AuthorGRIFFIN, KAITLYN RENEE
AdvisorSaavedra, Scott S.
MetadataShow full item record
PublisherThe University of Arizona.
AbstractCell membranes are composed primarily of amphipathic lipids either in a single circular layer or as a bilayer in which all of the hydrophilic and hydrophobic groups face the same direction respectively. Diffusion across a lipid membrane can occur spontaneously or be facilitated by integral membrane proteins. The extent of this diffusion relies on the structure of both the membrane and the diffusing species. Artificial lipid membranes that mimic some of the properties of natural cell membranes can be prepared on synthetic supports for use in membrane-based biosensors. We are working to develop artificial membrane-based sensors for target molecules that should lead to more effective drug discovery and more efficient treatment and diagnosis of diseases. In order to better understand the properties of these artificial membranes and their potential effects on the functionality of a successful biosensor, fluorescence recovery after photobleaching (FRAP) was used to determine the inherent diffusion in the membranes themselves. The formation of planar supported lipid bilayers in specially designed Teflon wells on bare glass supports yields lateral diffusion coefficients (D) for 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and 1,2-diphytanoyl-sn-glycero-3-phosphocholine (DPhPC) which indicate a typical fluidity. With the goal of combining these membranes with an epoxy-based negative photoresist, SU-8 3050, which is used as the base material in the proposed biosensors, studies of artificial membrane properties on SU-8 3050 were undertaken. Fluorescence intensities for the membranes formed on the SU-8 indicate monolayer formation consistent with the chemical structure of the hydrophobic SU-8 support surface. Moreover, the decreased diffusion coefficients for DOPC and DPhPC on SU-8 3050 indicate a reduced fluidity for the monolayer and a more viscous membrane environment. Modification of the SU-8 3050 surface to enhance both membrane stability and fluidity are being investigated while not inhibiting the function of the sensor. Modification of the SU-8 3050 surface by plasma oxidation did not support membrane formation. Gas phase modification of the SU-8 3050 surface through silanization chemistry did not occur despite successful surface activation. Lipid deposition of DOPC by Langmuir Blodgettry yielded 100% transfer on bare glass and 70% transfer on oxidized SU-8, but only 16% transfer on untreated SU-8. Application of lipid deposition by Langmuir Blodgettry aims to examine the efficiency of lipid formation on the polymer surface in comparison to the vesicle fusion method employed for the study.