Self-healing and pH-responsive agar/κ-carrageenan hydrogels for dynamic burn wound dressings: Conventional versus microwave-assisted synthesis

The management of burn wounds in dynamic body regions requires wound dressings that combine robust mechanical performance with favorable biological activity. In this comparative study, the influence of conventional thermal heating (A/κ-CG) and microwave-assisted synthesis (MW-A/κ-CG) on the network formation and performance of self-healing, pH-responsive multiple-network hydrogels based on agar, κ-carrageenan, acrylamide, and acrylic acid was investigated following Fe³⁺-mediated ionic crosslinking and bromelain loading through passive immersion. Structural characterization by FTIR, SEM, EDX, and TGA demonstrated that the MW-A/κ-CG possessed a denser and more homogeneous polymeric network with a smaller average pore size (12.31 μm) and a higher gel fraction (93.85%). Accordingly, MW-A/κ-CG exhibited improved biomechanical performance, including rapid self-healing within 2 h over five consecutive cycles, a storage modulus of 92,700 Pa, a compressive strength of 645.59 kPa, and a tissue adhesive strength of 28.79 kPa. Bromelain release exhibited predominantly diffusion-controlled, pH-responsive behavior, reaching 86.31% after 120 h. MW-A/κ-CG also maintained excellent cytocompatibility (118% cell viability), promoted fibroblast migration (93.17% wound closure after 24 h), exhibited antioxidant and nitric oxide (NO) radical scavenging activity (63.85%), and demonstrated antibacterial activity against both Escherichia coli and Staphylococcus aureus , as evaluated by the agar diffusion assay. These findings demonstrate that the synthesis strategy influenced the structural organization and the resulting physicochemical, mechanical, and biological properties of the hydrogels, highlighting the potential of MW-A/κ-CG as a promising multifunctional wound dressing for burn wound management