Electrospun hydroxyapatite fibers from a simple sol–gel system

This work reports the production of hydroxyapatite (HA) sub-micron fibers by combining electrospinning and a non-alkoxide sol–gel system, using cheap precursors. Phosphorus pentoxide (P2O5) and calcium nitrate tetrahydrate (Ca(NO3)2.4H2O) were used as precursors of phosphorus and calcium, respectively. The fibers were electrospun from a mixture of the gel formed from the system Ca(NO3)2.4H2O/P2O5 with polymeric solutions of polyvinylpyrrolidone (PVP) in water and ethanol/water mixtures. The fibers were analyzed for their morphology (Scanning Electron Microscopy, SEM), chemical composition (Fourier Transform Infrared Spectroscopy, FTIR) and structure (X-ray diffraction, XRD). The fibers obtained were composed mainly of type B carbonated HA with traces of β-tricalcium phosphate (β-TCP). SEM analysis revealed that increasing the concentration of water in the solvent system, used in the preparation of electrospinning solutions, led to fibers with smaller diameters and narrower diameter distribution.

► We have produced hydroxyapatite (HA) fibers combining electrospinning and sol–gel. ► A simple non-alkoxide sol–gel system was used, for which no pH control is needed. ► Water and water/ethanol solutions of PVP and the gel were used for electrospinning. ► Carbonated HA fibres with traces of β-tricalcium phosphate (β-TCP) were obtained. ► Fibers diameter decreases with the amount of water on the electrospinning solutions.