Evaluation of a relationship between polymer bulk hydroxyl and surface oxygen content and in vitro serum–material interaction

Abstract

To evaluate serum-material interaction for six types of minimodule and to assess the relationship between the interaction and chemical composition, notably bulk polymer hydroxyl (-OH) percent of polymer, or surface oxygen (SO) percent, polymeric membranes with varying -OH and SO percents were evaluated with normal human serum. The membrane materials (-OH percent and SO percent) evaluated included polypropylene (PP; 0% and 1.9%), polyvinyl alcohol (PVA; 23.7% and 27.3%), ethylene vinyl alcohol (EVAL 4A and D; 30.4% and 25.3%), Cuprophan (CP; 31.5% and 37.4%), and Hemophan (HP; 30.9% and 23.6%), respectively. Data from serum perfusions expressed as percent changes to sham perfusion showed that solute percent decreases were less than 10% in all materials except PVA (10-22%). PVA and CP had higher C3a, C4a, and C5a, and C3a concentration increases, and had larger suppressive effects for all three mitogen-induced mononuclear cell transformation functions (MNCTF) and concanavalin A-induced MNCTF, respectively. PVA had higher SO percent than EVAL and CP was higher than HP, despite PVA and CP having lower or comparable bulk -OH percent to EVAL or HP. The results obtained in the serum material interaction studies related more with the SO percent of the polymer rather than bulk -OH percent. The differences for C4a and PHA-induced MNCTF observed between the two EVAL membranes may be associated with significantly different pore size and therefore different surface structural properties. These results suggest that surface chemical (SO percent on the materials) and structural property analyses are important factors in biocompatibility parameter studies.