Figure 4.

Nanoparticle uptake by MKN-45 cells revealed by flow cytometry. A total of 5 × 10⁴ MKN-45 cells were seeded in a 24-well plate for 24 hours prior to assay. The medium was then replaced with fresh RPMI 1640 without serum before ibuprofen-loaded PLGA NPs were added. After 2 hours of incubation, the cell monolayers were rinsed three times with PBS buffer to remove excess NPs and incubated with complete medium. NP uptake was verified by flow cytometry. The cells were collected and washed twice with cold PBS. The pellets were resuspended in FACSFlow Sheath Fluid and analyzed by a FACSCanto II cytometer. For each sample, >20,000 cells were analyzed by FACSDiva software. Typical fluorescence histograms (A) and the percentage of fluorescent cells (B) at different time intervals are shown. Nearly 100% of the cells were fluorescent at 24 and 48 hours.

Notes: Values represent the means of three independent experiments performed in triplicate; (^†P < 0.005; Student’s t-test).

Abbreviations: PLGA, poly(lactic-co-glycolic acid); NPs, nanoparticles; PBS, phosphate-buffered saline.