Preparation and characterization of calcium metaphosphate nanofibers via electrospinning

Bioresorbable calcium metaphosphate (CMP) nanofibers were produced by an electrospinning technique. In order to produce the nanofibers, CMP sol was prepared by the mixing of two precursors, such as calcium nitrate tetrahydrate (Ca[NO3]center dot 4H(2)O) and triethyl phosphate (TEP, [C2H5O](3)PO), using methyl alcohol as a solvent. The Ca/P ratio of the mixture was set to be 0.50 to produce stoichiometric CMP sol. At least 5 hrs of pre-hydrolysis of phosphorus precursor were required to obtain beta-CMP phase. Viscous solutions for the electrospinning were made by the mixing of CMP sol and high-molecular weight polymeric solution at various ratios. The ratio of CMP sol and polymer solution was controlled to obtain an appropriate viscosity for the electrospinning. As-electrospun CMP nanofibers were dried in a drying oven at 70 degrees C for 24 hrs and then heat-treated at various temperatures at a ramp of 1 degrees C/min in air for 1 hr. The as-electrospun and heat-treated CMP nanofibers were characterized using X-ray analysis, FT-IR, TG-DTA and SEM techniques. The results showed that the preparation of CMP sol, mixed solution properties, and heat-treatment condition of as-electrospun nanofibers significantly affect the spinability and surface morphology of the CMP nanofibers.