Methods for Detecting Nucleic Acid Hybridization Using Liquid Crystals

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CBET-1160202SchwartzThe overall objectives of this project involve the development of methods where liquid crystals(LC) are used to detect nucleic acid hybridization. Also, to obtain an improved understanding ofthe fundamental molecular-level mechanisms by which the interfacial interactions of nucleicacids affect LC orientation. The ultimate long-term goal of this research is to enable LC-baseddetection in medical diagnostic applications, e.g. multiplexed methods (i.e. DNA microarrays)based on the orientational response of LCs to DNA hybridization, that use the transmission ofpolarized light to detect the LC response.Intellectual MeritTwo distinct approaches will be developed, and so the specific aims and research strategies ofthis project fall into two groups. The first approach involves a dynamic change of the LC polar tiltangle at the LC/aqueous interface in the presence of a monolayer of cationic surfactant, and thespecific aims associated with this approach include the development of a multiplexed platform,quantitative studies of sensitivity and target generality, the development of fluorescencemicroscopy methods that can be used to study the LC/aqueous interface, and the application ofthese methods to understand the molecular mechanisms of LC response to DNA hybridization.Finally, this method will be directly validated by experiments that will discriminate betweenclosely-related bacterial pathogens.The second approach involves a characteristic chiral rotation of the azimuthal orientation ofplanar-anchored LC when the LC is in contact with extended dsDNA. The associated specificaims include quantitative studies of the macroscopic optical response, extension of the methodto the detection of single hybridized molecules, development of methods that enable multiplexeddetection using covalently immobilized probes, and mechanistic studies aimed at understandingthe distinctive LC response to ssDNA and dsDNA. Similar validation experiments (i.e.discrimination between related bacteria) will be pursued for this method as for the first method.Broader ImpactThe methods developed here have the long-term potential to be used in new medical diagnostictechnologies that are appropriate for point-of-use applications including those in low resourceenvironments. Furthermore, the fundamental understandings obtained about LC-biomoleculeinteractions will be broadly useful for researchers pursuing LC-based biosensing approaches.More broadly, the optical characterization methods developed will be of use for studies of theLC-liquid interface and for other liquid-liquid interfaces.The researchers involved in this project will gain expertise in multidisciplinary areas projected tobe at the forefront of science and technology in the coming decades, including liquid crystaldevices, biodetection, single-molecule microscopy, and self-assembled molecular systems.Also, through their participation in a variety of educational and outreach programs (e.g. REU,RET, GAANN, CU-Discovery Learning Center, Materials Science from CU K-12 outreach,Colorado High School Honors Institute), the researchers will continue to share this project withstudents, teachers, and other community members. As summarized in the proposal the PI andprevious students and post-docs involved in this project have demonstrated a sincere andcontinuing commitment to the creative use of their research in the pursuit of education andoutreach; the integration of basic discovery and cutting-edge microscopy methods in this projectwill provide an ideal platform from which to communicate the excitement of research to thegeneral public.