Sprayable polysaccharide-based biomimetic double dressing with synergistic regulation for wound healing

Current sprayable hydrogel dressings often fail to achieve the functional integration required for complex wounds, owing to inherent design flaws and a lack of synergistic action, which delays healing and promotes scarring. Inspired by the stratified structure and dynamic repair functions of human skin, we developed a sprayable, biomimetic double-layer polysaccharide dressing (BDD) that integrates the immunomodulatory compound mangiferin (MGF). This integrated system, termed MGF@BDD, rapidly self-assembles via sequential spraying, offering adhesion and wound adaptability. The distinctive strength of MGF@BDD is its spatiotemporally coordinated bioactivity, enabled by synergistic regulation between its layers in response to the dynamic wound microenvironment. The dense top layer, reinforced by Ca²⁺-Ba²⁺ dual-ion coordination, provides immediate hemostasis and enzyme-resistant mechanical protection. In contrast, the porous bottom layer acts as an intelligent reservoir for MGF, maintaining a regenerative niche. During the inflammatory phase, the acidic environment triggers the hydrolysis of dynamic bonds within the bottom-layer, accelerating MGF release for anti-inflammatory and anti-oxidative effects, while Ca²⁺-Ba²⁺ ions released from the top layer synergistically suppress inflammation at its source. As healing progresses into the proliferative phase, the network stabilizes under neutral conditions, switching to the sustained co-release of MGF and Ca²⁺ to effectively promote angiogenesis and tissue remodeling. Both in vitro and in vivo experiments have confirmed that MGF @BDD can effectively promote wound healing, as evidenced by significantly accelerated wound closure and reduced collagen disorder. Constructed via a simple two-syringe process, this work presents an adaptive system capable of dynamically regulating the healing cascade, offering a novel strategy for the functional regeneration of complex wounds.