Research Center for Analytical Sciences, Chemistry Department, College of Sciences, Northeastern University, Shenyang 110819, China.
Research Center for Analytical Sciences, Chemistry Department, College of Sciences, Northeastern University, Shenyang 110819, China.
Talanta. 2018 May 15;182:247-252. doi: 10.1016/j.talanta.2018.01.090. Epub 2018 Feb 2.
Electrokinetic stacking (ES) is effective for improving sensitivity of paper-based analytical device (PAD) for charged analytes. In this paper, we successfully demonstrated ES of electrically neutral analytes on PAD, and the performance was characterized by smartphone-based colorimetry and fluorescence. Firstly, SDS from cathode reservoir stacked as a micelle band on an open paper fluidic channel by ES, and the target analyte was swept by the micelle. Meanwhile, the probes at the other side were carried by electroosmotic flow (EOF). Eventually, neutral components preloaded on the channel were concentrated as the narrow stacking band. Taking the rhodamine B as a probe, the effects of EOF, background electrolyte concentration and anionic surfactant concentration were investigated. Fluorescence detection of rhodamine B and colorimetric analysis of Sudan III demonstrated the sensitivity enhanced and its potential for the semi-quantitative test. Under the optimized conditions, fluorescence detection limit of 50 nM of rhodamine B was achieved with a linear range of 1.0-10 μM (R = 0.99). The colorimetric detection limit for Sudan III was 5.2 μM and the linear range was 5-40 μM (R= 0.99). Compared with direct analysis without stacking, the signal levels of rhodamine B and Sudan III were increased by 30-fold and 6-fold, respectively. This study showed that with ES, sensitive and rapid PAD detection of electrically neutral analytes could be achieved.
电动堆积（ES）可有效提高基于纸的分析器件（PAD）对带电分析物的灵敏度。本文成功地展示了 ES 对 PAD 上中性分析物的电动堆积效果，并通过智能手机比色法和荧光法对其性能进行了表征。首先，SDS 从阴极储液器通过 ES 堆积在开放的纸流体通道上形成胶束带，目标分析物被胶束扫过。同时，另一侧的探针被电渗流（EOF）携带。最终，通道上预先加载的中性成分被浓缩为狭窄的堆积带。以罗丹明 B 为探针，考察了 EOF、背景电解质浓度和阴离子表面活性剂浓度的影响。罗丹明 B 的荧光检测和苏丹 III 的比色分析表明了其灵敏度的提高及其用于半定量测试的潜力。在优化条件下，罗丹明 B 的荧光检测限达到 50 nM，线性范围为 1.0-10 μM（R = 0.99）。苏丹 III 的比色检测限为 5.2 μM，线性范围为 5-40 μM（R = 0.99）。与直接分析不堆积相比，罗丹明 B 和苏丹 III 的信号水平分别提高了 30 倍和 6 倍。本研究表明，通过 ES 可以实现对中性分析物的灵敏、快速的 PAD 检测。
