Development and Characterization of Titanium Dioxide Gel with Encapsulated Bacteriorhodopsin for Hydrogen Production.

We study bacteriorhodopsin (BR) in its native purple membrane encapsulated within amorphous titanium dioxide, or titania, gels and in the presence of titania sol particles to explore this system for hydrogen production. Förster resonance energy transfer between BR and titanium dioxide sol particles was used to conclude that there is nanometer-scale proximity of bacteriorhodopsin to the titanium dioxide. The detection of BR-titania sol aggregates by fluorescence anisotropy and particle sizing indicated the affinity amorphous titania has for BR without the use of additional cross-linkers.

Biomembrane-Compatible Sol-Gel-Derived Photocatalytic Titanium Dioxide.

Titanium dioxide gel monoliths were synthesized using an organic precursor and 0-30 vol % ethanol in water. The visible-light-activated proton pump, bacteriorhodopsin, in its native purple membrane form, was successfully encapsulated within the titanium dioxide gels. Absorption spectra showed that the folded functional state of the protein remained intact within gels made with 0 and 15 vol % ethanol and retained the ability to make reversible conformational changes associated with the photocycle within the gel made with 0 vol % ethanol.

Dynamics of Crowding-Induced Mixing in Phase Separated Lipid Bilayers.

We use fluorescence microscopy to examine the dynamics of the crowding-induced mixing transition of liquid ordered (L)-liquid disordered (L) phase separated lipid bilayers when the following particles of increasing size bind to either the L or L phase: Ubiquitin, green fluorescent protein (GFP), and nanolipoprotein particles (NLPs) of two diameters. These proteinaceous particles contained histidine-tags, which were phase targeted by binding to iminodiacetic acid (IDA) head groups, via a Cu chelating mechanism, of lipids that specifically partition into either the L phase or L phase. The degree of steric pressure was controlled by varying the size of the bound particle (10-240 kDa) and the amount of binding sites present (i.