REDV-Functionalized Recombinant Spider Silk for Next-Generation Coronary Artery Stent Coatings: Hemocompatible, Drug-Eluting, and Endothelial Cell-Specific Materials.

Coronary artery stents are life-saving devices, and millions of these devices are implanted annually to treat coronary heart disease. The current gold standard in treatment is drug-eluting stents, which are coated with a biodegradable polymer layer that elutes antiproliferative drugs to prevent restenosis due to neointimal hyperplasia. Stenting is commonly paired with systemic antiplatelet therapy to prevent stent thrombosis. Despite their clinical success, current stents have significant limitations including inducing local inflammation that drives hyperplasia; a lack of hemocompatibility that promotes thrombosis, increasing need for antiplatelet therapy; and limited endothelialization, which is a critical step in the healing process. In this research, we designed a novel material for use as a next-generation coating for drug-eluting stents that addresses the limitations described above. Specifically, we developed a recombinant spider silk material that is functionalized with an REDV cell-adhesive ligand, a peptide motif that promotes specific adhesion of endothelial cells in the cardiovascular environment. We illustrated that this REDV-modified spider silk variant [eADF4(C16)-REDV] is an endothelial-cell-specific material that can promote the formation of a near-confluent endothelium. We additionally performed hemocompatibility assays using human whole blood and demonstrated that spider silk materials exhibit excellent hemocompatibility under both static and flow conditions. Furthermore, we showed that the material displayed slow enzyme-mediated degradation. Finally, we illustrated the ability to load and release the clinically relevant drug everolimus from recombinant spider silk coatings in a quantity and at a rate similar to that of commercial devices. These results support the use of REDV-functionalized recombinant spider silk as a coating for drug-eluting stents.

Biocompatible Optical Fibers Made of Regenerated Cellulose and Recombinant Cellulose-Binding Spider Silk.

The fabrication of green optical waveguides based on cellulose and spider silk might allow the processing of novel biocompatible materials. Regenerated cellulose fibers are used as the core and recombinantly produced spider silk proteins eADF4(C16) as the cladding material. A detected delamination between core and cladding could be circumvented by using a modified spider silk protein with a cellulose-binding domain-enduring permanent adhesion between the cellulose core and the spider silk cladding. The applied spider silk materials were characterized optically, and the theoretical maximum data rate was determined. The results show optical waveguide structures promising for medical applications, for example, in the future.

Free-standing spider silk webs of the thomisid Saccodomus formivorus are made of composites comprising micro- and submicron fibers.

Our understanding of the extraordinary mechanical and physico-chemical properties of spider silk is largely confined to the fibers produced by orb-weaving spiders, despite the diversity of foraging webs that occur across numerous spider families. Crab spiders (Thomisidae) are described as ambush predators that do not build webs, but nevertheless use silk for draglines, egg cases and assembling leaf-nests. A little-known exception is the Australian thomisid Saccodomus formivorus, which constructs a basket-like silk web of extraordinary dimensional stability and structural integrity that facilitates the capture of its ant prey. We examined the physical and chemical properties of this unusual web and revealed that the web threads comprise microfibers that are embedded within a biopolymeric matrix containing additionally longitudinally-oriented submicron fibers. We showed that the micro- and submicron fibers differ in their chemical composition and that the web threads show a remarkable lateral resilience compared with that of the major ampullate silk of a well-investigated orb weaver. Our novel analyses of these unusual web and silk characteristics highlight how investigations of non-model species can broaden our understanding of silks and the evolution of foraging webs.