Bio-inspired sensor based on glutathione peroxidase mimetic for hydrogen peroxide detection

Bio-inspired sensors based on a mimetic selenoenzyme immobilized in a film of chitosan-graphite nanoplatelets (CHI-GN) co-electrodeposited on a gold surface were constructed in order to determine hydrogen peroxide in pharmaceuticals by chronoamperometry. In these sensors a glutathione peroxidase mimetic (GPx), an amino selenide (2-(benzylselanyl)phenyl)methanamine, was immobilized on CHI-GN by crosslinking with glyoxal. In the presence of hydrogen peroxide, GPx catalyzes the oxidation of reduced glutathione (GSH), used as a cofactor of GPx, which is electrochemically reduced, and the current obtained is proportional to the H2O2 concentration. The best analytical responses were obtained employing GPx (7.4 μg per electrode), CHI-GN (0.10:0.05%, w/v) and 0.1 M Britton-Robinson buffer solution (pH 7.0) containing 99.0 μM of GSH. The analytical curves were linear for H2O2 concentrations of 2.47–284 μM with a detection limit of 2.24 μM. The recovery of H2O2 in pharmaceutical samples ranged from 98.9 to 101.3% and the results obtained using the proposed bio-inspired sensors are in agreement with those obtained using the standard method.