Highly sensitive photoelectrochemical biosensing detection of early cardiac injury enabled by novel self-assembled Bi2O3/MgIn2S4 photoelectrode coupled with ZnSnO3 quencher

The development of photoelectrochemical (PEC) biosensors plays a critical role in enabling timely intervention and personalized treatment for cardiac injury. Herein, a novel approach is presented for the fabrication of highly sensitive PEC biosensor employing Bi2O3/MgIn2S4 heterojunction for the ultrasensitive detection of heart fatty acid binding protein (H-FABP). The Bi2O3/MgIn2S4 heterojunction, synthesized through in-situ growth of MgIn2S4 on Bi2O3 nanoplates, offers superior attributes including a larger specific surface area and more homogeneous distribution, leading to enhanced sensing sensitivity. The well-matched valence and conduction bands of Bi2O3 and MgIn2S4 effectively suppress the recombination of photogenerated carriers and facilitate electron transfer, resulting in a significantly improved photocurrent signal response. And the presence of the secondary antibody marker (ZnSnO3) introduces steric hindrance that hinders electron transfer between ascorbic acid and the photoelectrode, leading to a reduction in photocurrent signal. Additionally, the competition between the ZnSnO3 marker and the Bi2O3/MgIn2S4 heterojunction material for the excitation light source further diminishes the photocurrent signal response. After rigorous repeatability and selectivity tests, the PEC biosensor exhibited excellent performance, and the linear detection range of the biosensor was determined to be 0.05 pg/mL to 100 ng/mL with a remarkable detection limit of 0.029 pg/mL (S/N = 3).