The effect of tri-calcium phosphate (TCP) addition on the degradation of polylactide-co-glycolide (PLGA)

This paper investigates the effects of alpha-tri-calcium phosphate (alpha-TCP) addition on the properties of polylactide-co-glycolide (PLGA). Samples with additions of 5, 10, 15, 20, 30 and 40 wt% alpha-TCP were prepared via a hotpressing method. Long-term in vitro studies (up to 60 days) were carried out in pH 7.4 phosphate-buffered saline (PBS). Degradation properties were investigated by monitoring pH, water uptake and mass loss. Dissolution of calcium was analysed with inductively coupled plasma spectroscopy (ICP). Internal changes of the sample structure were studied with X-ray microtomography (mu CT). Change in the mechanical properties was assessed in tensile tests prior to degradation. With an addition of 40 wt% alpha-TCP, the onset of mass loss could be retarded by 18 days; at the end of the study the pH of the buffer solution was reduced to only 4.3 in comparison to 3 for pure PLGA. Although degradation properties seemed to be strongly dependent on the amount of alpha-TCP added, all samples appeared to show faster internal degradation when assessed with mu CT.