Surfactant-driven optimization of iron-based nanoparticle synthesis: a study on magnetic hyperthermia and endothelial cell uptake

K Riahi; I Dirba; Y Ablets; A Filatova; S N Sultana; E Adabifiroozjaei; L Molina-Luna; U A Nuber; O Gutfleisch

doi:10.1039/d3na00540b

Surfactant-driven optimization of iron-based nanoparticle synthesis: a study on magnetic hyperthermia and endothelial cell uptake

Nanoscale Adv. 2023 Oct 4;5(21):5859-5869. doi: 10.1039/d3na00540b. eCollection 2023 Oct 24.

Authors

K Riahi¹, I Dirba¹, Y Ablets¹, A Filatova², S N Sultana^{1

3}, E Adabifiroozjaei³, L Molina-Luna³, U A Nuber², O Gutfleisch¹

Affiliations

¹ Functional Materials, Institute of Materials Science, Technical University of Darmstadt Peter-Grünberg-Str. 16 64287 Darmstadt Germany kalthoum.riahi@tu-darmstadt.de.
² Stem Cell and Developmental Biology, Technical University of Darmstadt 64287 Darmstadt Germany.
³ Advanced Electron Microscopy Division, Institute of Materials Science, Technical University of Darmstadt Peter-Grünberg-Str. 22 64287 Darmstadt Germany.

Abstract

This work examines the effect of changing the ratio of different surfactants in single-core iron-based nanoparticles with respect to their specific absorption rate in the context of magnetic hyperthermia and cellular uptake by human umbilical vein endothelial cells (HUVEC). Three types of magnetic nanoparticles were synthesized by separately adding oleic acid or oleylamine or a mixture of both (oleic acid/oleylamine) as surfactants. A carefully controlled thermal decomposition synthesis process led to monodispersed nanoparticles with a narrow size distribution. Spherical-shaped nanoparticles were mainly obtained for those synthesized with oleic acid, while the shape changed upon adding oleylamine. The combined use of oleic acid and oleylamine as surfactants in single-core iron-based nanoparticles resulted in a substantial saturation magnetization, reaching up to 140 A m² kg^-1 at room temperature. The interplay between these surfactants played a crucial role in achieving this high magnetic saturation. By modifying the surface of the magnetic nanoparticles using a mixture of two surfactants, the magnetic fluid hyperthermia heating rate was significantly improved compared to using a single surfactant type. This improvement can be attributed to the larger effective anisotropy achieved through the modification with both (oleic acid/oleylamine). The mixture of surfactants enhances the control of interparticle distance and influences the strength of dipolar interactions, ultimately leading to enhanced heating efficiency. Functionalization of the oleic acid-coated nanoparticles with trimethoxysilane results in the formation of a core-shell structure Fe@Fe₃O₄, showing exchange bias (EB) associated with the exchange anisotropy between the shell and the core. The biomedical relevance of our synthesized Fe@Fe₃O₄ nanoparticles was demonstrated by their efficient uptake by human umbilical vein endothelial cells (HUVECs) in a concentration-dependent manner. This remarkable cellular uptake highlights the potential of these nanoparticles in biomedical applications.