Incorporation and in vitro release of Farnesiterol C in thermally sensitive micellar nanoparticles made from poly (N-isopropylacrylamide- b-poly (L-lactide-co-glycolide) with varying compositions

Polymeric micelles structured from amphiphilic copolymers are regarded as one of the most promising carriers for drug delivery. Polymeric micelles have a small size (< 200nm) and can solubilize hydrophobic drugs in their inner cores, while exposing their hydrophilic shells to the external environment. This enables them to exhibit prolonged activity in the systemic circulation by avoiding the scavenging of the reticuloendothelial systems (RES). Poly (lactide) (PLA) and poly (lactide-co-glycolide) (PLGA) are often used as hydrophobic core-forming segments for fabrication of micelles because of their superior biocompatibility and biodegradability [1-3]. Polymeric micelles have highly hydrated outer shells composed of hydrophilic segments, and their high structural stability in aqueous media is obtained irrespective of high contents of hydrophobic drugs incorporated within the micelle inner core. Furthermore, polymeric micelles are considered to be a long-circulating carrier system in the blood stream due to not only their highly hydrated shell structure but their very small size (10–100 nm) according to researches [4] on size-dependent non-selective scavenging by the reticuloendothelial system (RES).To investigate thermosensitive polymeric nanoparticle, amphiphilic block copolymers of poly (N-isopropylacrylamide-b-poly (L-lactide) [P (NIPAAm)-b-poly (L-lactide) (PLA)] and poly (N-isopropylacrylamide-b-poly (L-lactide-co-glycolide) [P (NIPAAm)-b-poly (L-lactide-co-glycolide) (PLGA)] with different compositions and lengths of PLA and PLGA block were synthesized. Hydroxy-terminated poly (N-isopropyoacrylamide) (PNIPAAm-OH) was used as a novel initiator for ring opening polymerization of lactide and glycolide in the presence of SnOct as catalyst. The lower critical solution temperature (LCST) of copolymers and the effect of salt, pH and polymer concentration on the phase transition behaviors of temperature-sensitive amphiphilic polymers was studied. Then we use these polymers as drug delivery agent for release of a potential anti cancer drug (Farnesiterol C).