Preparation of new dendrimer-like star-shaped amphiphilic poly(ethylene glycol)-poly(ϵ -caprolactone) copolymers for biocompatible and high-efficiency curcumin delivery

Abstract

Novel amphiphilic star-shaped terpolymers comprised of hydrophobic poly(ϵ-caprolactone), pH-sensitive polyaminoester block and hydrophilic poly(ethylene glycol) (Mn = 1100, 2000 g mol−1) were synthesized using symmetric pentaerythritol as the core initiator for ring-opening polymerization (ROP) reaction of ϵ-caprolactone functionalized with amino ester dendrimer structure at all chain ends. Subsequently, a second ROP reaction was performed by means of four-arm star-shaped poly(ϵ-caprolactone) macromer with eight -OH end groups as the macro-initiator followed by the attachment of a poly(ethylene glycol) block at the end of each chain via a macromolecular coupling reaction. The molecular structures were verified using Fourier transform infrared and 1H NMR spectroscopies and gel permeation chromatography. The terpolymers easily formed core–shell structural nanoparticles as micelles in aqueous solution which enhanced drug solubility. The hydrodynamic diameter of these agglomerates was found to be 91–104 nm, as measured using dynamic light scattering. The hydrophobic anticancer drug curcumin was loaded effectively into the polymeric micelles. The drug-loaded nanoparticles were characterized for drug loading content, encapsulation efficiency, drug–polymer interaction and in vitro drug release profiles. Drug release studies showed an initial burst followed by a sustained release of the entrapped drug over a period of 7days at pH = 7.4 and 5.5. The release behaviours from the obtained drug-loaded nanoparticles indicated that the rate of drug release could be effectively controlled by pH value. Altogether, these results demonstrate that the designed nanoparticles have great potential as hydrophobic drug delivery carriers for cancer therapy. © 2015 Society of Chemical Industry