Processing conditions for the formation of spider silk microspheres.

Spider silk is a material consisting of very large (>200 kDa) proteins and has a high potential for biomedical applications as a result of its biocompatibility and biodegradability. We report on the influence of physicochemical factors on structure formation of the engineered spider silk protein eADF4(C16), which mimics the known sequence of the dragline protein ADF4 from the spider Araneus diadematus. Under certain experimental conditions, eADF4(C16) forms stable microspheres that have been analyzed with respect to sphere size, size distribution, and surface inertness upon different preparation methods (dialysis, pipette and micromixing). As a result of their material strength, biocompatibility, and the possibility of functionalization, spider silk microspheres have a high potential for the development of targeted drug-delivery systems.