Читать книгу Materials for Biomedical Engineering - Mohamed N. Rahaman - Страница 168

Apart from its effect in controlling hydrophilicity or hydrophobicity, surface energy by itself has not played a major role in the applications of biomaterials. This is due to a variety of factors. One factor is that the true effect of surface energy is often difficult to separate from contributions from the effects of other surface properties such as surface charge and surface topology. Another factor is the difficulty in correlating surface energy with the interactions of biomaterials with the physiological environment. Often, surface energy is determined from experiments performed under certain ideal conditions that are different from practical conditions in vitro and in vivo. Prior to surface energy measurement, the biomaterial is often subjected to grinding and polishing, and thermal treatment to remove physically and chemically adsorbed water. These treatments can lead to a surface that is different from that of the implanted biomaterial due to adsorption of moisture and impurities such as hydrocarbons from the environment or from the container used for packaging. Standard liquids such as deionized water or, in some cases, phosphate buffered saline used experimentally are also different from the aqueous medium of the physiological environment which contains a variety of ions, small molecules, and proteins.