• ADA
• bi-layer scaffold
• biocompatibility
• electrospinning
• hydrogel
• Mesoporous bioactive glass nanoparticles (MBGNs)
• nanofibers
• nanomaterial
• PCL
• phytotherapeutic agents
• scaffold
• Tissue engineering
• wound healing

The skin is the largest organ of the body and performs multiple functions: it acts as a protective barrier against chemicals and pathogens, provides shielding from UV radiation, and contributes to excretion, hydration, thermoregulation, and vitamin D synthesis. It represents the body’s protective covering and interface with the environment, which makes it highly exposed and prone to frequent injuries. Skin regeneration, and therefore wound healing, is a highly complex process closely associated with other conditions such as cardiovascular diseases and diabetes. With the increasing incidence of these diseases, cases of chronic wounds are also rising. Traditional therapies, which mainly aim to reduce infection risk and promote wound closure, are proving to be limited and inefficient in response to this growing demand. The major limitation is that these approaches do not fully restore the skin’s original function or appearance, and scars that form may cause further problems in the patient’s life. Regenerative medicine seeks to restore the natural function of the skin and proposes scar-free solutions. Within regenerative medicine, tissue engineering represents a promising strategy that could revolutionize the treatment of chronic wounds. Tissue engineering integrates principles of engineering, medicine, and biology to develop biological substitutes for the repair and regeneration of damaged tissues and organs. It is based on three key elements: scaffolds, cells, and bioactive signals. Among scaffold fabrication techniques, electrospinning is widely used because it produces poly-ε-caprolactone (PCL) fibers that resemble the extracellular matrix. To improve scaffold biocompatibility and functionality, nanomaterials and bioactive compounds can be added. Mesoporous bioactive glass nanoparticles (MBGNs) are particularly useful thanks to their large surface area and controlled ion release, which support cell adhesion, proliferation, and tissue regeneration. Curcumin, a phytotherapeutic agent with strong anti-inflammatory properties, can also be embedded in PCL fibers to enhance their biological activity, especially during the inflammatory phase of healing. Hydrogels are another important group of biomaterials in tissue engineering. Alginate dialdehyde gelatine (ADA–GEL) hydrogels, with their high-water content and soft structure like the extracellular matrix, promote cell proliferation and tissue repair. They also provide a moist environment and allow controlled drug release. Their properties can be further improved by adding phytotherapeutic agents such as tea tree oil (TTO), which provides antimicrobial, anti-inflammatory, and antioxidant effects. In this study, a bilayer scaffold was developed for wound healing, with each layer supporting different phases of the healing process. The first layer is made of ADA–GEL hydrogel functionalized with TTO. Because of its antibacterial and anti-inflammatory effects, TTO is particularly suited for the inflammatory phase. ADA was synthesized from Laminaria hyperborea and Laminaria digitata with different oxidation degrees. Hydrogels were prepared at two different ADA-to-GEL ratios and crosslinked with calcium chloride and microbial transglutaminase. Morphological and compositional analyses were used to select the best formulation. This layer is designed to release TTO quickly, to prevent infection and control inflammation in the early healing stage. The second layer consists of aligned electrospun PCL fibers with curcumin and boron-doped MBGNs. Electrospinning creates fibers that mimic the extracellular matrix and support adhesion, proliferation, and tissue regeneration. PCL is biodegradable, biocompatible, and mechanically strong, but its hydrophobic nature and acidic degradation products may limit cell response. Adding MBGNs helps buffer the local pH, improve the cellular environment, and regulate degradation. Boron doping increases the angiogenic and antibacterial activity of MBGNs. Curcumin is gradually released to support the proliferative and remodelling phases by reducing inflammation, limiting oxidative stress, and promoting regeneration. Overall, the bilayer scaffold combines a TTO-loaded ADA–GEL hydrogel layer with a curcumin- and MBGN-loaded PCL fiber layer. This system not only supports all phases of wound healing in a controlled way but also mimics the multilayered structure of the epidermis, making it a promising strategy for advanced wound care.