Biocompatible material

In surgery, a biomaterial is a synthetic material used to replace part of a living system or to function in intimate contact with living tissue. Compare this definition to that of bio-based material.

In the first Consensus Conference of the European Society for Biomaterials a biomaterial was defined as "a nonviable material used in a medical device, intended to interact with biological systems" but was later in the second round defined as a "material intended to interface with biological systems to evaluate, treat, augment or replace any tissue, organ or function of the body" (see list of 5 below).

A biomaterial is different from a biological material such as bone that is produced by a biological system. Artificial hips, vascular stents, artificial pacemakers, and catheters are all made from different biomaterials and comprise different medical devices.

Biomimetic materials are not made by living things but have compositions and properties similar to those made by living things. The calcium hydroxylapatite coating found on many artificial hips is a sort of fake bone that allows for easier attachment of the implant to the living bone.

Surface functionalization may provide a way to transform a bio-inert material into a biomimetic or even bio-active material by coupling of protein layers to the surface. Different approaches to functionalization of biomaterials exist. Plasma processing has been successfully applied to chemically inert materials like polymers or silicon to graft various functional groups to the surface of the implant.

Six definitions of the word biomaterial and some comments

• 1. non-viable material used in a medical device, intended to interact with biological systems.

ESB Consensus Conference I

• 2. material intended to interface with biological systems to evaluate, treat, augment or replace any tissue, organ or function of the body

ESB Consensus Conference II - Note - This is refined version of definition 1 so that the reference to non-viable materials was removed and that made the intended functions of biomaterials more explicit. This is the recommended definition.

• 3. synthetic, natural or modified natural material intended to be in contact and interact with the biological system

ISO - This definition from an ISO Technical Report is not recommended since it implies that tissues are biomaterials which they are not and because of the ambiguity of the phrase “in contact”

• 4. any substance (other than a drug), synthetic or natural, that can be used as a system or part of a system that treats, augments, or replaces any tissue, organ, or function of the body.

Dorland Medical - Note - This definition is not recommended since it does not imply any reference to an interface with tissues, furthermore this definition would include any microelectronic component of a pacemaker that is not normally considered to be a biomaterial.

• 5. solid materials which occur in and are made by living organisms, such as chitin, fibrin or bone.

Larousse Science - Note – This definition is not recommended since it aims at materials of biological origin (bio-material) rather than materials to be used in medical devices. See more on bio-based materials.

• 6. a systemically and pharmacologically inert substance designed for implantation within or in corporation with living systems

The Clemson University Advisory Board for Biomaterials - Note - this seems to be a remainder from the time when everyone thought that a biomaterial should be inert to achieve optimal biocompatibility but this is no longer the case.

References

• Dorland medical dictionary
• Larousse dictionary of science and technology
• William's dictionary of biomaterials, DF Williams, 1999, ISBN 0-85323-921-5