Tailored surface coatings have been used for decades to improve material performance in blood. Among different approaches, heparin based biomedical coatings have found great success in the commercial catheter market. However, they have their own limitations. Coating of a vascular device with a heparin binding peptide (HBP), which can sequester the circulating heparin, presents numerous advantages over both systemic heparin therapy and direct heparin bound surfaces. Embedding HBP in a silk biopolymer provides the mechanical integrity necessary under dynamic flow conditions to both insert the catheter and maintain proper blood flow. Furthermore, due to the similarity in structure of HBP with antimicrobial peptides, it is predicted that the fusion protein will also show antimicrobial property, a critical and unique aspect to combat catheter related blood stream infections and extend the longevity of hemodialysis catheters. To assess this hypothesis, a recombinant fusion protein (S4H4) containing both silk amino acid motifs and HBP was assessed as a coating on a silicone surface. After validating that, the protein was deposited on the surface via XPS, Raman spectroscopy, ATR and SEM imaging, antimicrobial and anticoagulant activities were evaluated. The coating was able to prevent not only planktonic bacterial growth but also prevented the growth of a biofilm. Finally, the coating had both antibacterial and anticoagulant effect simultaneously. This study proves the successful production of a silk-based biopolymer that can be embedded with a heparin-binding functionality to create a dual functional device coating that can prevent infection and thrombosis together.
Keywords: Thrombosis; coating; heparin-binding peptide; infection; silk protein.