Medicine artificial implants

Nanofibers have applications in medicine, artificial organ components, tissue engineering, implant material, drug deliveiy, wound dressing, and medical textile materials. Nanofiber meshes... 

The polysulfones are biologically inert and resistant to steam sterilization and y-radiation what avails people to use them in medicine when implanting artificial lens instead of removed due to a surgical intervention and when producing medical tools and devices (inhalers bodies, ophthalmoscopes, etc.). 

Biological systems produce proteins that possess the ability to self-assemble into complex, yet highly ordered structures [1], These remarkable materials are polypeptide copolymers that derive their properties from precisely controlled sequences and compositions of their constituent amino add monomers. There has been recent interest in developing synthetic routes for preparation of these natural polymers as well as de novo designed polypeptide sequences to make products for apphcations in medicine (artificial tissue, implants), biomineralization (resihent, lightweight, ordered inorganic composites), and analysis (biosensors, medical diagnostics) [2, 3]. 

For much of the last century, scientists attempted to make useful plastics from hydroxy adds such as glycolic and lactic acids. Poly(glycolic acid) was first prepared in 1954, but was not commercially developed because of its poor thermal stability and ease of hydrolysis. It did not seem like a useful polymer. Approximately 20 years later it found use in medicine as the first synthetic suture material, useful because of its tendency to undergo hydrolysis. After the suture has served its function, the polymer biodegrades and the products are assimilated (Li and Vert 1995). Since then, suture materials, prosthetics, artificial skin, dental implants, and other surgical devices made from polymers and copolymers of hydroxy carboxylic acids have been commercialized (Edlund and Albertsson 2002). 

In the field of medicine, biomimetic solutions and products span the range from externally worn biomimetic devices that augment the function of sensory organs such as hearing aids and artificial corneas to implantable biomimetic devices. Implantable devices function as (i) simple physical replacements including silicone implants used in cosmetology, dentures and dental implants, and artificial... 

Engineering plastics, particularly thermosets, are also used in composite materials. Their excellent technological properties make them suitable for applications in cars, ships, aircraft, telecommunications equipment, etc. In recent years, important new areas of application for plastics have emerged in medicine (fabrication of artificial organs, orthopaedic implants, and devices for the controlled release of drugs), electronics (development of conductive poly-... 

The application of polymeric materials in medicine is a fairly specialized area with a wide range of specific applications and requirements. Although the total volume of polymers used in this application may be small compared to the annual production of polyethylene, for example, the total amount of money spent annually on prosthetic and biomedical devices exceeds 16 billion in the United States alone. These applications include over a million dentures, nearly a half billion dental fillings, about six million contact lenses, over a million replacement joints (hip, knee, finger, etc.), about a half million plastic surgery operations (breast prosthesis, facial reconstruction, etc.), over 25,000 heart valves, and 60,000 pacemaker implantations. In addition, over AO,000 patients are on hemodialysis units (artificial kidney) on a regular basis, and over 90,000 coronary bypass operations (often using synthetic polymers) are performed each year (]J. 

The main requirement imposed on all polymer biomaterials applied in medicine is a combination of their desired physicochemical and physicomechanical characteristics with biocompatibility. Depending on particular applications, the biocompatibility of polymers can include various requirements, which can sometimes be contradictory to each other. Thns, in the case of artificial vessels, drainages, intraocular lenses, biosensors, or catheters, the interaction of the polymer with a biological medium should be minimized for the rehable operation of the corresponding device after implantation. In contrast, in the majority of orthopedic applications, the active interaction and fusion of an implant with a tissne is required. General requirements imposed on all medical polymers consist in non-toxicity and stability. 

Other uses are found in plastic surgery, artificial skin and blood substitutes. An unique field is found in membranes for dialysis. PE, mostly linear (including UHMW), serves in many implants or in artificial joints. PVC is the most useful polymer in medicine, in plasticized form for flexible tubing, dialysis and infusion systems. PP is offered for disposible injections and, together with ethylene (copolymer), in blood bags. PS serves as a substitute for glass in tubes, bottles and petri dishes, and as the copolymers SAN or ABS in a wide host of uses. Polyester (PET) is used in sewing threads or nets in prostheses. PC is used (as a replacement for cellophane) in membranes for dialysis as well as in blood pumps and other systems. 

Textile materials are used in a wide variety of applications in healthcare and medicine which include implantable materials for in vivo applications. Vascular grafts, artificial ligaments, artificial blood vessels and mesh gra are typical implantable medical devices. High-tech advances in tissue engineering have enabled researchers to cultivate implantable hiunan organs to the required shape by growing living cells on textile sc olds. 

Chapter 5 by Ishihara and Fukazawa focuses on polymers obtained from 2-methacryloylo>yethyl phosphorylcholine (MPC) monomer. Indeed, the molecular design of MPC polymers with significant functions for biomedical and medical applications is summarized in detail. It is especially shown that some MPC polymers can provide artificial cell membrane-like structures at the surface as excellent interfaces between artificial systems and biological systems. In the clinical medicine field, MPC polymers have been used for surface modification of medical devices, including long-term implantable artificial organs to improve biocompatibilily. Thus some MPC polymers have been provided commercially for these applications. 

When sensors detect that a patient needs medication, the artificial muscles will shrink away from the holes in the wall to let medicine pass into the bloodstream. Once the right amount of medicine has left the capsule the muscles will swell back up and plug the holes once again. When the capsule runs out of medicine, it could be surgically removed and a new one implanted. In a new application for artificial muscles a scientist at Ohio State University has developed a system for automatically dispensing medicines from an implant. 

Finally, it should be stressed that an antithrombogenic surface is merely one condition of the blood compatibility of biomaterials which can be used in medicine. If the biomaterial is implanted as blood pumps of artificial heart and vascular grafts, we should also take into consideration other important properties such as mechanical durability, calcification, bonding strength with respect to host tissue, etc. Studies on blood-compatible polymers have been started only since recently. 

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