INTEC (Universidad Nacional del Litoral-CONICET), Predio CCT-CONICET, RN 168, 3000, Santa Fe, Argentina.
CIMEC (Universidad Nacional del Litoral-CONICET), Predio CCT-CONICET, RN 168, 3000, Santa Fe, Argentina.
Talanta. 2023 Jan 15;252:123782. doi: 10.1016/j.talanta.2022.123782. Epub 2022 Aug 23.
Organophosphorus compounds such as chlorpyrifos (CPS) are causing serious environmental problems worldwide. Efficient monitoring of the CPS levels in water resources demands portable devices for on-field testing. Here we report the development of a CPS sensor coupled with smartphones for automated reading and data analysis. The sensing mechanism makes use of gold nanoparticles stabilized by a CPS-specific aptamer, where colloidal destabilization occurs in presence of competing CPS molecules. In particular, an innovative readout is proposed: quantitative analysis of the stain patterns left by evaporating drops of the test solutions. We have found that the CPS-induced destabilization suppresses the typical coffee-ring stain of the colloidal gold, and then exploited the phenomenon to quantitatively determine the CPS concentration in water samples. A strong correlation between CPS level in samples and the alteration of the stain patterns was established for a wide range of CPS concentrations (0.048 μM-482 μM). The limit of detection of the sensor was 0.2 μM. The assay was implemented on Whatman filter paper cards that were specially patterned by wax-printing. A smartphone-based Python program was written for fully automated image capture and processing. Notably, as we analyze the spatial configuration of the stains, the reading system is independent of external illumination. The system also enables data management and traceability, which are highly desirable attributes for environmental monitoring.
有机磷化合物，如毒死蜱（CPS），正在对全球环境造成严重问题。对水资源中 CPS 水平进行有效的监测需要便携式现场测试设备。在此，我们报告了一种与智能手机耦合的 CPS 传感器的开发，用于自动读取和数据分析。该传感机制利用由 CPS 特异性适体稳定的金纳米颗粒，在存在竞争 CPS 分子的情况下发生胶体失稳。特别是，提出了一种创新的读出方法：通过蒸发测试溶液的液滴来定量分析留下的染色图案。我们发现，CPS 诱导的胶体金失稳抑制了胶体金的典型咖啡环染色，然后利用该现象来定量确定水样中的 CPS 浓度。对于广泛的 CPS 浓度（0.048 μM-482 μM），在样品中的 CPS 水平与染色图案的改变之间建立了很强的相关性。传感器的检测限为 0.2 μM。该测定在经过特殊蜡印图案设计的沃特曼滤纸卡片上进行。编写了一个基于智能手机的 Python 程序，用于全自动图像采集和处理。值得注意的是，由于我们分析了染色的空间配置，因此读取系统不受外部照明的影响。该系统还能够进行数据管理和可追溯性，这是环境监测的高度期望的属性。
