Silver nanoparticles/polyethyleneimine/graphene oxide composite combined with surfactant film for construction of an electrochemical biosensor

Abstract

A novel electrochemical biosensor was constructed based on the combination of hemoglobin (Hb), silver nanoparticles (AgNPs) assembled on the surface of polyethyleneimine (PEI) functionalized graphene oxide (PEI-GO), and didodecyldimethylammonium bromide (DDAB) surfactant. AgNPs were formed on the surface of PEI-GO through the direct reduction of silver nitrate by the amine-containing PEI. The resulting AgNPs/PEI-GO composite was combined with DDAB to entrap Hb on the surface of a glassy carbon electrode for fabricating the electrochemical biosensor. The synergistic effects of the AgNPs/PEI-GO and DDAB enhanced the effectiveness of Hb immobilization and made possible its direct electrochemistry. The apparent surface concentration (Γ*) of electroactive Hb in the DDAB/Hb/AgNPs/PEI-GO film was estimated at 8.50 × 10⁻¹¹ mol cm⁻². Moreover, this biosensor showed excellent electrocatalytic activities for reduction of H₂O₂ with rapid response, high sensitivity, and reliable stability. The catalytic current was linear with H₂O₂ concentration in the range of 0.50 μmol L⁻¹ to 1.87 mmol L⁻¹ with a detection limit of 0.65 μmol L⁻¹. The apparent Michaelis–Menten constant (K^app_M) was calculated to be 0.29 mmol L⁻¹. The real samples were detected by the proposed sensor with recoveries from 98.7% to 102.7%. Therefore, the strategy based on combining nanocomposite and surfactant demonstrates a new avenue for the interface fabrication of electrochemical biosensors.