9.7.2.1 Definition and classification of medical d...
Medical dressing is a kind of biomedical material that can stick to the wound，control the infection，promote the repair of the skin injury and avoid the formation of the scar.Biomedical dressings can be divided into passive dressings，interactive dressings and bioactive dressings.The different materials，physical forms，architecture of theses dressings leading to functions and applicable wound types are also different.
（ⅰ）Passive dressings，such as gauze and tulle dressings，are used to cover the wound and restore the structural function.
（ⅱ）Interactive dressings，such as foams，hydrogels and hydrocolloids，are used to prevent the penetration of bacteria in the wound.(https://www.daowen.com)
（ⅲ）Bioactive dressings，such as collagen，hyaluronic acid，chitosan（CS），alginate and elastin，are biocompatible，biodegradable and non-toxic.They can be used separately and in combination.Interactive dressings and bioactive dressings belong to modern dressings that can prevent wound dehydration and promote healing.Hydrogel dressing is considered ideal for wound dressings.Nanotechnology is also being used in medical dressings，organic and non-organic NPs（e.g.，polymeric NPs and silver NPs，respectively）can carry growth factors，antimicrobials and drugs to stimulate wound healing.A variety of biomedical dressings have been reported for skin burns：such as Ag+sulfadiazine-containing nanosheetbased ultra-thin films，NO-releasing polymer films，and tyrothricin（cyclic polypeptide antibiotic）-containing CS-based film-forming gel layers.These dressings are non-toxic，which can inhibit inflammation，reduce scarring，and promote epithelialization and granulation tissue formation.