DLP 3D printing of pH-sensitive hydrogel wound dressings with tunable porosity and antimicrobial properties

3D printed hydrogel dressings offer new opportunities to combine structural customization with responsive therapeutic functionality for wound healing. In this work, pH-sensitive hydrogel scaffolds with tunable porosity and antimicrobial properties were fabricated via Digital Light Processing (DLP) printing. Two photocurable formulations were prepared: a non-responsive polyethylene glycol diacrylate (PEGDA) network and a pH-responsive PEGDA-acrylic acid (PEGDA-AAc) network containing ionizable carboxylic groups. Scaffolds with 0, 30, and 60% porosity were produced to investigate the combined effects of pore architecture and network chemistry. The printed scaffolds showed good external shape fidelity, while increasing porosity reduced compressive strength and strain at break in both formulations. PEGDA-AAc scaffolds displayed reversible pH-dependent swelling, with enhanced water uptake at neutral and mildly alkaline pH, whereas PEGDA controls remained essentially pH-independent. AAc incorporation markedly increased the loading of the cationic antiseptics benzalkonium chloride (BAC) and chlorhexidine digluconate (CHX), an effect further enhanced by scaffold porosity. The most porous PEGDA-AAc scaffolds achieved the highest loading and sustained release over 7 days. Both BAC- and CHX-loaded scaffolds inhibited planktonic and adherent P. aeruginosa and S. aureus , with BAC-loaded scaffolds exhibiting the strongest antibacterial efficacy under the tested conditions. PEGDA-AAc scaffolds also promoted higher fibronectin adsorption and supported mesenchymal stem cell metabolic activity more effectively than PEGDA controls. Unloaded scaffolds were non-hemolytic, and in ovo HET-CAM assays confirmed good tissue compatibility. These findings demonstrate that combining controlled porosity with pH-responsive PEGDA-AAc chemistry enables the design of multifunctional 3D-printed wound dressings with tunable swelling, sustained antimicrobial delivery, and promising biological performance.