Preparation and in vitro evaluation of linear and star-branched PLGA nanoparticles for insulin delivery

Biodegradable nanoparticles, as drug delivery paradigms, have been extensively used for delivery of a wide range of small molecules as well as macromolecules, such as peptides, proteins, and genes. The morphological modification may improve the physicochemical characteristics of the biodegradable polymers. In the current investigation, the synthesis and characterization of linear, poly( D, L-lactide-co-glycolide) (PLGA)-poly( ethylene glycol) (PEG-PLGA), star-branched b-cyclodextrin-PLGA (b-CD-PLGA), and glucose-PLGA (Glu-PLGA) copolymers containing insulin as a model peptide drug have been reported. Linear and star-branched copolymers of PLGA were synthesized by bulk melt polymerization of the lactones ( lactide and glycolide) in the presence of PEG, glucose, or b-CD using Sn-octoate as catalyst. Nanoparticles were prepared by a modified (w(1)/o/w(2)) double emulsion method. Bovine insulin was successfully encapsulated into the linear and star-branched PLGA nanoparticles with retention of insulin stability and the nanoparticles preparation process was optimized to reduce the burst effect and provide in vitro sustained release. The average particle size of samples was 120-355 nm. The cumulative amount of 65-84% insulin was released from the samples after 24 days. The yield of encapsulation of insulin was superior to 95%. Based on these findings, it is suggested that the novel PLGA nanoparticles can be used as a carrier for prolonged delivery of protein-peptide drugs.