11.1.2　Wound dressings

Wound dressings are materials that wrap wounds to cover sores，wounds，or other damage.Wound dressings include primary dressings that are in direct contact with the wound bed and secondary dressings that play an auxiliary role on top of the covered primary dressings.The primary dressings directly cover the wound surface，to treat and protect the wound surface.The secondary dressings can play a role in consolidating the primary dressing，to more fully meet the needs of wound healing.

Early wound dressing products include gauze，tape，natural or synthetic bandages，and absorbent cotton.The gauze dressings are made of woven and non-woven fiber cotton，rayon，and polyester.Because they are cheap and easy to obtain，they are suitable for drainage of many wounds.While due to their dry nature，they can adhere to the wound and cause pain during removal.The gauze dressings can provide some protection to the wound，but it needs to be changed frequently to prevent the maceration of healthy adjacent tissues，which may increase costs and cause repetitive tissue damage.Therefore，when using gauze as a dressing，it can be impregnated with paraffin，iodine，or petroleum to avoid drying，providing a non-adhesive coverage.In 1971，Dr.Winter firstly proposed the concept of“wet wound healing”.They found that the intact blister healed about 2 times quicker than the broken blister，and pointed out that because the epithelial cells could not migrate through the dry or crusted cell layer，they took time to migrate to the moist bed under the scab，allowing the epithelial cells heal longer.A moist environment could promote epithelial cells crawling and reduced scar formation.This conclusion laid the foundation for modern wet wound healing theory，and at the same time promoted the rapid development of new wet wound healing dressings.Compared with the early traditional dressings（e.g.，gauze，oily gauze），new dressings have a positive effect on the wound，promoting hemostasis and the rapid healing of the wound.New dressings mainly include hydrogel dressings and fiber dressings，and these functional dressings are mainly produced by polymer materials.Therefore，the following sections will focus on the research progress of polymer materials in new wound healing dressings and composite functional dressings.(https://www.daowen.com)