Abstract: BACKGROUND: As a high-water-content polymer similar to extracellular matrix, hydrogels are widely used in various tissue repairs due to their excellent biocompatibility. However, pure hydrogels are difficult to meet the complex clinical situations, such as bacterial infection and slow tissue regeneration rate. Therefore, it is necessary to develop bio-functional composite hydrogels.
OBJECTIVE: To develop a methacrylated gelatin/MXene/calcium peroxide hydrogel with high antibacterial properties and evaluate its photothermal effect and antibacterial properties in vitro.
METHODS: (1) Methacrylated gelatin solutions, methacrylated gelatin solutions containing 300 μg/mL MXene, methacrylated gelatin solutions containing 5 mg/mL calcium peroxide, and methacrylated gelatin solutions containing 300 μg/mL MXene and 5 mg/mL calcium peroxide were prepared. After adding a photoinitiator, the solutions were cured under 365 nm ultraviolet light for 5 minutes. Methacrylated gelatin hydrogels (G hydrogel), methacrylated gelatin/300 μg/mL MXene hydrogel (GX hydrogel), methacrylated gelatin/calcium peroxide hydrogel (GC hydrogel), and methacrylated gelatin/MXene/calcium peroxide hydrogel (GXC hydrogel) were obtained. The surface morphology and photothermal properties of the four hydrogels were characterized. The GC and GXC hydrogels were immersed in PBS and incubated with vibration to measure Ca2+ release. (2) Staphylococcus aureus suspensions were co-cultured in each of the four hydrogel groups. A single culture of the bacteria served as a control. The hydrogels were irradiated with a near-infrared laser (808 nm, 1.5 W/cm²) for 5 minutes (or without near-infrared laser irradiation). The antibacterial properties of the hydrogels were evaluated by scanning electron microscopy, plate spread assay, live/dead staining, 5-cyano-2,3-ditolyl tetrazolium chloride (CTC) staining, and reactive oxygen species staining. (3) The four hydrogel groups were co-incubated with rat erythrocyte suspensions to measure hemolysis rates. The four hydrogel groups were co-cultured with osteoblast precursor cells MC3T3-E1 (or mouse fibroblast L929). Cell viability was assessed using CCK-8 assay and cell viability was assessed using live/dead staining.
RESULTS AND CONCLUSION: (1) Scanning electron microscopy revealed that all four hydrogel groups had a loose porous structure. The pore surfaces of the G and GX hydrogels were smoother, while those of the GC and GXC hydrogels were rougher. After near-infrared laser irradiation, the GX and GXC hydrogels exhibited excellent photothermal performance and stability, meeting the requirements of subsequent photothermal antibacterial applications. Both GC and GXC hydrogels were able to slowly release Ca2+ for up to 20 days. (2) Scanning electron microscopy, plate coating assay, live/dead staining, CTC staining, and reactive oxygen species staining revealed that the GC and GXC hydrogels exhibited excellent antibacterial properties without infrared laser irradiation. After near-infrared laser irradiation, the GX, GC, and GXC hydrogels exhibited excellent antibacterial properties, with the antibacterial properties of the GX and GXC hydrogels significantly enhanced compared to those without infrared laser irradiation. (3) The hemolysis rates of all four hydrogel groups were less than 5%, demonstrating excellent hemocompatibility. Live/dead staining and CCK-8 assay revealed that the four groups did not significantly affect the viability and activity of MC3T3-E1 and L929 cells, demonstrating good cytocompatibility. (4) These results demonstrate that the methacrylated gelatin/MXene/calcium peroxide hydrogel exhibits excellent antibacterial properties and biocompatibility.

Key words: 复合水凝胶, 甲基丙烯酸酐化明胶, 感染, 抗菌, 光热效应, 成骨前体细胞, 小鼠成纤维细胞, 生物材料