A low-background aptasensor based on enzyme-linked multifunctional carbon nanosheets for the detection of Salmonella

Herein, a low-background aptasensor has been developed based on enzyme-linked multifunctional multi-layer carbon nanosheets (MLCN) for detection of Salmonella. The ZIF-8-derived MLCN have large specific surface area, pore structure and enzyme-like activity, which is multifunctional and used not only as carrier for enzyme and aptamer loading but also cascade catalytic probe for signal transduction. When the Salmonella was present, the MLCN functionalized with GOx and aptamer binded to the aptamer-modified magnetic nanoparticles specifically to form a sandwich structure. Then the GOx oxidized the glucose to generate H2O2 and triggered the peroxidase-like detection system. Compared to commonly used signal probe consisting of H2O2, the inactive glucose dose not oxidize TMB to cause color change, leading to the low-background signal. The limit of detection is 0.2 CFU/mL and the linear range is 1.0–107 CFU/mL. The proposed aptasensor was applied to the detection of Salmonella in real milk samples and the bactericidal effect evaluation of antibiotic, which proved the practicability.