Structural characterization of silk-polyurethane composite material for biomaterials using solid-state NMR

In this paper, we performed solid-state nuclear magnetic resonance (NMR) measurements, including T 1 H and T 1 ρ , of silk fibroin (SF)/polyurethane (PU) composites to examine their possible use as a material for artificial vascular grafts. In the development of new artificial vascular grafts made from SF/PU, it is important to examine the miscibility of the composites and their molecular dynamics, because these properties are intimately involved in the resulting physical properties of the resulting vascular graft. The T 1 H measurements showed that the domain size of the SF/PU=1:1 composite is smaller than the domain size of the 1:10 and 1:2 composites, indicating that the molecular miscibility between SF and PU are partially in close proximity, particularly in the SF/PU=1:1 composite. Additionally, we observed that the molecular motion of the soft segment of PU in the SF/PU composites becomes slow, suggesting that the soft segment of PU interacts with SF to some extent. These analyses provided basic structural information for the development of silk-based artificial vascular grafts using PU. In this study, we investigated the molecular structure of the composite material of silk fibroin and polyurethane as coating agent of vascular grafts by using solid-state nuclear magnetic resonance (NMR) techniques. To elucidate the structure and dynamics, 13 C cross-polarization (CP)/magic angle spinning (MAS) NMR studies including NMR relaxation experiments were performed. These observations showed that there is a partial interacted portion between soft segment of PU and SF, in particular, the domain size of PU:SU=1:1 composite was smaller than that of the other composites. This study gave basic information on development of new silk-like materials for vascular grafts.