Chromaticity Evolutionary Detection of Food Contaminant\nSemicarbazide through an Upconversion Luminescence-Based Nanosensor

Semicarbazide\n(SEM) is a widespread carcinogenic and neurotoxic\nfood contaminant, originating from the metabolite of antibiotic nitrofurazone,\nwhich is used in aquaculture, or thermal decomposition byproduct of\na flour blowing agent azodicarbonamide. Although optical detection\ntechnologies are powerful tools considering the advantages of fast\nresponse and visualization detection, there are few optical nanosensors\nfor highly sensitive and visual assays of SEM due to no luminescence\nresponse and UV absorbance of SEM. Herein, an upconversion luminescence\n(UCL)-based nanosensor was designed for visual detection of SEM with\nhigh sensitivity and good selectivity. The nanosensor was constructed\nby combining upconversion nanoparticles (UCNPs) and phosphomolybdic\nacid (PMA), which was used as the specific recognition element of\nSEM. The developed nanosensor exhibited selective absorbance enhancement\nand UCL quenching behavior with the addition of SEM based on the inner\nfilter effect (IFE). Since the change in absorbance translated into\nan exponential change in the luminescence, the sensitivity of the\nnanosensor was greatly improved. The nanosensor realized a highly\nsensitive and visual response to SEM in the linear range of 0.5–16\nμM with a low limit of detection of 58 nM. Moreover, satisfactory\nrecovery values ranging from 90 to 112% in spiked real samples indicated\nthe practical applicability of the nanosensor. The nanosensor designed\nhere provides a sensitive and convenient sensing strategy for visual\ndetection of hazardous substances and is expected to develop the upconversion\nsensing application in food safety.