A synergistic antibacterial effect between terbium ions and reduced graphene oxide in a poly(vinyl alcohol)–alginate hydrogel for treating infected chronic wounds

An antibacterial hydrogel shows promise for treating infected chronic wounds, but it is commonly difficult to disrupt bacterial biofilms, and incorporation of antibiotics in the hydrogel may lead to antibiotic resistance. To overcome these limitations, reduced graphene oxide (rGO) and rare earth terbium ions (Tb3+) were incorporated in a poly(vinyl alcohol) (PVA)-alginate (SA) hydrogel. Compared with the PVA-SA hydrogel, the PVA-SA hydrogel containing Tb3+ (PVA-SA-Tb) reduced the number of Gram-positive Staphylococcus aureus and Gram-negative Pseudomonas aeruginosa in biofilms by 1.5 and 1 orders of magnitude, respectively. Further incorporation of rGO that did not exhibit antibacterial properties alone in the PVA-SA-Tb hydrogel (PVA-SA-rGO-Tb) raised the killing efficacy of Staphylococcus aureus and Pseudomonas aeruginosa in biofilms by 1.5 and 2 orders of magnitude, respectively. We found that such a synergistic antibacterial effect between Tb3+ and rGO resulted from the increased loading and release of Tb3+ owing to rGO-induced loosening of the hydrogel network. The in vivo assay further shows that the PVA-SA-rGO-Tb hydrogel can effectively promote the healing of infected wounds in diabetic rats. These results demonstrated that the PVA-SA-rGO-Tb hydrogel which contains no antibiotics shows promise for treating infected chronic wounds.