DNA walker-mediated biosensor for target-triggered triple-mode detection of Vibrio parahaemolyticus

Herein, we have constructed a target-triggered and DNA walker-mediated biosensor with triple signal (BTS) outputs mode for sensitive and reliable detection of pathogenic bacteria. Vibrio parahaemolyticus (VP) being the detection target model, the aptamer conformational changes induced by VP have been designed to activate the DNA walk on the modifiable and conductive surface of Fe₃O₄ nanoparticles to generate triple signal outputs, including electrochemiluminescence (ECL), fast scan cyclic voltammetry (FSCV) and fluorescent pixel counting (FLPC). Limits of quantification (LOQ) of VP were as low as 1 CFU⋅mL^-1 by ECL with a linear range of 1-10⁶ CFU⋅mL^-1, 1 CFU⋅mL^-1 by FSCV with a linear range of 1-10⁶ CFU⋅mL^-1, and 10 CFU⋅mL^-1 by FLPC with a linear range of 10-10⁷ CFU⋅mL^-1 respectively, all squared correlation coefficients R² being > 0.99. In addition, optical and electrochemical results, signal-on and signal-off results, electrode phase and solution phase results could be mutually verified by integrating of multiple detection techniques in one biosensor, greatly improving the accuracy and reliability. Therefore, the designed BTS has provided a powerful strategy for pathogenic bacteria detection considering its high detection sensitivity and accuracy, exhibiting great potential in food safety, water quality and biological contamination.