Dual-mode ECL/SERS immunoassay for ultrasensitive determination of Vibrio vulnificus based on multifunctional MXene

Herein, a dual-mode ECL/SERS immunoassay for ultrasensitive determination of pathogenic bacteria Vibrio vulnificus (VV) was developed, based on a multifunctional MXene material R6G-Ti3C2Tx@AuNRs-Ab2/ABEI acting as the signal unit. In it, the Ti3C2Tx MXene with high electric conductivity could load a great number of SERS signal tags Rhodamine 6G (R6G) and gold nanorods (AuNRs) on which R6G, electrochemiluminescence (ECL) signal tags ABEI and detection antibodies Ab2 were immobilized. The dual-mode ECL/SERS immunosensor could be built with a high detection sensitivity due to following reasons. First, the number of signal tags was increased owing to the large surface area of MXene. Second, all ECL signal tags were electrochemically activated due to the Faraday cage-type sensor construction method. Third, the introduction of AuNRs brought significant enhancement of SERS signals. Under optimal experimental conditions, the linear range and limit of quantification (LOQ) of ECL were from 1 to 108 CFU/mL and 1 CFU/mL, while those of SERS were from 102 to 108 CFU/mL and 102 CFU/mL respectively. Stability, reproducibility and selectivity were all satisfied. In addition, dual-mode signals could be mutually checked, effectively improving the accuracy and reliability. The detection principle is widely applicable for other pathogenic bacteria, having broad application prospects in food safety and medical detection.