Superoxide radical biosensor based on a nano-composite containing cytochrome c

چکیده مقاله

A biosensor for the quantification of superoxide radical (O2_) was developed based on a nanocomposite
containing cytochrome c (Cyt c), carboxylated multi-walled carbon nanotubes and a room
temperature ionic liquid (RTIL). The immobilized Cyt c was characterized by field emission scanning
electron microscopy, electrochemical impedance spectroscopy and cyclic voltammetry. Using this
biosensor a formal potential of 280 mV (vs. Ag/AgCl) and electron transfer rate constant of 1.24 was
recorded for the immobilized Cyt c in 0.1Mphosphate buffer solution (pH 7.0). The biosensor showed
a relatively high sensitivity (7.455 A M1 cm2) and a long term stability (180 days) towards O2_ in the
concentration range from 0.05 to 8.1 mM with a detection limit of 0.03 mM. The selectivity of the
biosensor to O2_ was verified when its response was compared with those obtained by four potential
interfering substances (ascorbic acid, uric acid, acetaminophen and hydrogen peroxide).