Dual‐mode biosensing platform for ultrasensitive Salmonella detection based on cascaded signal amplification coupled with DNA‐functionalized Ag2S NPs@PB

Abstract

Abstract Salmonella is one of the most common zoonotic foodborne pathogens and can cause serious threats to public health and global economy. A dual‐mode biosensing platform was demonstrated based on cascaded signal amplification coupled with DNA‐functionalized Ag2S NPs@PB (Ag2S NPs@PB‐DNA) for ultrasensitive and selective Salmonella detection. Specifically, once Salmonella was recognized and captured by the control probe, the primer was released to trigger rolling circle amplification and generate a multimeric single‐stranded DNA (ssDNA) with repetitive sequences. The ssDNA could form multicomponent nucleic acid enzyme with cleavage activity to destroy multiple pieces of L‐DNA, achieving cascaded signal amplification and cleaving L‐DNA as a linker between DNA‐functionalized magnetite microspheres (MMs@DNA) and Ag2S NPs@PB‐DNA, leading to reduction in the capture of Ag2S NPs@PB by MMs@DNA. Due to the excellent photothermal properties of Ag2S NPs@PB under near‐infrared irradiation, the changes of temperature and pressure could be simultaneously monitored in the detection system, and the dual‐mode biosensing platform showed outstanding sensitivity, with a limit of the detection value of 100 CFU mL−1 in temperature and 101 CFU mL−1 in pressure. Moreover, the developed biosensing platform could successfully detect 5.7 CFU of Salmonella in spiked chicken breast after 4 h of enrichment. All the results show this study provides a new avenue for specific, sensitive, and convenient bacterial detection in food analysis and environment safety.

Keywords

• cascaded signal amplification
• dual‐mode biosensing platform
• food safety
• photothermal
• Salmonella