Biocompatible coatings with high albumin affinity

A process was developed to coat complex medical devices with a thin, transparent, biocompatible film. The film is based on silicone rubber (SR) but has higher albumin affinity than SR. Two polymer forms have been developed: one substitutes hydroxyl groups (OH), the other, 16 carbon acyl groups (C16) in the siloxane side chains. Oxymercuration/demercuration or hydroboration reactions can be used. SEM reveals film surfaces are smooth, uniform, and featureless. ATR/FTIR spectra and advancing/receding water contact angle measurements confirm the presence of surface OH groups and suggest the presence of surface acyl groups. Albumin adsorption and retention are markedly enhanced for surface OH and C16 concentrations as low as 5% reaction yield. Kinetics, isotherm, and competitive albumin/fibrinogen adsorption studies suggest that surface hydroxylation, and perhaps C16 acylation as well, markedly improve the albumin affinity, but not the fibrinogen affinity, of this material. The SR film can be durably coated on several materials, making it possible to favorably treat many blood-contacting devices, using a simple immersion process.