P(OEGMA-co-LMA) hyperbranched amphiphilic copolymers as self-assembled nanocarriers

We report on the synthesis of novel amphiphilic hyperbranched copolymers, namely Hyperbranched-[poly (ethylene glycol) methyl ether methacrylate-co-lauryl methacrylate] (H-[P(OEGMA-co-LMA)]), obtained by reversible addition-fragmentation chain transfer (RAFT) polymerization utilizing the divinyl monomer, ethylene glycol dimethacrylate (EGDMA) as the branching agent. Molecular characterization by size exclusion chromatography (SEC) and proton nuclear magnetic resonance (¹H-NMR) spectroscopy indicated the success of the polymerization. The self-assembly behavior in aqueous media was investigated by light scattering techniques and fluorescence spectroscopy. The hyperbranched copolymers form multimolecular aggregates of nanoscale dimensions with a low critical aggregation concentration. In addition, the model hydrophobic drug, curcumin (CUR), known also for its intrinsic fluorescence properties, was used in order to investigate the H-[P(OEGMA-co-LMA)] copolymers drug encapsulation ability. Curcumin is successfully loaded into the polymeric nanoparticles, as confirmed by dynamic light scattering and UV–Vis spectroscopy. Interestingly, curcumin hydrophobic interactions with the hyperbranched copolymers result in more well-defined co-assembled nanostructures, in terms of size and size distribution. The mixed copolymer-CUR nano-assemblies consist of small size nanoparticles (<100 nm) which exhibit relatively high size uniformity, colloidal stability and fluorescent properties. Overall, results signify that the biocompatible H-[P(OEGMA-co-LMA)] nanostructures could potentially serve as nanocarrier systems for drug delivery and bio-imaging applications.