Ionic-liquid/NH2-MWCNTs as a highly sensitive nano-composite for catalase direct electrochemistry

چکیده مقاله

A nano-composite material consisting of amine functionalized multi-walled carbon nanotubes and a
room temperature ionic-liquid (1-butyl-3-methylimidazolium tetrafluoroborate) was prepared and used
to construct a novel catalase (Ct) based biosensor for the determination of hydrogen peroxide. The modified
electrode exhibited a quasi-reversible cyclic voltammogram corresponding to the Fe(II)/Fe(III) redox
couple in the heme prosthetic group of Ct with a formal potential of −460mV in 0.1M phosphate buffer
solution at pH 7.0. The nano-composite film showed an obvious promotion of the direct electron transfer
between Ct and the underlying electrode. The apparent charge transfer rate constant and transfer
coefficient for electron transfer between the electrode surface and enzyme were calculated as 2.23 s−1
and 0.45, respectively. The immobilized Ct exhibited a relatively high sensitivity (4.9 nA/nM) toward
hydrogen peroxide. Under the optimized experimental conditions, hydrogen peroxide was detected in
the concentration range from 8.6 to 140nM with a detection limit of 3.7nM at S/N = 3. The modified
electrode was stable for two weeks with no observable change in the cyclic voltammograms.