Silk fibroin is a high molecular weight protein that is fabricated by certain species of insects and arachnids, including <i>Bombyx mori</i> silkworms. <i>B. mori</i> fibroin consists of hydrophilic blocks that can be modified using different chemistries and hydrophobic blocks that are capable of hydrogen bonding, which results physical crosslinking to form beta sheet secondary structures. This physical crosslinking provides unique opportunity to tune the mechanical and degradation properties of the protein-based materials. In addition to its tunable properties, silk fibroin has been shown to be biocompatible in a variety of biomedical applications. This work utilizes surface-initiated atom transfer radical polymerization to grow grafted polymers from the surface of silk fibroin films. This approach was found to lead to higher degrees of substitution compared to existing methods to functionalize silk fibroin. The surfaces of silk fibroin were first oxidized with ammonium persulfate and ultraviolet light to introduce hydroxyl groups, which increased the reactive sites for grafting. Hydrophilic polymers containing varying types and amounts of charges (cationic, anionic, zwitterionic, and polymers lacking charge), were synthesized and characterized for their ability to tailor the protein adsorption to silk surfaces. A reduction in water contact angle was observed after oxidation and each polymerization, indicating successful surface modification. Further characterization by attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy showed the formation of new vibrations after grafting, and atomic force microscopy showed that the morphology of the chains exhibited globular conformations. The adsorption of bovine serum albumin and fibrinogen was lower for the zwitterionic silk films compared to the positively or negatively charged films. The manipulation of surface charges on silk fibroin thus provides a route for degradable and controlled protein attachment to implantable biomaterials.

Surface modification of silk fibroin to control protein deposition

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.