We report hereby a sensitive and rapid label free colorimetric assay of two amino acids, viz.L-arginine (L-Arg) and L-cysteine (L-Cys), through silver sol synthesized via a wet chemical method using 2-boronobenzoic acid (2- BBA) as a reducing and capping reagent in an aqueous alkaline medium. 2-BBA was synthesized in situ by the reaction of 2-formylphenylboronic acid (2-FBPA) and silver nitrate through Tollen's method. The as-synthesized silver sol exhibited the formation of nanocubes having their most predominant size in the range of 20–25 nm upon their TEM scanning and exhibiting an SPR band at 401 nm in their UV-vis spectrum. The same were further characterized by SEM, EDX, AFM, FTIR, XPS, DLS, and zeta potential measurements also. Separate interaction of the two amino acids, viz., L-Arg and L-Cys, with diluted AgNCs (1 : 2; AgNCs and Millipore water V/V) exhibited two different colors, pinkish grey and blue, respectively accompanied by distinctive shifts in their surface plasmon resonance (SPR) band also. The detection limits were found to be 6 μM and 3 μM for L-Arg and L-Cys respectively. Furthermore, L-Arg and L-Cys were quantified in a pharmaceutical sample each with their respective recovery rates of 99.2% and 90.1%. These AgNCs exhibited rich SERS characteristics also by intensifying the Raman peaks of L-Arg and L-Cys. Only a few one-pot aqueous chemical syntheses of silver nanocubes have been reported previously. Most probably, this is the third report of its kind. To the best of our knowledge, no silver nanoprobe exhibiting simultaneous detection of L-Arg and L-Cys has been reported to date.

中文翻译：

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2-硼基苯甲酸功能化银纳米立方体，用于在真实样品应用中无标记检测 L-精氨酸和 L-半胱氨酸


我们在此报告通过使用 2-硼苯甲酸通过湿化学方法合成的银溶胶对两种氨基酸（即 L-精氨酸 (L-Arg) 和 L-半胱氨酸 (L-Cys)）进行灵敏且快速的无标记比色测定(2- BBA) 在碱性水介质中作为还原剂和封端剂。 2-BBA是由2-甲酰基苯基硼酸(2-FBPA)与硝酸银通过Tollen法反应原位合成的。合成的银溶胶在 TEM 扫描时表现出纳米立方体的形成，其最大尺寸在 20-25 nm 范围内，并在 UV-vis 光谱中表现出 401 nm 处的 SPR 谱带。还通过 SEM、EDX、AFM、FTIR、XPS、DLS 和 zeta 电位测量对其进行了进一步表征。两种氨基酸（即 L-Arg 和 L-Cys）与稀释的 AgNC（1:2；AgNC 和 Millipore 水 V/V）的单独相互作用表现出两种不同的颜色：粉红色灰色和蓝色，分别伴随着独特的变化也在其表面等离子共振（SPR）带中。 L-Arg 和 L-Cys 的检测限分别为 6 μM 和 3 μM。此外，对药物样品中的 L-Arg 和 L-Cys 进行了定量，回收率分别为 99.2% 和 90.1%。这些 AgNC 通过增强 L-Arg 和 L-Cys 的拉曼峰也表现出丰富的 SERS 特征。以前只报道过一些银纳米立方体的一锅水化学合成。这很可能是第三份此类报告。据我们所知，迄今为止还没有银纳米探针能够同时检测 L-Arg 和 L-Cys 的报道。