| Abstract: | Haemocompatibility is the number one target of membrane development for haemodialysis, because chronic renal failure and the subsequent dialysis-treatment is affecting more and more patients. Two strategies are currently in use to achieve the goal of new blood compatible polymers: Firstly, existing cellulosic membranes are modified by introducing functional groups through ether and ester bonds and secondly, synthetic polymers are mixed with bulk additives or copolymerized with other polymers. Biological responses as a consequence of blood/material interaction are common observations. However, blood compatibility in general cannot be improved by a single membrane surface feature. The assessment of a series of surface properties shows that physiological defense systems, like complement and cell activation, or coagulation are differently stimulated by means of the same surface structures of biomaterials. Thus, a compromise has to be found, already during membrane development. We synthetized a series of modifications of cellulosic membranes with the aim to investigate whether the type of substituent and its degree of substitution has an influence on the blood compatibility of these dialysis membranes. Data indicate that alterations in the lipophilic/ hydrophilic balance (HLB) on the polymer surface may explain substituent-related changes in haemocompatibility. Optimal degrees of substitution are characteristic for a given type of substituent and enables the membrane manufacturer to tailor materials for improved blood compatibility. |
