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Abstract: Poly(lactide-co-glycolide) (PLGA) copolymers are the most prevalent materials for tissue engineering applications. To mimic the real microenvironment of extracellular matrix (ECM) for cell growth, nanofibrous PLGA scaffolds are preferred. PLGA5050 (in which the molar ratio of lactidyl to glycolidyl units is 50:50), which is an utterly amorphous polymer, was first reported to be made into nanofibrous networks (fiber diameter around 500nm) using phase separation from PLGA5050/THF solutions in this study. The concentration of polymeric solution had significant effects on fiber diameter and unit length. Nonsolvent (e.g. H2O) was unnecessary to form the PLGA5050 gel, which was critical to nanofibrosis, as if the environmental temperature for gelation occurrence was low enough (−70°C). The physical crosslinks to stabilize the PLGA5050/THF gel were believed to be GA segments along the backbone owing to their inferior solubility in THF. The addition of H2O would cause adverse effects of liquid–liquid phase separation and nanofibrosis failure owing to the hydrophilicity of glycolidyl units. Associating with the phase separation method, particle-leaching technique was applied to fabricate three-dimensional scaffolds with macroporous and nanofibrous structures. To ensure the occurrence of nanofibrosis on macropore walls, the temperature of salt particles should be best lowed to −70°C beforehand. Accordingly, scaffolds prepared under varied parameters exhibited different nanofiber and pore morphologies, which affected the pore size, porosity, specific surface area, water contact angle and protein adsorption ability etc. The preliminary cell (MC3T3-E1) culture confirmed the cell ingrowth into the macroporous and nanofibrous PLGA5050 scaffolds in comparison with the solely nanofibrous matrixes. This kind of bi-scaled three dimensional matrixes can be superior candidate scaffolds for tissue engineering applications. [Copyright &y& Elsevier]

Calcium silicate (CS) is envisioned as a good substrate for bone tissue engineering applications because it can provide bioactive ions like Ca2+ and Si4+ to promote bone regeneration. Calcination temperature is a critical factor in determining the crystallinity of CS ceramic, which subsequently influences its degradation and ion release behaviors. To investigate the effect of calcination temperature on the capacity of CS in inducing bone regeneration, CS nanofibers were fabricated via electrospinning of precursor sol-gel and subsequent sintering at 800 °C, 1000 °C or 1200 °C. As the calcination temperature was increased, the obtained CS nanofibers displayed higher crystallinity and slower degradation rate. The CS nanofibers calcined at 800 °C (800 m) would like to cause high pH (>9) in cell culture medium due to its rapid ion release rate, displaying adverse effect on cell viability. Among all the preparations, it was found the CS nanofibers calcined at 1000 °C (1000 m) demonstrated the strongest promotion effect on the osteogenic differentiation of bone marrow mesenchymal stromal cells. To facilitate in vivo implantation, the CS nanofibers were shaped into three-dimensional macroporous scaffolds and coated with gelatin to improve their mechanical stability. By implanting the scaffolds into rat calvarial defects, it was confirmed the scaffold made of CS nanofibers calcined at 1000 °C was able to enhance new bone formation more efficiently than the scaffolds made of CS nanofibers calcined at 800 °C or 1200 °C. To summarize, calcination temperature could be an effective and useful tool applied to produce CS bioceramic substrates with improved potential in enhancing osteogenesis by regulating their degradation and bioactive ion release behaviors. Unlabelled Image • Calcium silicate nanofibers are produced by sol-gel electrospinning and calcination. • Calcination temperatures decide degradation and bioactive ion release behaviors of calcium silicate nanofibers. • Calcination temperatures influence cell proliferation and differentiation on calcium silicate nanofibers. • Calcium silicate nanofibers sintered at 1000 °C demonstrate an efficient capacity in inducing osteogenesis. • Macroporous scaffolds developed from calcium silicate nanofibers promote bone regeneration. [ABSTRACT FROM AUTHOR]