Shen Yafang, Li Bingyan, Hao Guijie, Duan Miaolin, Zhao Yan, Liu Zunying, Li Xingmin, Jia Fei
Key Laboratory of Healthy Freshwater Aquaculture, Ministry of Agriculture and Rural Affairs; Huzhou Key Laboratory of Aquatic Product Quality Improvement and Processing Technology, Zhejiang Institute of Freshwater Fisheries, Huzhou 313001, China.
College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China.
Food Chem. 2025 Apr 1;470:142693. doi: 10.1016/j.foodchem.2024.142693. Epub 2024 Dec 28.
This research developed a magnetic relaxation switching (MRS) biosensor based on hydrogel sol-gel transition and the CRISPR/Cas12a system (MRS-CRISPR) to detect Salmonella. Herein, the alkaline phosphatase (ALP) labeled with streptavidin was captured by the biotin-modified DNA on magnetic nanoparticles (MNPs) surface, which generated an acidic environment via enzymatic reaction to release Ca and induced the transformation of alginate sol to hydrogels. In contrast, Salmonella activated the trans-cleavage activity of the CRISPR/Cas12a system, interrupting the capture of ALP and the subsequent sol-gel transition. Then, transverse relaxation time (T), which was regulated by the hydrogelation process was measured for Salmonella detection. The MRS-CRISPR biosensor enables sensitive detection of Salmonella with a detection limit of 158 CFU/mL. It directly alters the state of water molecules, overcoming the disadvantages of traditional MRS sensors that rely on MNPs to produce T signals indirectly. This method offers innovative insights for the application of the MRS technology in food safety analysis.
本研究基于水凝胶溶胶-凝胶转变和CRISPR/Cas12a系统开发了一种用于检测沙门氏菌的磁弛豫开关（MRS）生物传感器（MRS-CRISPR）。在此，用链霉亲和素标记的碱性磷酸酶（ALP）被磁性纳米颗粒（MNPs）表面生物素修饰的DNA捕获，通过酶促反应产生酸性环境以释放Ca并诱导藻酸盐溶胶转变为水凝胶。相比之下，沙门氏菌激活CRISPR/Cas12a系统的反式切割活性，中断ALP的捕获和随后的溶胶-凝胶转变。然后，测量由水凝胶化过程调节的横向弛豫时间（T）以检测沙门氏菌。MRS-CRISPR生物传感器能够灵敏地检测沙门氏菌，检测限为158 CFU/mL。它直接改变水分子的状态，克服了传统MRS传感器依赖MNPs间接产生T信号的缺点。该方法为MRS技术在食品安全分析中的应用提供了创新见解。
