Alginate–Nanosilver Hydrogels: A Self-Dissolving System for Comprehensive Preservation of Waterlogged Wooden Artifacts

The utilization of biomass-based hydrogels represents a versatile approach toward the conservation of waterlogged wooden artifacts, showcasing the potential of sustainable technologies in mild and long-term cultural relic treatments while simplifying preservation procedures to minimize environmental impact. Alginate/polyacrylamide hydrogels offer promising potential as substrate materials for conserving waterlogged wooden artifacts. Their robust mechanical properties and flexible functionality address specific preservation requirements, such as antimicrobial, moisturizing, and deacidifying needs, thereby enhancing the effectiveness and adaptability of conservation efforts. Herein, a self-dissolving hydrogel with antibacterial and deacidifying effects was prepared using silver nanoparticles (AgNPs) embedded in alginate/polyacrylamide hydrogels and used for the conservation of waterlogged archeological wood obtained from Nanhai No. 1, an 800-year-old shipwreck salvaged from the South China Sea. Its self-dissolving characteristics can effectively avoid damage to the wood when removing the hydrogel. The embedded AgNPs were found to provide a good preservation effect on wooden cultural relics in terms of solubility, stretchability, and antibacterial properties due to their tunable interaction with the polymer chains, which was characterized through scanning electron microscopy (SEM), gel permeation chromatography (GPC), mechanical testing, antibacterial experiments, etc. The gels can be stretched to 20 times their initial length and demonstrate a 99% reduction in bacterial presence. This innovative hydrogel effectively neutralizes the acid generated by bacteria metabolism and notably possesses self-dissolution behavior that avoids the damage caused by peeling off the hydrogel from the wood surface. These characteristics provide a distinct advantage for the timely protection and multipurpose preservation of wooden artifacts and offer potential in other comparable scenarios.