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标题：A Cationic Surfactant-Decorated Liquid Crystal-Based Aptasensor for Label-Free Detection of Malathion Pesticides in Environmental Samples
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作者：Duy Khiem Nguyen ; Chang-Hyun Jang
期刊名称：Biosensors
电子版ISSN：2079-6374
出版年度：2021
卷号：11
期号：3
页码：92
DOI：10.3390/bios11030092
出版社：MDPI Publishing
摘要：We report a liquid crystal (LC)-based aptasensor for the detection of malathion using a cationic surfactant-decorated LC interface. In this method, LCs displayed dark optical images when in contact with aqueous cetyltrimethylammonium bromide (CTAB) solution due to the formation of a self-assembled CTAB monolayer at the aqueous/LC interface, which induced the homeotropic orientation of LCs. With the addition of malathion aptamer, the homeotropic orientation of LCs changed to a planar one due to the interactions between CTAB and the aptamer, resulting in a bright optical image. In the presence of malathion, the formation of aptamer-malathion complexes caused a conformational change of the aptamers, thereby weakening the interactions between CTAB and the aptamers. Therefore, CTAB is free to induce a homeotropic ordering of the LCs, which corresponds to a dark optical image. The developed sensor exhibited high specificity for malathion determination and a low detection limit of 0.465 nM was achieved. Moreover, the proposed biosensor was successfully applied to detect malathion in tap water, river water, and apple samples. The proposed LC-based aptasensor is a simple, rapid, and convenient platform for label-free monitoring of malathion in environmental samples.
关键词：malathion; liquid crystals; liquid crystal biosensor; pesticides; DNA aptamer; polarized light microscopy malathion ; liquid crystals ; liquid crystal biosensor ; pesticides ; DNA aptamer ; polarized light microscopy