Stability study of nanoparticles of poly(var epsilon-caprolactone), poly(d,l-lactide) and poly(d,l-lactide-co-glycolide)

The objective was to evaluate the stability of nanoparticles prepared with poly(var epsilon-caprolactone), poly(d,l-lactide) and poly(d,l-lactide-co-glycolide) polymers and stored at different temperatures and in different media. The stability parameters studied were molecular weight and crystallinity of the polymer, nanoparticle size and pH. The results show that the stability of polymeric nanoparticles depends on (i) the type of polymers with the following increasing order of polymer stability: PLA25GA50 < PLA37.5GA25 < PLA50 = PCL, (ii) the storage temperature: PCL and PLA50 nanoparticles can be kept at 4 °C and RT during one year, while PLA37.5GA25 and PLA25GA50 nanoparticles have to be stored at 4 °C, and (iii) the storage conditions: buffering or freeze-drying nanoparticles improves stability.