Listeria monocytogenes (L. monocytogenes) is an important foodborne pathogen responsible for foodborne listeriosis, a significant issue for high risk groups such as pregnant women. Currently available detection techniques for this bacterium, primarily nucleic acid-based methods, can achieve low detection limits; however, the assays are generally complex and lengthy. This pathogen can also be indirectly detected via the sensing of Listeriolysin O (LLO), a pore-forming toxin secreted by L. monocytogenes. We present simple and rapid solution- and paper-based assays for the detection of pore-forming toxin LLO. Liposomes are used as the natural recognition element in this assay because LLO acts primarily on lipid membranes. Pore-forming LLO triggers the release of cysteine from liposomes, which subsequently induces a rapid aggregation of gold nanoparticles present in the assay. The colorimetric response elicited by this aggregation enables LLO detection as low as 7.6 μg mL^–1 for the solution-based assay, and limits of detection of 12.9 and 19.5 μg mL^–1 LLO in PBS and spiked human serum, respectively, were obtained in 5 min for the paper-based assay. The assay does not require separation, enzyme-associated amplification, or washing steps, which are superior features in relation to point-of-care applications. The simplicity and rapidness of the nanoscale assay provides an opportunity for further development of portable sensors, specifically in resource-limited regions.

中文翻译：

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基于纳米脂质体-金纳米颗粒平台的李斯特菌溶血素O毒素快速检测

单核细胞增生李斯特氏菌（L. monocytogenes）是导致食源性李斯特菌病的重要食源性病原体，对孕妇等高风险人群而言，这是一个重要问题。该细菌目前可用的检测技术，主要是基于核酸的方法，可以达到较低的检测限。然而，这些测定通常是复杂且冗长的。也可以通过单核细胞增生李斯特菌分泌的孔形成毒素李斯特菌溶血素O（LLO）的检测间接检测到这种病原体。我们介绍了用于检测成孔毒素LLO的简单，快速的基于溶液和基于纸张的测定方法。由于LLO主要作用于脂质膜，因此脂质体在此测定法中用作天然识别元件。形成毛孔的LLO触发脂质体释放半胱氨酸，随后诱导测定中存在的金纳米颗粒的快速聚集。这种聚集引发的比色响应使基于溶液的测定的LLO检测低至7.6μgmL ^–1，检测限为12.9和19.5μgmL ^–1在5分钟内分别获得了PBS和加标的人血清中的LLO，用于基于纸张的测定。该测定不需要分离，酶相关扩增或洗涤步骤，这是与现场护理应用相关的优越功能。纳米级测定的简单性和快速性为进一步开发便携式传感器提供了机会，特别是在资源有限的地区。