Surface Modification of Polymers for Biomedical Applications: Chemical, Biological, and Surface Analytical Challenges

Abstract

Synthetic polymers are widely used in contact with biological systems. Applications in medicine, biotechnology, food processing and natural water environments are common. Millions of medical devices comprised of synthetic materials (biomaterials) are used in humans each year (Table 1). These medical devices can be designed, synthesized, and fabricated to have appropriate mechanical properties, durability, and functionality. Examples are a knee prosthesis that should withstand high localized mechanical stresses, a blood oxygenator membrane that should have the requisite permeability characteristics, and the leaflets in a heart valve that should flex for millions of cycles without failure. The bulk structure of the materials governs these properties. Biological responses to biomaterials, on the other hand, are dominated by their surface chemistry and structure. Thus, the rationale for the surface modification of biomaterials is straightforward: retain the key physical properties while modifying only the outermost surface to influence biointeraction. If surface modification is properly effected, the bulk mechanical properties and functionality of the medical device will be unchanged, but the biological performance will be improved. Improvements in certain important surface physical properties such as lubricity are also readily achieved by surface modification.