Color-changeable and separable PLA/PVP/chitosan tri-layer self-pumping dressing containing astragalus for promoting the healing of infectious burn wound

Infectious burn wounds are characterized by substantial exudate and inflammation. Ordinary wound dressings struggle to absorb substantial exudate. In this study, a color-changeable and separable polylactic acid/polyvinylpyrrolidone/chitosan tri-layer self-pumping dressing containing astragalus polysaccharide was developed. The dressing had an outer layer of polyacrylonitrile/polyvinylpyrrolidone/CoCl 2 nanofiber, a middle layer of polylactic acid/polyvinylpyrrolidone/chitosan nanofiber, and an inner astragalus polysaccharide drug-carrying layer. It could unidirectionally absorb wound exudate and change color after absorbing exudate. In addition, after absorbing the exudate, the outer layer of the dressing could be separated, the remaining double layers consisted of a drug layer and antimicrobial chitosan promoted wound healing and reduced infection. The water absorption rate of the tri-layer nanofibers reached 2770.70 ± 122 % per time, and the water vapor transmission rate was 4585.99 ± 65 g∙m −2 ∙day −1 . The nanofiber dressing promoted the proliferation, migration, and adhesion of L929 cells. After treating burn-infected rats with this dressing for 14 days, the rats' collagen content and anti-inflammatory levels increased. In conclusion, the color-changeable and separable polylactic acid/polyvinylpyrrolidone/chitosan tri-layer self-pumping dressing containing astragalus developed in this study can effectively accelerate wound healing.