Hybrid chain reaction-based and Au/Bi 4 NbO 8 Cl/In 2 S 3 layer-by-layer assembled dual-mode photoelectrochemical-electrochemical aptasensor for the detection of Salmonella enteritidis.

Salmonella enteritidis (SE) is a food-borne pathogens that can cause acute gastroenteritis. With the increasing social attention to food safety, the detection method of SE has attracted wide attention. In response to the demand for efficient detection methods of SE, this study constructed a novel dual-mode photoelectrochemical-electrochemical (PEC-EC) aptamer-based biosensor. The sensor was constructed using Bi 4 NbO 8 Cl/In 2 S 3 heterojunction as the electrode substrate material, the hybridization chain reaction (HCR) and dye sensitization were used as the signal amplification strategies. Bi 4 NbO 8 Cl/In 2 S 3 heterojunction could provide an excellent initial photocurrent response for the sensing platform, and the HCR was opened by the end of complementary DNA (cDNA) and generated an ultra-long DNA double-stranded (dsDNA) "super structure" on the surface of the electrode, which could be embedded with a large number of methylene blue (MB) as the bifunctional probes. Thus, dual-mode output was achieved via the PEC and EC activity of MB. Under the optimized conditions, the PEC and EC signal responses of the system were linear to the logarithm of SE concentration in a range from 1.5 × 10 2  CFU/mL to 1.5 × 10 7  CFU/mL. The detection limits were found to be 12.9 CFU/mL and 12.3 CFU/mL using the PEC and EC methods, respectively. The constructed dual-mode biosensor exhibited good performance for real sample analysis, and demonstrated great application potential in the field of SE rapid detection. Moreover, this dual-mode detection strategy provided more accurate and reliable results than the single-mode output.