3D printing of wet-bonded multilayer scaffolds for skin wound repair

The skin repair process is significantly influenced by the regulation of a dynamic mechanical microenvironment. However, traditional single-layer scaffolds face limitations, including poor mechanical compatibility and weak interfacial adhesion. These drawbacks stem from their inability to mimic the multilayer heterogeneous structure and functional synergy of natural skin. In this paper, a biomimetic skin extracellular matrix (ECM) scaffold with a layered structure bio-polycaprolactone (PCL) skin (BPS) is proposed, consisting of three layers: a surface layer (SL), a support layer (PL), and a base layer (BL). The SL consists of a 3D-printed microporous PCL structure, which simulates the epidermal barrier’s antibacterial and breathable properties. The PL, a surface-modified multilayer PCL scaffold, mimics the dermal layer and provides essential mechanical support and elasticity. The BL, a hydrogel coated onto the surface of the PL, provides excellent biological properties. Genipin serves as a crosslinker, and ethylenediamine is used for amination treatment of the PCL scaffold surface. This chemical crosslinking strengthens interlayer connections, enhancing functional synergy and tripling the anti-swelling properties of the hydrogel. Additionally, it improves the wet adhesion of the scaffold to skin tissue, ensuring stable adherence to the wound surface. Compared to traditional scaffolds, this multilayer structure effectively integrates biological functions with mechanical performance, providing sustained protection and support during wound healing.