A new type of biodegradable micelles for glutathione-mediated drug delivery was developed on the basis of amphiphilic polyurethane (PCL-SS-MPEG) with disulfide linkages between the hydrophobic and hydrophilic moieties.The disulfide contained amphiphilic polyurethane was synthesized as follows:first

cystamine capped linear prepolymer polyurethane was synthesized with poly(-caprolactone diol) (PCL) as soft segment

lysine dⅡsocyanate (LDI) and cystamine as hard segment

then epoxy group of -methoxy--epoxy propyl glycol (EO-MPEG) reacted with amine of cystamine capped linear prepolymer polyurethane.The molecular weight of polyurethane was characterized by GPC

the structure was characterized by 1H-NMR and FTIR.Polyurethane micelles was prepared by dialysis method

the critical micelle concentration was 5.610-3g/L measured by fluorescence techniche.TEM analysis showed that the morphology of micelles is spherical

DLS analysis showed that the average particle size of micelles was 82 nm

both TEM and DLS analysis indicated that PCL-SS-MPEG was able to self-assemble into micelles in aqueous solutions benefitting from its amphiphilic structure.Reduction-triggered destabilization of PCL-SS-MPEG was determined by DLS measurements

the results showed the size of micelles significantly increased under 10 mmol/L glutathione

indicating that the micelles had reduction sensitive characteristics.Finally

a hydrophobic anti-cancer drug methotrexate (MTX) was used as a model drug to study drug release in glutathione

the results indicated glutathione can accelerate the release of the drug by breaking the disulfide bridge linkages and destabilizing the micelle structure.This result shows that the polyurethanes are promising to be used as reduction-stimulus materials in drug delivery.