Applications of the High Polymers in Medical Science

Introduction

With the wide application of high polymers, more and more extensive researches on high polymers have been conducted in recent years. Many papers and monographs discussed the important characteristics of high polymers and their important applications in medicine. Macromolecule/high polymers can be used in surgery, suture, orthopedic fixation and tissue repair. They can also be used as drug carrier materials in drug controlled release systems. According to relevant researches, the following describes the important applications of several common polymers in medicine science.

1 Surgical suture

Due to its biodegradability and absorbability in the body,polylactic acid and its copolymers can be used as surgical sutures to promote wound healing and can be automatically degraded and absorbed after wound healing. So it is not necessary to remove this kind of sutures after surgery. The ideal surgical suture material should have a strong initial tensile strength and a degradation rate that is consistent with the wound healing time. Only in this way can the polymer possess good mechanical properties in the initial stage of the suture wound, and afterwards, with the healing of the wound, the mechanical strength decreases and the suture slowly degrades.

2 Orthopedic fixation and tissue repair

2.1 Polylactic acid can be used as a fixed material

The lactic acid material can be processed into sheets, plates or nails and can be used as internal fixation devices such as bone splints and bone screws. Compared with the traditional stainless steel metal materials, polylactic acid materials avoid the secondary surgery to remove the fixed material after healing due to the biodegradability and absorbability of lactic acid material. In the 1980s, polylactic acid was successfully used as a bone material. A large number of clinical trials have shown that polylactic acid, as a fixed material in the human body, has a low incidence of inflammation, high intensity, and no postoperative infection. At present, researches are being accelerated at home and abroad. Polylactic acid materials are expected to be used in the repair and cultivation of blood vessels, ligaments, skin, liver and other tissues.

2.2 Polyanhydride can be used for tissue repair

The water-soluble protein such as cartilage protein, bone protein and polyanhydride carriers were implanted into the wound site of the bone tissue. The protein substances were used to react with the wound cells to promote wound healing.

2.3 Polydioxanone can be used as a fixing material

The biodegradability, low glass transition temperature, high room-temperature strength and stretchable properties of Poly(dioxanone) make it a unique material to be used in surgical internal fixation. For example, it can be processed into a pedicle screw to fix the mandibular horn fracture. And it can be processed into dish-shaped shims to repair the orbital floor fracture, the eyeball will naturally return to the right position after the spacer is absorbed.

3 Drug delivery material in drug delivery system

Polylactic acid and its copolymers can be used as soluble carrier materials for the preparation of sustained-release preparations and targeted delivery preparations. Polylactic acid and its copolymers can be made into specific pharmaceutical dosage forms based on the nature of the drug, the release requirements, and the route of administration. For example, the release rate of the drug can be adjusted by selecting lactic acid copolymers with different molecular weights and different photoactivity. At present, some sustained-release drugs such as polylactic acid sustained-release tablets of insulin, poly-lactic acid cylinders of gentamycin, and block-like implants of growth hormone releasing hormone are mainly prepared by solution molding and hot pressing. Polylactic acid can also be made into films, emulsions and other dosage forms to control the release of drugs. At present, the research hotspot is how to prepare more powerful drug preparations that can effectively control the release of drug and can be targeted for treatment.

4 Ophthalmic materials

With the increasing pressure of work and study, the incidence of ophthalmologic diseases has gradually increased, and especially retinal detachment, which has become one of the most common eye diseases. The traditional surgical treatment of implanting silicone rubber and silicone sponge fillers on the surface of the sclera has been replaced by implanting polylactic acid material to avoid the foreign body reaction. These two materials cannot be degraded and easily cause foreign body reactions.

Development prospect in future

With the application of nanomaterials in polymer science and the synthesis of new polymer nanoparticles, the application of high polymers in medicine has more extensive development prospects. For example, the University of Tokyo, Japan, has developed a new gel-like medical material by combining nanoscale micromolecular rings and high polymer. The passing rate of visible light of this new material is as high as 98.2%, and the material can be restored to its original shape without any damage even it is elongated by 8 times. This excellent material is expected to be used to produce contact lenses and other medical products. Adding nano-particles to medical chemical fiber products and textiles can play a role in deodorization, sterilization, and disinfection.

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