Fluorescence Quenching SERS Detection: a 2D MoS₂ Platform Modified with a Large π‐Conjugated Organic Molecule for Bacterial Detection

Abstract Surface‐enhanced Raman spectroscopy (SERS) has emerged as a powerful tool for biological detection and analysis. However, it is confronted with challenges from fluorescence interference. This study develops a CuPc/MoS₂ heterostructure with S‐scheme junction through interfacial band alignment. The SERS evaluation of methylene blue (MB) demonstrated a detection limit as low as 10 −10 M, which is 23.37‐fold higher than that of the pristine components. Meanwhile, a fluorescence quenching fraction of 0.925 is achieved by non‐radiative charge recombination, effectively addressing the issue of fluorescence interference and achieving a significant enhancement of SERS signals through the fluorescence quenching of MB molecules. The substrate demonstrates a detection sensitivity of up to 0.611 CFU mL −1 against Escherichia coli (E. coli). Notably, the platform successfully monitored polystyrene nanoplastic (PS‐NP)‐bacteria interactions, revealing size‐dependent membrane disruption mechanisms through flavin adenine dinucleotide (FAD) signal variations. This study establishes a development for non‐metallic SERS substrates in environmental monitoring and nanotoxicology research.