“Dandelion” magnetic bead-driven CDs@CeO2 based-multifunctional nanoplatform for tri-modal ultrasensitive detection and efficient eradication of pathogenic bacteria

To address the challenge of foodborne pathogens, we have developed an ultra-sensitive tri-modal detection and effective pathogen eradication strategy utilizing a “dandelion” magnetic bead-driven cerium dioxide doped with carbon dots (CDs@CeO₂) multifunctional nanoplatform. Aptamer (Apt) modification CDs@CeO₂ specifically recognizes and binds to the outer membrane proteins of Salmonella typhimurium (S. typhimurium). Concurrently, mannose-functionalized dandelion-like magnetic beads selectively recognize adhesins of S. typhimurium, avoiding competition with Apt for binding sites and leveraging the strong bacterial capture capability for high-sensitivity detection. The prepared CDs@CeO₂ has been demonstrated to exhibit favourable fluorescence characteristics. In the presence of H₂O₂, CDs@CeO₂ is capable of oxidising colorless 3,3′,5,5′-tetramethylbenzidine (TMB) into blue oxide, displaying exceptional photothermal properties. CDs@CeO₂ have the potential to generate •OH through a Fenton-like reaction, which could directly damage cells. Notably, coupling the photosensitizer Ce6 to CDs@CeO₂ and subsequent illumination generates ¹O₂, which synergistically eradicates bacteria with •OH. Detection limits of the fluorescence, colorimetry, and photothermal methods were 3.85 cfu/mL, 9.44 cfu/mL, and 5.00 cfu/mL, respectively. The platform successfully achieves precise detection of S. typhimurium in actual pre-prepared food samples through fluorescence, colorimetry, and photothermal tri-modal signals, and effectively kills bacteria, achieving trace detection and source control.