Study On Ultrafine Calcium Phosphate Fibers And Its Composite Membranes With Gelatin Prepared By Electrospinning

Electrospinning is an important method to prepare ultrafine fibers which were widely concerned in the filter devices, wound dressing, control release and tissue engineering scoffolds because of its small diameter and high specific surface area. Recent years, electrospinning is not only limited to produce polymeric ultrafine fibers, but also combined with other techniques to prepare ultrafine inorganic fiber materials.In this work, ultrafine apatite fibers were prepared by electrospinning a sol-gel precursor solution (SOL) of triethyl phosphate and calcium nitrate with addition of poly(vinyl pyrrolidone) (PVP) and followed by calcination. Firstly electrospinning of PVP was studied, and then the influence of PVP concentration, SOL/ethanol volume ratio and dry temperature on the morphology of PVP/SOL fibers were observed by scanning electron microscope (SEM) and optical polarizing microscope. Calcined fibers were characterized by thermogravimetric-differential thermal analyses, Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD). Results showed that fibers calcined at 600°C were apatite fibers.Although apatite is widely used in bone regeneration, it has shown brittleness and poor toughness properties. To improve its mechanical properties composite fibrous membrane of gelatin/low crystalline calcium phosphate were prepared by co-electrospinng, followed by heat-treatment in the vaccum at 60°C for 12 h. Effect of the solvent, solutions properties and process parameters on the electrospinning of gelatin were studied. The fibers morphologies were observed by SEM and the composities of the composite membrane was verified by XRD, X-ray photo electron spectroscopy and FT-IR. Gelatin and composite membrane were crossed by glutaraldehyde vapor because of the solubility of gelatin in water. Mechanical properties were evaluated. Water uptake was tested by incubating the membrane in phosphate buffer solution. Results suggested that after crosslinking the tensile modulus and strength of gelatin membrane increased from 41.53±6.15 MPa and 1.124±0.157 MPa to 100.7±1.04 MPa and 1.398±0.286 MPa respectively, and the composite membrane improved its tensile modulus and strength from 71.94±10.88 MPa and 1.300±0.239 MPa, to 219.4±13.25MPa and 5.181±0.820MPa respectively. Because of both gelatin with good toughness and low crystal calcium phosphate in this composite membrane, it had a good potential application in bone regeneration.