Ratiometric electrochemical aptasensor for point-of-care testing Vibrio parahaemolyticus together with antimicrobial peptide-labeled nano metal-organic framework signal tag

It is critically important to develop assays for point-of-care testing (POCT) vibrio in water. In this study, an aptamer-modified electrode was used in conjunction with an antimicrobial peptide-labeled nano metal-organic framework (NMOF) signal tag to screen Vibrio parahaemolyticus (VP) as a model. Firstly, single stranded DNA labeled methylene blue (cDNA-MB) was hybridized with VP aptamer (Apt) on the electrode to form an electroactive DNA probe. Simultaneously, NMOF modified antimicrobial peptide and ferrocene ([email protected]) was prepared as signal tag. The aptasensor was incubated in VP samples that would compete with aptamer and release the cDNA-MB into the supernatant. Afterwards, the [email protected] signal tag was conjugated with the captured VP to form a sandwich complex, resulting in the generation of an electrical signal from Fc. The cDNA-MB signal (IMB) decreased and the Fc signal (IFc) accordingly increased as VP concentration increased. The IFc/IMB ratio was proportional to the logarithm value of VP concentration, with a lower limit of detection as 4 CFU·mL-1. The whole analysis was completed within 30 min with high sensitivity and specificity, which was due to the dual recognition from antimicrobial peptide and aptamer then the amplification of NMOF. The aptasensor could on-site monitor vibrio contamination in aquaculture water.