A colorimetric assay has been developed for Zn²⁺ and homocysteine (Hcy) detection using functionalized silver nanoparticles (AgNPs). AgNPs have been synthesized using silver nitrate, where sodium citrate is used as a stabilizing agent and NaBH₄ as a reducing agent. Then, the nanoparticles (citrate@AgNPs) were functionalized with 1H-imidazole-4,5-dicarboxylic acid (IDCA). UV–visible and FTIR spectra suggested that IDCA was functionalized on the surface of citrate@AgNPs through the N atom of the imidazole ring. The IDCA-functionalized silver nanoparticles (IDCA@AgNPs) simultaneously detected Zn²⁺ and Hcy from aqueous solution and showed different responses to the two analytes (Zn²⁺ and Hcy) based on the aggregation-induced color change of IDCA@AgNPs. They showed the color change from yellow to red, which was easily discriminated by visual inspection as well as UV–visible spectroscopy. The surface plasmon resonance absorbance values of Zn²⁺ and Hcy are 485 and 512 nm, respectively, when Zn²⁺ and Hcy react with IDCA@AgNPs. IDCA@AgNPs showed linearity with Zn²⁺ and Hcy concentrations, with the detection limit of 2.38 μM and 0.54 nM, respectively (S/N = 3). The IDCA@AgNPs showed excellent selectivity toward Zn²⁺ and Hcy compared to the different metal ions and amino acids, respectively. Optimal detection was achieved toward Zn²⁺ and Hcy in the pH range 3–10. In addition, IDCA@AgNPs were used to detect Zn²⁺ and Hcy from lake water, showing low interference.

中文翻译：

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1H-咪唑-4,5-二羧酸功能化银纳米粒子的合成和表征：Zn2+ 和同型半胱氨酸的双比色传感器

已开发出一种使用功能化银纳米粒子 (AgNPs) 检测Zn ^{2+和同型半胱氨酸 (Hcy) 的比色测定法。}AgNPs 已使用硝酸银合成，其中柠檬酸钠用作稳定剂，NaBH ₄用作还原剂。然后，纳米粒子（柠檬酸盐@AgNPs）用 1 H-咪唑-4,5-二羧酸（IDCA）功能化。紫外可见和 FTIR 光谱表明 IDCA 通过咪唑环的 N 原子在柠檬酸盐@AgNPs 的表面上被功能化。IDCA 功能化银纳米粒子 (IDCA@AgNPs) 同时检测水溶液中的Zn ^{2+和 Hcy 并对两种分析物 (Zn 2+}和 Hcy）基于 IDCA@AgNPs 的聚集引起的颜色变化。它们显示了从黄色到红色的颜色变化，这很容易通过目视检查和紫外-可见光谱来区分。^{当Zn 2+}和Hcy 与IDCA@AgNPs 反应时，Zn ²⁺和Hcy的表面等离子共振吸光度值分别为485 和512 nm 。IDCA@AgNPs 与 Zn ²⁺和 Hcy 浓度呈线性关系，检测限分别为 2.38 μM 和 0.54 nM (S/N = 3)。与不同的金属离子和氨基酸相比，IDCA@AgNPs 对 Zn ^{2+和 Hcy 分别表现出优异的选择性。}实现了对 Zn ^{2+的最佳检测}和 Hcy 在 pH 值范围 3-10。此外，IDCA@AgNPs 用于检测湖水中的 Zn ²⁺和 Hcy，显示出低干扰。