Polyelectrolyte multilayer film containing polydiacetylene vesicles for naked eye detection of aromatic compounds

For preliminary analytical screening in the field test of toxic chemicals, it is desirable to have a sensing system which is inexpensive and convenient to use. Polydiacetylene is known to possess unique colorimetric sensing properties in which its color changing upon exposure to chemical stimulants can be easily observed by naked eyes. In this thesis study, a sensing system consisting of an active polydiacetylene agent, poly(10,12-pentacosadiynoic acid) (PCDA) vesicle, is constructed in a form of polyelectrolyte multilayer (PEM) film using a layer-by-layer deposition technique. The PEM film using PCDA as a polyanion and chitosan as a polycation has the most satisfactory film quality. The color of poly(PCDA)/chitosan PEM film can be induced from blue to red by aqueous solution of 10 mM α-cyclodextrin (α-CD). The α-CD induced color transition of poly(PCDA) PEM film can be inhibited by equimolar some aromatic compounds such as p-nitrophenol, benzoic acid and 2,4-dichlorophenoxyacetic acid (2,4-D) probably by the competitive inclusion complexation. There are some selectivity in the color transition inhibition of various aromatic compounds probably depended on their binding strength with α-CD. The multichannel chip constructed from the poly(PCDA)/chitosan PEM film and the polydimethylsiloxane channel show fast colorimetric response to α-CD that can provide a simultaneous test of multiple samples on the chip.

针对有毒化学品现场测试中的初步分析筛选需求，开发一款成本低廉、使用便捷的传感系统是十分必要的。聚二乙炔（Polydiacetylene）具有独特的比色传感特性：当其暴露于化学刺激物时，颜色会发生变化，且该变化可通过肉眼直接观测。本论文研究构建了一种以聚(10,12-二十五碳二炔酸)（PCDA）囊泡作为活性聚二乙炔传感单元的传感系统，并通过逐层沉积技术将其制备为聚电解质多层膜（PEM）。以PCDA作为聚阴离子、壳聚糖作为聚阳离子所制备的PEM膜，具有最优的成膜质量。10 mM的α-环糊精（α-CD）水溶液可将聚(PCDA)/壳聚糖PEM膜的颜色从蓝色诱导转变为红色。当存在等摩尔量的对硝基苯酚、苯甲酸与2,4-二氯苯氧乙酸（2,4-D）等芳香族化合物时，α-CD诱导的聚(PCDA) PEM膜颜色转变会受到抑制，其机制可能为竞争性包合络合作用。不同芳香族化合物对该颜色转变的抑制效果存在选择性，这可能与其与α-CD的结合强度相关。由聚(PCDA)/壳聚糖PEM膜与聚二甲基硅氧烷（PDMS）微流道构建的多通道芯片，对α-CD具有快速比色响应，可实现芯片上多样本的同步检测。