RESUMO
Objective:To investigate whether the antibacterial copper sulfide (CuS)/graphene oxide (GO) nanosheets composite film can promote angiogenesis and osteogenesis in vitro. Methods:GO and CuS/GO nanosheets were synthesized and mixed into polyvinyl alcohol (PVA)/carboxymethyl cellulose (CMC) hydrogel films. The study was conducted in 4 groups: PVA/CMC/GO, PVA/CMC/CuS/GO, PVA/CMC (only PVA/CMC-based film) and blank control (no material). The PVA/CMC, PVA/CMC/GO and PVA/CMC/CuS/GO films were characterized by electron scanning microscopy and energy dispersive spectrometer. The biocompatibility of different films (PVA/CMC/CuS/GO films with concentrations of CuS/GO nanotablets of 0, 50, 100, 200, 400, and 800 μ g/mL) was evaluated by CCK-8, live/dead cell staining, and hemolysis test. The angiogenesis was evaluated by cell migration and tube forming test in vitro. Alkaline phosphatase and alizarin red staining were used to evaluate osteogenesis in vitro, and the expression of osteogenic genes was measured by immunofluorescence staining and RT-qPCR. In addition, the bacterial plate counting method and bacteriostatic circle method were used to evaluate the antibacterial activity of films. Results:In the PVA/CMC/GO and PVA/CMC/CuS/GO groups, the surface of the PVA/CMC-based film was smooth and flat whereas the nanosheets composite films were irregularly flaky and convex. The biosafety experiments showed that the PVA/CMC-based film composited with GO or CuS/GO nanosheets at the concentration of 100 μg/mL had good biocompatibility. The results of angiogenesis in vitro showed that the migration ratio of HUVEC cells in the PVA/CMC/CuS/GO group was significantly better than those in the PVA/CMC/GO, PVA/CMC and control groups ( P<0.001). In the experiment of tube forming area and length, the PVA/CMC/CuS/GO group was significantly better than the PVA/CMC/GO, PVA/CMC and control groups ( P<0.001). The osteogenic differentiation in vitro displayed that the alkaline phosphatase and alizarin red staining of MC3T3-E1 cells in the PVA/CMC/CuS/GO group were significantly better than those in the PVA/CMC/GO, PVA/CMC and control groups ( P<0.001). In addition, the fluorescence intensity of immunofluorescence staining in alkaline phosphatase and type Ⅰcollagen on MC3T3-E1 cells, and the mRNA expression levels of osteogenic related genes including alkaline phosphatase, bone morphogenetic protein 2, osteocalcin and osteopontin in the PVA/CMC/CuS/GO group were significantly higher than those in the PVA/CMC/GO, PVA/CMC and control groups ( P<0.001). The antibacterial assay showed that the PVA/CMC/CuS/GO group had a significantly greater antibacterial activity and a significantly larger inhibition zone against Gram-positive bacteria and Gram-negative bacteria than the PVA/CMC/GO, PVA/CMC and control groups ( P< 0.001). Conclusions:PVA/CMC films composited with GO or CuS/GO nanosheets demonstrate ideal biocompatibility and antibacterial properties which promote angiogenesis and osteogenic differentiation in vitro. In particular, antibacterial PVA/CMC/CuS/GO composite films with the coupling function of angiogenesis and osteogenesis are expected to provide a new strategy for infectious bone defects.