A composite prepared from carboxymethyl chitosan and aptamer-modified gold nanoparticles for the colorimetric determinat
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ORIGINAL PAPER
A composite prepared from carboxymethyl chitosan and aptamer-modified gold nanoparticles for the colorimetric determination of Salmonella typhimurium Jiecan Yi 1 & Pian Wu 1 & Guiyin Li 2 & Wen Xiao 3 & Lei Li 4 & Yayuan He 1 & Yafei He 1 & Ping Ding 1 & Cuimei Chen 5 Received: 5 May 2019 / Accepted: 14 September 2019 # Springer-Verlag GmbH Austria, part of Springer Nature 2019
Abstract An aptamer-based assay is described for the determination of Salmonella typhimurium (S. typh). Carboxymethyl chitosan was loaded with amino-modified aptamer against S. typh, and then adsorbed on gold nanoparticles by electrostatic interaction to form a composite that acts as the molecular recognition element. In the presence of S. typh, it will be bound by the aptamer, and this changes the structure of the recognition element. On addition of salt solution, the gold nanoparticles agglomerate so that the color of the solution changes from red to blue. S. typh can be detected via measurement of the absorbance at 550 nm. Absorbance increases linearly with the logarithm of the S. typh concentration in the range from 100 to 109 cfu·mL−1. The limit of detection is 16 cfu·mL−1. The specificity and practicability of the assay were evaluated. The recoveries of S. typh from spiked milk samples are between 92.4 and 97.2%. The analytical results are basically consistent with those of a plate counting method. Keywords Food-borne pathogens . Nanotechnology . Aptamer sensor . Bacterial detection . Optical characteristics . Methodological evaluation
Introduction Salmonella typhimurium (S. typh) can infect people or animals through food, which has a serious impact on food safety [1].
Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00604-019-3827-5) contains supplementary material, which is available to authorized users. * Ping Ding [email protected] * Cuimei Chen [email protected] 1
Xiang Ya School of Public Health, Central South University, Changsha 410078, Hunan, China
2
School of Life and Environmental Sciences, Guilin University of Electronic Technology, Guilin 541014, Guangxi, China
3
Hunan Institute of Food Quality Supervision Inspection and Research, Changsha 410000, Hunan, China
4
Center for Global Health, School of Public Health, Nanjing Medical University, Nanjing 211166, Jiangsu, China
5
School of Public Health, Xiangnan University, Chenzhou 423000, Hunan, China
Between 2006 and 2010, 70% to 80% of reported outbreaks of bacterial food-borne diseases in China were caused by Salmonella. About 1000 people died from acute Salmonella infection in the United States annually [2, 3]. However, the traditional detection methods such as bacterial culture and ELISA are time consuming and susceptible to environmental factors such as pH, temperature and so on. They can no longer meet the current detection requirements for S. typh. Therefore, the research of a new method for rapid and reliable detection of S. typh has great significance for the prevention of various bacterial
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