The Construction And Performance Of Mesoporous Silica Drug Delivery System With The Functions Of Bone Targeted And Magnetic Resonance Imaging

Osteoporosis is an invisible killer for the elderly and it is not easy to be realized and can lead to fracture. Nowadays, the treatment of osteoporosis mainly depends on chemical drug, such as estrogen, bisphosphonates, calcitonin, calcium and vitamin D, et al, but the therapeutic efficacies are not effective. The treatment of fractures mainly based on the use of scaffold materials to repair the bone defective site, but the healing ability is dissatisfied and has certain limitations. So the development of a n effective way of treatment and prevention of osteoporosis is imminent. Bone mesenchymal stem cells are a kind of pluripotent stem cells which are not only easy to separate and purify but also have the ability of osteogenic differentiation. So it is widely used for the researches of bone tissue engineering. In this paper, we designed and synthesized a nano drug carrier with the dual- functions of bone targeted and magnetic resonance imaging based on the mesoporous silica. We studied the osteogenesis ability of nano drug carrier to bone mesenchymal stem cells before the evaluat ion of biocompatibility and the drug loading and release behaviors with dexamethasone as drug model. The results are as follows,1.We synthesized monodisperse defect-related luminescent mesoporous silica nanoparticles with diameters about 100 nm, and have obvious mesoporous structure and larger surface area. It has the functions of bone targeted and dual- mode magnetic resonance imaging with the conjugate of alendronate as a bone targeted ligand and DTPA chelate gadolinium ion as magnetic resonance imaging contrast agent.2. Dexamethasone was adsorbed mainly through electrostatic interaction, and can sustain release from nano carriers. The unique defect-related luminescent property can monitor the drug release effectively. In addition, the nano carriers have good biocompatibility, and were uptaked mainly via an energy-dependent endocytosic process which was mediated by the macropinocytosis pathway. Dexamethasone loaded nano carriers can significantly enhance the alkaline phosphatase activity and promote the formation of matrix nodules of the bone mesenchymal stem cells.To sum up, the drug delivery system with bone targeted and magnetic resonance imaging provides an important reference value for the visual treatment of osteoporosis which can significantly improve the bioavailability and red uce the drug side effect of dexamethasone, and can significantly enhance the osteogenic differentiation of bone mesenchymal stem cells.