2.2.2.1　Skin wound infection

Skin acts as the external barrier of body，which is susceptible to the insult of pathogenic microorganisms.In addition，there are a lot of resident flora on the skin surface.Skin wounds are likely to be infected when the integrity of skin is destroyed.Excessive sustained inflammation process caused by infection is one of the main factors in non-healing wounds.It is estimated that more than 2％of the American population suffer non-healing wounds and more than$20 billion annually poured into treating wound related infections.

Conventional therapies of skin wounds include topical antibiotic ointments，growth factor agents and wound dressings.However，this method is often accompanied by antibiotic-resistance，intensive pain during dressing change，and professional operations.As the proposal of the theory of wet wound healing and the synthesis of new materials，hydrogel which contain many water is developing rapidly in the medical field.Hydrogel could keep the wound moist，absorb exudate of tissue and possess well biological safety.Currently，more studies focus on hydrogel with antibacterial drugs，combined the antibacterial properties and the advantages of promoting wound healing.(https://www.daowen.com)