- Academic Editor
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Background: Ultrasound-responsive nanodroplets (NDs) targeting tumors
have shown great potential in ultrasound imaging and tumor therapy, but most of
these studies are based NDs with lipid shells that cannot overcome the uptake by
cells of the reticulo-endothelial system (RES). NDs with shells comprised of
polyethylene glycol (PEG)-based polymers could effectively suppressed the uptake
of RES, but the phase transition, contrast-enhanced imaging and drug release
about these NDs have not been well illuminated. Methods: Folate receptor
targeted NDs with shells of polymers and loaded with DOX (FA-NDs/DOX) were
prepared. The particle size distribution and morphology of NDs was characterized
with dynamic light scattering (DLS) and microscope. Phase transition and
contrast-enhanced ultrasound imaging under different mechanical indices (MIs) was
studied, and the intensity of contrast enhancement were quantitatively analyzed.
The targeting property of FA-NDs/DOX to MDA-MB-231 cells and cellular uptake were
observed using a fluorescence microscope. The anti-tumor effects of FA-NDs/DOX
combined with low-intensity focused ultrasound (LIFU) was studied through
cytotoxicity tests. Flow cytometry assays were used to detect cell apoptosis.
Results: The average particle size of the FA-NDs/DOX was 448.0