J Agric Food Chem. 2019 Aug 14;67(32):9104-9111. doi: 10.1021/acs.jafc.9b03400. Epub 2019 Aug 1.
Gold nanoflowers (GNFs) exhibit stronger light scattering ability than gold nanospheres (GNSs) with the same diameter, thereby contributing to enhancing the sensitivity of the scattering-based sensing method. However, the application of GNFs in biosensors based on dynamic light scattering (DLS) has not been yet reported. Herein, we describe for the first time an improved no-wash immunosensor based on dynamic light scattering for the detection of O157:H7 ( O157:H7) in milk using GNFs for sensitive signal transduction. To achieve this goal, a thiolated amphiphilic carboxyl ligand was introduced to modify the GNF surface and improve solution stability and antibody functionalization. Several key factors that affect the detection sensitivity of our developed GNF_DLS immunosensor were systematically investigated. Under the optimal conditions, our proposed GNF_DLS immunosensor provided an excellent linear detection for O157:H7 within the range from 6 × 10 to 6 × 10 colony-forming units (CFU)/mL, with a limit of detection of 2.7 CFU/mL. Combined with our previously reported two-step large-volume immunomagnetic separation (IMS) method, the designed GNF_DLS immunosensor can sensitively, selectively, and accurately detect the presence of O157:H7 in pasteurized milk. The potential of our GNF_DLS method for monitoring the presence of a single bacterial cell in 1 mL of sample solution was also demonstrated. Overall, the developed GNF_DLS immunosensor can be used for the rapid and high-sensitivity determination of pathogenic bacteria and can be extended for the ultrasensitive no-wash detection of other trace analytes.
金纳米花（GNFs）比具有相同直径的金纳米球（GNSs）具有更强的光散射能力，从而有助于提高基于散射的传感方法的灵敏度。然而，GNFs 在基于动态光散射（DLS）的生物传感器中的应用尚未报道。在此，我们首次描述了一种改进的无洗涤基于动态光散射的免疫传感器，用于检测牛奶中的 O157:H7（O157:H7），该传感器使用 GNFs 进行灵敏的信号转导。为了实现这一目标，引入了一种巯基双亲羧酸配体来修饰 GNF 表面，以提高溶液稳定性和抗体功能化。系统研究了影响我们开发的 GNF_DLS 免疫传感器检测灵敏度的几个关键因素。在最佳条件下，我们提出的 GNF_DLS 免疫传感器为 O157:H7 提供了从 6×10 到 6×10 个菌落形成单位（CFU）/mL 的优异线性检测范围，检测限为 2.7 CFU/mL。结合我们之前报道的两步大容量免疫磁分离（IMS）方法，设计的 GNF_DLS 免疫传感器可以灵敏、选择性和准确地检测巴氏杀菌牛奶中 O157:H7 的存在。还证明了我们的 GNF_DLS 方法用于监测 1 毫升样品溶液中单个细菌细胞存在的潜力。总体而言，开发的 GNF_DLS 免疫传感器可用于快速和高灵敏度地测定病原菌，并可扩展用于其他痕量分析物的超灵敏无洗涤检测。
