Zwitterion-modified antifouling swab joint “Snake-Eye” for detection of Salmonella in colored foodstuffs

Salmonella can be found in foods such as meat, eggs and milk, posing a serious threat to human health. To address the challenge of interference with detection signals from large molecular contaminants and colored substances in complex food matrices, we had dived into easy-to-use antifouling swabs, which were modified with sodium sulfonyl methacrylate (SBMA) by photopolymerization and incubated with Salmonella-specific aptamers. Surface modification of SBMA showed the antifouling property of the swab, and the aptamer collected Salmonella in the sample. Gold-palladium (Au-Pd) nanoparticles with photothermal properties were combined with the aptamer by freezing technique to identify Salmonella on the swab and output the signal. In addition, we used a simple "Snake-Eye" device, which consists of laser transmitter, infrared thermometer and smartphone to quantitatively identify Salmonella in colored foodstuffs. The linear detection range was 102-107 CFU mL-1, and the detection limit was 13.20 CFU mL-1. The findings suggest that our swabs had strong antifouling effect, exhibit high sensitivity in complex food matrices especially colored foodstuffs, and was easy to use on site.