Abstract Silver nanoparticles (AgNPs) have a large number of technological applications, such as photonic devices, molecular diagnostics, antimicrobial coating and biomedical devices. These nanomaterials can be synthesized using common fungi, which represents a green approach with the additional advantage of biocompatibility. Here we applied Tip-Enhanced Raman Spectroscopy (TERS) to obtain optical characterization with resolution beyond the diffraction limit of AgNPs produced by Rhodotorula glutinis and Rhodotorula mucilaginosa fungi. Those fungi are conventional found in ordinary soil of north part of Brazil, which biosynthesize core-shell AgNPs with protein-capping layer. With TERS we were able to investigate with lateral resolution of few nanometers the size and structure of the protein capping layer, how it interacts with the Ag core, and how sensitive the system (core + protein) is to visible light illumination. Despite the complex data generated which depends on the orientation of the protein, which is highly, it was possible to detect the stretching of the S - S sulfur bridge in amino acids. This stretch band is induced by a trans C α - S conformation acid on Rm-AgNPs, thus showing the potential of characterization of TERS in nanobiosystems.

中文翻译：

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黏液红酵母和红酵母真菌合成的核壳银蛋白纳米颗粒的尖端增强拉曼光谱研究

摘要 银纳米粒子（AgNPs）具有大量的技术应用，如光子器件、分子诊断、抗菌涂层和生物医学设备。这些纳米材料可以使用普通真菌合成，这代表了一种具有生物相容性的额外优势的绿色方法。在这里，我们应用尖端增强拉曼光谱 (TERS) 来获得光学表征，其分辨率超出了由 Rhodotorula glutinis 和 Rhodotorula mucilaginosa 真菌产生的 AgNPs 的衍射极限。这些真菌通常存在于巴西北部的普通土壤中，它们生物合成具有蛋白质覆盖层的核壳型 AgNPs。使用 TERS，我们能够以几纳米的横向分辨率研究蛋白质覆盖层的大小和结构，以及它如何与银核相互作用，以及系统（核心 + 蛋白质）对可见光照明的敏感程度。尽管生成的复杂数据取决于蛋白质的方向，但仍可以检测到氨基酸中 S-S 硫桥的拉伸。该拉伸带是由 Rm-AgNPs 上的反式 Cα-S 构象酸诱导的，因此显示了纳米生物系统中 TERS 表征的潜力。