| Research Abstract |
To investigate the characterizatics of interaction forces between proteins and end-grafted polymer surfaces, force-versus-distance curves (f-d curves) were measured between protein-fixed probe tips (albumin and lysozyme) and surfaces graft-polymerized with N,N-dimethylacrylamide or acrylic acid in an aqueous solution, using an atomic force microscope. The effects of grafted chain length, grafting density, and electrostatic properly of the grafted chain segments on the interaction forces in the processes of protein adsorption onto and desorption from the graft-polymerized surfaces were analyzed from the approaching and retracting traces of he observed f-d cures, respectively. The grafting state affects the adhesion characteristics of the protein and a polyanionic surface provides a significant adhesion force not only to a positively charged protein but also to a negatively charged one at physiological pH.
On the other hand, vascular-like tubular tissues named biotubes consisting of autol
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ogous tissues were prepared using in vivo tissue engineering and their mechanical properties were evaluated for application as a small caliber artificial vascular prosthesis. The biotubes were prepared by embedding six kinds of polymeric rods (poly(ethylene)(PE), poly(fluoroacetate)(PFA), poly(methyl methacrylate)(PMMA), segmented poly(urethane)(PU), poly(vinyl chloride)(PVC) and silicone (Si)as a mold in six subcutaneous pouches in the dorsal skin of New Zealand White rabbits. For rods apart from PFA, biotubes were constructed after 1-month of implantation by encapsulation around the polymeric implants. The wall thickness of the biotubes ranged from about 50 to 200 μm depending on the implant material and were in the order PFA<PVC<PMMA<PU<PE. As for PE, PMMA, and PVC, the thickness increased after 3-month of implantation and ranged from 1.5 to 2 fold. None of the biotubes were ruptured when a hydrostatic pressure was gradually applied to their lumen up to 200 mmHg. The relationship between the intraluminal pressure and the external diameter, which was highly reproducible, showed a 'J'-shaped curve similar to the native artery. The tissue mostly consisted of collagen-rich extracellular matrices and fibroblasts. Generally, the tissue was relatively firm and inelastic for Si and soft for PMMA. For PMMA, PE and PVC the stiffness parameter of the biotubes obtained was similar to those of the human coronary, femoral and carotid arteries, respectively. Biotubes which possess the ability for wide adjustments in their matrices, mechanics, shape and luminal surface design can be applied for use as small caliber blood vessels and are an ideal implant since they avoid immunological rejection. Less
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