Controlled influence of quantum dots on purple membranes at interfaces.

The development of bio-sensitized nanofilms engineered from biomembrane components and inorganic nanoparticles is a promising field of colloid and interface science and technologies. Recent nano-bioengineering approaches employing quantum dots (QDs) permit the enhancement of the purple membrane (PM) "light-harvesting capacity" compared to native PMs. The influence of QDs on the PM properties, especially the bacteriorhodopsin (bR) photocycle, has been found that has both fundamental (mechanisms of photoreception) and applied implications (including the fabrication of hybrid bionanomaterials). Samples of PM-QD complexes capable of energy transfer and characterized by increased rates of M-intermediate formation and decay have been obtained. The modified bR photocycle kinetic parameters may be explained by changes in the PM interface upon QD adsorption. The increase and decrease in absorption at 410 nm (or photopotential) for PM-QD complexes are, on average, several times more rapid than for PM suspensions or PM dry films. These results provide a strong impetus for the development of nanomaterials with advanced properties.