A label-free carbon dots-based fluorescent aptasensor for the detection of V. cholerae O139

Abstract

The V. cholerae O139 contamination in the environmental water sources causes a greater threat to humans. In this study, a sensitive and label-free aptamer-based fluorescent biosensor was successfully developed. The aptamer specifically identifies the V. cholerae O139 and the quantum dots (QD) used as the fluorescent probe. The aptamer adsorbed to the QD through electrostatic interactions. The quantum dots emitted blue fluorescent at 430 nm with a quantum yield of 45.3 %, which could be effectively quenched on the binding upon the target pathogen. The sensor's fluorescence signal has a linear relationship with the concentration of V. cholerae O139 with a 426 CFU/mL detection limit. Besides, the aptasensor has been tested in detecting V. cholerae O139 through recovery studies using spiked water samples. The recovery of water samples ranges from 85.2 % and 93.46 %, and the relative standard deviation was from 1.13 % to 3.86 %. The result indicated the reliability and reproducibility of the aptasensor in the on-field detection of the pathogen.