Direct electrochemistry of myoglobin at reduced graphene oxide-multiwalled carbon nanotubes-platinum nanoparticles nanocomposite and biosensing towards hydrogen peroxide and nitrite

Abstract

We described the preparation of a novel nanobiocomposite, reduced graphene oxide- multiwalled carbon nanotubes-platinum nanoparticles/myoglobin (RGO-MWCNT-Pt/Mb) for the direct electrochemistry of myoglobin and its application towards determination of hydrogen peroxide (H2O2) and nitrite (NO2−). RGO-MWCNT-Pt nanocomposite has been prepared by simple solution based approach and its structure was characterized. RGO-MWCNT-Pt/Mb nanobiocomposite was prepared and attained the direct electrochemistry of Mb with pair of well-defined redox peaks with the formal potential of −0.33V and peak to peak separation of 22mV. Amount of electroactive protein (Г) and heterogeneous electron transfer rate constant (ks) were calculated to be 1.04×10−9molcm−2 and 9.47s−1. The sensor displayed lowest detection limit (LOD) of 6pM which is the lowest LOD ever achieved for the detection of H2O2. Two linear ranges were observed for the detection of H2O2: (1) 10pM–0.19nM with sensitivity of 1.99 (±0.058)µApM−1cm−2 and (2) 0.25nM–2.24µM with sensitivity of 0.037 (±0.081)µAnM−1cm−2. In addition, the biosensor offered good analytical parameters towards determination of NO2− with wide linear range of 1µM to 12mM and high sensitivity of 0.1651 (±0.026)µAµM−1cm−2. The sensor acquires good selectivity, repeatability, reproducibility and stability. The practical feasibility of the sensor has been addressed.