A thromboresistant surface by enzyme immobilization

Enhanced albumin binding to polypropylene beads via anhydrous ammonia gaseous plasma

Plasma surface modification technique was used to add amino groups onto the surfaces of polypropylene beads by exposing them to anhydrous ammonia plasma. Through these amino groups, albumin was attached to the polypropylene beads. Attached albumin was further stabilized by crosslinking with glutaraldehyde. The effect of washing albuminated polypropylene beads with saline and human plasma was investigated. It was found that after initial rapid removal of albumin, the concentration of attached albumin tended to reach a steady-state. After 52 h of washing, the amount of albumin retained on the beads varied between 125 and 171 micrograms/cm2.

Albuminated polymer surfaces for biomedical application

Amino groups were added on to the surfaces of Celgard-2400 membranes by exposing them to an ammonia plasma. The presence of amino groups on the surfaces was detected by an attenuated total reflection Fourier Transform infrared spectrometer and by the Auger electron spectrometer. Through these amino groups, albumin was attached to the membranes. In some experiments, the attached albumin was further stabilized by cross-linking with glutaraldehyde. The effect of washing the albuminated membranes with saline and with plasma was investigated. It was observed that after the initial wash-out of albumin, the concentration of attached albumin tends to level off. The amount of albumin retained on the membranes varied between 275 to 357 micrograms/cm2.

Surface hydroxylation of styrene-butadiene-styrene block copolymers for biomaterials

This work pertains to the development of high strength elastomers potentially useful as nonthrombogenic cardiovascular prostheses. Triblock copolymers of the styrene-butadiene-styrene type have been subjected to surface hydroxylation which provide reactive sites at the surface for the subsequent coupling of heparin while retaining the unique mechanical properties of the SBS copolymers. Curves of hydroxyl content versus the copolymer film thickness demonstrate the effect of swelling in the surface region on the product distribution and on the time dependence of the hydroxylation process. In addition, the effect of time, temperature, and the composition of the reaction bath on the diffusion/reaction process is shown. Finally, the general applicability of this surface modification scheme to the development of biomaterials is discussed.