Micro/nanoparticles fabricated with triblock PLLA-based copolymers containing PEG-like subunit for controlled drug release: Effect of chemical structure and molecular architecture on drug release profile

Novel A-B-A triblock copolymers based on poly(L-lactic acid) (PLLA) were designed with an ad hoc chemical structure to prepare micro- and nanoparticles for controlled drug delivery. A block is formed by PLLA, while central B block is a copolymeric system based on poly(butylene succinate) and poly(triethylene succinate): more specifically, two copolymers with fix composition (50:50 mol:mol) and different molecular architecture were synthesized. One of them is characterized by a block architecture, i.e. long butylene succinate and triethylene succinate sequences form the macromolecular chains, the other being on the contrary a random copolymer with short sequences. The so-obtained materials were characterized from the molecular and thermal point of view. Moreover, to investigate the effect of both chemical structure and molecular architecture of the polymers synthesized on drug release kinetics, Dexamethasone-encapsulated micro- and nanoparticles were prepared by oil-in-water miniemulsion technique. These particles were subjected to thermal and morphological characterization. After that, drug release studies were carried out, and the effect of chemical composition, sequence distribution and particle size on release profile was evaluated.