Design and development of biocompatible silk fibroin coatings for breast implant applications

Abstract

Globally, Breast cancer accounts for about 23% of all cancers. PDMS or silicone breast implant is used in the breast reconstruction surgery to recreate the original shape and size of the breast post mastectomy. However, the safety of silicone based implantable medical devices has been a challenge since their introduction. The common clinical problems associated with silicone implants are autoimmune diseases, capsular contracture, biofilm formation, allergic reaction and recently there is also a presence of a rare type of cancer. Coating the surface of biomedical implants is a promising strategy to reduce the failure rate of implants. In this work, we coat the surface of silicone implant using a biocompatible natural protein polymer silk fibroin (SF). The PDMS surfaces have been modified using oxygen plasma treatment and 3-amino-propyl-triethoxy-silane (APTES) treatment. Interestingly, testing of the coated samples using a bulk technique such as tensile and bending deformation showed that the SF nano-coating exhibits improved crack resistance when the PDMS surface has been modified using APTES treatment as compared to oxygen plasma treatment. These results were validated at the microscopic and mesoscopic length scales through nano-scratch and nano-indentation measurements. Further, the work demonstrates that a novel process combining conventional dip coating with electrospinning results in the formation of a crack-resistant coating. The coating was also further functionalized using a green biomolecule – glycomonoterpene prepared using citronellal and glucose. These functional compounds are being touted as the next generation antibiofilm molecules on account of quorum sensing inhibitory activity. Also, we report functional coatings of silk fibroin and its blends with biopolymers and the effect of molecular weight of PEO on mechanical properties and aqueous stability of SF/PEO blend coatings on PDMS surface. Further, SF coatings have also been developed by blending with a novel polymers such as recombinantly produced elastin-like peptide (ELP), a class of polypeptide obtained from the primary sequence of mammalian elastin with a repeat unit of (GVGVP). The SF-ELP coatings were characterized for their physio-chemical and mechanical properties and their properties were compared with a selected molecular weight of PEO used for blending. The mechanical stability of SF-ELP blends shows more stable coatings than SF-PEO blends. The biological evaluation of these SF blends was performed by doing protein adsorption, accelerated degradation and cytotoxicity studies. Thus, this study shows various material science strategies that can be used to mitigate the risk of silicone implant failure.