Laser-modulated MnBiTe terahertz biosensor for high-sensitivity marine bacterial detection.

The prompt and precise identification of marine bacteria is essential for assessing ecosystem health and mitigating microbial contamination in aquatic environments. In this study, we introduce a terahertz (THz) biosensor that utilizes magneto-topological MnBiTe thin films, capitalizing on their quantum anomalous Hall effect and surface-dominated optoelectronic characteristics for label-free bacterial detection. Through the application of surface engineering and laser modulation techniques, the sensor achieves a detection limit of 9.4 CFU/mL for Ruegeria pomeroyi DSS-3, exhibiting adjustable THz photoresponses under ambient conditions. Notably, distinct THz absorption signatures were identified for the bacterial proteins sulfide-quinone oxidoreductase (SQR) and flavocytochrome c subunit B (FccB), with responsivity values ranging from 0.018 to 0.042 A/W at 0.1 THz. Field validation conducted in natural seawater across various latitudes (20-38°N) demonstrated minimal environmental interference (< 1%), indicating the sensor's robustness in complex marine matrices. This research represents a pioneering effort in the integration of topological materials with THz photonics, providing a biocompatible, non-destructive, and cost-effective platform for real-time biomonitoring in marine environments.