Analyzing the structure factor of nanoparticles internalized in carcinoma cells.

PAULA A. SOTO; MARCELA B. FERNÁNDEZ VAN RAAP; DIEGO CORAL; J. MERA; GUILLERMO MUÑOZ MEDINA

Campinas

Congreso; 29th Annual Users Meeting of the Brazilian Synchrotron Light Laboratory (RAU/LNLS); 2019

Laboratorio Nacional de Pesquisa em energia e materiais-CNPEM

Magnetic nanoparticles (MNP) are widely used in biomedical applications such as drug delivery, MRI and magnetic hyperthermia [1]. Due to the magnetic characteristics, MNP tend to aggregate, this problem is solved coating the MNP with an organic surfactant shell [2], but, when MNP are internalized by living cells, these are enclosed in highly concentrated structures called endosomes, where the inter-particle distance is reduced increasing the magnetic interaction. For this reason, MNP properties related with the magnetic interactions are modified [3] and how particles are structured inside endosomes must be studied. In this work, MNP different in size, morphology and chemical composition were internalized by in vitro cultured B16-f0 murine melanoma cells. MNP in colloidal suspensions and internalized cells cultures were analyzed with SAXS technique. SAXS patterns were fitted using a spherical form factor (F(r,q)) model and a LogNormal size distribution (g(r)), the structure factor (S(q)) were added following the monodisperse approximation model. From SAXS patterns, MNP morphological parameters and the experimental S(q) were retrieved and compared with the fitted structure factor. Results show that the correlation peak positions is different for colloidal and internalized samples. Due to particle magnetic moment controls the structuring of MNP, for samples with smaller particles a mass-fractal structure factor describes the experimental S(q) while a sticky hard sphere structure factor describes the structuring of samples with bigger particles. The bigger the particle the more compacted structure.