In this work, we investigate the effect of chitosan hydrophobization on the internalization and cytotoxic effect
of chitosan-based nanoparticles (NPs) on breast cancer cells (MDA-MB-231), cervical cancer cells (HeLa) and noncancer
cells (Arpe-19). We also analyzed the interaction of NPs with a phospholipid (DPPC) membrane model at the airwater
interface. An alkylation procedure to insert 8 carbon chains along the chitosan macromolecule with final 10 and 30
% substitution degrees was used. Nuclear magnetic resonance (NMR) and infrared spectroscopes (IR) were used to evaluate
the success and extent of the hydrophobization procedure. Size, shape, and charge of NPs were evaluated by dynamic
light scattering (DLS), atomic force microscope (AFM), and zeta potential, respectively. The effect of hydrophobicity on
NPs was the reduction of the NPs average size, the formation of slightly elongated structures and the enhancing of the interaction
of NPs with a DPPC monolayer at the air-water interface. By using fluorescence images on fluorescein-chitosan
NPs, we observed a higher internalization of hydrophobic chitosan NPs in cancer cells in comparison with a low internalization
of these NPs in normal cells. Even when non modified chitosan NPs were highly internalized in all cell lines, hydrophobized
chitosan NPs showed a significantly higher cytotoxic effect on cancer cells in comparison with a lower effect
showed by non-modified chitosan NPs on these cells. The cytotoxic effect on the normal cell line used was low for native
chitosan NPs and negligible for hydrophobized chitosan NPs.
Keywords: Chitosan, hydrophobization, chitosan nanoparticles, cytotoxicity, cellular uptake, langmuir monolayers.
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