Polyethylene oxide (PEO) surfaces reduce non-specific
protein and cell interactions with implanted
biomaterials and may improve their biocompatibility. PEO-like polymerized
tetraglyme surfaces were made by glow discharge plasma deposition onto
fluorinated ethylene propylene copolymer (
FEP) substrates and were shown to adsorb less than 10 ng/cm2 of
fibrinogen in vitro. The ability of the polymerized
tetraglyme surfaces to resist leukocyte adhesion was studied in vitro and in vivo. Polymerized
tetraglyme and
FEP were implanted subcutaneously in mice and removed after 1 day or 4 weeks. Histological analysis showed a similar degree of fibrous encapsulation around all of the 4-week implants. Darkly stained wells were present in the fibrous tissues at the tissue-material interface of both
FEP and
tetraglyme. Scanning electron micrographs showed that in vivo macrophage adhesion to polymerized
tetraglyme was much higher than to
FEP. After 2-hour contact with heparinized whole blood, polymorphonuclear leukocyte (PMN) adhesion to polymerized
tetraglyme was much higher than to
FEP, while platelet adhesion to polymerized
tetraglyme was lower than to
FEP. When PMNs isolated from blood were suspended in 10% autologous plasma, cell adhesion to polymerized
tetraglyme was higher than to
FEP; however when the cells were suspended in heat inactivated serum, cell adhesion to
FEP was higher than to polymerized
tetraglyme. The surface chemistry of polymerized
tetraglyme did not change after 2-hour blood contact, but displayed
nitrogen functional groups after 1-day implantation and became slightly degraded after 4-week implantation. The surface chemistry of
FEP did not change significantly after blood contact or implantation. Loosely bound
proteins such as
fibrinogen on polymerized
tetraglyme may contribute to the adhesion of PMNs and macrophages and ultimately to fibrous encapsulation (the
foreign body response) around the implants.