Preparation Of Nano - Bioactive Glass And Its Application With Biopolymer Composite Scaffolds

Bioactive glass (BG) has a similar composition to the natural bone and teeth. Compared with HA, BG with better biological activity, biocompatibility, degradation, higher bone bonding strength, can directly induce stem cells into osteoblasts, and the bone has been induced. In addition, BG can stimulate certain genes in bone cells expressing, control cell behavior, promote the proliferation and differentiation of bone cells and improve the proliferation of fibroblast cells and other soft tissue, thus being an important class of bone repair material. In recent years, micro and nano scale biomaterials has become a hot research field of medical biological materials. Numerous studies indicate that the biological material with the characteristics of micro and nano structures exhibit a positive biological response. Compared with other biological materials, micro and nano scale biomaterials can significantly promote adhesion, proliferation and differentiation of cells. BG prepared by high-temperature melting method has entered the clinical application. However, high-temperature volatile and crucibles’material can easily lead to BG material changes such as glass composition fluctuations and uneven harmful impurity doping problems, which make it difficult to control the structure and properties of glass, and result in poor performance of the material degradation. In recent years, BG prepared by the sol-gel technique possesses lot of advantages such as mild preparation conditions, high specific surface area, nanopore structure, good bioactivity, possibility in regulated degradation performance, and controlled composition and design, which make it has the very high value of research and application, thus expected to become the third generation of the important types of biological material.In this work, a stober method similar to the sol-gel technique was applied to prepare nanoparticles of bioactive glass (NBG). The degradation behaviour of NBG in simulated body fluid (SBF) was carried out through a dynamic process. The morphological features and microstructures of NBG before and after soaking in SBF were characterized by means of TEM, SEM, EDS, FT-IR and XRD. The results indicated that, the glass has a composition of75%SiO2,25%CaO (75S25C), the appearance of the particles showing spherical, and the particle size is50～90nm in diameter. Some agglomeration between particles should be due to the higher surface energy of nanomaterials. The rapid bone-like apatite deposition on the surface after soaking in SBF for4hours and gradually increasing HCA amount with soaking time indicate the good bioactivity of NBG.The mechanical strength of NBG/PCL composites made by melt blending is significantly higher than that of composites prepared by solution blending molding method. By modifying the NBG with aminomethyl triethoxy silane (APTES) to be mNBG, the strength of the composites with mNBG adding increased obviously. When the NBG content was30wt.%, the tensile strength mNBG/PCL composite reached24,3MPa, increasing by16.2%than that of NBG/PCL composite materials20.91MPa, meanwhile57.7%compared to the pure PCL15.41MPa. However, the40wt%NBG addition led to the obvious decrease of strength of both NBG/PCL and mNBG/PCL composites, which was attributed to the agglomeration of nanoparticles especially in high filling content, as is often seen in inorganic and polymer composites.The results of NBG/PCL composite degradation in SBF indicate that NBG is helpful to the pH adjustment of the solution between the process of degradation, playing a role in buffering, and the composite exhibit good biological activity.Porous composite scaffolds with a high porosity of about91%were successfully prepared by the help of the polyurethane (PU) template replication method. The pore connectivity of scaffold is good and pore size is90～650μm in diameter. The study found that the crystalline structure of NBG changed after1000℃calcined and the main crystalline phase of the calcined material is CaSiO3.After immersing in SBF for7days, some HCA fluffy particles on the surface of scaffold emerged and some HCA shape present long needle-like.14days later, the former needle-like HCA on the particle surface grew into flower-like flakes, which cluster into flower-like HCA particles. With the degradation time prolonged, HCA generation amount was gradually increased, which almost completely covered the surface of the scaffold. The results combined with XRD, FT-IR and SEM showed that three-dimensional porous scaffolds with the main crystalline phase CaSiO3have good apatite-forming activity. In addition, PVA polymer coating can be a greater degree of improvement in the shortcomings of the scaffold strength, but it will probablly reduce the material’s porosity and pore connectivity. Therefore, in order to obtain scaffolds with high porosity and good pore structure, excellent biological activity and biocompatibility, high mechanical strength, the process of material preparation needs further research.