Simultaneous electrochemical determination of Staphylococcus aureus and Listeria monocytogenes based on Ti3C2Tx MXene nanoribbons/copper nanoparticles coupled with aptamer-gated probe/UiO-66 framework

Abstract

Foodborne pathogenic bacteria pose severe threats to human health and often coexist within the same environment. Thus, developing a sensitive and reliable method for their simultaneous detection is critically important. In this study, we first synthesized Ti₃C₂T_x MXene nanoribbons/copper nanoparticles (Ti₃C₂T_xNR/Cu) via a simple self-reduction method to modify electrodes for signal amplification. Concurrently, we constructed UiO-66 MOFs encapsulated with distinct probes and gated by target-specific aptamers (Apts) as bio-gatekeepers. We then proposed an innovative electrochemical strategy for the simultaneous detection of two model pathogens: Staphylococcus aureus (S. aureus) and Listeria monocytogenes (LM). The Ti₃C₂T_xNR/Cu nanohybrid synergistically enhanced the current signals of the probes by leveraging the combined advantages of Ti₃C₂T_xNR and Cu nanoparticles. For S. aureus detection, methylene blue (MB) and S. aureus-specific aptamer (S-Apt) were employed as the probe and bio-gatekeeper, respectively, while ferrocene (Fc) and LM-specific aptamer (L-Apt) were used for LM. Upon target binding, the Apts dissociated from the UiO-66 MOFs, releasing the encapsulated probes (MB or Fc). The resulting current signals, measured at the Ti₃C₂T_xNR/Cu electrode, enabled the quantitative and simultaneous detection of both pathogens. This platform's modular design allows easy adaptation for detecting other bacteria by simply replacing the aptamers, offering broad potential applications in controlling food safety.