Minocycline Hydrochloride Loaded Graphene Oxide Enables Enhanced Osteogenic Activity in the Presence of Gram-Positive Bacteria

Abstract

Background: Implant failures still occur due to bacterial infections and insufficient bone-implant osseointegration. Therefore, biomaterials possessing both superior antibacterial ability and osteogenic activity are urgently needed to conquer these disadvantages. Methods: In this work, graphene oxide (GO) films loaded with minocycline hydrochloride (MH) were fabricated on the titanium implant surfaces, and the antibacterial ability and osteogenic activity were investigated in the presence of S. aureus and rat bone mesenchymal stem cells (rBMSCs) under in vitro and in vivo environments, respectively. MH loaded GO films on titanium surfaces (M@GO-Ti) exhibited enhanced osteogenic activity in vitro with improved alkaline phosphatase (ALP) activity and enhanced expressions of osteogenic related genes including ALP, collagen-I, osteocalcin, and osteopontin. In vitro results of co-culture of rBMSCs and S. aureus indicated that the rBMSCs grew well on M@GO-Ti sample with higher coverage of cells and the bacteria were almost unable to observe on the surface. In the in vivo experiments, the M@GO-Ti exhibited excellent antibacterial and osteogenic activities with the presence of S. aureus. No inflammatory cells e.g. neutrophils were found and superior bone-implant integration was obtained. Interpretation: with the superior antibacterial activity, M@GO-Ti could kill the bacteria and establish a proper tissue microenvironment for bone-implant osseointegration, which makes rBMSCs adhere and grow well on M@GO-Ti. Then, with the synergistic effect of inducing osteogenic differentiation capability of MH and GO, M@GO-Ti surface presented enhanced osteogenic activity to bone cells that resulted in superior bone-implant integration in vivo. This study offers a clinical solution to tackle the problems of inferior bone-implant osseointegration and implant-related bacterial infections simultaneously. Funding Statement: National Natural Science Foundation of China (51831011). National Natural Science Foundation for Distinguished Young Scholars of China (51525207). Natural Science Foundation of Shanghai (17ZR1426700). Scientific Research Project of Science and Technology Commission of Xuhui Municipality (SHXH201613). International Partnership Program of Chinese Academy of Sciences (GJHZ1850). Science and Technology Commission of Shanghai Municipality (18410760600). Scientific Research Project of Xuhui Provincial Commission of Health and Family Planning (SHXH201706). Beijing Municipal Natural Science Foundation (7161001). Declaration of Interests: There are no conflicts of interest to declare. Ethics Approval Statement: The animal experiments were approved by the Animal Care and Experiment Committee of Zhongshan Hospital affiliated with Fudan University.