Biocompatibility

from Wikipedia, the free encyclopedia

As biocompatible (gr. Bios = life + compatible = compatible) refers to materials or components that have no negative impact on living creatures have in their environment.

The biocompatibility of implants is particularly relevant as they are in direct contact with living beings for a long period of time. The certification of the biocompatibility of medical materials and products is carried out according to ISO 10993 1-20. In order to achieve a high level of biocompatibility, the implants made of a non-biocompatible material can be coated with a biocompatible layer, for example made of proteins . This is then called surface compatibility. If the shape and internal structure of the implant (e.g. fiber thickness) are adapted to the recipient tissue, one speaks of structural biocompatibility.

To test the biocompatibility, various biological substances and implants are tested in laboratory tests for their compatibility in the human and animal body. These lengthy test series are part of the strict worldwide approvals for implants and drugs.

Subdivision of biocompatibility

If a material cannot be described as incompatible, biocompatibility is divided into three terms: biotolerant, bioinert and bioactive.

Bio-tolerant

The products, which are called "biotolerant", allow the medical device to stay in the body from months to several years. There are minor deficiencies in the tissue reaction. This species is not bioactive and not “bioinert” in the long term. The term long-term means that there is no decomposition, no cell change and no toxic effect during the period of use (in vivo).

Bioinert

The term “bioinert” actually means that there is no chemical and / or biological interaction between the implant and the tissue. No toxic substances are released. However, this can never be fully achieved, as there is always an interaction between tissue and implant. However, if this interaction is sufficiently small so that the substances carried into the body never exceed certain limit values, it is called a bio-inert material. The body usually reacts to this material with a non-adherent (non-fused) connective tissue encapsulation around the implant, and there is no rejection reaction of the body. This connection can only transmit compressive forces, as the layer of connective tissue causes the implant to slide off when subjected to tensile forces. The term “bioinert” assumes corrosion resistance. The material should be thermally stable (e.g. for sterilization), refractory (not appealing) and passivatable (e.g. for coating) in order to be classified as “bioinert” as a material. This class includes some ceramics (e.g. Al 2 O 3 ), plastics, and most metals.

Bioactive

In endoprosthetics, “bioactive” is the reaction of a bone to the implant, which allows the bone to adhere to the interface with the implant. This can be achieved with a coating. So a bioinert material z. B. react “bioactive” with a coating. The implant material , but mostly only the coating, is converted into bone material. This chemical connection is cohesive and, compared to bio-inert materials, allows the transmission of tensile loads. In other medical fields of application, it is understood as the active endeavor of the body to allow the implant to perform the required task (e.g. for heart valves, pacemakers) in the long term (see above) and thus to produce a complete replacement. Typical materials, which are usually included in the term “bioactive”, consist of carbon, ceramics and glasses (for example BioGlass®).

Biocompatibility in waste management

In the case of wastewater , biocompatibility is a measure of the biodegradability of the contaminating substances. It is calculated from the quotient of the biological oxygen demand (BOD) and the chemical oxygen demand (COD). For solids, the time that is necessary for the biological-chemical decomposition is a suitable measure for describing the biocompatibility.

literature

  • J. Wiest: Chemically Defined - A Cell-Based Cytotoxicity Assay Without Fetal Calf Serum. In: BIOspectrum. Volume 23, No. 1, 2017, pp. 61-62. doi: 10.1007 / s12268-017-0768-6
  • Erich Wintermantel , Suk-Woo Ha: Medical technology Life Science Engineering. 5th, revised and expanded edition. Berlin / Heidelberg / New York 2009, ISBN 978-3-540-93935-1 .
  • Pschyrembel: Clinical Dictionary. 258th edition. Walter de Gruyter Verlag, Berlin 1998.
  • Gottfried Schmalz, Dorthe Arenholt-Bindslev: Biocompatibility of Dental Materials . Springer, Berlin / Heidelberg / New York 2009, ISBN 978-3-540-77781-6 .