Dual-FRET platform based on dsDNA-functionalized Ti3C2Tx MXene for highly sensitive detection of bacteria

Pathogenic bacteria represent a considerable threat to public health and food safety, necessitating the development of advanced detection methodologies. In this study, a novel fluorescence sensing platform based on fluorescence resonance energy transfer (FRET) was established to detect Pathogenic bacteria with rapid response, exceptional sensitivity, and stable selectivity. Using carboxyl-modified Ti 3 C 2 T x MXene (Ti 3 C 2 T x -COOH) as nanocarriers, double-stranded DNA (dsDNA) were assembled to functionalize the MXene for rapidly efficient quenching of fluorescence dye-labeled aptamers and specific recognition of target bacteria. Upon the incorporation of target bacteria, the aptamer preferentially bound to bacteria, dissociating from the MXene and resulting in a significant and rapid increase in fluorescence intensity. Using E. coli O157:H7 and S. aureus as exemplar biotargets, the sensor demonstrated ultra-sensitive detection of E. coli O157:H7 and S. aureus with limits of detection (LOD, S/N = 3) as low as 0.61 CFU/mL and 1.62 CFU/mL, respectively, within a rapid response time of 15 min, thereby demonstrating superior performance in comparison to the majority of existing FRET-based biosensors. Moreover, this method demonstrates excellent reproducibility and stability, having been successfully applied to spiked milk samples. The recovery rates for S. aureus ranged from 90.2 % to 114.3 %, with acceptable RSDs of 1.4 % to 7.4 %, while those for E. coli O157:H7 ranged from 91.7 % to 93.6 %, with acceptable RSDs of 5.2 % to 8.7 %, confirming its strong potential for practical sample analysis. The present study establishes a foundational framework for subsequent research into biosensors for detecting targets and provides a new pathway for the analysis of other biological factors.