title: Application of the optical waveguide lightmode spectroscopy to monitor lipid bilayer phase transition.
abstract: An instrument for optical waveguide lightmode spectroscopy (OWLS) was designed and developed for measurements at different and controlled temperatures in a range of 15 degrees C around room temperature. The instrument allows to scan the waveguide modes at different wavelengths on the same optical chip using different lasers. This instrument was used to monitor DMPC lipid bilayer main phase transition around the critical temperature. The main problem in these experiments is that the OWLS measurements do not give enough information about an optically anisotropic system like a lipid bilayer. Experimental OWLS data at two different wavelengths can however approximately solve the problem. The temperature dependence of the thickness and the refractive indices (ordinary and extraordinary) for the lipid bilayer around the phase transition is presented. (A theoretical derivation of the extraordinary refractive index is given in.)
authors.affiliation: Department of Biological Physics, Eötvös University, Pázmány Péter sétány 1A, 1113 Budapest, Hungary.
authors.forename: R
authors.initials: R
authors.lastname: Horváth
authors.forename: G
authors.initials: G
authors.lastname: Fricsovszky
authors.forename: E
authors.initials: E
authors.lastname: Papp
mesh_terms: D003198:Computer Simulation; D004134:Dimyristoylphosphatidylcholine / Q000737:chemistry*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D008051:Lipid Bilayers / Q000737:chemistry*; D008560:Membrane Fluidity; D008958:Models, Molecular; D055095:Optics and Photonics / Q000295:instrumentation; D044367:Phase Transition; D012031:Refractometry / Q000295:instrumentation* / Q000379:methods; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013057:Spectrum Analysis / Q000295:instrumentation* / Q000379:methods; D013696:Temperature
chemical_list: D008051:Lipid Bilayers; D004134:Dimyristoylphosphatidylcholine