Miktoarm star polymers nanocarrier: synthesis, characterisation, and in-vitro drug release study

Conjugation of poly(ethylene glycol) (PEG) to poly(lactide-co-glycolide) (PLGA) renders the latter with enhanced biocompatibility and broader overall capability in biomedical application. Novel miktoarm star polymers comprising PLGA and PEG segments are of interest for their potential as drug carriers. Thus, a series of miktoarm star copolymers, PLGA-(mPEG)(2), with different PLGA arm molecular weights and methoxy-PEG (mPEG) arm (2000g/mol), were synthesised via a four-step reaction using carbodiimide chemistry with a low steric hindrance trifunctional linker aminoadipic acid (AAA) and characterised by proton nuclear magnetic resonance (H-1 NMR), fourier transform infrared (FTIR), gel permeation chromatography (GPC) and differential scanning calorimetry (DSC). Results show that the miktoarm star polymers PLGA(17.0)-AAA(mPEG)(2) and PLGA(43.4)-AAA(mPEG)(2) formed stable nanoparticles and PLGA(4.6)-AAA(mPEG)(2) self-assembled into stable nanomicelles. Fluorescence spectroscopy showed that the critical micelle concentration of PLGA(4.6)-AAA(mPEG)(2) was very low at 6.03x10(-7)g/mL. Model drug ibuprofen encapsulated nanoparticles and nanomicelles had good drug loading, high encapsulation efficiency, narrow size distribution, and spherical morphology with negative surface charges. The mean particle size increased with increasing PLGA molecular weights, from 37.28 +/- 1.03 to 151.5 +/- 0.86nm. In-vitro release of model drug ibuprofen over 7days from PLGA(43.4)-AAA(mPEG)(2) nanoparticles (61.65 +/- 3.04%) was higher than those of PLGA(4.6)-AAA(mPEG)(2) nanomicelles (26.93 +/- 1.49%) and PLGA(17.0)-AAA(mPEG)(2) nanoparticles (10.57 +/- 0.29%), with all demonstrating controlled release characteristics. In conclusion, the novel miktoarm star polymers PLGA(43.4)-AAA(mPEG)(2) and PLGA(17.0)-AAA(mPEG)(2) and their nanoparticles, and PLGA(4.6)-AAA(mPEG)(2) and its nanomicelles have a great potential as a nanocarrier for controlled delivery of hydrophobic drugs.