Polygalactose Containing Nanocages: The RAFT Process for the Synthesis of Hollow Sugar Balls

Abstract

Hollow poly(6-O-acryloyl-alpha-D-galactopyranose) (PAGP) nanospheres were prepared in a facile manner using the RAFT (reversible addition fragmentation chain transfer) process. Initially, an amphiphilic block copolymer, poly(lactide)-block-poly(6-O-acryloyl-alpha-D-galactopyranose) (PLA-b-PAGP), was synthesized using a poly(lactide) (PLA) macroRAFT agent. It was attained in high yields and displayed low PDI values. The block copolymers self-assembled in aqueous solution to form micelles with pendent galactose moieties covering the surface. By using hexandiol diacrylate the micelles were cross-linked at the nexus of the copolymer, creating stable aggregates. Aminolysis with hexylamine allowed the removal of the PLA core without any detrimental effect on the glycopolymer units to produce hollow nanocages. Characterization of these hollow "sugar balls" with transmission electron microscopy (TEM) showed the cross-linked micelles with a central void due to the removal of the hydrophobic block. These micelles are advantageous in drug delivery applications, especially those involving the liver, thanks to the pendent galactose functionalities covering the surfaces of the nanocages.