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

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.