Photoelectrochemical Determination of Cardiac Troponin I as a Biomarker of Myocardial Infarction Using a BiS Film Electrodeposited on a BiVO-Coated Fluorine-Doped Tin Oxide Electrode.

A sensitive and selective label-free photoelectrochemical (PEC) immunosensor was designed for the detection of cardiac troponin I (cTnI). The platform was based on a fluorine-doped tin oxide (FTO)-coated glass photoelectrode modified with bismuth vanadate (BiVO) and sensitized by an electrodeposited bismuth sulfide (BiS) film. The PEC response of the BiS/BiVO/FTO platform for the ascorbic acid (AA) donor molecule was approximately 1.6-fold higher than the response observed in the absence of BiS. The cTnI antibodies (anti-cTnI) were immobilized on the BiS/BiVO/FTO platform surface to produce the anti-cTnI/BiS/BiVO/FTO immunosensor, which was incubated in cTnI solution to inhibit the AA photocurrent. The photocurrent obtained by the proposed immunosensor presented a linear relationship with the logarithm of the cTnI concentration, ranging from 1 pg mL to 1000 ng mL. The immunosensor was successfully employed in artificial blood plasma samples for the detection of cTnI, with recovery values ranging from 98.0% to 98.5%.