EFFECT OF C-4-ALKYLATION, C-8-ALKYLATION AND C-18-ALKYLATION OF POLY(VINYL ALCOHOL) HYDROGELS ON THE ADSORPTION OF ALBUMIN AND FIBRINOGEN FROM BUFFER AND PLASMA - LIMITED CORRELATION WITH PLATELET INTERACTIONS

Polyvinyl alcohol (PVA) hydrogel was partially alkylated with short (C -4), intermediate (C-8) and long (C-18) alkyl chains to test the hypot hesis that an alkylated surface might promote enhanced interaction wit h albumin and thus exhibit low platelet thrombogenicity. PVA hydrogel was reacted with alkyl halides (C-4, C-8 or C-18) and coated onto poly ethylene. The effect of surface alkylation (extent of alkylation and a lkyl chain length) on the adsorption of human serum albumin and fibrin ogen to these surfaces was investigated in both buffer and plasma. Pla telet interactions were investigated in vitro using flow cytometry met hods. The maximum surface concentrations of albumin and fibrinogen ads orbed from buffer onto PVA and alkylated PVA were characteristic of mo nolayers. At low concentrations differences in adsorption among the su rfaces appeared to be related to hydrophobicity as determined by dynam ic advancing water contact angle, and to degree of alkylation as deter mined by angle dependent XPS analysis. Alkyl chain length dependence w as not observed. Adsorption from plasma was considerably lower than fr om buffer, except for albumin on C-8-PVA where monolayer adsorption wa s observed. Fibrinogen adsorption from plasma was similar on PVA, C(8) PVA and C(18)PVA, but was higher on C-4-PVA, For albumin adsorption fr om plasma, the initial slope of the adsorption-concentration curve was highest for C-18-PVA, suggesting higher albumin affinity despite the low degree of substitution of the C-18-PVA material. These data sugges t possible selectivity of the C-18 alkylated PVA for albumin. Platelet studies showed that C-4-PVA was the least platelet reactive (micropar ticle generation and P-selectin expression) of the alkyl derivatized m aterials. (C) 1998 Elsevier Science Limited. All rights reserved.