Target-regulated Ag₂S/FeOOH heterojunction activity: a direct label-free photoelectrochemical immunosensor

Myoglobin (Mb), an important cardiac marker, plays a crucial role in diagnosing, monitoring, and evaluating the condition of patients with cardiovascular diseases. Here, we propose a label-free photoelectrochemical (PEC) sensor for the detection of Mb through target regulated the photoactivity of Ag₂S/FeOOH heterojunction. The Ag₂S/FeOOH nanospindles were synthesized and served as a sensing platform for the fabrication of bio-recognized process for Mb. Mb-aptamer was used as the responsive group to grasp the target Mb in a real sample due to its advantages of strong affinity, high stability, and ease of preparation. Mb-aptamer immunocomplex is formed in the presence of Mb, which hinders the interfacial electron transfer and then reduce the photocurrent. The proposed PEC aptasensor exhibited excellent analytical performance including wide linear range (1.0 pg mL^-1 ~ 50 ng mL^-1), low limit of detection (0.28 pg mL^-1), and good selectivity and stability. This work introduces an innovative approach to PEC aptasensor, offering a promising method for precise determination of human biomarkers.