A sensitive sensing system based on fluorescence dipeptide nanoparticles for sulfadimethoxine determination

Various types of fluorescent nanoparticles have been proposed for the detection of veterinary drug residues in food. However, structure-induced fluorescence nanoparticles with biodegradability and the capacity to conjugate with molecular recognition elements are lacking. Here, a biodegradable tryptophan-phenylalanine dipeptide-based nanomaterial was assembled and modified with a sulfadimethoxine aptamer (TPNPs@aptamer). Then, a novel and efficient fluorescence sensing strategy, based on TPNPs@aptamer and BHQ1-labeled single-stranded DNA (BHQ1@cDNA), was developed for sulfadimethoxine determination. Under optimal conditions, the fluorescence was linear in the range of 0-200 ng/mL sulfadimethoxine with a detection limit of 1.47 ng/mL (S/N = 3). Satisfactory recoveries of standard additions were found between 92.88 % and 114.15 % for water and milk samples with a relative standard deviation less than 5.0 %, suggesting that the proposed fluorescence sensing strategy can be applied reliably in sulfadimethoxine analysis of liquid foods.