Synthesis and characterization of an amphiphilic methoxy poly(l-lactide)-block-poly(glycidylmethacrylate) copolymer as a drug nanocarrier

Abstract

Present research is a preliminary report on the amphiphilic diblock copolymer (mPLA-b-PGMA) comprising hydrophobic methoxy poly(L-lactide) (mPLA) and hydrophilic poly(glycidyl methacrylate) (PGMA) segments was used as a promising drug carrier. Diblock copolymer was synthesized via ring opening polymerization (ROP) and atom transfer radical polymerization (ATRP) methods. Methanol first initiated ROP of L-lactide in the presence of tin(II)bis(2-ethylhexanoate) (Sn(oct)2) as a catalyst. The resulting monohydroxyl-terminated polylactic acid (mPLA) was subsequently converted to a bromine-ended macroinitiator (mPLA-Br) by esterification with 2-bromisobutyryl bromide. The copolymer mPLA-b-PGMA was synthesized in a subsequent ATRP of GMA. The obtained polymers were characterized by means of 1H NMR, FTIR, DSC and TGA. The copolymer mPLA-b-PGMA self-assembled into nanoscale micelles in aqueous solutions, as investigated by transmission electron microscopy (TEM) and dynamic light scattering (DLS). The TEM image of polymeric micelles showed that the micelles were spherical in shape and that their diameters were in the range of 80-140 nm. Then by using the naproxen as a hydrophobic model drug, the drug-loaded micelles with 81.18 % loading efficiency and 16.24 % loading capacity were prepared. Moreover, in vitro release study of naproxen was performed using dialysis bag in phosphate-buffered solution at 37°C and pH at 7.4. Accordingly, these polymeric micelles may provide as an effective drug carrier for controlled drug release.