writer：Weijia Wang, Shaobing Zhou*, Laiyang Guo,
keywords：Biodegradable;nanoparticle,controlled release
source：期刊
specific source：International Journal of Nanomedicine 2010:5 557–566.
Issue time：2010年

polymer particles present a promising approach for intracellular
delivery of drugs, proteins, and nucleic acids. Poly-d,l-lactide-poly(ethylene glycol) (PELA)
copolymers with different weight ratios of polyethylene glycol (PEG) were used as drug carriers
in the present study. PELA particles entrapped with fluorescein isothiocyanate (FITC) as
a fluorescent marker were formulated using a double emulsion-solvent evaporation technique.
The size and morphology of the particles were observed with scanning electron microscope
(SEM), atomic force microscope (AFM), and laser diffraction particle size analyzer (LDPSA).
The purpose in the present work was to investigate the cytotoxicity and the process of endocytosis
of PELA particles with different contents of PEG and variable particle size using rat
osteoblasts (OBs). The cytotoxicity of the particles was investigated using 5-dimethylthiazol-
2-yl-2,5-diphenyltetrazolium bromide (MTT) assay and flow cytometry. Results indicate that
as the content of PEG in the polymer increased, so did cell survival. Endocytosis was observed
through a light microscope and a fluorescence microscope; intracellular uptake and retention
were determined quantitatively using fluorescence spectrophotometer (FSP). The results showed
that as PEG content in PELA copolymer increased, there was a reduction in endocytosis of