| In recent years, mesoporous bioactive glasses with tunable nano-pore, well-ordered mesoporous channel structure, high specifical surface area and porosity, great bioactivity and biodegradability is becoming the focus of controlled drug delivery system. It is confirmed that mesoporous bioactive glasses show better bioactivity and controlled drug delivery ability than mesoporous silica. Applying the success of mesoporous silica spheres as targeted drug delivery system to the research of mesoporous bioactive glasses, an excellent targeted drug delivery system could be obtained. Furthermore, synthesizing monodispersed spheres with a series of sizes could be favor to determine the size range recognized by the macrophagus, thus to prepare the targeted drug delivery system that can stay away from the macrophagus. These kinds of monodispersed spheres could be obtained by employing three-dimensional ordered macroporous PS template.In this work, an orthogonal experimental design method combining with quantitive analysis of small-angle X-ray scattering (SAXS) pattern was applied to evaluate the impact degree of multifactors to the formation of ordered mesoporous structure within the magnetic mesoporous bioglasses and screen optimum formula. All results suggested that the impact degrees of the factors were as follows:Fe(NO3)3·9H2O>TEOS>Ca(NO3)2·4H2O>F127. The optimum formula which was concluded and confirmed was TEOS (0.015mol)-Ca(NO3)2·4H2O (0.005mol)-Fe(NO3)3·9H2O (0.0015mol)-F127(3.6g).Based on the experiment above, magnetic mesoporous bioactive glass spheres were prepared by using a sol-gel method combining an evaporation-induced self-assembly (EISA) process in a PS template. The morphological features and microstructures of various synthesized MMBGs powders were studied with transmission electron microscope (TEM), X-ray diffractometer (XRD) and N2adsorption. The particle size and polydispersity was investigated by dynamic light scattering (DLS). The impacts of the species and contents of components, F127and PS template on the mesoporous structure were studied. The results revealed that the optimum formula of the MMBGs with the best mesoporous structure. The obtained MMBGs showed an average size of240nm. The surface area and pore size were300cm2/g and5nm, which made the ability of loading drugs with big size. PS decreased the center to center distance between the mesopores of the MMBGs in the restricted space of PS template. The impacts of F127, the species and contents of the components to the mesoporous structure of the MMBGs were consistent with the results revealed by the orthogonal experiments. Based on the optimum formula, the MMBGs with high Fe content was obtained through a preprocessing dealt with Fe(NO3)3·9H2O sol. The results of VSM demonstrated that, the obtained MMBGs exhibited superparamagnetism, its saturation magnetization value was11.35emu/g, which was100times higher than that of the MMBGs got from the optimum formula.The degradation behaviour of75S25C-MMBGs in SBF was carried out through a static process and a dynamic process. The influence of both the static process and dynamic process to the biodegradability of75S25C-MMBGs were evaluated. The structures of75S25C-MMBGs were investigated by FTIR, TEM, and XRD. The results suggested the excellent biodegradation of MMBGs, and the dynamic process could accelerate the degradation process. An anti-cancer drug As2O3was loaded into the75S25C-MMBGs through a wet-impregnated method.75S25C-MMBGs were chemically modified with PEG and PDLLA-PEG. The morphological features and microstructures of the drug loaded MMBGs were carried out with TEM, XRD and SAXS; the mass of PEG modified onto the surface of MMBGs were detected by the thermal gravimetric analysis (TGA); the drug loading and drug release behaviour were studied by the inductively coupled plasma emission spectrometry (ICP). The results indicated that, MMBGs could efficiently load As2O3; MMBGs/PEG and MMBGs/PDLLA-PEG. composites could evidently decrease the release behavior. All the results above showed the promising applications of MMBGs/PEG and MMBGs/PDLLA-PEG composites as controlled drug delivery system. |
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