A Highly Sensitive and Selective Enzymatic Biosensor Based on Direct Electrochemistry of Hemoglobin at Zinc Oxide Nanoparticles Modified Activated Screen Printed Carbon Electrode

A sensitive enzymatic biosensor has been developed for the detection of hydrogen peroxide (H 2 O 2 ), nitrite ( ${{\rm NO}{{- \hfill \atop 2\hfill}}}$ ) and trichloroacetic acid (TCA) by using hemoglobin (Hb) immobilized on activated screen printed carbon electrode (ASPCE) and zinc oxide (ZnO) composite. A pair of well defined redox peaks is observed with a heterogeneous electron transfer rate constant (K s ) of 5.27 s −1 for Hb at ASPCE/ZnO. The biosensor exhibits the detection of H 2 O 2 , TCA and ${{\rm NO}{{- \hfill \atop 2\hfill}}}$ in the concentration range of 0.5–129.5 µmol L −1 , 2.5–72.5 mmol L −1 and 0.2–674 µmol L −1 with the detection limit of 0.083 µmol L −1 , 0.12 mmol L −1 and 0.069 µmol L −1 , respectively.