Luorescent microscopy after staining with 1 mg/ml DAPI for 10 min at room temperature. Red: Cy3-labeled siRNAs. Blue: cell nuclei. The bars are 20 mm. doi:10.1371/journal.pone.0060860.g2.8 Cytotoxicity AssayBMECs were seeded in 24-well plates at a density of 2.56104 cells per well in 500 ml of M131 and incubated for 24 h. The cells were then transfected, as described earlier, using Lipofectamine 
2000 or nanoparticles. There were four wells for each mixture. Twenty four hours following transfection, 40 ml of CCK-8 (Dojindo, Japan) was added to each well, and the mixtures were incubated for 4 h. The absorbance (A) was measured at 450 nm with a microplate reader (BioTek, USA). The cell viabilities were K162 custom synthesis normalized using blank cells. To evaluate the cytotoxicity of ENPs at higher concentrations, BMECs were seeded in 96-well plates at a density of 5000 cells per well in 100 ml of M131 and incubated for 24 h. After the media was replaced with a fresh medium, ENPs with siRNA concentrations ranging from 0 mg/ml to 4 mg/ml were added into the cells, followed by a 24 h incubation period. There were four cells for each 11089-65-9 concentration. CCK-8 assays were performed similarly to theexperiments above. NPs with siRNA, ENPs, and siRNAs were used as controls.Results 3.1. Characterization of NanoparticlesThe nanoparticles prepared by blending M-PEG-PLGA and Mal-PEG-PLGA had an average diameter of approximately 92 nm, and this diameter increased to approximately 100 nm after EGFP-EGF1 conjugation. When the siRNAs were entrapped in the nanoparticles, the ENPs and NPs had average diameters of 106 nm and 96 nm, respectively. The zeta potential values of siRNA-loaded NPs and siRNA-loaded ENPs were negative and ranged from 29 mV to 211 mV (Table. 1.). The nanoparticles were generally spherical and uniform. And the conjugation of the EGFP-EGF1 fusion protein is shown in Fig. 1.C. For the PLGA nanoparticles with a high encapsulationFigure 4. Intracellular localization of Cy3-labeled siRNAs and 6-coumarin-loaded ENPs. The cells were cultured in 35 mm glass bottom dishes for 24 h, then co-incubation with ENPs and TNF-a (100 ng/ml) at 37uC for 4 h, and subsequently examined by confocal microscopy. Red: Cy3labeled siRNAs (A). Green: 6-coumarin labeled nanoparticles (B). Blue: cell nuclei (C). Yellow: superimpose red fluorescence on green fluorescence (D). After incubated with 6-coumarin labeled ENPs for 4 h, many of the ENPs had been phagocytize by cells and released Cy3-labeled siRNAs. 15755315 
The bars are 20 mm. doi:10.1371/journal.pone.0060860.gsiRNA-Loaded ENPs for Efficient RNA InterferenceFigure 5. Cell viability assays. (A) BMECs were transfected with different nanoparticles and liposomes at 37uC for 24 h. (B) BMECs were treated with different concentrations of nanoparticles at 37uC for 24 h. The assays were performed in triplicate and the standard errors are shown. doi:10.1371/journal.pone.0060860.gefficiency prepared using the double emulsion solvent evaporation (DESE) method [26], the drug loading capacity of the ENPs and NPs were 1.3660.01 mg/mg and 1.3260.01 mg/mg, respectively. No differences were observed in the drug loading capacity (DLC) and encapsulation efficiency (EE) of ENPs and NPs (Table. 2.). The cumulative release rates of siRNA in PBS (0.01 M) over 6 hours at pHs of 4.0 and 7.4 were 42.5 and 42.49 , respectively. The siRNAs were delay-released over the next 72 hours. There was no significant difference in the in vitro release rate (Fig. 2).3.2. BMECs’.Luorescent microscopy after staining with 1 mg/ml DAPI for 10 min at room temperature. Red: Cy3-labeled siRNAs. Blue: cell nuclei. The bars are 20 mm. doi:10.1371/journal.pone.0060860.g2.8 Cytotoxicity AssayBMECs were seeded in 24-well plates at a density of 2.56104 cells per well in 500 ml of M131 and incubated for 24 h. The cells were then transfected, as described earlier, using Lipofectamine 2000 or nanoparticles. There were four wells for each mixture. Twenty four hours following transfection, 40 ml of CCK-8 (Dojindo, Japan) was added to each well, and the mixtures were incubated for 4 h. The absorbance (A) was measured at 450 nm with a microplate reader (BioTek, USA). The cell viabilities were normalized using blank cells. To evaluate the cytotoxicity of ENPs at higher concentrations, BMECs were seeded in 96-well plates at a density of 5000 cells per well in 100 ml of M131 and incubated for 24 h. After the media was replaced with a fresh medium, ENPs with siRNA concentrations ranging from 0 mg/ml to 4 mg/ml were added into the cells, followed by a 24 h incubation period. There were four cells for each concentration. CCK-8 assays were performed similarly to theexperiments above. NPs with siRNA, ENPs, and siRNAs were used as controls.Results 3.1. Characterization of NanoparticlesThe nanoparticles prepared by blending M-PEG-PLGA and Mal-PEG-PLGA had an average diameter of approximately 92 nm, and this diameter increased to approximately 100 nm after EGFP-EGF1 conjugation. When the siRNAs were entrapped in the nanoparticles, the ENPs and NPs had average diameters of 106 nm and 96 nm, respectively. The zeta potential values of siRNA-loaded NPs and siRNA-loaded ENPs were negative and ranged from 29 mV to 211 mV (Table. 1.). The nanoparticles were generally spherical and uniform. And the conjugation of the EGFP-EGF1 fusion protein is shown in Fig. 1.C. For the PLGA nanoparticles with a high encapsulationFigure 4. Intracellular localization of Cy3-labeled siRNAs and 6-coumarin-loaded ENPs. The cells were cultured in 35 mm glass bottom dishes for 24 h, then co-incubation with ENPs and TNF-a (100 ng/ml) at 37uC for 4 h, and subsequently examined by confocal microscopy. Red: Cy3labeled siRNAs (A). Green: 6-coumarin labeled nanoparticles (B). Blue: cell nuclei (C). Yellow: superimpose red fluorescence on green fluorescence (D). After incubated with 6-coumarin labeled ENPs for 4 h, many of the ENPs had been phagocytize by cells and released Cy3-labeled siRNAs. 15755315 The bars are 20 mm. doi:10.1371/journal.pone.0060860.gsiRNA-Loaded ENPs for Efficient RNA InterferenceFigure 5. Cell viability assays. (A) BMECs were transfected with different nanoparticles and liposomes at 37uC for 24 h. (B) BMECs were treated with different concentrations of nanoparticles at 37uC for 24 h. The assays were performed in triplicate and the standard errors are shown. doi:10.1371/journal.pone.0060860.gefficiency prepared using the double emulsion solvent evaporation (DESE) method [26], the drug loading capacity of the ENPs and NPs were 1.3660.01 mg/mg and 1.3260.01 mg/mg, respectively. No differences were observed in the drug loading capacity (DLC) and encapsulation efficiency (EE) of ENPs and NPs (Table. 2.). The cumulative release rates of siRNA in PBS (0.01 M) over 6 hours at pHs of 4.0 and 7.4 were 42.5 and 42.49 , respectively. The siRNAs were delay-released over the next 72 hours. There was no significant difference in the in vitro release rate (Fig. 2).3.2. BMECs’.
