Star-shaped polymers consisting of a [small beta]-cyclodextrin core and poly(amidoamine) dendron arms: binding and release studies with methotrexate and siRNA

To develop multifunctional polymeric carrier for small interfering RNA (siRNA) and drug delivery, novel star-shaped polymers were synthesized by the copper catalyzed azide alkyne cyclization reactions of propargyl focal point poly(amidoamine) dendrons with per-6-azido-[small beta]-cyclodextrin, and were characterized by 1H NMR, FTIR and GPC analyses. Their physicochemical properties such as buffering capability, siRNA binding ability and in vitro cytotoxicity as well as their complexation with siRNA in aqueous system were also investigated. Under the optimized conditions, such cationic polymers could exhibit high siRNA transfection efficiency and low cytotoxicity in fibroblast cells. Moreover, their [small beta]-cyclodextrin core with internal hydrophobic cavities could be used simultaneously for the entrapment and sustained release of a poorly water-soluble anti-cancer drug (methotrexate).