Post-Competitive Interface Reprogramming for Amplified Multiplex Bacterial Fingerprinting in Biofluids

Low-burden bacterial infections demand rapid and reliable pathogen fingerprinting, yet cross-reactive sensor arrays remain limited by weak and overlapping optical signatures. Here we introduce postcompetitive interface reprogramming (PCIR), a sensor-array strategy that extracts latent bacterial-surface information by reprogramming preformed reporter-bacterium interfaces rather than merely expanding readout dimensionality. Boronic-acid-modified perylene diimide (PDI) reporters first bind bacterial surfaces, generating weak aggregation-caused quenching signals. Subsequent addition of D-chitosan (D-CS), a bacterial-surface-mimicking postcompetitor, differentially perturbs the preformed interfaces while modulating PDI aggregation, thereby producing amplified fluorescence recovery fingerprints. PCIR links the initial bacteria-bound state with the D-CS-reprogrammed end point, unlocking interfacial information inaccessible to either state alone and boosting bacterial LDA-based discrimination capacity index (DCI) 35-fold over direct interface readout. Notably, at an OD600 as low as 0.002, PCIR directly discriminated 20 clinically relevant uropathogens in urine, without sample pretreatment or pre-enrichment incubation, achieving 97.5% blind-test accuracy. Together, these results establish PCIR as an interface-centered strategy for converting weak bacterial-surface information into high-resolution pathogen fingerprints in complex biofluids.