Surface-enhanced Raman scattering (SERS) probes offer considerable opportunities in label-based biosensing and analysis. However, achieving specific and reproducible performance, where low detection limits are needed in complex media, remains a challenge. Herein, we present a general strategy employing gold nanorod SERS probes and rationally designed surface chemistry involving protein resistant layers and antibodies to allow for the selective detection of species in complex media. By utilizing the ability of gold nanorods for selective surface modification, Raman reporters (4-mercaptobenzoic acid) were attached to the tips. Importantly, the sides of the nanorods were modified using a mixed layer of two different length stabilizing ligands (carboxyl-terminated oligo ethylene glycols) to ensure colloidal stability, while antibodies were attached to the stabilizing ligands. The nanoparticle interfacial design improves the colloidal stability, unlocks the capability of the probes for targeting biomolecules in complex matrices, and gives the probes the high SERS efficiency. The utility of this probe is demonstrated herein via the detection of Salmonella bacteria at the single bacterium level in complex food matrices using an anti-Salmonella IgG antibody-conjugated probe. The modular nature of the surface chemistry enables the SERS probes to be employed with a molecularly diverse range of biorecognition species (e.g., antibodies and peptides) for many different analytes, thus opening up new opportunities for efficient biosensing applications.

中文翻译：

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功能化金纳米棒探针：复杂介质中生物检测的 SERS 免疫分析的精密设计

表面增强拉曼散射 (SERS) 探针为基于标记的生物传感和分析提供了大量机会。然而，在复杂介质中需要低检测限的情况下，实现特定和可重复的性能仍然是一个挑战。在此，我们提出了一种通用策略，采用金纳米棒 SERS 探针和合理设计的表面化学，包括蛋白质抗性层和抗体，以允许选择性检测复杂介质中的物种。通过利用金纳米棒进行选择性表面改性的能力，拉曼报告基因（4-巯基苯甲酸）连接到尖端。重要的是，纳米棒的侧面使用两种不同长度的稳定配体（羧基封端的低聚乙二醇）的混合层进行改性，以确保胶体稳定性，而抗体附着在稳定配体上。纳米粒子界面设计提高了胶体稳定性，释放了探针靶向复杂基质中生物分子的能力，并使探针具有高 SERS 效率。此处展示了该探针的效用通过使用抗沙门氏菌IgG 抗体偶联探针在复杂食品基质中的单一细菌水平上检测沙门氏菌。表面化学的模块化特性使 SERS 探针能够与分子不同范围的生物识别物种（例如抗体和肽）一起用于许多不同的分析物，从而为有效的生物传感应用开辟了新的机会。