The cellular uptake mechanism of SPIONs: an in-vitro study

The Superparamagnetic Iron Oxide Nanoparticles (SPIONs) of sizes ranging from 10-50 nm are being used in a large number of biological studies because of their peculiar characteristics of inducing local hyperthermia, MR imaging, specific targeting and drug delivery. An in-vitro study of the cytotoxicity and an understanding of the specific pathway of cellular uptake will enable manipulation of conditions for optimal cellular uptake of SPIONs for targeted therapy. The objective of the present study was to identify the endocytotic pathway through which the SPIONs are taken up by C6 glioma cells. The cells were pre-incubated with different concentrations of pharmacological inhibitors and then exposed to SPIONs for a few hours. The endocytosed particles were localized and quantitatively estimated using Perl's or Prussian Blue reaction. There was significant reduction in the uptake of SPIONs when incubated with the inhibitor indicating the uptake of nanoparticles is being inhibited. This reduction in SPION uptake was found to be dependent on the concentration of the inhibitors and also the nature of the inhibitors. By a systematic study of choosing various inhibitors, the data can be narrowed down to the final pathway that may be involved in the SPION uptake. The present preliminary investigation is expected to provide insight of testing the possible mechanisms with complementary techniques.