Physical characterization

The particle size and zeta potential (ζ) of the K237/FA-PEG-PLGA NPs were characterized using a ZetaSizer Nano ZS (Malvern Instruments Ltd., Malvern, UK). The average diameters and size distribution parameters of the NPs were obtained by dynamic light scattering. The ζ was determined under a He-Ne laser beam at a wavelength of 633.8 nm at room temperature.

The morphology of the NPs was examined with an H-800 transmission electron microscope (TEM) from Hitachi Ltd., (Tokyo, Japan). The samples were prepared by depositing 10 μL of NPs suspension on a 200 mesh, copper grid with a formvar film, and then air-drying at room temperature [34–37].