Site-Specific Functionalization of Recombinant Spider Silk Janus Fibers

Biotechnological production is a powerful tool to design materials with customized properties. The aim of this work was to apply designed spider silk proteins to produce Janus fibers with two different functional sides. First, functionalization was established through a cysteine-modified silk protein, ntag(Cys)eADF4(kappa 16). After fiber spinning, gold nanoparticles (AuNPs) were coupled via thiol-ene click chemistry. Significantly reduced electrical resistivity indicated sufficient loading density of AuNPs on such fiber surfaces. Then, Janus fibers were electrospun in a side-by-side arrangement, with non-functional eADF4(C16) on the one and functional ntag(Cys)eADF4(kappa 16) on the other side. Post-treatment was established to render silk fibers insoluble in water. Subsequent AuNP binding was highly selective on the ntag(Cys)eADF4(kappa 16) side demonstrating the potential of such silk-based systems to realize complex bifunctional structures with spatial resolutions in the nano scale.

Automated summary

This study used spider silk proteins to produce Janus fibers with two different functional sides. Functionalization and coupling of gold nanoparticles were achieved through modification and post-treatment processes. The results demonstrated the potential of this silk-based system to realize complex bifunctional structures at the nano scale.