AbstractThe work describes a gold nanoparticle-based colorimetric enzyme-linked immunosorbent assay (ELISA) for ractopamine. The ELISA is based on an indirect competitive approach. In the presence of ractopamine, gold(III) ions are oxidized by H2O2 to form red AuNPs. On the other hand, the AuNP in solution are purple-blue due to aggregation if the sample does not contain ractopamine. The absorption, best measured at 560 nm, increases linearly in the 2 to 512 ng·mL−1 ractopamine concentration range, and the detection limit is as low as 0.35 ng·mL−1 in urine. Ractopamine can also be detected visually, even in the presence of other β-agonists and antibiotics. The results obtained by this method are consistent with those obtained by LC-MS/MS as demonstrated by analysis of sheep urine. The ELISA method described here is inexpensive, easy-to-use, and suitable for rapid screening of ractopamine in animal samples. Graphical abstractSchematic presentation of a colorimetric indirect competitive immunoassay for ractopamine. It is based on the use of catalase labeled IgG and the measurement of the absorption of red gold nanoparticles (AuNPs) that are generated by the reaction of gold ions with H2O2. In the absence of ractopamine, the solution becomes blue.

中文翻译：

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用于莱克多巴胺定量的基于金纳米颗粒的比色 ELISA

摘要这项工作描述了一种基于金纳米颗粒的莱克多巴胺比色酶联免疫吸附试验 (ELISA)。ELISA 基于间接竞争方法。在莱克多巴胺存在下，金 (III) 离子被 H2O2 氧化形成红色 AuNP。另一方面，如果样品不含莱克多巴胺，溶液中的 AuNP 由于聚集而呈紫蓝色。吸收最好在 560 nm 处测量，在 2 至 512 ng·mL-1 莱克多巴胺浓度范围内线性增加，尿液中的检测限低至 0.35 ng·mL-1。即使存在其他 β-激动剂和抗生素，莱克多巴胺也可以肉眼检测。通过这种方法获得的结果与通过羊尿分析证明的 LC-MS/MS 获得的结果一致。此处描述的 ELISA 方法价格低廉、易于使用，适用于动物样品中莱克多巴胺的快速筛查。图形摘要 莱克多巴胺比色间接竞争免疫测定的示意图。它基于使用过氧化氢酶标记的 IgG 以及对由金离子与 H2O2 反应生成的红金纳米粒子 (AuNP) 的吸收的测量。在没有莱克多巴胺的情况下，溶液变成蓝色。