Weight loss, ion release and initial mechanical properties of a binary calcium phosphate glass fibre/PCL composite

Composites comprising a biodegradable polymeric matrix and a bioactive filler show considerable promise in the field of regenerative medicine, and could potentially serve as degradable bone fracture fixation devices, depending on the properties obtained. Therefore, glass fibres from a binary calcium phosphate (50P2O5 + 50CaO) glass were used to reinforce polycaprolactone, at two different volume fractions (Vf). As-drawn, non-treated and heat-treated fibres were assessed. Weight loss, ion release and the initial mechanical properties of the fibres and composites produced have been investigated. Single fibre tensile testing revealed a fibre strength of 474 MPa and a tensile modulus of 44 GPa. Weibull analysis suggested a scale value of 524. The composites yielded flexural strength and modulus of up to 30 MPa and 2.5 GPa, respectively. These values are comparable with human trabecular bone. An 8% mass loss was seen for the lower Vf composite, whereas for the two higher Vf composites an approximate 20% mass loss was observed over the course of the 5 week study. A plateau in the degradation profile at 350 h indicated that fibre dissolution was complete at this interval. This assertion was further supported via ion release studies. The leaching of fibres from the composite created a porous structure, including continuous channels within the polymer matrix. This offers further scope for tailoring scaffold development, as cells from the surrounding tissue may be induced to migrate into the resulting porous matrix.