A multi-channel microfluidic chip based on fluorescent distance readout-mode for rapid, simultaneous and visual detection of multiplex pathogens using phage- AIEgen-antimicrobial peptide-encoded tags

Conventional fluorescence (FL) biosensors based on intensity quantification mode, are susceptible to individual or detector differences, and background light. In this study, a multi-channel microfluidic chip (D-chip) based on visual fluorescence distance-readout mode was self-made for rapid and simultaneous detection of three bacteria. In the chip, different phages for specifically capturing three kinds of bacterial strains were pre-modified in the channels, respectively. After the sample with multiplex bacteria was pumped into the chip, different target bacteria could be captured by corresponding channels and travel in the flow direction, respectively. Subsequently, novel aggregation-induced emission fluorophore photosensitizer-labeled antimicrobial peptides (AIE@AMPs) signal tags were used to conjugate with all captured bacteria to boost their light emissions. The AIE@AMPs can enhance FL signals after conjugating with bacteria. Consequently, the qualification and quantification of different species of bacteria can be carried out by measuring corresponding luminous channel distances. Under optimized conditions, the D-chip with FL distance readout mode was successfully applied for detecting Escherichia coli O157:H7 ( E. coli 44484) and two Salmonella typhimurium strains (S. T 14028 and S. T 25928) within 30 min. The linear range for E. coli was from 10 2 to 10 6 CFU/mL, with a limit of detection (LOD) of 64 CFU/mL. For two S. T strains , the linear range is from 10 2 to 10 6 CFU/mL, with an LOD of 58 CFU/mL. The multi-channel microfluidic platform based on naked-eye FL distance readout mode shows great potential for practical application in on-site screening of pathogen bacteria.