Sensitive detection of carcinoembryonic antigen (CEA) is highly important in clinical diagnosis because CEA is an effective tumor marker associated with gastric, lung, rectal, and breast cancers. Thus, the development of an accurate, simple, and efficient method for the detection of CEA remains a long-term clinical goal. In this study, a liquid crystal-based aptasensor was constructed for the labelfree and sensitive detection of CEA. The aptamer, as a molecule identification element, was immobilized onto (3-aminopropyl)triethoxysilane (APTES)- and dimethyloctadecyl[3-(trimethoxysilyl) propyl]ammonium chloride (DMOAP)-modified surface slides through glutaraldehyde (GA); this aptamer can specifically bind to CEA. In the presence of CEA molecules, the loop-stem structure of the aptamers coated onto the surface of the slides opens, and the aptamer then combines with CEA, leading to the formation of aptamer-CEA complexes, which causes the orientation of the liquid crystal molecules (LCs) to transition from a homeotropic to a random alignment. This transition can easily be observed using polarized light microscopy, based on the change of dark optical images into bright ones. The aptasensor system is quite sensitive, as the detection limit is as low as 0.12 pg/ml, with a linear equation of Grayscale=20.318logC_CEA+26.329 (R²=0.9925), for a CEA concentration range of 0.05 pg/ml to 50 ng/ml. Bovine serum albumin (BSA) and human serum albumin (HSA) were also tested in this experiment, indicating that this sensor can selectively distinguish between CEA and other interfering compounds with similar protein structures. Moreover, these results were further confirmed by atomic force microscopy (AFM) and ellipsometry.

中文翻译：

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使用发夹形适体的简单的基于液晶的传感器，用于裸眼检测癌胚抗原。

癌胚抗原（CEA）的敏感检测在临床诊断中非常重要，因为CEA是与胃癌，肺癌，直肠癌和乳腺癌相关的有效肿瘤标志物。因此，开发用于检测CEA的准确，简单和有效的方法仍然是长期的临床目标。在这项研究中，构建了基于液晶的适体传感器，用于CEA的无标记和灵敏检测。作为分子识别元件的适体通过戊二醛（GA）固定在（3-氨基丙基）三乙氧基硅烷（APTES）-和二甲基十八烷基[3-（三甲氧基甲硅烷基）丙基]氯化铵（DMOAP）修饰的表面玻片上；该适体可以特异性结合CEA。在存在CEA分子的情况下，涂在玻片表面上的适体的环茎结构打开，然后，适体与CEA结合，导致形成适体-CEA络合物，从而导致液晶分子（LC）的取向从垂直取向转变为无规排列。使用偏光显微镜可以轻松地观察到这种转变，这是基于将暗光学图像转换为亮光学图像的结果。aptasensor系统非常灵敏，检测限低至0.12 pg / ml，线性方程为Grayscale = 20.318logC_CEA +26.329（R ² = 0.9925 ），CEA浓度范围为0.05 pg / ml至50 ng / ml。在该实验中还测试了牛血清白蛋白（BSA）和人血清白蛋白（HSA），表明该传感器可以选择性区分CEA和其他具有相似蛋白质结构的干扰化合物。此外，这些结果通过原子力显微镜（AFM）和椭偏仪进一步证实。