Modification of lipid transport through a microporous PTFE membrane wall grafted with poly(ethylene glycol)

摘要

Lipid interaction with ePTFE arterial prostheses has been identified in previous studies as being one of the causes leading to graft failure. Our research group has previously proposed a mathematical model of the lipid uptake mechanism in Teflon Prostheses as two first-order reactions based on in vitro experiments. The present study sought to determine whether surface modification with methoxy poly(ethylene glycol) (MPEG) derivatives of various molecular weights modified the kinetics of lipid transport through microporous PTFE membranes. PTFE films and ePTFE tubular microporous membranes were functionalized with amine groups using an ammonia radio frequency glow discharge plasma. MPEGs were conjugated as succinimidyl activated esters on the aminated-PTFE surfaces. In order to maximize the surface coverage by MPEGs, the conjugation reactions were performed under conditions near the cloud point. XPS and contact angle analyses confirmed the ability to covalently graft activated MPEGs to amino-functionalized PTFE surfaces of the films and microporous membranes. Lipid adsorption onto PTFE films monitored by ATR-FTIR spectroscopy demonstrated that the surface coverage by each MPEG resulted in a significant decrease in lipid adsorption regardless of the MPEG molecular weight (M_w). ATR-FTIR spectroscopy and FTIR microscopy were used to characterize lipid adsorption onto the PTFE microporous membrane surface and lipid absorption across the microporous structure, respectively. The surface modification by the MPEG, regardless of its M_w, resulted in both decrease of lipid adsorption onto the surface of the modified membrane and delayed lipid uptake kinetics. It was concluded that MPEG anchored to the surface of a PTFE microporous membrane may modify mass transport through the ePTFE porous structure.