The understanding, characteristics and classification of functional polymer materials are briefly described, and then the development prospect and trend of biomedical polymers, the understanding and importance of biomedical functional polymers are emphatically written.

Key words: functional polymer materials, biomedical polymer materials.

Functional polymer material

Functional polymer materials generally refer to polymers and their composites with the function of transferring, converting or storing substances, energy and information, or specifically refer to polymers and their composites with the functions of chemical reactivity, photosensitivity, conductivity, catalysis, biocompatibility, medicine, selectivity, energy conversion and magnetism on the basis of the original mechanical properties. Functional polymer material is a new field developed in 1960s, and it is a new material developed after polymer material permeates into the fields of electronics, biology and energy. In recent years, the annual growth rate of functional polymer materials is generally above 10%, among which the growth rate of polymer separation membranes and biomedical polymers is as high as 50%.

The so-called functional polymer materials generally refer to polymer materials that have some special functions or can be used in some special environments, but this is relative to general polymer materials. This definition is just a generalization, not necessarily exact. Many people think that the so-called functional polymer materials refer to polymer materials and their composites with the functions of material energy and information transmission, conversion and storage. Such as some polymer compounds with photoelectric, thermoelectric, piezoelectric, acoustoelectric, chemical conversion and other functions. It can be seen that this is a kind of polymer material with wide range, wide use and many varieties, which is often encountered in life and production activities.

Functional polymer materials can be generally divided into the following categories according to their functional characteristics:

(1) separating materials from chemically functional materials; (2) Polymer materials with electromagnetic function; (3) polymer material with optical function; (4) Biomedical polymer materials. Functional polymer material is an important branch of polymer science, and its importance lies in that each polymer contained has special functions.

With the development of the times, it is more and more urgent to develop various new materials that can be applied to medical treatment in the medical field. After years of research, it is found that many polymer compounds can meet the medical requirements, and we also classify them as functional polymer materials.

Generally speaking, medical polymer materials should meet the following requirements:

1, which has good chemical stability and is not affected or changed in the contact part of human body;

2, good histocompatibility, no inflammation and rejection in human body;

3, it will not cause cancer;

4, biological aging resistance, and the long-term performance of the material in the human body has no change;

5. Treatment methods such as cooking resistance, sterilization and liquid medicine disinfection;

6. Wide sources of materials, easy to process and shape.

After years of research, there are two kinds of polymer compounds that can meet the above requirements, one is silicone compound, the other is organic fluoride, and the two main products are silicone rubber and polytetrafluoroethylene. For example, GE Company of the United States has developed many functional polymer compounds, which are mainly used in the medical field in silicone.

Present situation and development trend of biomedical polymer materials

Biomedical polymer materials, used for medical purposes and in contact with living tissues, can diagnose, treat or replace tissues and organs in vivo or enhance their functions. Biomedical polymer material is a kind of biomaterial gradually developed during the infiltration of polymer material science into medicine and life science. Polymer material is widely used in medical field and has formed a frontier discipline between modern medicine and polymer science. In the field of functional polymer materials, biomedical polymer materials have sprung up suddenly and become an important branch with the fastest development.

The development of biomedical polymer materials has gone through three stages. The first stage starts from 1937, which is characterized in that the polymer materials used are all ready-made materials, such as the gums of dentures made of methyl acrylate. The second stage began at 1953, marked by the appearance of medical grade silicone rubber, and then polyhydroxyacetate suture and four kinds of poly (ether ammonia) ester cardiovascular materials were developed, which entered the development period based on molecular engineering research. The characteristic of this stage is to optimize the composition, formula and process of synthetic polymers at the molecular level, and to develop the required polymer materials purposefully. At present, the research focus has shifted from looking for synthetic materials to studying a new material that can actively induce and stimulate the regeneration and repair of human tissues and organs, which indicates that the development of biomedical polymer materials has entered the third stage. It is characterized by the organic combination of living tissue and artificial materials, and its expected function in molecular design is to promote the growth of surrounding tissues and cells. The key is to induce the ligand to interact with special sites on the surface of tissue cells to improve the division and growth rate of tissue cells. Abroad, biomedical polymer materials have been studied for more than 50 years, and the United States published a prospective paper as early as 1947. Subsequently, the United States, Japan, Europe and other industrialized countries have successively reported articles, some of which have been applied to clinical practice. China's research history is very short. In 1970s, artificial organs were developed, and some organs entered clinical application. 1980 set up China society of biomedical engineering, 1982 set up the professional committee of artificial organs and biomaterials of china medical engineering society to further develop biomedical equipment. Biomedical polymer materials, as a frontier science, combines knowledge of polymer chemistry and physics, polymer material technology, pharmacology, pathology, anatomy and clinical medicine, and also involves many engineering problems. The development of biomedical polymer materials is of great significance for overcoming diseases that endanger human beings, ensuring people's health and exploring the mysteries of human life.

1 Basic requirements and biocompatibility of biomedical polymer materials

For biomedical polymer materials, in addition to medical functions, safety must also be emphasized, that is, not only to treat diseases, but also to be harmless to human health. Of course, the requirements for biomedical polymer materials are not uniform, but different according to their use environment or function. For example, the requirements for external medical materials are slightly lower when they contact the body for a short time, while the requirements for materials that directly contact blood or are used in the body are higher.

2 Types and development of biomedical polymer materials

Biomedical polymer materials can be divided into two categories according to their properties: non-degradable and biodegradable. Non-biodegradable biomedical polymers include: polyethylene, polypropylene, polyacrylate, aromatic polyester, polysiloxane, polyoxymethylene and so on. It can remain stable in physiological environment for a long time without degradation, crosslinking or physical wear, and has good mechanical properties. Biodegradable biomedical polymer materials include collagen, aliphatic polyester, polyamino acid, polycaprolactone and so on. These substances can be structurally destroyed in the physiological environment, and the degradation products can be absorbed or excreted by the matrix through normal metabolism. Non-degradable and biodegradable biomedical polymer materials have their unique development position in the biomedical field. However, with the development of biomedicine and materials science, people put forward higher requirements for biomedical polymer materials, and biodegradable biomedical polymer materials are increasingly favored by people. Therefore, the types of biodegradable medical polymer materials are mainly discussed here.

According to the source, biodegradable medical polymer materials can be divided into natural biodegradable and synthetic biodegradable.

Application and prospect of biomedical polymer materials

Biotechnology will be the most promising technology in 2 1 century, and biomedical polymer materials will play an important role in it, its performance will be continuously improved, and its application fields will be further broadened. The application of biomedical polymer materials mainly includes the following aspects:

(1) Polymer material in contact with blood. Polymer materials in contact with blood refer to biomedical materials used to make artificial blood vessels, artificial heart blood sacs, artificial heart valves, artificial lungs, etc. It is required that this material should have good anticoagulant and antibacterial adhesion, that is, it will not cause thrombosis, platelet deformation and infection centered on biomaterials on the surface of the material. In addition, it is also required to have elasticity and ductility similar to human blood vessels, as well as good fatigue resistance.

(2) Polymer materials for tissue engineering. Tissue engineering is a new interdisciplinary subject developed in recent ten years. It is a science that applies the principles and methods of engineering and life science to understand the structure-function relationship between normal and pathological tissues of mammals and develop biological substitutes to restore, maintain or improve their functions. With the maturity of large-scale cell culture technology and the development of biocompatible materials, it is possible to create artificial biological tissues or organs composed of living cells and biocompatible materials.

(3) Medical polymer materials. Compared with low molecular weight drugs, pharmaceutical polymers have the advantages of low toxicity, high efficiency, slow release, long-acting and fixed-point release. According to the structure and preparation form of medicinal polymers, medicinal polymers can be divided into three categories: a. Polymer drugs with pharmacological activity have pharmacological effects themselves, and they lose their medicinal properties after chain breakage, so they are real polymer drugs. B. Macromolecules of low molecular weight drugs. Low-molecular-weight drugs have fast metabolism, short half-life, and rapid decline in body concentration, which affects the curative effect. Therefore, it is necessary to take large doses of drugs frequently, and too high drug concentration will aggravate the side effects. In addition, low molecular weight drugs also lack the selectivity to enter the human body. The methods of combining low molecular weight drugs with polymers include adsorption, polymerization, block and grafting. C. Medicinal polymer microcapsules, that is, drug particles are wrapped by polymer films to form microcapsules, which have the functions of delaying and controlling drug release and improving curative effect; Cover up the toxicity, irritation and bitterness of drugs and reduce the stimulation to human body; The medicine is isolated from the air, which prevents the adverse reactions such as oxidation and moisture absorption during the storage of the medicine and increases the storage stability.

(4) Polymer materials for pharmaceutical packaging. Polymer materials used for drug packaging are increasing year by year, and polymer materials used for drug packaging can generally be divided into soft and hard. Hard materials such as polyester, polystyrene and polycarbonate. Because of its high strength, good transparency, stable size and good air tightness, it is often used to replace glass containers and metal containers to make the packaging of solid preparations such as decoction pieces and capsules. The new polyester polyethylene naphthalate not only has excellent mechanical properties and barrier properties, but also has strong ultraviolet resistance, which can be used for hot packaging of oral liquid, syrup and so on. Soft materials, such as polyethylene, polypropylene, polyvinylidene chloride, ethylene-vinyl acetate polymer, etc., are often processed into composite films, which are mainly used to package drugs such as solid particles and tablets. Semi-rigid PVC sheets are used as blister materials for aluminum-plastic blister packaging of tablets and capsules. As for the packaging of ointment, lotion, tincture, etc. Teflon with strong corrosion resistance and excellent comprehensive performance is adopted.

(5) Contact lenses are the most commonly used polymer materials in ophthalmology. The basic requirements for this kind of material are: ① excellent optical properties and refractive index close to cornea; ② Good wettability and oxygen permeability; (3) Bioinert, that is, resistant to degradation, and does not chemically react with the contact surface; (4) It has certain mechanical strength, is easy to arrange and is resistant to stain precipitation. Commonly used contact lens materials include β-hydroxyethyl methacrylate, β-hydroxyethyl methacrylate -N- vinyl pyrrolidone, β-hydroxyethyl methacrylate-amyl methacrylate, polyglycerol methacrylate -N- vinyl pyrrolidone and so on. The titanium siloxane compound studied by Wu Runde of Zhejiang University of Technology, due to the addition of titanium alkoxide crosslinking agent in the polymerization system, increased the density of the material, reduced the curing shrinkage, and prepared excellent contact lens materials. In addition, the diseased cornea and lens can also be replaced by artificial cornea and intraocular lens. Artificial cornea can be made of silicone rubber, polymethacrylate or polyester film. The main material of intraocular lens can be polymethacrylate, and its additional claw branches can be polymers of methyl methacrylate and butyl methacrylate or polymers of cyclohexyl methacrylate and butyl methacrylate.

(6) Medical adhesives and sutures. Biomedical adhesive refers to tissue adhesive that binds tissues together. They should not only meet the requirements of ordinary soft tissue implants, but also meet the following requirements: ① Curing under the conditions that the living body can bear to achieve tissue adhesion; (2) rapid polymerization without excessive heat and toxic by-products; ③ Adhesive can be absorbed in the process of wound healing without interfering with the normal healing process. Commonly used adhesives are alkyl α-cyanoacrylate, methyl methacrylate-styrene * * * polymer and methylallyl methylene malonate. Surgical sutures can be divided into two categories: absorbable sutures and absorbable sutures. Non-absorbent fibers include natural fibers (such as silk, kapok, hemp and horse hair) and synthetic fibers (such as PET, PA, PP, PE monofilament, PTFE and PU). Absorbable materials include natural polymer materials (such as catgut, collagen, fibrin, etc. ) and synthetic polymer materials (such as polyvinyl alcohol, polyhydroxybutyrate, polylactic acid, polyamino acid and polyhydroxyacetic acid). Among them, sutures made of polylactic acid and polyglycolic acid or their polymers have attracted much attention because of their superior properties. This kind of suture is reliable in strength, strong in wound suture, biodegradable and absorbed by human body, and it is an ideal medical suture.

(7) Polymer materials for medical devices. Medical devices made of polymer materials include disposable medical supplies (syringes, infusion sets, examination instruments, nursing instruments, anesthesia and operating room instruments, etc. ), blood bags, urine bags, orthopedic materials. Disposable medical supplies are mostly made of common polymer materials such as polypropylene, poly-4- methyl-1- pentene. Blood bags are generally made of soft PVC or LDPE. The bandage made of PU has the advantages of fast healing speed, light weight and thin layer, and is not easy to cause skin inflammation. It can replace the traditional fixation material-gypsum for fracture fixation. Silicone rubber, polyester, polytetrafluoroethylene, polyanhydride and polyvinyl alcohol are all orthopedic materials with good performance, which have been widely used in artificial limb manufacturing and plastic surgery.

The development direction of medical polymer materials mainly includes:

(1) Biodegradable medical polymer materials have attracted much attention because of their good biodegradability and biocompatibility, and will be greatly developed both as slow-release drugs and as skeleton materials to promote tissue growth.

(2)En rillich put forward the concept of targeted drug delivery for the first time in 1906, that is, drugs are selectively distributed in the lesion to reduce its toxic and side effects on normal tissues, increase the drug concentration in the lesion tissues, and thus improve the drug utilization rate. Since then, the carrier materials of targeted drugs have attracted the interest of medical workers for a century. Among them, polymer nanoparticles are extremely important research hotspots at home and abroad in recent years because of their unique advantages.

(3) Any kind of material is in contact with environmental media through its surface, so the development and application of materials will inevitably involve the study of its surface problems. Generally, the surface of polymer materials has a weak reaction to the outside world, but due to the changes of external conditions (such as pH, temperature, stress, light, electric field, etc.), the structural morphology of some polymer surfaces will change in a short time. ), resulting in changes in surface properties. This is a smart polymer surface. Therefore, designing this smart surface will be an important aspect of the development of biomedical polymer materials.

(4) With the development of science, artificial organs made of polymer materials are developing from in vitro use to implantation. In order to meet the requirements of medical functionality and biocompatibility, enzymes and biological cells are immobilized on synthetic polymer materials to make various organs, which will make the development prospect of biomedical polymer materials more and more broad.

(5) Generally, in the application of tissue engineering, polymer scaffolds should be loaded with growth factors to promote tissue regeneration in living organisms. On the other hand, combining special adhesion factors, such as adhesin, on the scaffold can promote the adhesion of some cells and exclude other kinds of cells, that is, the scaffold can selectively adhere to cells. In order to combine growth factors and adhesion factors with degradable polymer materials, it is necessary to modify the surface of the materials, which is sometimes very difficult. Therefore, we can achieve the above goal by hybridizing with natural polymers. At the same time, because these materials have good mechanical properties, they can make up for the shortcomings of low strength and poor stability of natural polymer materials. It can be seen that the performance of bio-hybrid materials in this respect is quite outstanding, and it will certainly become a major trend in the development of medical bio-polymer materials.

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