Abstract
Composite gels and films of CMC and PEO have been used to separate healing tissues and have been demonstrated to reduce postsurgical adhesions in animal models of adhesion formation. Gels of CMC/PEO were studied here to elucidate the mechanism by which the combination of PEO with CMC is effective in reducing adhesions between tissues. CMC and PEO were demonstrated to undergo micro phase separation to form a twoβphase system. Protein partitioning was measured in this system for albumin, fibrinogen, and gamma globulin. All of these proteins were found to partition preferentially into the CMC phase. When gels of CMC and PEO were examined for tissue adherence, the addition of PEO reduced the adherence of CMC to tissues. To further investigate the effects of PEO on tissue adherence of the gel, the extent of thrombus formation of citrated blood initiated by calcium chloride in CMC/PEO gels was measured in vitro. The extent of thrombus formation by CMC was reduced proportionally to the content of PEO in gels of CMC/PEO. A model was developed to explain how CMC and PEO contribute to the effectiveness of CMC/PEO gels that form a barrier between healing tissues to reduce postsurgical adhesions. In an open system PEO is released from the gel faster than CMC is dissolved, resulting in a shell structure with CMC coated by PEO. The PEOβrich outer layer functions to inhibit protein deposition and thrombus formation. The CMCβrich layer functions to anchor the gel to the tissue surface. Β© 2002 Wiley Periodicals, Inc. J Biomed Mater Res (Appl Biomater) 63: 326β332, 2002