The aim of this project is to design and engineer channel proteins that can act as controllable gates once embedded in the membrane of nanovesicles. The reversible control of the transport of molecules through the channel protein can be established by changes in pH, temperature or light.

OmpF channel protein has been chosen as model channel protein due to its thermal and chemical stability. The OmpF channel protein will be equipped with polymers that are pH or temperature sensitive. The reversibility of the switch introduced inside the channel proteins' pores will be characterized once the channel proteins are embedded in the wall of polymer nanovesicles. The polymeric nanovesicles are created by self-assembly of amphiphilic block copolymers in water. Amphiphilic block copolymers are made of a hydrophobic block and a hydrophilic block and they spontaneously form vesicles in water. The polymeric systems are a novel alternative to the liposome carriers, and are more stable, while preserving all the advantages of lipidic systems, such as lack of immunogenicity. The obtained vesicles reconstituting engineered channel proteins will be characterized using fluorescence and spectroscopic methods. The pH/temperature-sensitive OmpF hybrid system will be a first step in mimicking nature (e.g. ligand gated channels like acetylcholine receptors, light gated like channel rhodopsin) to produce functional proteins with potential applications in biotechnology or biomedicine.

We anticipate that channel proteins engineered for reversible transport induced by changes in external stimuli (pH, temperature, light) will be used for tunable release of the content of liposomes or polymeric vesicles. This general system will be of special interest for various biomedical, biotechnological and biosensing applications. A biomedical application would be polymeric vesicles containing drugs or drug producing enzymes inside and embedded channel proteins that allow switchable transport of the prodrug/drug across the polymer membrane. With this specific system a precise control of the rate and the moment of the release of the drugs could be achieved.