Engineered n-n heterointerface architectures: Bi2S3@porphyrin-MOF heterojunction-based photoelectrochemical immunosensor for ultrasensitive monitoring of gentamicin

Herein, a robust photoelectrochemical (PEC) immunosensor was constructed based on an n-n heterojunction between a copper-porphyrin-based metal organic framework and Bi 2 S 3 (Bi 2 S 3 @Cu-TPyP) for efficient detection of gentamicin (GEN). The integration of Cu-TPyP features (enhanced electron transfer capability, improved photoabsorption performance, large specific surface area, and high antibody bioaffinity) with Bi 2 S 3 characteristics (narrow bandgap and visible light absorption capacity) established an efficient interfacial architecture. Enhanced separation of photogenerated electron-hole pairs and improved photoelectric conversion efficiency in the Bi 2 S 3 @Cu-TPyP heterojunction contributed to the amplified photocurrent. The immunosensor exhibited an ultralow detection limit of 0.041 fg mL −1 (1.0 fg mL −1 –1.0 ng mL −1 linear range) with high selectivity and validated applicability in analyzing GEN across diverse food matrices. This study establishes a PEC biosensing paradigm enabling ultrasensitive and rapid antibiotic monitoring in food products due to the synergistic signal amplification mechanisms without compromising specificity.