1H MRI study of small-diameter silk vascular grafts in water

Small-diameter vascular grafts (VG) made from silk fibroin (SF) fibers by a double-raschel knitting method were prepared by coating their interior and exterior with different materials, such as SF or polyurethane (PU). The 1H spin density, 1H spin–spin relaxation time (T2) and diffusion coefficient (D) of the water molecules in the layer of the VG coated by these materials were non-destructively observed in water using 1H NMR imaging. The inner and outer coating materials significantly affected the amount and mobility of water molecules in the VG. The water content of the SF-coated VG was considerably higher than that of PU-coated VG. The T2 value of the water molecules in the SF-coated VG layer was smaller than that of the PU-coated VG, which means that the rotational motion of the water molecules in the layer of the SF-coated VG was restricted by the intermolecular interaction between the SF and water molecules. The diffusion coefficient (D) of the water molecules in the SF-coated VG layer was larger than that of the PU-coated VG, indicating that the water molecules were confined to the pores in the graft layer of the PU-coated VG. Polymer Journal (2012) 44, 868–875; doi:10.1038/pj.2012.77; published online 30 May 2012