Photoelectrochemical Determination of Cardiac Troponin I as a Biomarker of Myocardial Infarction Using a Bi 2 S 3 Film Electrodeposited on a BiVO 4 -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 4 ) and sensitized by an electrodeposited bismuth sulfide (Bi 2 S 3 ) film. The PEC response of the Bi 2 S 3 /BiVO 4 /FTO platform for the ascorbic acid (AA) donor molecule was approximately 1.6-fold higher than the response observed in the absence of Bi 2 S 3 . The cTnI antibodies (anti-cTnI) were immobilized on the Bi 2 S 3 /BiVO 4 /FTO platform surface to produce the anti-cTnI/Bi 2 S 3 /BiVO 4 /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 -1 to 1000 ng mL -1 . 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%.