Khan Mashooq, Khan Abdur Rahim, Shin Jae-Ho, Park Soo-Young
Department of Polymer Science &Engineering, Polymeric Nanomaterials Laboratory, School of Applied Chemical Engineering, Kyungpook National University, #1370 Sangyuk-dong, Buk-gu, Daegu 41566, Korea.
School of Applied Biosciences, Kyungpook National University, #1370 Sangyuk-dong, Buk-gu, Daegu 41566, Korea.
Sci Rep. 2016 Mar 4;6:22676. doi: 10.1038/srep22676.
A liquid-crystal (LC)-filled transmission electron microscopy (TEM) grid cell coated with the cationic surfactant dodecyltrimethylammonium bromide (DTAB), to which a single-stranded deoxyribonucleic acid probe (ssDNAprobe) was adsorbed at the LC/aqueous interface (TEMDTAB/DNA), was applied for the highly specific detection of target DNA molecules. The DTAB-coated E7 (used LC mixture) in the TEM grid (TEMDTAB) exhibited a homeotropic orientation, and changed to a planar orientation upon adsorption of the ssDNAprobe. The TEMDTAB/DNA was then exposed to complementary (target) ssDNA, which resulted in a planar-to-homeotropic configurational change of E7 that could be observed through a polarized optical microscope under crossed polarizers. The optimum adsorption density (2 μM) of ssDNAprobe enabled the detection of ≥0.05 nM complementary ssDNA. This TEMDTAB/DNA biosensor could differentiate complementary ssDNA from mismatched ssDNA as well as double-stranded DNA. It also successfully detected the genomic DNAs of the bacterium Erwinia carotovora and the fungi Rhazictonia solani. Owe to the high specificity, sensitivity, and label-free detection, this biosensor may broaden the applications of LC-based biosensors to pathogen detection.
一种填充有液晶（LC）的透射电子显微镜（TEM）网格单元，其表面涂覆有阳离子表面活性剂十二烷基三甲基溴化铵（DTAB），单链脱氧核糖核酸探针（ssDNAprobe）吸附在LC/水界面处（TEMDTAB/DNA），用于高特异性检测靶DNA分子。TEM网格（TEMDTAB）中涂覆有DTAB的E7（所用的LC混合物）呈现垂直取向，在吸附ssDNAprobe后转变为平面取向。然后将TEMDTAB/DNA暴露于互补（靶）ssDNA，这导致E7从平面构型转变为垂直构型，可通过交叉偏振器下的偏振光学显微镜观察到。ssDNAprobe的最佳吸附密度（2μM）能够检测≥0.05 nM的互补ssDNA。这种TEMDTAB/DNA生物传感器能够区分互补ssDNA与错配ssDNA以及双链DNA。它还成功检测到了胡萝卜软腐欧文氏菌和立枯丝核菌的基因组DNA。由于具有高特异性、高灵敏度和无标记检测的特点，这种生物传感器可能会拓宽基于LC的生物传感器在病原体检测中的应用。
