A novel fluorescence sensor for streptomycin detection based on hairpin DNA-AgNCs and core-shell gold-palladium nanoparticles

A novel strategy for streptomycin (STR) detection in milk was described. It was realized based on guanine (G) base-regulated hairpin DNA silver nanoclusters (DNA-AgNCs) and core-shell gold-palladium nanoparticles (Au@PdNPs) according to the principle of fluorescence resonance energy transfer (FRET). It differs from most strategies to light up the DNA-AgNCs with weak fluorescence emission due to the proximity of the G bases sequences. Different numbers of G bases were added to the hairpin loop to obtain a redshift of the emission spectrum and increase the fluorescence intensity of the DNA-AgNCs. In addition, the Au@PdNPs were prepared by seed growth and deposition. The Au@PdNPs composite material improved the quenching ability of the palladium nanoparticles (PdNPs) in the long wavelength range and significantly expanded the ultraviolet absorption range of gold nanoparticles (AuNPs). These characteristics ensure that the Au@PdNPs are excellent quenching material for fluorescent sensors. The developed sensor showed a good detection performance for STR in the range of 50–1250 nM with a limit of detection of 18.7 nM. In addition, this strategy was successfully applied for STR detection in milk, indicating its suitability for STR detection in animal-derived foods.