基于核酸适体的新型液晶生物传感用于检测血小板源性生长因子BB

摘要

利用核酸适体与其靶分子具有高度特异性结合的原理,建立了基于液晶取向改变的以核酸适体为捕获探针用于检测血小板源性生长因子BB( Platelet-derived growth factor BB, PDGF-BB)分子的新型液晶生物传感方法。核酸适体通过戊二醛偶联固定在3-氨丙基三乙氧基硅烷/N,N-二甲基-N-十八烷基[3-(三甲氧基硅基)丙基]氯化铵[(3-Aminopropyl ) trimethoxysilane/N, N-dimethyl-N-octadecyl (3-aminopropyl ) trimethoxysilyl chloride, APTES/DMOAP]混合自组装的传感基底表面,当靶分子PDGF-BB存在时,可与核酸适体发生特异性作用结合于传感基底表面,根据生物分子的空间尺寸效应能诱导液晶分子取向发生变化,从而引起光学信号的亮度和色彩发生改变,实现对PDGF-BB的快速检测。本方法具有操作简单、选择型好、灵敏度高的特点,在PDGF-BB浓度为5 nmol/L时仍可观察到明显的光学信号变化。%A novel liquid crystal ( LC ) biosensor was developed for the detection of platelet-derived growth factor BB ( PDGF-BB) based on the orientation changes of liquid crystals. One glass slide of the LC cell was first modified with the APTES/DMOAP ( ( 3-aminopropyl ) trimethoxysilane/N, N-dimethyl-N-octadecyl ( 3-aminopropyl) trimethoxysilyl chloride) self-assembled monolayer ( SAM) to trigger the homeotropic alignment of LC molecules and thereby produced an black background optical image under the crossed polarized light, and then the specific aptamer of PDGF-BB was immobilized on SAM through glutaraldehyde crosslinking to construct a LC sensing substrate. In the presence of PDGF-BB, the stable triple helix structure of PDGF-BB aptamer was formed by the specific binding event and thus led to the target PDGF-BB captured to the sensing substrate, making a visible optical change observed under the crossed polarized light via the huge steric effect of the PDGF-BB on disrupting the LC alignment. But in the absence of PDGF-BB, the low packing density of the PDGF-BB aptamer had little effect on disrupting the ordered alignment to the LC and caused the black background optical image still observed under the crossed polarized light. There was an obvious optical change when the concentration of target PDGF-BB was 5 nmol/L. The proposed LC biosensing method permits the label-free detection of PDGF-BB with good selectivity and high sensitivity, making them sufficiently simple and particularly useful for low-cost screening bioassay performed away from central laboratories.