(646e) Biophysical Characterization of Immobilized, Self-Assembled Phospholipid Bilayer Based Structures in Sol-Gel Derived Silica

The entrapment of Nanolipoprotein Particles (NLPs) and liposomes in transparent, nanoporous silica derived from the precursor Tetramethylorthosilicate (TMOS) was investigated. NLPs are discoidal patches of lipid bilayer that are belted by amphiphilic scaffold proteins and have an average thickness of 5 nm, with a diameter that ranges from 10-15 nm. Liposomes, which are spherical self-assemblies of lipid bilayer, have previously been examined inside of silica gels and have been shown to be somewhat unstable. This is attributed by their size (~150 nm) and altered structure and lipid dynamics upon entrapment within the nanometer scale pores (5-50 nm) of the silica gel. We have demonstrated that NLPs are much more compatible with the nanometer scale size of the porous environment by analysis of lipid phase behavior via fluorescence anisotropy and analysis of scaffold protein conformation via circular dichroism spectroscopy.

NLPs are capable of solubilizing a wide variety of Integral Membrane Proteins (IMPs). NLP immobilization allows for the synthesis of bio-inorganic hybrid nanomaterials that exploit the functionality of IMPs. These types of materials were either previously non feasible or very limited. We have examined temperature-dependant visible light absorption spectra of the IMP bacteriorhodopsin (BR) inside of NLPs as a means of investigating protein functionality. We intend to immobilize and examine BR-NLPs inside of silica gels via various biophysical characterization techniques as a model system for IMPs. The success of this work could lead to the development of novel platforms in several areas, including high-throughput drug screening, chromatography, and biosensors.