Core-shell MOF collapse-amplified fluorescent aptasensor with self-sedimentation for Staphylococcus aureus detection

Staphylococcus aureus (S. aureus) is a prevalent foodborne pathogen that produces heat-stable enterotoxins, causing severe food poisoning and systemic infections, thus posing a persistent threat to public health and food safety. Conventional detection methods are limited by time-consuming procedures, equipment dependence, and matrix interference. Therefore, rapid and reliable detection of S. aureus remains an urgent challenge in point-of-care testing (POCT).

Here, we report a self-sedimentation-assisted and signal-amplified fluorescent aptasensor that integrates target-triggered competitive displacement with acid-triggered metal organic framework (MOF) collapse. In this system, high-density SiO₂@PDA@Au-Apt microspheres function as capture substrates, while CDs@ZIF-8@ZIF-90-cDNA nanoprobes serve as signal reporters. Upon S. aureus recognition, competitive binding releases the nanoprobes into the supernatant, whereas target-bound substrates rapidly self-sedimentation via gravity, thereby efficiently eliminating matrix interference without external force. Subsequent acidification of the isolated supernatant induces instantaneous MOF framework collapse via protonation-induced cleavage of coordination bonds, leading to burst release of encapsulated carbon dots and strong fluorescence amplification. Under optimal conditions, this platform exhibits a broad linear range from 1 × 10² to 1 × 10⁷ CFU/mL, alongside excellent selectivity against interfering bacteria and satisfactory recoveries ranging from 92.0% to 103.0% in spiked lake water and honey water samples.

Overall, this core-shell MOF collapse-amplified fluorescent aptasensor eliminates the need for centrifugation or magnetic separation, enabling simple and equipment-free operation. Its high sensitivity, broad linear range, and reliable performance in real samples make it a robust and practical platform for on-site pathogen monitoring.