Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, USA.
Lab Chip. 2018 May 15;18(10):1485-1493. doi: 10.1039/c8lc00168e.
An improved paper-based analytical device (PAD) using color screening to enhance device performance is described. Current detection methods for PADs relying on the distance-based signalling motif can be slow due to the assay time being limited by capillary flow rates that wick fluid through the detection zone. For traditional distance-based detection motifs, analysis can take up to 45 min for a channel length of 5 cm. By using a color screening method, quantification with a distance-based PAD can be achieved in minutes through a "dip-and-read" approach. A colorimetric indicator line deposited onto a paper substrate using inkjet-printing undergoes a concentration-dependent colorimetric response for a given analyte. This color intensity-based response has been converted to a distance-based signal by overlaying a color filter with a continuous color intensity gradient matching the color of the developed indicator line. As a proof-of-concept, Ni quantification in welding fume was performed as a model assay. The results of multiple independent user testing gave mean absolute percentage error and average relative standard deviations of 10.5% and 11.2% respectively, which were an improvement over analysis based on simple visual color comparison with a read guide (12.2%, 14.9%). In addition to the analytical performance comparison, an interference study and a shelf life investigation were performed to further demonstrate practical utility. The developed system demonstrates an alternative detection approach for distance-based PADs enabling fast (∼10 min), quantitative, and straightforward assays.
描述了一种使用颜色筛选来增强器件性能的改进型纸质分析器件 (PAD)。目前基于距离信号模式的 PAD 检测方法可能比较缓慢，因为检测时间受到毛细流动速率的限制，而这些速率会将液体吸进检测区域。对于传统的基于距离的检测模式，对于 5 厘米长的通道，分析可能需要长达 45 分钟的时间。通过使用颜色筛选方法，可以通过“蘸取和读取”方法在几分钟内实现基于距离的 PAD 的定量分析。使用喷墨打印将比色指示剂线沉积在纸基底上，对于给定的分析物会发生浓度依赖性的比色响应。这种基于颜色强度的响应已经通过覆盖具有与开发的指示剂线颜色相匹配的连续颜色强度梯度的滤色片，转换为基于距离的信号。作为概念验证，对焊接烟尘中的镍进行了定量分析，作为模型分析。多次独立用户测试的结果分别给出了 10.5%的平均绝对百分比误差和 11.2%的平均相对标准偏差，这比基于简单视觉颜色比较和阅读指南的分析（12.2%，14.9%）有所改善。除了分析性能比较之外，还进行了干扰研究和保质期研究，以进一步证明其实用性。所开发的系统展示了一种替代基于距离的 PAD 的检测方法，能够实现快速（约 10 分钟）、定量和简单的检测。
