A novel carboxymethylcellulose-gelatin-titanium dioxide-superoxide dismutase biosensor; electrochemical properties of carboxymethylcellulose-gelatin-titanium dioxide-superoxide dismutase

Abstract

A novel highly sensitive electrochemical carboxymethylcellulose-gelatin-TiO(2)-superoxide dismutase biosensor for the determination of O(2)(•-) was developed. The biosensor exhibits high analytical performance with a wide linear range (1.5 nM to 2 mM), low detection limit (1.5 nM), high sensitivity and low response time (1.8s). The electron transfer of superoxide dismutase was first accomplished at the carboxymethylcellulose-gelatin-Pt and carboxymethylcellulose-gelatin-TiO(2)-Pt surface. The electron transfer between superoxide dismutase and the carboxymethylcellulose-gelatin-Pt wihout Fe(CN)(6)(4-/3-) and carboxymethylcellulose-gelatin-Pt, carboxymethylcellulose-gelatin-TiO(2)-Pt with Fe(CN)(6)(4-/3-) is quasireversible with a formal potential of 200 mV, 207 mV, and 200 mV vs Ag|AgCl respectively. The anodic (ks(a)) and cathodic (ks(c)) electron transfer rate constants and the anodic (α(a)) and cathodic (α(c)) transfer coefficients were evaluated: ks(a)=6.15 s(-1), α(a)=0.79, and ks(c)=1.48 s(-1) α(c)=0.19 for carboxymethylcellulose-superoxide dismutase without Fe(CN)(6)(4-/3-), ks(a)=6.77 s(-1), α(a)=0.87, and ks(c)=1 s(-1) α(c)=0.13 for carboxymethylcellulose-superoxide dismutase with Fe(CN)(6)(4-/3-), ks(a)=6.85 s(-1), α(a)=0.88, and ks(c)=0.76 s(-1) α(c)=0.1 carboxymethylcellulose-gelatin-TiO(2)-superoxide dismutase. The electron transfer rate between superoxide dismutase and the Pt electrode is remarkably enhanced due to immobilizing superoxide dismutase in carboxymethylcellulose-gelatin and TiO(2) nanoparticles tend to act like nanoscale electrodes.