Pesticide contamination of drinking water is of high concern due to their hazardous effects on ecosystems. Several detection methods are available which are associated with many drawbacks, e.g. slow response time and laborious procedural techniques. This limits their practicability. Therefore, there is a dire need to develop quick, simpler but equally sensitive and practical methods for pesticide detection. Herein, we report a highly sensitive assay using fluorescent AuNCs for the detection of a pesticide i.e., 2-methyl-4-chlorophenoxyacetic acid (MCPA). For this purpose, three different fluorescent Au nanoclusters stabilized by histidine (His-AuNCs), lysozyme (Lys-AuNCs) and RNase (RNase-AuNCs) were systematically studied as optical probes for the detection of MCPA using a turn-on assay. The fluorescence of these AuNCs was initially quenched with Cu²⁺ ions followed by the quantitative recovery of their fluorescent signals in the presence of MCPA. The sensitivity and selectivity of these clusters for MCPA were in a linear dynamic range, i.e., 110–180 nM, 100–170 nM and 90–160 nM in case of His-AuNCs, Lys-AuNCs and RNase-AuNCs, respectively. Also, the aforesaid clusters were having a different limit of detection (LOD) by each type, i.e., highest by His-AuNCs (21.87), intermediate by Lys-AuNCs (12.97) and lowest by RNase-AuNCs (9.26 nM). Hence, the RNase-AuNCs are found to be the most sensitive, whereas His-AuNCs are least sensitive for the detection of MCPA. These findings offer a rapid, sensitive and selective assay for MCPA detection and have potential implications for the on-site, real-time monitoring of noxious pollutants.

饮用水中农药的污染由于对生态系统的危害而备受关注。有几种检测方法可供使用，这些检测方法有许多缺点，例如响应时间慢和费力的程序技术。这限制了它们的实用性。因此，迫切需要开发一种快速，简单，但同样灵敏和实用的农药检测方法。在本文中，我们报告了使用荧光AuNCs进行农药（即2-甲基-4-氯苯氧基乙酸（MCPA））检测的高灵敏度检测方法。为此，系统地研究了由组氨酸（His-AuNCs），溶菌酶（Lys-AuNCs）和RNase（RNase-AuNCs）稳定化的三种不同的荧光金纳米簇，作为光学探针使用开启测定法检测MCPA。²⁺离子，然后在MCPA存在下定量恢复其荧光信号。这些簇对MCPA的敏感性和选择性处于线性动态范围内，即在His-AuNC，Lys-AuNC和RNase-AuNC的情况下分别为110-180 nM，100-170 nM和90-160 nM。同样，上述簇在每种类型上具有不同的检出限（LOD），即，His-AuNCs最高（21.87），Lys-AuNCs最高（12.97），RNase-AuNCs最低（9.26 nM）。因此，发现RNase-AuNC对MCPA的检测最敏感，而His-AuNC对MCPA的检测最不敏感。这些发现为MCPA检测提供了一种快速，灵敏和选择性的测定方法，对有毒污染物的现场实时监测具有潜在的影响。