| The hybrids of carbon nanofibers (CNF) containing biomaterials gained much attention in the field of tissue engineering due to the excellent biological performance, effectively mimicing natural bone extracellular matrix and promoting osteoblast proliferation as well as attachment. Based on the previous investigations in our lab, in this study, carbon nanofiber containing bioglasses (CNF/BG) was successfully synthesized via sol-gel method, electrospinning technique, and subsequently the process of heat treatment. The relevance between the effect of silicon content and aging time on BG and micro-structure and biological performance of CNF/BG composites was systematically investigated.Firstly, the study contrasted the relevance between the effect of silicon contents (45S and 68S) on BG and the micro-structure and biological performance of PAN-based carbon nanofibers containing bioceramics. Through nuclear magnetic resonance analyzer (CP-NMR), laser particle size analyzer (LASP) and other characterization method, the results showed that the linking degree and sizes of silicate network of 68S sol-gel was larger than 45S sol-gel at the same aging time (7 days). Via electron microscope (SEM), transmission electron microscope (TEM) and X-ray diffraction (XRD), the results indicated that the 45S-type BG crystallized into ?-CaSiO3, while the 68S-type BG transformed to ?-CaSiO3 The above differences derived from the influence of sintering atmosphere on nanofibers and the addition of PAN into BG nanoparticles. Especially in the process of sol-gel method and oxidation, the C=N groups in PAN interacted strongly with calcium elements in BG sol-gels, this directly influenced the crystallization of BG nanoparticles. Besides, the hybridized CNF/BG was immersed in simulated body fluid (SBF) to evaluate bioactivity. The apatite-forming ability of CNF/BG-45 was better than CNF/BG-68. This attributed to the fact that the "3-ring" crystal structures in ?-CaSiO3 was easier to hydrolyze than the chain structures in ?-CaSiO3 thus better to improve the deposition and growth of minerals.Meanwhile, the study also investigated the relationships of aging time in BG sol-gel precursors and micro-structure and biological performance of PVP-based carbon nanofibers decorating bioactive glasses. The sizes and lingking degree of pure silicate network in precursor aging various time (1,3,7 days) was investigated through NMR and LASP. The results showed that the linkage degree increased from 1 to 7 days, on the other hand, from 1 to 3 days, silicate network underwent morphological changes from small sol clusters with a loosely and randomly branched structure to a fully developed Si-network structure and finally to a dense Si-network at 7 days. Based on those results, BG nanoparticles in CNF/BG was studied via SEM, TEM, X-ray photoelectron spectroscopy (XPS), thermogravimetry (TG) and element analyzing (Mapping). The results showed more BG particles migrated toward the fiber surface as aging time prolonging and the residual BG elements in the CNF was less with increasing aging time. The carbonyl groups in PVP interacted with calcium ions in BG sol-gels which led to the different intermiscibility between them and further influence the amounts of BG nanoparticles on the surface of CNF. During the process of aging and heat treatment, phosphorus element was prominently lost which gave rise to the formation of CaSiO3 in the final CNF/BG and the crystallization changed from weak to strong. Besides, by soaking in simulated body fluid, it was found that the CNF/BG composites with longer aging time demonstrated the fastest apatite deposition, which was ascribed to those abundant BG nanoparticles on the fiber surface having exposed numerous nucleation sites for the apatite deposition. |
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