A novel fluorescence resonance energy transfer (FRET)-based paper sensor with smartphone for quantitative detection of Vibrio parahaemolyticus

In recent years, food poisoning events caused by Vibrio parahaemolyticus have shown an upward trend. Therefore, there is a growing need for a rapid, sensitive and simple detection method for V. parahaemolyticus. The aim of this study was to develop a novel aptamer-based paper sensor for the rapid, sensitive, portable and specific detection of V. parahaemolyticus in seafood through the fluorescence resonance energy transfer (FRET) principle. The capture probes for this strategy were made by chemically coupling carbon dots (CDs) to amino-modified single -stranded DNA. Switches were double-stranded DNA formed by hybridization of anti -V. parahaemolyticus aptamers (aptamer) and gold nanoparticles (AuNPs)-probes. Once V. parahaemolyticus was introduced, the aptamer in the double-stranded DNA bound specifically to the target bacteria and the sensor was 'On', releasing the AuNPs-probes to bind to the capture probes. The fluorescence color of the CDs changed significantly from bright blue to colorless because of the FRET between CDs and AuNPs. As expected, when filter paper was used as the assay liquid carrier, an ingenious FRET-based paper sensor was presented for accurate field reporting of V. parahaemolyticus, with a linear range of 101-106 cfu/mL. This strategy has a detection limit of 8.9 cfu/mL for V. parahaemolyticus in culture and 6.7 x 101 cfu/mL in artificially contaminated cod samples. The results indicate that this study has good potential as a new portable sensor for the detection of V. parahaemolyticus in complex food matrices.