Biomaterial is a kind of natural or artificially synthesized special functional material, which is also called biomedical material. It is used to contact and interact with life system, and can diagnose, treat, replace, repair or induce regeneration of its cells, tissues and organs. Biomaterials are a cross-penetrating field of many developing disciplines in the field of material science, which involves material science, life science, chemistry, biology, anatomy, pathology, clinical medicine, pharmacology and other disciplines. At the same time, it also involves the scope of engineering technology and management science. Biomaterials include synthetic materials and natural materials. There are single materials, composite materials, and hybrid materials formed by the combination of living cells or natural tissues and inanimate materials. Biomaterials themselves are not drugs, and their therapeutic approaches are characterized by direct binding and interaction with biological bodies.
- Blood compatibility materials: Such as artificial valve, artificial trachea, artificial heart, plasma separation membrane, adsorbent for hemoperfusion, cell culture substrate, etc.
- Soft tissue compatibility materials: Such as polymer materials of invisible eye tablets, intraocular lenses, polysiloxane, polyamino acids, etc., used in artificial skin, artificial trachea, artificial esophagus, artificial ureter, soft tissue repair and other fields.
- Hard histocompatibility material: Such as medical metals, polyethylene, bioceramics, joints, teeth, other bones, etc.
- Biodegradable materials: Such as chitin, polylactic acid, etc., used for sutures, drug carriers, adhesives, etc.
- High molecular drug: Such as peptides, insulin, synthetic vaccines for diabetes, cardiovascular diseases, cancer and inflammation.
Biomaterials are widely used. There are many kinds of biomaterials, and the classification methods are diverse.
- Biomaterials include metal materials (such as alkali metals and their alloys), inorganic materials (bioactive ceramics, hydroxyapatite, etc.) and organic materials. Organic materials are mainly polymer aggregates, while polymer materials are usually divided into synthetic polymer materials (polyurethane, polyester, polylactic acid, polyglycolic acid, lactic acid glycolic acid copolymer and other medical synthetic plastics and rubber, etc.), and natural polymer materials (such as collagen, silk protein, cellulose, chitosan, etc.).
- According to their use and application areas, these materials can be divided into bioinert (bioinert), bioactive (bioactive) or biodegradable (biodegradable) materials.
- According to whether the degradation products can be metabolized and absorbed by the body, degradable polymers can be divided into bioabsorbable ones and bio-non-absorbable ones.
- According to the influence of material contact with blood on blood composition and performance, biomaterials can be divided into blood compatible polymers and blood incompatible polymers.
- According to the affinity and reflection of materials to body cells, materials can be divided into biocompatible and bioincompatible polymers.
Figure 1. Schematic of stem cells and biomaterials application.
Biomaterials are mainly used in human beings, and the selection criteria are very strict and must have four characteristics:
- Biological function: It varies with the use of various biomaterials, for instance, if to be used as a sustained-release drug, the sustained-release performance of the drug is its biological function.
- Biocompatibility: It can be summarized as the relationship between materials and living bodies, including blood compatibility and histocompatibility (non-toxic, non-carcinogenic, non-pyrogen reaction, no immune rejection, etc.).
- Chemical stability: It requires resistance to biological aging (particularly stable) or biodegradability (controllable degradation).
- Processability: It can be shaped and disinfected (UV sterilization, high-pressure boiling, ethylene oxide gas disinfection, alcohol disinfection, etc.).
- D.G. Anderson, S. Levenberg(2004). "Nanoliter-scale synthesis of arrayed biomaterials and application to human embryonic stem cells" Nat. Biotechnol. 22 (7):863-866
- J.A. Burdick, G. Vunjak-Novakovic(2009). "Engineered microenvironments for controlled stem cell differentiation" Tissue Eng. A. 15 (2) : 205-219