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Over the past few years, considerable attention has been devoted to the development of low-cost photovoltaic device technologies. In this context, organic solar cells have the potential advantage of being cheaper and less energy consuming in fabrication, yet they still lack efficiency. Here we studied how wild type Bacteriorhodopsin (bR) a membrane protein found in the archae Halobacterium salinarum may be used as efficient light harvester in organic solar cells. bR is a light-driven pump that uses the energy of a photon to translocate protons vectorially across the membrane. In order to make an efficient bR-based organic solar cell it is important that the membrane matrix in which the bR is embedded is optimal for protein function and storage of the photon-generated proton electrochemical gradient. Therefore we reconstituted bR in lipid/polymer based biomimetic membranes and investigated how the host matrix affected protein function and proton gradient storage. We demonstrate how the barrier properties of lipid membranes can be modulated by organic solvents and how mixed lipid-polymer systems can be used to control orientation and efficiency of the reconstituted bR. Take together our results points to how the bR host matrix may be optimized in order to create robust efficient organic solar cells.

Recent studies suggest that alternation in serum calcium influences the level of gallbladder bile ionized calcium (Ca2+). Theoretically, this could increase the risk of calcium precipitation in the gallbladder.We therefore measured serum and gallbladder bile minerals in patients with gallstones (n = 27) and without (n = 10, controls). The serum samples were taken just prior to induction of anaesthesia and gallbladder bile was aspirated before any manipulation of the gallbladder.The active molality of Ca2+ in gallbladder bile was not statistically significant different between cases and controls (0.44 +/- 0.16 vs. 0.40 +/- 0.10 mmol/kg), whereas pH was significantly lower (6.94 +/- 0.31 vs. 7.36 +/- 0.28, p0.0001) and cholesterol higher (4.37 +/- 2.70 vs. 1.79 +/- 1.33 mmol/l; p0.01) in gallbladder bile obtained from cases. Serum Ca2+ at actual pH, magnesium and phosphate were significantly higher among cases than in controls. Gallbladder bile active molality of Ca2+ was significantly correlated with bile total calcium in both groups (r = 0.72; p0.001 and r = 0.91; p0.001, respectively). In controls only, we observed a positive relationship between serum Ca2+ at actual pH and the active molality of Ca2+ in bile (r = 0.61; p0.05).Our study demonstrates that Ca2+ in gallbladder bile does not differ between cases and controls. The lack of correlation between serum and gallbladder bile constituents in cases compared to controls suggests that changes in calcium equilibration between bile and serum in patients with gallstone disease might be of importance for the formation of gallstones.