Highly sensitive and selective hydrogen peroxide biosensor based on hemoglobin immobilized at multiwalled carbon nanotubes-zinc oxide composite electrode

A highly sensitive and selective amperometric hydrogen peroxide (H ₂O₂) biosensor based on immobilization of hemoglobin (Hb) at multiwalled carbon nanotubes-zinc oxide (MWCNT/ZnO) composite modified glassy carbon electrode (GCE) is reported. ZnO microsponges were electrochemically grown on MWCNT surface by the simple, cost-effective, green, electrochemical method at room temperature. The MWCNT/ZnO/Hb composite film showed a pair of well-defined, quasi-reversible redox peaks with a formal potential (E°′) of -0.336 V, characteristic features of heme redox couple of Hb. The electron transfer rate constant (k_s) of immobilized Hb was 1.26 s^-1. The developed biosensor showed a very fast response (>2 s) toward H₂O₂ with good sensitivity, wide linear range, and low detection limit of 0.02 μM. The fabricated biosensor showed interesting features, including high selectivity, acceptable stability, good reproducibility, and repeatability along with excellent conductivity, facile electron mobility of MWCNT, and good biocompatibility of ZnO. The fabrication method of this biosensor is simple and effective for determination of H ₂O₂ in real samples with quick response, good sensitivity, high selectivity, and acceptable recovery.