Controllable Preparation Of Micro-mesoporous Calcium-silicon Nanospheres And Its Dual Drug-loading System

Bone defects caused by diseases,trauma and other reasons have increased year by year,which have been a serious clinical problem that affect human life and health.The key challenge to solve the problem is that the traditional bone defect repair materials have an insufficient bone regeneration capacity for lacking the ability to promote osteogenic differentiation of cells.MicroRNAs and small molecule drugs have a good regulatory ability for cell proliferation and differentiation to promote their bone formation.However,the free miRNA is easily degraded and hardly uptaken by cells,while the small molecule drugs usually have a bad solution in water,causing an extremely low bioavailability.Therefore,loading miRNA and small molecule drugs in one nanocarrier to achieve their delivery simultaneously is of great significance for the research and application of the new bone repair materials.In this study,micro-mesoporous calcium-silica nanospheres with good dispersibility and excellent biocompatibility were synthesized to construct two dual-loading drug systems.The one was to promote osteogenesis and label stem cells,the other was to promote osteogenesis and angiogenesis.By the dual-loading drug system,we achived the high efficiency transfection of miRNA and infrared labeling of stem cells.And we also found that miRNA transported with small molecule drugs have a good synergistic therapeutic effect.Micro-mesoporous calcium-silicon nanospheres(DPNP)with good dispersibility,uniform particle size,high specific surface area and radial pore structure were synthesized by a modified sol-gel method.By controlling the synthesis conditions,the DPNPs with three particle sizes(55 nm,117 nm,and 207 nm)were prepared.The results of cell experiments in vitro showed that DPNPs had a good cytocompatibility and could enter cells by endocytosis.Among the threesizes DPNP,DPNP-55 nm had the best cytocompatibility and the highest cells endocytic efficiency.The miR-26 A was loaded into mesopores of DPNP,and ICG small molecules was loaded into its micropores.So that we constructed a dual-loaded ICG/DPNP/miR-26 A,which have the functions of stem cell imaging and osteogenesis.The results showed that DPNP could significantly improve the stability and transfection efficiency of miRNA,and its transfection efficiency could reach more than 80%,which was higher than that of commercial transfection reagent siRNA-Mate.What’s more,DPNP has a better biocompatibility.The fluorescence intensity was attenuating by only 20% after treated with light and heat for 24 h when the ICG was loaded into DPNP,and the ICG/DPNP/miR-26 A composite nanospheres had good bonepromoting properties and infrared labeling properties.Based on the two chapters above,we constructed the Siv/DPNP/miR-210 dual-loading drug system,which had the ability of promoting osteogenesis and angiogenesis.The experimental results showed that DPNP had good drug-release properties,and the encapsulation efficiency of miRNA and Siv could reach 45.5% and 73.8%,respectively.In the Siv/DPNP/miR-210 dual-loading drug system,miR-210,DPNP and Siv have multiple synergistic effects on osteogenesis.For the ability to promote angiogenesis,due to the efficient cell transfection ability of DPNP,the content of miR-210 in HUVECs could be well promoted,thereby promoting angiogenesis.In addition,Siv and miR-210 also have synergistic effects on angiogenesis.