2025, Vol. 29 ›› Issue (34): 7333-7343

Preparation and antibacterial evaluation of nanosilver-reduced graphene oxide/polydopamine/methacrylated gelatin@Gap19 hydrogel

Li Ruotong1, 2, 3, Wu Yuening1, 2, 3, Deng Yunyi2, 3, 4, Chen Shichao2, 3, 4, Lan Xiaorong2, 3, 4, Li Shiting1, 2, 3, Li Guangwen2, 3, 4   

Abstract: BACKGROUND: Vital pulp therapy is one of the main treatments for common oral diseases such as deep caries. The antibacterial properties of pulp-capping materials are crucial to the efficacy of the treatment. Currently, commonly used pulp-capping material has weak antibacterial properties and may induce a certain degree of inflammatory response in the pulp tissue, leading to treatment failure.
OBJECTIVE: To investigate the antibacterial effects of nanosilver-reduced graphene oxide/polydopamine/methacrylated gelatin@Gap19 (AgNPs-rGO/PDA/GelMA@Gap19) hydrogel material.
METHODS: Nanosilver-reduced graphene oxide was prepared. Human dental pulp stem cells were cultured in complete medium containing different mass concentrations of nanosilver-reduced graphene oxide. Cell proliferation was detected by CCK-8 assay. The inhibition zone assay was used to detect the inhibitory effect of different mass concentrations of nanosilver-reduced graphene oxide on Staphylococcus aureus. The nanosilver-reduced graphene oxide mass concentration with the most obvious cell proliferation and antibacterial effects was screened by the results of CCK-8 and inhibition zone assays, and loaded into hydrogels. Human dental pulp stem cells were cultured in complete medium containing different concentrations of Gap19 (a specific inhibitor of connexin 43 hemichannels), and cell proliferation was detected by CCK-8 assay. The Gap19 concentration with the most obvious cell proliferation effect was screened and loaded into hydrogels. AgNPs-rGO/PDA/GelMA@Gap19 hydrogel was prepared, and the physicochemical properties of the hydrogel material were characterized. The suspension of Staphylococcus aureus (or Escherichia coli, Streptococcus mutans, Lactobacillus) was co-cultured with mineral trioxide aggregates, polydopamine/methacrylated gelatin hydrogel, nanosilver-reduced graphene oxide/polydopamine/methacrylated gelatin hydrogel and AgNPs-rGO/PDA/GelMA@Gap19 hydrogel. The bacterial suspension cultured alone was used as the blank control group to detect the antibacterial rate of each group of hydrogels.
RESULTS AND CONCLUSION: (1) The optimal mass concentration of nanosilver-reduced graphene oxide was determined to be 12.5 μg/mL by CCK-8 assay and inhibition zone test results, and the optimal concentration of Gap19 was determined to be 20 μmol/L by CCK-8 assay. (2) Scanning electron microscopy showed that AgNPs-rGO/PDA/GelMA@Gap19 hydrogel was wrinkled and porous, and nanosilver was loaded on the surface and inside of the hydrogel. Energy spectrum analysis results showed that nanosilver-reduced graphene oxide and Gap19 were successfully loaded on the hydrogel. (3) The four hydrogels had obvious inhibitory effects on Staphylococcus aureus, Escherichia coli, Streptococcus mutans, and Lactobacillus, and the antibacterial effects of nanosilver-reduced graphene oxide/polydopamine/methacryloyl gelatin hydrogel and AgNPs-rGO/PDA/GelMA@Gap19 hydrogel were the most significant, indicating that AgNPs-rGO/PDA/GelMA@Gap19 hydrogel, as a new type of pulp capping material, has an obvious antibacterial effect.

Key words: silver nanoparticle, reduced graphene oxide, Gap19, methacryloyl gelatin, hydrogel, antibacterial property, engineered dental material