Digital light processing (DLP) 3D-fabricated antimicrobial hydrogel with a sustainable resin of methacrylated woody polysaccharides and hybrid silver-lignin nanospheres

Lithography-based digital light processing (DLP) 3D printing has gained increasing interest in the fabrication of custom-designed hydrogel scaffolds. Current research development calls for the versatility of the bio-based resin formulations that deliver a suitable printability for fabricating biomedical hydrogel using DLP printing. Here, a bio-based antimicrobial resin was developed for DLP printing engaging the methacrylated O-acetyl-galactoglucomannan (GGMMA) as a photo-crosslinkable polymeric matrix and the nanocomposite lignin nanoparticles that are surface-embedded with silver nanoparticles (LNP@Ags) as a high-performance antimicrobial reagent. The alkali-resistance of LNPs as demanded for in situ reduction of silver nanoparticles (AgNPs) from silver ammonia solution (pH 11) was achieved by upgrading the technical lignin via a combination of lignin solvent fractionation with laccase-catalyzed polymerization. The dimension of the as-prepared LNPs (in the range of 120-290 nm) and the content of residual phenolic hydroxyl and methoxyl groups for reducing Ag ⁺ could be modulated by tuning the laccase-catalyzed lignin polymerization degree. The encapsulation of nanocomposite LNP@Ag into the GGMMA hydrogel did not significantly alter the gelation rate of the GGMMA/LNP@Ag resin and the mechanical property of the resulted hydrogel, when the dosage of LNP@Ag was less than 0.1 wt% in 10 wt% GGMMA. The GGMMA/LNP@Ag hydrogel also possesses high antimicrobial activity due to the bactericidal ability of Ag ⁺ that was leached out of the hydrogel in a sustained manner. Upon the layer-by-layer photocuring in DLP printing, the GGMMA/LNP@Ag resin allowed us to fabricate hydrogel constructs, including honeycomb and crosshatch with good structural stability and printing fidelity. This study proposes a green and effective fabrication route for LNP supported AgNPs as well as a novel case study for a sustainable resin suitable for DLP 3D hydrogel printing.