Surfactant-free nanoparticles Of poly(DL-lac-tide-co-glycolide) (PLGA) nanoparticles were prepared with or without poly(L-lactide)-poly(ethylene oxide) (LE) diblock copolymer (abbreviated as PLGA/LE and PLGA nanoparticles) by dialysis method. LE diblock copolymer was used to make PLGA nanoparticles to alternate conventional surfactant. The size of PLGA and PLGA/LE nanoparticles was 295.3 +/- 171.3 and 307.6 +/- 27.2 nm, respectively, suggesting LE diblock copolymer might be coated onto the surface of nanoparticles. Observation of scanning electron microscope (SEM) showed that PLGA/LE nano articles have spherical T shapes ranging similar to 200-500 nm. In H-1-NMR study, characteristic peaks of the methyl protons of PLGA disappeared in D2O, whereas characteristic peaks of the methyl proton of both PEG and PLGA were shown in both CDCl3, and D2O, indicating that LE diblock copolymer coated on the surface of the PLGA nanoparticles. The higher the initial content of drug, the higher the drug contents and the lower the loading efficiency. PLGA/LE nanoparticles at higher drug contents resulted in slower adriamycin-HCl (ADR) release rate than that of lower drug contents. Also, slower release rate of ADR was achieved by entrapped into the PLGA/LE nanoparticles, whereas LE polymeric micelles showed rapid ADR release. (C) 2003 Wiley Periodicals, Inc.