The Synthesis Methodology and Characterization of Nanogold-Coated Fe3O4 Magnetic Nanoparticles

Abstract

Core-shell nanostructures are widely used in many fields, including medicine and the related areas. An example of such structures are nanogold-shelled Fe₃O₄ magnetic nanoparticles. Systems consisting of a magnetic core and a shell made from nanogold show unique optical and magnetic properties. Thus, it is essential to develop the methodology of their preparation. Here, we report the synthesis methodology of Fe₃O₄@Au developed so as to limit their agglomeration and increase their stability. For this purpose, the impact of the reaction environment was verified. The properties of the particles were characterized via UV-Vis spectrophotometry, dynamic light scattering (DLS), X-ray diffraction (XRD), and Scanning Electron Microscopy-Energy Dispersive X-ray analysis (SEM-EDS technique). Moreover, biological investigations, including determining the cytotoxicity of the particles towards murine fibroblasts and the pro-inflammatory activity were also performed. It was demonstrated that the application of an oil and water reaction environment leads to the preparation of the particles with lower polydispersity, whose agglomerates' disintegration is 24 times faster than the disintegration of nanoparticle agglomerates formed as a result of the reaction performed in a water environment. Importantly, developed Fe₃O₄@Au nanoparticles showed no pro-inflammatory activity regardless of their concentration and the reaction environment applied during their synthesis and the viability of cell lines incubated for 24 h with the particle suspensions was at least 92.88%. Thus, the developed synthesis methodology of the particles as well as performed investigations confirmed a great application potential of developed materials for biomedical purposes.

Keywords: Arabic gum; core-shell nanostructures; gold nanoparticles; magnetic nanoparticles; nanoparticles agglomeration; pro-inflammatory activity; sonication-assisted agglomerates disintegration.

Figure 1

The scheme of Fe₃O₄@Au synthesis.

Figure 2

Images showing the behavior of the nanoparticles under the influence of the magnetic field applied.

Figure 3

SEM images of Fe₃O₄ nanoparticles.

Figure 4

XRD pattern of magnetic nanoparticles washed with 0.1 M sodium citrate solution.

Figure 5

The size analysis of Fe₃O₄@Au particles obtained in the water environment.

Figure 6

The size analysis of Fe₃O₄@Au particles obtained in the water environment and subjected to 6 h sonication.

Figure 7

The size analysis of Fe₃O₄@Au particles obtained in the oil and water environment.

Figure 8

The size analysis of Fe₃O₄@Au particles obtained in the oil and water environment after 15 min sonication.

Figure 9

UV-Vis spectrum of Fe₃O₄@Au particles obtained in the oil and water environment.

Figure 10

UV-Vis spectra of suspensions obtained under various Fe₃O₄@Au nanoparticle synthesis conditions.

Figure 11

SEM images of Fe₃O₄@Au nanoparticles supported with EDS analysis of two points (a,b).

Figure 12

TEM images of the Fe₃O₄ particles after Massart synthesis (a) and Fe₃O₄@Au nanoparticles (b).

Figure 13

Results of MTT reduction assay of Fe₃O₄@Au nanoparticle suspensions prepared in the water environment (the cell viability over 70%—this has been marked via a red dotted line—indicates non-cytotoxicity of tested materials).

Figure 14

Results of MTT reduction assay of Fe₃O₄@Au nanoparticle suspensions prepared in the oil and water environment (the cell viability over 70%—this has been marked via a red dotted line—indicates non-cytotoxicity of tested materials).

Figure 15

Analysis of the pro-inflammatory activity of Fe₃O₄@Au nanoparticle suspensions prepared in the water environment.

Figure 16

Analysis of the pro-inflammatory activity of Fe₃O₄@Au nanoparticle suspensions prepared in the oil and water environment.