Saltatory Rolling Circle Amplification-Based Ratiometric Electrochemical Biosensor for Rapid Detection of Salmonella enterica serovar Typhimurium in Food
2022
Yu, Haotian | Yuan, Ning | Zhang, Yunzhe | Guo, Wei | Lu, Xin | Yang, Qian | Zhang, Wei
Salmonella enterica serovar Typhimurium (S. enterica ser. Typhimurium) is one of the main causes of human bacterial gastroenteritis. Therefore, there is an urgent need to develop a highly specific and accurate method for S. enterica ser. Typhimurium detection in food. In the study, we constructed a ratiometric electrochemical biosensor based on saltatory rolling circle amplification (SRCA) and dual-signal electrochemical readout. The mercapto-modified β-cyclodextrin (SH-β-CD) was immobilized on the electrode surface by combining with gold nanoparticles (AuNPs) to form Au–S bond. After SRCA reaction with specially designed primers, a large number of amplified products with ferrocene (Fc) were obtained within 1 h. These products could bind to β-CD through host-guest interactions. In addition, the current had a significant change due to the insertion of methylene blue into the SRCA products. By optimizing the reaction conditions, the electrochemical biosensor displayed a wide detection range from 30 fg/μL to 30 ng/μL with a low detection limit of 15.8 fg/μL. Furthermore, by testing food samples, the ratiometric electrochemical biosensor showed consistency with the real-time fluorescence quantitative PCR (RT-qPCR). In conclusion, this electrochemical biosensor may be a promising alternative detection method for S. enterica ser. Typhimurium.
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