An enzyme-free multi-stage hybridization chain reaction for the electrochemiluminescence detection of MRSA using MoS2 NF@AuNPs catalyst.

Methicillin-resistant Staphylococcus aureus (MRSA) is a ubiquitous foodborne pathogen capable of causing food poisoning and producing enterotoxins in foodstuffs, which ultimately results in various illnesses, such as vomiting, diarrhea, and pneumonia. In this study, we present a MoS2 NF@AuNPs enhanced electrochemiluminescence (ECL) biosensor for MRSA detection based on a DNA branching tree structure formed via enzyme-free hybridization chain reaction (HCR) amplification. This approach integrates bacterial aptamers with multistage HCR amplification to achieve highly sensitive and specific target recognition. Furthermore, MoS2 NF@AuNPs act as a synergistic catalyst for Ru(bpy)32+ molecules, which in turn substantially enhances the signal readout of the biosensor. The biosensor exhibits a robust linear correlation for MRSA detection over a concentration range of 100 to 107 cfu/mL, with a detection limit of 1 cfu/mL. In addition, the biosensor demonstrates excellent selectivity and high sensitivity when applied to real samples such as water, juice, and milk.