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

摘要

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 (G*) of electroactive Hb in the DDAB/Hb/AgNPs/PEI-GO film was estimated at 8.50 x 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 mu mol L-1 to 1.87 mmol L-1 with a detection limit of 0.65 mu mol L-1. The apparent Michaelis-Menten constant (K-M(app)) 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.