Use of Polyurethane and Composites in Medical Textiles

Medical textiles and the related care and hygiene sector constitute an important and growing area of the textile industry. This growth is being realized through continuous progress and innovations in both textile technology and medical methods. Textile materials and products manufactured to meet specific requirements are suitable for medical and surgical applications where strength, elasticity, and sometimes moisture and air permeability characteristics are jointly needed. The materials used are monofilament or multifilament yarns, woven, knitted, nonwoven and composite-structured fabrics. Medical textile applications are used across a broad spectrum ranging from surgical sutures to complex composite structures used in bone transplantation and from simple cleaning cloths to advanced protective gown fabrics used in operating rooms. These materials can be classified according to four separate and distinct application areas (Özdemir, 2006).   Non-Implantable (Non-Injectable) Materials: These are wound dressings, bandages, and plasters. Extracorporeal Devices: This category includes artificial kidneys, livers, and lungs. Implantable Materials: Examples include surgical sutures, vascular grafts, artificial ligaments, and artificial joints. Care/Hygiene Products: Medical textiles in this category include bed linens, garments, surgical gowns, fabrics, and cleaning cloths. Non-Implantable Materials: These materials are used in external applications on the body. They may or may not come into contact with the skin. Implantable Materials: These materials are used in the body to successfully repair through wound closure (surgical sutures) or implantation surgery (vascular graft, artificial ligament, etc.). On the other hand, the biological compatibility of these group products is the most important matter.

Surgical Sutures

Medical textiles in the surgical field are biologically degradable collagen, polyglycolic acid, polylactic acid, monofilament, braided, biologically non-degradable polyamide, PTFE, polyester, polypropylene, steel monofilament, and braided.

Soft Tissue Implants

These are artificial tendons made of PTFE, polyester, polyamide, silk, polyethylene. Additionally, woven, braided, artificial ligaments made of polyester, carbon braided, artificial cartilage made of low-density polyethylene fall into this category. Furthermore, artificial skin made of chitin, polymethyl methacrylate woven, nonwoven, contact lens/artificial cornea made of silicone, collagen polymer method also fall into this category.

Orthopedic Implants

Orthopedic implants are artificial joints/bones made of silicone, polyacetal, polyethylene, collagen, chitin, DBC, nonwoven, 3D woven, polymer method.

Cardiovascular Implants

These are vascular grafts made of polyester, PTFE knitted, woven, heart valves, polyester woven and knitted materials. In hospitals, potential sources of infection from patients are contaminating particles dispersed from bacteria-carrying care personnel. Conventional surgical gowns only prevent particles emanating from the surgeon; they are also a source of contamination that generates high levels of dust. For this reason, disposable surgical gowns are adopted products in protecting patients from these sources of contamination. These are generally composite materials made of, for example, nonwoven fabrics and polyethylene films (Rigby and Anand, 1997). The most commonly used natural fibers in this field are cotton and silk. However, regenerated cellulose fibers (viscose rayon) can also be included in this group. These are commonly used in non-implantable materials and care/hygiene products. On the other hand, synthetic fibers are also used due to their product diversity, special application areas, and unique characteristics they exhibit. The commonly used synthetic materials are polyester, polyamide, polytetrafluoroethylene (PTFE), polypropylene, carbon, and glass fiber. The second type of classification is related to the biological degradability of fibers. Biologically degradable fibers are cotton, viscose, polyamide, polyurethane, collagen, and alginate fibers that can be absorbed by the body within 2-3 months after implantation. Fibers that are slowly absorbed by the body and take more than 6 months to decompose are known as biologically non-degradable fibers. Some examples of these include polyester (for example Dacron), polypropylene, PTFE, and carbon (Anand, 1998).

Dressings Used in Wound and Burn Treatment

In wounds and burns, semi-permeable film dressings produced with various polyurethane mixtures are also used. These dressings can provide moisture vapor transmission at a rate of 3000 g/m2/24 hours or higher through high-tech films. Semi-permeable film dressings are frequently used today in surgical wounds and in the treatment of pressure ulcers. These dressings are ideal for preventing skin damage from friction because they adhere well to the wound surface and show good compatibility with the wound surface. Film dressings generally find a broad range of applications together with hydrogel, hydrocolloid, and alginate dressings (Hanna and Giacopelli, 1997; Langenhove, 2007). Another type of dressing used for wound coverage purposes is cellulosic dressings derived from bacteria (Figure 10). Due to its extraordinary physicochemical properties such as high purity, strong mechanical properties, and high water retention capacity in the wet phase, bacterial cellulose has a wide range of applications in the medical field (Klemm et al., 2001). Another type of dressing found within modern wound dressings is hydrocolloid dressings. Hydrocolloid dressings have found various applications within medical textiles. These dressings are composed of hydrophilic polymer particles. These particles are polymers with hydrophilic structure such as sodium carboxymethyl cellulose, pectin, gelatin, and sodium alginate. Hydrocolloid dressings generally consist of a hydrocolloid matrix coated over a polymeric membrane or film layer. When hydrophilic particles come into contact with wound fluid, they absorb the wound fluid and convert this fluid into gel form. Hydrocolloid dressings can remain on the wound for up to seven days (Menaker, 2001; Langenhove, 2007; Altay and Başal, 2010).

Biomaterials

Biomaterial is a natural or synthetically produced material that is in continuous contact with living tissue for the purpose of performing the functions of living tissues in a living system, supporting them, or treating their functional part. Biomaterials are divided into four main classes. These are metals, ceramics, polymers, and composites. Composite is a type of biomaterial formed by two or more materials while maintaining their own boundaries. It can be composed of reinforcement and matrix structures. In the electrospinning method, polymers are used as matrix material while additives are used as reinforcement elements [1-3]. Polylactic Acid (PLA) is an environmentally friendly thermoplastic polymer. Aliphatic polyesters like PLA are biologically compatible polymers with mechanical properties, transparency, and non-toxic characteristics. With these properties, it is used in consumer products such as packaging, automotive, furniture, food, textile, and pharmaceutical industries. As a consumer product manufactured using PLA are clothes, kitchen utensils, and food packages. PLA used in the medical sector can be used in diapers, women's hygiene products, medical sutures, stents, and pharmaceutical applications [1-3]. In this study, the production of mats manufactured using nanotechnological electrospinning technique as mask material with filtering properties against viruses and bacteria has been achieved.   Filter Production with Electrospinning Technique: A 10% PLA polymer solution was prepared according to the desired temperature and stirring speed with the aid of a heated magnetic stirrer [3-5]. The production stages of filter mask material with electrospinning technique are shown in Figure 2.

References/Resources 1- "Investigation of Antibacterial Properties of Textile Surfaces", Umut Burak ALTINOK, Süleyman Demirel University Institute of Science, Department of Textile Engineering 2- "Dressings Used in Wound and Burn Treatment", Ahmet KOYUTÜRK, Devrim DEMİRAY SOYASLAN, Mehmet Akif Ersoy University, Institute of Science, Department of Materials Technology Engineering, Burdur 3- "Production of Nanotechnological Filters Effective Against Viruses and Bacteria", Erdi Buluş, Metallurgy and Materials Engineer, Materials Technology Specialist, Istanbul Arel University ArelPOTKAM (Polymer Technologies and Composite Application and Research Center), Gülseren Sakarya Buluş, Specialist Nurse, Silivri District Health Directorate