Melatonin-loaded 3D-printed carboxymethyl cellulose-gold nanoparticles composite hydrogels for wound healing.

Developing sustainable, multifunctional materials that combine regenerative, antibacterial, and sensing properties remains a central challenge in advanced wound care. This work aims to develop biocompatible and biodegradable inks suitable for Digital Light Processing (DLP) 3D printing of personalized hydrogels capable of hosting melatonin and inducing gold nanoparticle formation for multifunctional composite wound dressings. The use of synthetic polymers in medical devices often raises concerns regarding post-use accumulation and environmental impact; therefore, sodium carboxymethyl cellulose (CMC) was selected as a renewable and versatile structural component. CMC was grafted with reactive double bonds to enable photopolymerization, yielding cost-effective, water-based inks that produced 3D-printed hydrogels with stable lattice-like architectures and mechanical integrity. The hydrogel discs hosted a pH-indicator dye, enabling a simple colorimetric display for real-time monitoring of the wound healing process. The 3D-printed hydrogels showed excellent biocompatibility, facilitated re-epithelialization, and promoted angiogenesis in an in ovo model. The hydrogels allowed for in situ formation of gold nanoparticles (AuNPs), and the obtained AuNP-composite hydrogel discs displayed antibacterial efficacy against S. aureus and E. coli upon near-infrared (NIR) irradiation (808 nm; 100 mW) through photothermal activation, highlighting their potential as advanced materials for regenerative and infection-responsive wound therapy.