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  • Visualization of internalization of functionalized cobalt ferrite nanoparticles and their intracellular fate.

Visualization of internalization of functionalized cobalt ferrite nanoparticles and their intracellular fate.

International journal of nanomedicine (2013-03-15)
Vladimir B Bregar, Jasna Lojk, Vid Suštar, Peter Veranič, Mojca Pavlin
ABSTRACT

In recent years, nanoparticles (NPs) and related applications have become an intensive area of research, especially in the biotechnological and biomedical fields, with magnetic NPs being one of the promising tools for tumor treatment and as MRI-contrast enhancers. Several internalization and cytotoxicity studies have been performed, but there are still many unanswered questions concerning NP interactions with cells and NP stability. In this study, we prepared functionalized magnetic NPs coated with polyacrylic acid, which were stable in physiological conditions and which were also nontoxic short-term. Using fluorescence, scanning, and transmission electron microscopy, we were able to observe and determine the internalization pathways of polyacrylic acid-coated NPs in Chinese hamster ovary cells. With scanning electron microscopy we captured what might be the first step of NPs internalization - an endocytic vesicle in the process of formation enclosing NPs bound to the membrane. With fluorescence microscopy we observed that NP aggregates were rapidly internalized, in a time-dependent manner, via macropinocytosis and clathrin-mediated endocytosis. Inside the cytoplasm, aggregated NPs were found enclosed in acidified vesicles accumulated in the perinuclear region 1 hour after exposure, where they stayed for up to 24 hours. High intracellular loading of NPs in the Chinese hamster ovary cells was obtained after 24 hours, with no observable toxic effects. Thus polyacrylic acid-coated NPs have potential for use in biotechnological and biomedical applications.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Poly(acrylic acid, sodium salt) solution, average Mw ~8,000, 45 wt. % in H2O
Sigma-Aldrich
Poly(acrylic acid, sodium salt) solution, average Mw ~1,200, 45 wt. % in H2O
Supelco
Poly(acrylic acid sodium salt), analytical standard, for GPC, 16,000
Sigma-Aldrich
Poly(acrylic acid sodium salt), average Mw ~2,100
Sigma-Aldrich
Poly(acrylic acid sodium salt), average Mw ~5,100 by GPC, powder