Paper chip-based colorimetric assay for detection of Salmonella typhimurium by combining aptamer-modified Fe 3 O 4 @Ag n
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ORIGINAL PAPER
Paper chip-based colorimetric assay for detection of Salmonella typhimurium by combining aptamer-modified Fe3O4@Ag nanoprobes and urease activity inhibition Shengnan Wei 1 & Juan Li 1 & Jingya He 2 & Wei Zhao 3 & Feng Wang 2 & Xiuling Song 1,4 & Kun Xu 1,4 & Juan Wang 1 Chao Zhao 1
&
Received: 26 March 2020 / Accepted: 28 August 2020 # Springer-Verlag GmbH Austria, part of Springer Nature 2020
Abstract A rapid and sensitive colorimetric assay is described for Salmonella typhimurium (S. typhimurium) detection using urea/phenol red impregnated test paper. Aptamer-modified Fe3O4@Ag multifunctional hybrid nanoprobes (apt-Fe3O4@Ag NPs) were used to specifically captured S. typhimurium; the nanoprobes were quickly etched by H2O2 to form Ag+. The generated Ag+ can inhibit the urease-catalyzed hydrolysis reaction of urea to produce NH4+. Consequently, the as-prepared test paper displayed a yellow color. In the presence of S. typhimurium, the target bacteria can cause aggregation of apt-Fe3O4@Ag NPs, and the deposited Ag on the nanoprobe’s surface is shielded against H2O2-induced oxidative decomposition leading to reduced Ag+ production. The catalytic activity of urease cannot be inhibited completely by inadequate amount of Ag+. An obvious color change from yellow to pink can be monitored directly using our test paper as a result of increased NH4+. The entire assay procedure could be completed within 1 h. A limit of detection of 48 cfu/mL is achieved with a linear range of 1 × 102 to 1 × 106 cfu/mL. The recoveries of S. typhimurium spiked in pure milk samples were 92.48–94.05%. Keywords Food safety . Foodborne pathogen . Visual detection . Immunomagnetic separation . Urea/phenol red impregnated paper . Ag+-mediated urease activity inhibition
Introduction Foodborne diseases have been considered among the most important public health problems worldwide [1], and the Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00604-020-04537-8) contains supplementary material, which is available to authorized users. * Juan Li [email protected] * Juan Wang [email protected] * Chao Zhao [email protected] 1
School of Public Health, Jilin University, Changchun 130021, China
2
School of Stomatology, Jilin University, Changchun 130021, China
3
Jilin Provincial Center for Disease Control and Prevention, Changchun 130062, China
4
Public Health Detection Engineering Research Center of Jilin Province, Changchun 130021, China
number of foodborne disease incidences rises significantly in recent years [2]. Salmonella is widely known as one of the most prevalent pathogens causing foodborne illness outbreaks [3]. Salmonella contaminates food products, like eggs, fruits, vegetables, meat, poultry, and milk, typically through animal fecal contamination [4]. According to the World Health Organization, diarrheal diseases are the most common illnesses resulting from unsafe food, 550 million people falling ill each year, including 220 million children under the age of 5 years. Sa
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