Zero-Biased and Visible Light-Driven Immunosensing of Cardiac Troponin I Biomarker Based on a BiOI/S-g-C3N4/Bi-NaTaO3 Photoelectrochemical Platform

This work describes the development of a platform based on bismuth oxyiodide (BiOI), sulfur-doped graphitic carbon nitride (S-g-C3N4), and bismuth-doped sodium tantalate perovskite (Bi-NaTaO3) for zero-biased photoelectrochemical immunosensing of cardiac troponin I (cTnI) biomarker. The spectroscopic, structural, morphological, and compositional characteristics of the photoelectrochemical (PEC) materials were evaluated by Raman and Fourier-transform infrared spectroscopy (FTIR), powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS). Electrochemical impedance (EI) measurements were performed under the incidence and absence of light to investigate the effects of photons on the charge transfer resistance of the photoelectrochemical platform. The influence of the cTnI biomarker on the photoelectrochemical response of the anti-cTnI antibody-modified photoelectrochemical platform (anti-cTnI/BiOI/S-g-C3N4/Bi-NaTaO3/FTO) was evaluated by measuring the photocurrent of the system. The immunosensor presented a linear response range from 1 pg mL-1 to 50 ng mL-1, mean recovery percentage between 95.98 and 99.78% in real human serum samples, and selectivity for the cTnI biomarker.