AbstractThe authors describe a semi-quantitative colorimetric method for visual detection of organophosphorus pesticides (OPs). It is based on the aspect ratio dependent absorbance of gold nanorods (AuNRs) which is due to the localized surface plasmon resonance. The aspect ratio can be tailored by the Au(III) complex formed with cetyltrimethylammonium bromide (CTAB) which is affected by acetylcholinesterase (AChE) based hydrolysis. OPs act as inhibitors of this reaction. In the absence of OPs, the product (thiocholine) of enzymatic hydrolysis consumes almost all the Au(III) species. In this case, the amount of residual Au(III)-CTAB complexes is small, and etching of the AuNRs does not occur. In the presence of OPs, however, the activity of AChE is inhibited. Hence, only small quantities of (or no) thiocholine is produced, and Au(III) is not consumed. Au(III) is capable of etching AuNRs and to change their aspect ratio. This leads to a color change from brownish to gray, cyan, green, blue, purple, red, and colorless that can be easily observed with bare eyes. The AuNRs were incorporated into cellulose paper to obtain a paper stripe for visual detection of OPs. Under optimal conditions, both methods (AuNRs in aqueous solutions and on paper) allowed various OPs to be determined. Applied to parathion, the method had a detection limit as low as 1.2 ppb and a linear range from 0.01 to 1.84 ppm. It was applied to the analysis of cabbage washing solutions and sea water samples, and acceptable accuracy and good resolution were found. In our preconception, the method represents a valuable tool for on-site detection of OPs in agriculture products and food. Graphical abstractSchematic of a semi-quantitative method for the visual detection of organophosphate pesticides based on etching of gold nanorods. A color change from brownish to gray, green, blue, purple, red, and colorless can be observed and correlated to the concentration of pesticides.

中文翻译：

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Au(III)-CTAB配合物对金纳米棒的控制刻蚀及其在有机磷农药半定量目测中的应用

摘要作者描述了一种用于目视检测有机磷农药 (OPs) 的半定量比色法。它基于金纳米棒 (AuNRs) 的纵横比相关吸光度，这是由于局部表面等离子体共振。长宽比可以通过与十六烷基三甲基溴化铵 (CTAB) 形成的 Au(III) 络合物进行调整，该络合物受基于乙酰胆碱酯酶 (AChE) 的水解影响。OP 充当该反应的抑制剂。在没有 OP 的情况下，酶促水解的产物（硫代胆碱）消耗了几乎所有的 Au（III）物质。在这种情况下，残留的 Au(III)-CTAB 配合物的量很小，并且不会发生 AuNRs 的蚀刻。然而，在 OP 存在的情况下，AChE 的活性受到抑制。因此，只产生少量（或不产生）硫代胆碱，并且不消耗Au(III)。Au(III) 能够蚀刻 AuNR 并改变它们的纵横比。这导致颜色从褐色变为灰色、青色、绿色、蓝色、紫色、红色和无色，肉眼很容易观察到。AuNRs 被掺入纤维素纸中以获得用于视觉检测 OPs 的纸条。在最佳条件下，两种方法（水溶液中和纸上的 AuNR）都可以确定各种 OP。应用于对硫磷时，该方法的检测限低至 1.2 ppb，线性范围为 0.01 至 1.84 ppm。将其应用于卷心菜洗涤液和海水样品的分析，发现了可接受的准确度和良好的分辨率。在我们的先入之见中，该方法代表了一种用于现场检测农产品和食品中 OPs 的宝贵工具。基于金纳米棒蚀刻的有机磷农药视觉检测半定量方法示意图。可以观察到从褐色到灰色、绿色、蓝色、紫色、红色和无色的颜色变化，并与农药浓度相关联。