Polymeric nanoparticles have been increasingly investigated as promising nanocarriers for oral drug delivery.Based on the excellent characteristics of chitosan,two amphipathic copolymers polylysine-chitosan-polylactide(PL-CS-PLA)and polylysine-cysteine-chitosan-polylactide(PY-CS-PLA)were designed and synthesized for oral delivery of paclitaxel(PTX)to improve its oral bioavailability by increasing its water solubility and bypassing the P-gp drug efflux pumps.