Development of Antimicrobial Chitosan-Silver and Chitosan-Gold Nanocomposite Films by 3D Printing for Skin Application

Abstract Silver (AgNP) and gold (AuNP) nanoparticles are notable in nanomedicine for their unique properties and strong antibacterial effects; however, formulating them into skin-applied systems that preserve bioactivity while controlling nanoparticle exposure remains challenging. Herein, semisolid extrusion 3D printing of chitosan nanocomposite hydrogels loaded with AgNPs or AuNPs was used to manufacture personalized topical films with antimicrobial performance and minimized skin penetration risk. AgNPs and AuNPs were synthesized with comparable nanoscale dimensions (11.83 ± 3.74 nm and 11.67 ± 1.96 nm), enabling their uniform incorporation into chitosan matrices. The resulting inks presented topical-compatible pH (>4.0) and pronounced thixotropy with >90% viscosity recovery, translating into adequate performance in 3D printing. Nanoparticle incorporation afforded the tuning of properties such as swelling, mechanical behavior, and bioadhesion. Functionally, AgNP-loaded films exhibited the strongest broad-spectrum activity against Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans. Ex vivo porcine skin studies indicated that free nanoparticles were detectable only in the stratum corneum, whereas metals were not detected after application of the 3D-printed films, supporting effective nanoparticle confinement by the chitosan matrix. These results position 3D-printed chitosan-nanoparticle films as a promising platform for customizable antimicrobial dressings for infected skin wounds.