Biomacromolecules, Vol.14, No.12, 4189-4197, 2013
Synthesis of 2-Hydroxypropyl-beta-cyclodextrin/Pluronic-Based Polyrotaxanes via Heterogeneous Reaction as Potential Niemann-Pick Type C Therapeutics
Five polyrotaxanes were synthesized by threading 2-hydroxypropyl-beta-cyclodextrin (HP-beta-CD) onto a variety of a,alpha,omega w-ditriethylenediamino-N-carbamoyl-poly-(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) (Pluronic) triblock copolymers using a two-pot strategy under heterogeneous, nonaqueous conditions. The threaded HP-beta-CD units were retained on the pseudopolyrotaxane precursors by end-capping the branched diamine termini with sodium 2,4,6-trinitrobenzene sulfonate. Inclusion of the Pluronic copolymers within the HP-beta-CD cavities was more favorable in non-polar solvents, such as diethyl ether and n-hexane, both of which gave better coverage ratios than polar solvents. H-1 NMR and MALDI-TOF were used to estimate the average molecular weights of the purified polyrotaxane products. A globular morphology of aggregated polyrotaxanes was observed by tapping-mode AFM imaging of dried samples. Treatment of Niemann-Pick C (NPC) type 2-deficient fibroblasts with the polyrotaxane derivatives produced substantial reductions in sterol accumulation, as seen by diminished filipin staining in these cells, suggesting that Pluronic-based polyrotaxanes may be promising vehicles for delivery of HP-beta-CD to cells with abnormal cholesterol accumulation.