Degradable medical materials have good compatibility with human tissues, can be absorbed by the human body or completely excreted from the body after being degraded in the human body, will not accumulate in the internal tissues or organs of the human body, and have strong stability and ease of processing Simplicity, so it has broad development prospects in the medical field, and has been used in tissue repair, implant intervention, drug delivery, wound healing, etc.
More and more studies have shown that the effective application of biodegradable polymer materials in complex in vivo environments, especially the final clinical transformation of materials, still faces a series of key problems and challenges. In order to adapt to medical applications in different in vivo environments, degradable polymer materials are made into different types of materials or products such as micro-nano particles, gels, implantable devices, etc. through self-assembly, chemical reaction, and molding processing.
Natural biodegradable medical materials
Natural degradable polymer biomaterials include proteins (collagen, fibrin, silk, etc.), polysaccharides (starch, alginate, chitin, hyaluronic acid derivatives, etc.), natural polyesters, etc. Although natural biodegradable medical materials have a similar structure to human tissues, they will produce various undesirable consequences during their interactions with the human body. Therefore, synthetic biodegradable medical biomaterials that can be designed and custom-developed have greater application potential in the medical field.
Synthetic biodegradable medical materials
Synthetic biodegradable biomedical polymer materials can be degraded into small molecules or monomers under the action of acids, alkalis or enzymes in the body, or metabolized into carbon dioxide and water, and degraded by themselves after being implanted in the body. At present, the research on the synthesis of biodegradable biomedical polymer materials mainly uses the properties of polymer materials to develop their applications in the medical field.
Aliphatic polyester has good biocompatibility and biodegradability, and is an important raw material for the synthesis of biodegradable polymer medical materials. Polyglycolic acid (PGA), polylactic acid (PLA), and polylactic acid-glycolic acid copolymer (PLGA) are the most commonly used biodegradable biomedical polymer materials in biological tissue engineering and 3D scaffolds.
Polyglycolic acid (PGA) has fast degradable hydrophilicity and can be quickly dissolved in the human body. In addition, due to its flexibility in material properties, PGA can be used in tissue engineering structures based on stents, as well as in drug delivery and wound healing. Studies have proven that PGA combined with fibrin can treat soft tissue wounds.
Polylactic acid (PLA) is another widely used biodegradable material in biomedicine. Although its structure is similar to PGA, its performance is quite different. Due to its good relatively long-term mechanical properties in the human body, it becomes a load-bearing material such as orthopedic fixation. At present, a variety of orthopedic products have been developed based on PLA, such as soft tissue fixation screws and phantom suture anchors. The development of polylactic acid biodegradable medical polymer materials is one of the most active research topics in recent years.
Polylactic acid-glycolic acid copolymer (PLGA) adjusts the ratio of PGA and PLA to control the degradation rate and the time to maintain performance in the human body. Therefore, PLGA is often used in combination with ceramic/bioactive materials to enhance the ability of bone regeneration. Experiments have proved that PLGA and alloy composite implants have obvious antibacterial, bone conduction, and osteoinduction properties, which provide a new direction for plastic surgery.
Polycaprolactone (PCL) can be degraded by microorganisms, hydrolysis, enzymatic, etc. Compared with PLA, PGA, PLGA, the degradation rate is slow, so it is generally used for long-term implants and drug delivery. Studies have proved that PCL can be used for effective drug delivery and delivery. Research on micron and nano-level drug delivery systems with PCL as the core is still hot. In addition, PCL-calcium phosphate scaffolds have been proven to have cell compatibility in vitro and can be used for tissue repair.
Polyurethane (PUR) is an ideal choice for medical devices due to its toughness, durability, biocompatibility and biological stability. It is usually used as heart valves, blood vessel transplants, catheters and prostheses. The combination of PUR and lysine diisocyanate can enhance cell proliferation and adhesion, and can be used to develop highly porous scaffolds.
Polyethylene glycol (PEG) has excellent gelling and degradability, good biocompatibility, non-toxicity and low immunogenicity. In medical devices, PEG derivatives are mainly multi-arm structures. Due to their relatively large molecular weight, they can form hydrogels, which can be used for surgical sutures and hemostasis, as well as assist tissue regeneration and wound healing. After spraying the PEG hydrogel on the wound site, the hydrogel quickly solidifies to prevent bleeding and infection of the wound, and degrades by itself after the wound has healed. At the same time, spraying PEG hydrogel on the surface of organs can effectively prevent the adhesion of internal organs during surgery.
Application of biodegradable medical materials
1. Coronary stent
2. Vena Cava Filter
3. Oral Repair Film
The future development trend of the biodegradable medical materials industry will be to combine the functions and technologies of polymers for specific biomedical applications. The development of biodegradable medical materials should meet the development needs of the downstream medical device industry, develop a new generation of vascular stents, nerve repair catheters, bone tissue artificial repair materials and other products, explore the artificial construction of valve, liver, kidney and other tissues and organoids, and actively Promote the application of biological 3D printing technology.
