State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047, P. R. China; Jiangxi-OAI Joint Research Institute, Nanchang University, Nanchang 330047, P. R. China.
State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047, P. R. China; Jiangxi-OAI Joint Research Institute, Nanchang University, Nanchang 330047, P. R. China.
J Dairy Sci. 2019 Mar;102(3):1997-2007. doi: 10.3168/jds.2018-15580. Epub 2019 Jan 3.
We applied urease-induced silver metallization on the surface of gold nanorods (AuNR) to improve colorimetric ELISA for the rapid and sensitive detection of Salmonella enterica Choleraesuis. To this end, we introduced a biotin-streptavidin system as a bridge to determine the correlation between urease and S. enterica Choleraesuis concentrations. The captured urease can catalyze the hydrolysis of urea into carbon dioxide and ammonia, and the generated ammonia can then induce the deposition of silver shell on the surface of AuNR in the presence of silver nitrate and glucose. With the decreased aspect ratio (length divided by width) of AuNR, a multicolor change of AuNR solution and a significant blue shift in the longitudinal localized surface plasmon resonance absorption peak (Δλ) of AuNR were obtained at the target concentrations of 1.21 × 10 to 1.21 × 10 cfu/mL. Consequently, the detection limits of our proposed colorimetric ELISA were as low as 1.21 × 10 cfu/mL for qualitative detection with naked eyes, and 1.21 × 10 cfu/mL for quantitative detection, in which changes in Δλ of AuNR were recorded with a microplate reader. These values were at least 2 to 3 orders of magnitude lower than those obtained with conventional horseradish peroxidase-based ELISA. The analytical performance of our developed colorimetric ELISA in terms of selectivity, accuracy, reliability, and practicability were investigated by analyzing S. enterica Choleraesuis-spiked pasteurized whole milk samples.
我们在金纳米棒（AuNR）表面应用了脲酶诱导的银金属化，以改善比色 ELISA 用于快速灵敏地检测猪霍乱沙门氏菌。为此，我们引入了生物素-链霉亲和素系统作为桥梁，以确定脲酶和 S. enterica Choleraesuis 浓度之间的相关性。捕获的脲酶可以催化尿素水解成二氧化碳和氨，在存在硝酸银和葡萄糖的情况下，生成的氨可以诱导银壳在 AuNR 表面沉积。随着 AuNR 的纵横比（长度除以宽度）降低，在 1.21×10 至 1.21×10 cfu/mL 的目标浓度下，AuNR 溶液的颜色发生多色变化，AuNR 的纵向局域表面等离子体共振吸收峰（Δλ）发生明显蓝移。因此，我们提出的比色 ELISA 的检测限低至 1.21×10 cfu/mL，可用于肉眼定性检测，定量检测的检测限为 1.21×10 cfu/mL，其中使用微孔板读取器记录 AuNR 的 Δλ 变化。这些值至少比传统辣根过氧化物酶基于 ELISA 的检测低 2 到 3 个数量级。通过分析添加了猪霍乱沙门氏菌的巴氏全脂牛奶样品，研究了我们开发的比色 ELISA 在选择性、准确性、可靠性和实用性方面的分析性能。
