45-μm pore) to remove aggregated particles. Then, half of the empty and DOX-loaded micelles were used to study the pH-responsive behavior by the addition of NaOH or HCl (0.01 M) solution. And the remaining empty and DOX-loaded micelles were collected by freeze-drying to obtain dried product. The received white powder was stored at −20°C until further experiments. The values of D hs and morphologies of the empty and DOX-loaded micelles were monitored
by DLS and TEM. DOX-loaded micelles were XAV-939 mouse dissolved in 10 mL of DMSO under vigorous vortexing and analyzed by UV-vis spectrophotometer (UV-2450, Shimadzu, Kyoto, Japan) at 480 nm to obtain DOX loading content (LC), wherein a calibration curve was obtained with DOX-DMSO solutions with different DOX concentrations. The LC values were around 10% in the current work. In Kinase Inhibitor Library mw vitro DOX release The release profiles of DOX from the DOX-loaded micelles at a concentration of 1 mg/mL were studied in different Z-IETD-FMK cell line media (pH 5.0, pH 6.5, and pH 7.4). Briefly, 5 mg of DOX-loaded micelles
were immersed in 5 mL of PBS buffer (pH 7.4 or pH 6.5) or acetate buffer (pH 5.0) and then placed in a pre-swollen cellulose membrane bag (MWCO = 3.5 kDa). The whole bag was placed into 40 mL of PBS or acetate buffer with constant shaking (100 rpm) at 37°C (Dissolution Tester RCZ-8B, TDTF, Tianjin, China). At predetermined time intervals, a 4-mL buffer solution outside the dialysis bag was extracted and it was replaced by an equal volume of fresh media to keep the sink condition. The amounts of released DOX in different buffers were monitored by UV-vis spectrophotometer at 480 nm. Each experiment was done in triplicate, and the results were the average data. Cell
culture and cytotoxicity assay The in vitro cytotoxicity tests of the free DOX, empty, and DOX-loaded micelles were evaluated by the standard MTT assay against HepG2 cells. The HepG2 cells were first seeded on a 96-well plate at an initial density of 1 × 104 cells/well in DMEM supplemented with 10% FBS, penicillin (100 units/mL), and streptomycin (100 μg/mL) at 37°C in a CO2 (5%) incubator for 3 days to reach 60% to 70% confluence. Then, the empty old micelles with the final concentration from 1 to 400 μg/mL were added. After 48 h, 20 μL of MTT solution (5 mg/mL in PBS buffer) was added into each well and incubated for another 4 h. Afterwards, the medium in each well was then removed and 200 μL of DMSO was added to dissolve the internalized purple formazan crystals. The absorbance was measured at a wavelength of 490 nm by a microplate reader (Multiskan Spectrum, Thermo Scientific, Vantaa, Finland). Data were expressed as average ± SD (n = 3). HepG2 cells were incubated with free DOX and DOX-loaded micelles with DOX final concentration from 0.1 to 20 μg/mL in culture medium. After 24 and 48 h, 20 μL of MTT solution (5 mg/mL in PBS buffer) was added into each well and incubated for another 4 h.