α-Acetal, ω-Alkyne Poly(ethylene oxide) as a Versatile Building Block for the Synthesis of Glycoconjugated Graft-Copolymers Suited for Targeted Drug Delivery

alpha-Acetal, omega-alkyne poly(ethylene oxide) was synthesized as building block of glycoconjugated poly(epsilon-caprolactone)-graft-poly(ethylene oxide) (PCL-g-PEO) copolymers. The alkyne group is indeed instrumental for the PEGylation of a poly(alpha-azido-epsilon-caprolactone-co-epsilon-caprolactone) copolymer by the Huisgen's 1,3 dipolar cycloaddition, i.e., a click reaction. Moreover, deprotection of the acetal end-group of the hydrophilic PEO grafts followed by reductive amination of the accordingly formed aldehyde with an aminated sugar is a valuable strategy of glycoconjugation of the graft copolymer, whose micelles are then potential. A model molecule (fluoresceinamine) was first considered in order to optimize the experimental conditions for the reductive amination. These conditions were then extended to the decoration of the graft copolymer micelles with mannose, which is a targeting agent of dendritic cells and macrophages. The bioavailability of the sugar units at the surface of micelles was investigated by surface plasmon resonance (SPR). The same question was addressed to nanoparticles stabilized by the graft copolymer. Enzyme linked lectin assay (ELLA) confirmed the availability of mannose at the nanoparticle surface.