STRUCTURING OF MAGNETIC NANOPARTICLES IN LIVING CELLS

PAULA ANDREA SOTO; MARCELA B. FERNÁNDEZ VAN RAAP; DIEGO FERNANDO CORAL; PATRICIA SETTON; GUILLERMO ARTURO MUÑOZ MEDINA; FRANCISCO HOMERO SANCHEZ

Campinas

Congreso; lLNLS 27th Annual Users Meeting (RAU); 2017

Laboratorio Nacional de Luz Sincrotrón (LNLS)

The use of iron oxide magnetic nanoparticles (MNP) in the treatment of cancer by magnetic hyperthermia (MH) has been extensively studied. The success of the therapy lies in the optimization of the magnetic response of MNPs to radiofrequency fields (RF) [1]. Experiments are more often carried out on MNP suspensions, where particles-structuring is governed by the competition of the steric, electrostatic and magnetic interactions [2]. A second stage in MH investigations corresponds to study the MNP internalization by in-vitro cultured living cells. In these experiments, the MNP are loaded in endosomes inside the cell cytoplasma, where particles aggregation is observed. This effect produces compact structures composed by several MNP, different to structures observed in MNP suspensions. In these structures, the magnetic dipolar interaction is dominant and the MNP properties are affected, especially those related with their MH efficiency [3]. Small Angle X-ray scattering technique is a useful to characterize MNP structuring in suspension and in living cells, allowing structure comparison between both cases. In this work, the SAXS patterns of MNP in suspensions and internalized by A549 (human pulmonary carcinoma cells) and B16 (murine melanoma tumor) line cells, and ASC stem cells (Wistar Rat Adipose-derived Mesenchymal Stem Cells), cultured in vitro, are presented. In order to analyze the effects of size and coating in MNP structuring inside endosomes, iron oxide core MNP, and coated with different surfactants (DMSA, citric acid and sodium citrate) were used. A core/shell structure composed by iron/iron oxide coated with sodium citrate, and other system composed by iron oxide nanoflowers-like structures coated with sodium citrate were used. Results reveals that, for patterns analyzed with fractal-like structure factor, the fractal exponent increases indicating structures that are more compact. This result is confirmed by TEM images where ring-shape structures are observed inside cell endosomes. We are reporting for the first time the observation of structuring of MNP in cells with SAXS, no reports concerning with this issue has been published yet.[1] M.E. de Sousa, M.B Fernández van Raap, P.C. Rivas, P. Mendoza Zélis, P. Girardin, G. Pasquevich, J.L. Alessandrini, D. Muraca, F.H. Sánchez. Journal of Physical Chemistry C, Vol. 117, p. 5436−5445, (2013).[2] M.B. Fernández van Raap, P. Mendoza Zélis, D.F. Coral, T.E. Torres, C. Marquina, G.F. Goya, F.H. Sánchez, Journal of Nanoparticle Research, Vol. 14, p. 1072, (2012).[3] D.F. Coral, P. Mendoza Zélis, M. Marciello, M.P. Morales, A. Craeivich, F.H. Sánchez, M.B. Fernandez van Raap, Langmuir, vol. 32, p. 1201-1213, (2016).Acknowledgements: This work was supported by Brazilian Synchrotron Light Laboratory (Proposals: SAXS1-14429, SAXS2-22014, SAXS1-20160237), Brazilian Nanotechnology National Laboratory (Proposal: 16901), Campinas-Brazil, Universidad Nacional de La Plata-Argentina, and CONICET-Argentina.