چكيده به لاتين
The aim of the present research was to synthesis bioactive glass microspheres as bone filler with controlled ion release ability for stimulation of osteogenesis and angiogenesis as well. The glass microspheres were synthesized through a low temperature sol-microemulsion-gel method. Then, the effects of various processing parameters such as reaction chamber volume and stirring rate on obtained microspheres diameters were evaluated. Upon to results, the diameter of glass microspheres increased with increasing of reaction chamber volume as well as decreasing of stirring speed of solution; so that by increasing the stirring speed from 250 rpm to 1000 rpm, the glass microspheres diameter was decreased from 133.23 ± 62.79 µm to 13.19 ± 3.36 µm. The larger spheres cracked during drying and subsequent steps, while the smaller ones were defect-free. Under optimized processing parameters, narrow size glass microsphere with an average diameter of 19.36 ± 9.35 µ was synthesized; however, this average diameter did not satisfy the object of the present work.
Therefore, chitosan was included, and composite microspheres based on the chitosan/glass to induce properties similar to bone tissue and desirable bioactivity were synthesized. In order for controllable delivery of therapeutic ions, addition of copper and manganese to chitosan and glass composition, respectively, was considered.
Thus, bioactive glasses in the system SiO2- CaO- Na2O- P2O5, which contained 1, 2, 5 and 7 (mol.%) MnO, were synthesized via the sol-gel method, and the structure, bioactivity, and cytotoxicity of the resulted samples were studied. The thermal behavior, chemical composition, phase structure, specific surface area and chemical bonds of glass powder were studied by thermogravimetric analysis, differential thermal analysis, X-ray fluorescence, X-ray diffractometer, nitrogen absorption and desorption, Fourier transform infrared (FTIR), and Brunauer–Emmett–Teller (BET) techniques, respectively. The results showed a specific surface area of 15.741 m2/g, an average pore size of 14.118 nm, and crystallization of combeite and silicorhenanite in the glass after calcination at 650°C for 1h. In addition, MnO reduced the crystallization temperature of the glass, and prevent silicorhenanite to crystallize. In vitro bioactivity evaluation of the glass powders confirmed that MnO increases chemical stability and decreases their bioactivity. Also, while cellular test confirmed the non-cytotoxicity of the samples on rBMSCs cells up to 7 days, the mitochondrial activity of the glass powders was increased considerably for 7 days.
Then, chitosan-copper/ manganese containing bioactive glass microspheres with an approximate diameter of 910.8±2.75 µm were prepared by ion gelation method. The effect of glass powder addition on the surface texture, biodegradability, water absorption and bioactivity of composite microspheres was investigated. The SEM results showed that surface roughness of the resulted composites was increased in the presence of glass powder. Also, the water absorption capacity of the composite microspheres showed a glass concentration dependent trend after 30 min immersion in PBS, i.e. the less glass content the more water absorption. But, all of them showed approximately the same value, i.e. 70% , after immersing for 30 min.
The degradation rate of both composite and chitosan microspheres after immersing in phosphate buffer solution for 60 days was less than 10%. Besides, the degradation rate was increased with increasing the amounts of glass powder. Apatite formation evaluation of the samples in the simulated body fluid confirmed improved bioactivity in the presence of the glass. Manganese and copper ions release measurements in the cell culture medium showed a sequential and controlled release profiles of these ions. The cytotoxicity test showed the supporting role of the composite microspheres for rBMSCs cells, and in -vitro osteogenic potential evaluations confirmed the more deposition of calcium in the presence of bioactive glass.
