Photoelectrochemical biosensor for 1,4-dihydroxybenzene based on copper sulfide and horseradish peroxidase enzyme: Application in skin cream samples

This work presents the development and application of an ultrasensitive photoelectrochemical biosensor based on copper (I) sulfide (Cu2S) and horseradish peroxidase enzyme (HRP) immobilized on a fluorine-doped tin oxide modified glass slide (FTO) for the determination of 1,4-dihydroxybenzene (DHB). The Cu2S/FTO photoelectrochemical platform was characterized by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). The electrochemical properties of the proposed photoelectrochemical biosensor (HRP-Cu2S FTO) were evaluated by electrochemical impedance spectroscopy (EIS) and amperometry. The photocurrent of the photoelectrochemical platform was amperometrically monitored, using a commercial 20 W white LED light bulb as the source of light. After optimization of experimental parameters, the biosensor had shown good responses for detection of DHB, in the presence of 50 mu mol L-1 of hydrogen peroxide, exhibiting a wide linear range for DHB concentrations between 10 nmol L-1 up to 1 mmol L-1 (r(2) = 0.998), with a detection limit of 4.0 nmol L-1. The selectivity of the photoelectrochemical biosensor was also evaluated and the results demonstrated that the proposed biosensor presents a good selectivity for DHB detection. The HRP-Cu2S/FTO photoelectrochemical biosensor was applied in skin cream samples presenting recovery percentages for the analyte in the samples between 99.89 and 100.70%, suggesting a good accuracy for the proposed method.