A liquid-crystal-based DNA biosensor for pathogen detection

• Published in: Scientific reports 2016-03, Vol.6 (1), p.22676-22676, Article 22676
• Main Authors: Khan, Mashooq, Khan, Abdur Rahim, Shin, Jae-Ho, Park, Soo-Young
• Format: Article
• Language: English
• Subjects: 14/63; 639/638/11/511; 639/638/11/872; Adsorption; Biosensing Techniques - methods; Biosensors; Deoxyribonucleic acid; DNA; DNA, Single-Stranded - analysis; Electron microscopy; Fungi; Humanities and Social Sciences; Liquid Crystals; multidisciplinary; Pathogens; Pectobacterium carotovorum - genetics; Quaternary Ammonium Compounds; Rhizoctonia - genetics; Science; Sensitivity and Specificity; Transmission electron microscopy
• ISSN: 2045-2322; 2045-2322
• 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 (ssDNA probe ) was adsorbed at the LC/aqueous interface (TEM DTAB/DNA ), was applied for the highly specific detection of target DNA molecules. The DTAB-coated E7 (used LC mixture) in the TEM grid (TEM DTAB ) exhibited a homeotropic orientation, and changed to a planar orientation upon adsorption of the ssDNA probe . The TEM DTAB/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 ssDNA probe enabled the detection of ≥0.05 nM complementary ssDNA. This TEM DTAB/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.