Discovery of surface‐enhanced Raman scattering (SERS) followed by evolution of optical systems and nanoengineering approaches has paved a path to detection of essential organic molecules on solid SERS‐active substrates from solutions at concentrations attributed to single‐molecule ones, i. e. below 10⁻¹⁵ M. However, in practical terms confident SERS‐imaging of single molecules is still quite a challenge. In present work, we fabricated and comprehensively characterized tightly‐packed 3D silver dendrites with prevalent chevron morphology that demonstrated ultrahigh sensitivity as SERS‐active substrates resulted in 10⁻¹⁸ M detection limit. Using these substrates we achieved SERS‐imaging of single 5‐thio‐2‐nitrobenzoic acid (TNB) molecule released from the attomolar‐concentrated solution of of 5,5′‐dithio‐bis‐[2‐nitrobenzoic acid] (DTNB), which is vital compound for chemical and biomedical analysis. In contrast to generally accepted belief about adsorption of only uniform monomolecular TNB layer on surface of silver nanostructures, we showed formation of a coating constituted by TNB layer and DTNB nanoclusters on the dendrites’ surface at 10⁻⁶–10⁻¹² M DTNB concentrations confirmed by presence/absence of disulfide bonds signature in the SERS‐spectra and by scanning electron microscopy. DTNB concentrations below 10⁻¹⁴ M resulted in adsorption of TNB molecules in separated spots on the surface of silver nanostructures.

中文翻译：

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用于表面增强拉曼光谱的单分子成像的3D银树枝状晶体

表面增强拉曼散射（SERS）的发现以及随后光学系统和纳米工程方法的发展为从固态的SERS活性基质上检测归因于单分子浓度的溶液中必不可少的有机分子铺平了道路。e。低于10 ^-15M  。但是，实际上，对单分子进行SERS成像的信心仍然是一个挑战。在当前的工作中，我们制造并全面表征了具有普遍人字形形态的紧密包装的3D银树突，这表明超高灵敏度，因为SERS活性底物可产生10 ^-18 M检测极限。使用这些底物，我们实现了从5,5'-二硫代-双[2-硝基苯甲酸]（DTNB）的浓摩尔浓度溶液中释放的单个5-硫代-2-硝基苯甲酸（TNB）分子的SERS成像，对化学和生物医学分析至关重要。与通常公认的关于在银纳米结构表面仅吸附均匀的单分子TNB层的观点相反，我们证明了在树突表面上形成的由TNB层和DTNB纳米团簇构成的涂层已确认DTNB浓度为10 ^-6 –10 ^-12 M通过在SERS光谱中是否存在二硫键签名以及通过扫描电子显微镜观察。DTNB浓度低于10 ^-14 M导致TNB分子吸附在银纳米结构表面的分离点中。