Horseradish peroxidase immobilization on amine functionalized carbon nanotubes: direct electrochemistry and bioelectrocatalysis

چکیده مقاله

Horseradish peroxidase (HRP) was successfully immobilized on amine functionalized
TiO2-coated multiwalled carbon nanotubes (NH2–TiO2 – CNTs) by a
convenient and efficient method. Electrochemical impedance spectroscopy, cyclic
voltammetry and amperometry were applied to characterize the HRP=NH2 –
TiO2 – CNT nano-composite. These techniques showed that the NH2–TiO2 –
CNTs greatly enhance the electron transfer between HRP and the modified
electrode. Owing to the redox reaction of the electroactive centre of HRP, the
HRP=NH2–TiO2 – CNTs modified electrode exhibited a pair of quasi-reversible
peaks with a peak-to-peak separation (DEp) of 70.6mV and a formal potential
(E0 0) of 367.65mV (versus Ag=AgCl) in phosphate buffer solution. The charge
transfer coefficient (a) and the apparent charge transfer rate constant (ks) were
found to be 0.34 and 2.08 s1, respectively. The prepared biosensor responded to
H2O2 with a linear range, detection limit, sensitivity and response time of
1.06109 to 1.06107 M, 0.786 nM, 28.4 mA nM1 and 3 s, respectively.