AbstractThis article demonstrates a new kind of a highly sensitive lateral flow immunoassay (LFIA). It is based on the enlargement of the size of gold nanoparticles (GNPs) directly on the test strip after a conventional LFIA. Particle size enlargement is accomplished through the catalytic reduction of HAuCl4 in the presence of H2O2 and through the accumulation of additional gold on the surface of the GNPs. To attain maximal enhancement of the coloration of the zone in the test strip and to achieve a minimal background, the concentration of precursors, the pH value, and the incubation time were optimized. GNPs on the test strip are enlarged from 20 to 350 nm after a 1-min treatment at room temperature. The economically important and widespread phytopathogen potato virus X (PVX) was used as the target analyte. The use of the GNP enlargement method results in a 240-fold reduction in the limit of the detection of PVX, which can be as low as 17 pg·mL−1. The total duration of the assay, including virus extraction from the potato leaves, lateral flow, and the enhancement process, is only 12 min. The diagnostic efficiency of the technique was confirmed by its application to the analysis of potato leave samples. No false positives or false negatives were found. The technique does not depend on specific features of the target analyte, and it is conceivably applicable to numerous GNP-based LFIAs for important analytes. Graphical abstractAn enlargement solution (containing HAuCl4 and H2O2) was dripped on the strip after common lateral flow immunoassay. Gold nanoparticles on the strip (20 nm) catalyze gold reduction and the formation of larger particles (up to 350 nm), resulting in a 240-fold lower detection limit within 1 min.

中文翻译：

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金纳米粒子的测定后生长作为高灵敏度横向流动免疫测定的工具。在马铃薯X病毒检测中的应用

摘要本文展示了一种新型的高灵敏度侧向流动免疫分析（LFIA）。它基于在常规 LFIA 之后直接在测试条上放大金纳米粒子 (GNP) 的尺寸。通过在 H2O2 存在下催化还原 HAuCl4 以及通过在 GNP 表面上积累额外的金来实现粒径增大。为了最大限度地增强测试条中区域的着色并实现最小的背景，优化了前体的浓度、pH 值和孵育时间。在室温下处理 1 分钟后，测试条上的 GNP 从 20 nm 扩大到 350 nm。经济上重要且广泛传播的植物病原体马铃薯病毒 X (PVX) 被用作目标分析物。使用 GNP 放大法，PVX 的检测限降低了 240 倍，可低至 17 pg·mL-1。分析的总持续时间，包括从马铃薯叶中提取病毒、侧流和增强过程，仅为 12 分钟。该技术在马铃薯叶片样品分析中的应用证实了该技术的诊断效率。没有发现假阳性或假阴性。该技术不依赖于目标分析物的特定特征，可以想象它适用于许多基于 GNP 的重要分析物的 LFIA。图形摘要在普通侧流免疫分析后，将放大溶液（含有 HAuCl4 和 H2O2）滴在试纸上。