Читать книгу Materials for Biomedical Engineering - Mohamed N. Rahaman - Страница 177

As the surface of a biomaterial rapidly develops an electrostatic surface charge and an associated electrical double layer upon implantation in the physiological environment, it is realistic to assume that this surface charge system should influence subsequent interactions with the physiological environment. Depending on their composition, the components of the physiological fluid such as ions, amino acids, and proteins can be positively charged, negatively charged, polar or nonpolar (Chapter 3). Consequently, we might expect varying degrees of electrostatic interaction between these components and the charged surface. This interaction should influence, for example, the type of ions and molecules adsorbed at the surface and the conformation of adsorbed proteins, which, in turn, should influence the response of cells. In practice, a correlation between the surface charge of a biomaterial and its interaction with the physiological environment has been difficult to establish. While this is due to a variety of reasons, a major factor is the difficulty in separating the true effect of surface charge from the contributions of other surface properties such as wettability (contact angle) and surface topography.