On-site colorimetric detection of Salmonella typhimurium
Shengnan Wei, Zhenyue Su, Xiangong Bu, Xuening Shi, Bo Pang, Liang Zhang, Juan Li, Chao Zhao
Abstract
Abstract Rapid qualitative and quantitative detection of Salmonella typhimurium ( S. typhimurium ) takes an important role in ensuring food safety. Herein, a colorimetric assay aptasensor for S. typhimurium utilizing intrinsic peroxidase-like activity of gold nanoparticles embedded spherical covalent organic framework and the affinity and specificity of S. typhimurium -aptamer has been explored. This aptasensor can capture the S. typhimurium via the selective binding effect of aptamer, and the catalytically active sites were shielded. As a result, the colorimetric signals of the 3,3′,5,5′-tetramethylbenzidine-H 2 O 2 system were turned off. Under optimum conditions, the aptasensor gave a linear response over the range of 10 to 10 7 CFU/mL for S. typhimurium . The detection limit of 7 CFU/mL was obtained within 45 min and was effectively applied to detect S. typhimurium in milk and lake water samples with recoveries in the range from 96.4 to 101.0%. More importantly, combined with a self-developed smartphone-based image analysis system, the proposed aptasensor can be used for point-of-care testing applications.