A Programmable and Printable Microbial Bioelectronic Sensor for Real-Time and Targeted Pollutant Monitoring in Water

Rapid detection of toxic trace contaminants is critical for global water security, yet routine monitoring relies on costly, time-consuming laboratory analyses. Microbial sensors offer a promising alternative but suffer from limited specificity, insufficient stability, and slow kinetics. Herein, we report a programmable and printable microbial bioelectronic sensor that overcomes these bottlenecks through multi-scale chemical design. Using 2,4-dinitrotoluene as a model pollutant, we genetically reprogrammed the extracellular electron transfer pathway of Shewanella oneidensis by coupling specific pollutant recognition to inner-membrane cytochrome expression, thereby enabling highly specific bioelectrical detection of target pollutants. For robust deployment, these sensing microbes were encapsulated into a dual-network hydrogel sustained by reversible hydrogen bonding, ensuring structural resilience and biocompatibility. By 3D-printing the biosensor into a biomimetic fractal architecture, we minimized mass transport resistance, achieving a response time of 5 min, a 24-fold acceleration over conventional counterparts. The biosensor also exhibited a low detection limit of 6.75 µg L^-1 and a broad dynamic range from 20.4 to 700.0 µg L^-1 (R² > 0.999). Crucially, the biosensor maintained high accuracy (relative error < 4.2%) in actual wastewaters. This work establishes that the multiscale chemical design of microbial bioelectronic sensors enables real-time, targeted pollutant monitoring.