Integrated Biomaterials Science

Structure and Properties of Polymeric Materials 37
Systems employing enzymes immobilized in both natural and synthetic
polymers can find clinical application both for endocorporeal use and
as components of extracorporeal circuits for specific blood detoxifications, a
potentially important field of application.
The chemical, physical, and technological properties of biomedical
polymers can be very different: from water-soluble or biodegradable ones,
like poly(ethyleneglycol) or poly(lactic acid), to rigid polymers, hydrophobic
and designed to resist for many years mechanical stress and the hydrolytic
action carried out in the human body by chemical or enzymatic agents.
Examples of this latter class are the aromatic polyesters, the poly(alkylsiloxanes),
fluorinated polymers, and polyurethanes, which are preferably
employed for permanent endocorporeal prostheses.
2.3.1. Synthetic Polymers
Synthetic polymers can be employed in various fields of application,
as shown in Table 2.1. Polymers which, due to their fairly good intrinsic
hemocompatibility properties, have been largely employed in endocorporeal
permanent applications of prosthetic type include polyurethanes, silicone
rubbers, hydrogels, teflon, and some vinyl polymers or copolymers.