE, which was originated from heme FeIII/II redox couples within Mb. The electrochemical parameters such as apparent heterogeneous electron transfer rate constant(ks) and formal potential(Eο?) were estimated by fitting the data of SWV. The Mb-CA’s composite porous film modified GCE showed excellent electrocatalytic activity toward oxygen(O2), hydrogen peroxide(H2O2) and sodium nitrite(Na NO2), which have good stability and high sensitivity.