Nanomedicine options for colon cancer therapy have been limited by the lack of suitable carriers capable of delivering sufficient drug into tumors to cause lethal toxicity(1,2).To circumvent this limitation,we fabricated a camptothecin(CPT)-loaded poly(lactic-co-glycolic acid)nanoparticle(NP)with dual-surface functionalization—Pluronic F127 and chitosan—for inhibiting multi-drug resistant gene 1(MDR1)expression and enhancing tumor uptake.The resultant spherical NPs-P/C had a desirable particle size(~268 nm),slightly positive zeta-potential,and the ability to efficiently down-regulate the expression of MDR1.