A New Amperometric Benzaldhyde Biosensor Based on Aldehyde Oxidase Immobilized on Fe3O4-GrapheneOxide/Polyvinylpyrrolidone/Polyaniline Nanocomposite

A new biosensor for determination of benzaldehyde based on carbon past electrode (CPE) modified with a Fe3O4-graphen oxide/polyvinyl pyrrolidone/polyaniline (Fe3O4/GO/PVP/PANI) nanocomposite was developed. The nanocomposite was electrodeposited on the surface of CPE using cyclic voltammetry technique. The crude extract aldehyde (AOX) oxidase enzyme isolated from rat liver was immobilized on the Fe3O4/GO/PVP/PANI nanocomposite and the prepared biosensor was employed for benzaldehyde oxidation to H2O2. The benzaldhyde measured amperometrically based on reduction of produced H2O2 at -0.25 V(vs. Ag/AgCl). The cyclic voltammetry and electrochemical impedance spectroscopy studies of the modified electrode indicated that Fe3O4/GO has an excellent electrocatalytic activity and can be used as an electron mediator for H2O2 reduction. The presence of PVP in the nanocomposite could substantially improve the dispersibility of GO, leading to enhanced sensitivity of the biosensor. Under optimum conditions, the biosensor exhibited a fast response time to benzaldhyde within 10 s. The sensor showed a linear response to benzaldehyde concentration in the range of 0.5-50 mu M with a limit of detection of 0.4 mu M(S/N= 3) and sensitivity of 4.173 mA mu M-1 cm(-2). The biosensor revealed a preference for benzldehyde than studied aliphatic aldehydes. The new biosensor showed good performance to analysis of benzaldhyde in drugs injection formulations.