Functionalized Persistent Luminescence Nanoparticle-Based Aptasensor for Autofluorescence-free Determination of...

Selective and sensitive determination of trace kanamycin in complex food samples is of great importance for food safety because of its high toxicity. Here, we report a sensitive and autofluorescence-free persistent luminescence (PL) aptasensor for selective, sensitive, and autofluorescence-free determination of kanamycin in food samples. The aptamer for kanamycin was first conjugated onto the surface of magnetic nanoparticles Fe₃O₄ to serve as the recognition unit as well as the separation element, while the PL nanoparticles ZnGa₂O₄:Cr (PLNPs) were functionalized with the aptamer complementary DNA (cDNA) as the PL signal. The PL aptasensor consisted of the aptamer-conjugated MNPs (MNPs-apt) and cDNA-functionalized PLNPs (PLNPs-cDNA) and combined the merits of the long-lasting luminescence of PLNPs, the magnetic separation ability of MNPs as well as the selectivity of the aptamer, offering a promising approach for autofluorescence-free determination of kanamycin in food samples. The proposed aptasensor showed excellent linearity in the range from 1 pg mL^-1 to 5 ng mL^-1 with a limit of detection of 0.32 pg mL^-1. The precision for 11 replicate determinations of 100 pg mL^-1 kanamycin was 3.1% (relative standard deviation). The developed aptasensor was applied for the determination of kanamycin in milk and honey samples with the recoveries of 95.4-106.3%. The proposed aptasensor is easily extendable to other analytes by simply replacing the aptamer, showing great potential as a universal aptasensor platform for selective, sensitive, and autofluorescence-free detection of hazardous analytes in food samples.