Structurally simple redox polymersomes for doxorubicin delivery

Abstract

A simple redox amphiphilic tri-block copolyurethane capable of assembling in the form of polymersome has been easily synthesized. Thus, the hydrophobic core is constituted by a central block containing multiple disulfide linkages, and the hydrophilic segments are formed by poly(ethylene glycol) methyl ether (mPEG2000). The disulfide-containing block was obtained by the reaction of commercial 2,2′-dithiodiethanol and hexamethylene diisocyanate, which was further reacted with the mentioned PEG to afford the tri-block copolymer nominated as mPEG-PDH-mPEG, in above 80% yield. This copolymer self-assembled into polymersomes of size around 130 nm by the water addition/solvent evaporation method. Different systems of doxorubicin/polymer ratios (D/P 0.5 – 3) were prepared and the drug loading (%DL) and encapsulation efficiency (%EE) were studied by visible light absorbance measurements. Systems D/P 2 and 3 showed DL up to 62% and 69%, respectively. Besides that, D/P 1 and 2 presented EE values in the order of 83%. Finally, the release of DOX in the presence of 0.01 M glutathione solutions at 37 °C, was 74.6% and 82% from D/P 3 and D/P 0.5, respectively, after 5 days of incubation. Further studies on other water-soluble drugs for the cancer treatment would be of great interest to demonstrate the high potential of these redox polymeric systems.