Department of Food and Biological Sciences, Yanbian University, No. 977, GongYuan Street, Yanji, 133002, Jilin, China.
State Key Laboratory for Diagnosis and Treatment of Severe Zoonotic Infectious Diseases, Key Laboratory for Zoonosis Research of the Ministry of Education, Institute of Zoonosis, College of Veterinary Medicine, Jilin University, Changchun, 130062, China.
Anal Bioanal Chem. 2024 Nov;416(26):5779-5789. doi: 10.1007/s00216-024-05497-1. Epub 2024 Aug 30.
Listeria monocytogenes (L. monocytogenes) is a prevalent food-borne pathogen that can cause listeriosis, which manifests as meningitis and other symptoms, potentially leading to fatal outcomes in severe cases. In this study, we developed an aptasensor utilizing carboxylated magnetic beads and Cas12a to detect L. monocytogenes. In the absence of L. monocytogenes, the aptamer maintains its spatial configuration, keeping the double-stranded DNA attached and preventing the release of a startup template and activation of Cas12a's trans-cleavage capability. Conversely, in the presence of L. monocytogenes, the aptamer undergoes a conformational change, releasing the double-stranded DNA to serve as a startup template, thereby activating the trans-cleavage capability of Cas12a. Consequently, as the concentration of L. monocytogenes increases, the observable brightness in a blue light gel cutter intensifies, leading to a rise in fluorescence intensity difference compared to the control. This Cas12a aptasensor demonstrates excellent sensitivity towards L. monocytogenes, with a lowest detection limit (LOD) of 57.15 CFU/mL and a linear range of 4×10 to 4×10 CFU/mL (R=0.9858). Notably, the proposed Cas12a aptasensor exhibited outstanding selectivity and recovery in beef samples, and could be employed for precise monitoring. This Cas12a aptasensor not only provides a novel fluorescent and visual rapid detection method for L. monocytogenes but also offers simplicity, speed, and stability compared to previous detection methods. Furthermore, it is suitable for on-site detection of beef samples.
李斯特菌（L. monocytogenes）是一种常见的食源性病原体，可引起李斯特菌病，表现为脑膜炎和其他症状，在严重情况下可能导致致命后果。在本研究中，我们开发了一种基于羧基化磁珠和 Cas12a 的适体传感器来检测李斯特菌。在没有李斯特菌的情况下，适体保持其空间构象，使双链 DNA 保持附着状态，并防止起始模板的释放和 Cas12a 的转录切割能力的激活。相反，在存在李斯特菌的情况下，适体发生构象变化，释放双链 DNA 作为起始模板，从而激活 Cas12a 的转录切割能力。因此，随着李斯特菌浓度的增加，在蓝光凝胶切割机中观察到的亮度增强，导致与对照相比荧光强度差异增加。这种 Cas12a 适体传感器对李斯特菌具有出色的灵敏度，最低检测限（LOD）为 57.15 CFU/mL，线性范围为 4×10 至 4×10 CFU/mL（R=0.9858）。值得注意的是，所提出的 Cas12a 适体传感器在牛肉样品中表现出出色的选择性和回收率，可用于精确监测。这种 Cas12a 适体传感器不仅为李斯特菌提供了一种新颖的荧光和可视化快速检测方法，而且与以前的检测方法相比具有简单、快速和稳定的特点。此外，它适用于牛肉样品的现场检测。
