Retinol initiated poly(lactide)s: stability upon polymerization and nanoparticle preparation

Abstract

The synthesis of retinol initiated polylactide (PLA) by ring opening polymerization (ROP) of L-lactide via in situ calcium alkoxide formation with all-trans-retinol and Ca[N(SiMe₃)₂]₂(THF)₂ is described. PLAs with degree of polymerization (DP) values ranging from 13 to 60 were obtained and characterized in detail by means of ¹H nuclear magnetic resonance (NMR) spectroscopy, size exclusion chromatography (SEC), UV/vis spectroscopy and (tandem) mass spectrometry techniques. Stable nanoparticles (NPs) were prepared via a nanoprecipitation method and characterized by DLS and SEM. The stability of retinol upon conjugation to PLA as well as the nanoparticle formulation was investigated in detail and found to be significantly affected by the storage conditions such as exposure to light, oxygen and temperature.