On-site and dual-mode detection of live Vibrio parahaemolyticus in waters: A universal pathogen sensing platform based on a smart hydrogel aptasensor imbedded with gold nanoclusters

Usually, a low concentration of pathogens proliferate rapidly in waters to cause serious threats to human health. It is necessary to develop on-site and speedy assays to detect them. In this work, a smart hydrogel aptasensor was assembled in Eppendorf tubes for quantifying Vibrio parahaemolyticus (V.P). It employed a dual-mode detection strategy combining visual fluorescence (FL) and microfluidic chip (MC) methods. In this aptasensor, the hydrogel contained ATP aptamer together with gold nanoclusters (AuNCs) as signal tags, and V.P aptamer was modified on tube lids. Firstly, trace V.P in waters was specifically enriched by the lid and then hydrolyzed to release ATP which was combined with ATP aptamer in hydrogel to form ATP-aptamer complex. The complex together with AuNCs was subsequently released into the supernatant for dual-mode detection. ATP-aptamer was detected by MC and AuNCs by FL. By the assay, as low as 100 CFU·mL−1 V.P was determined by FL within 45 min and 10 CFU·mL−1 by MC. The dual-mode sensing platform exhibits the following advantages: Firstly, live pathogens were quantitatively and on-site detected. Secondly, the lid’s enrichment of V.P and signal transduction from one V.P to 1014 ATP could double-amplify signals and increase the detection efficiency. Finally, the samples quickly screened by visual FL on-site, and then accurately quantified by MC in the laboratory, which greatly shortens the detection period. It has been successfully utilized for on-site detecting V.P in aquatic waters and could be extended to other bacteria measurements through changing the relative aptamer on the tube lid.