Synthesis of magnetite/silica nanocomposites from natural sand to create a drug delivery vehicle

Abstract

In this study, we report the synthesis of the magnetite/silica nanocomposites and their structural and functional groups, magnetic properties, morphology, antimicrobial activity, and drug delivery performance. The X-ray diffraction characterization showed that magnetite formed a spinel phase and that silica formed an amorphous phase. The particle sizes of magnetite increased from 8.2 to 13.2 nm with increasing silica content, and the particles were observed to be superparamagnetic. The nanocomposites tended to agglomerate based on the scanning electron microscopy images. The antimicrobial activity of the magnetite/silica nanocomposites revealed that the increasing silica content increased the inhibition zones by 74%, 77%, and 143% in case of Gram-positive bacteria (B. subtilis), Gram-negative bacteria (E. coli), and fungus (C. albicans), respectively. Furthermore, doxorubicin was used as the model compound in the drug loading and release study, and drug loading was directly proportional to the silica content. Thus, the increasing silica content increased the drug loading owing to the increasing number of OH- bonds in silica, resulting in strong bonds with doxorubicin. Based on this study, the magnetite/silica nanocomposites could be applied as drug delivery vehicles.

Keywords: Biomedical engineering; Doxorubicin; Drug delivery vehicle; Magnetite/silica; Materials science; Nanocomposite; Nanotechnology; Natural sand.

Figure 1

Schematic synthesis of the magnetite/silica nanocomposites.

Figure 2

XRD patterns of the magnetite and amorphous silica.

Figure 3

XRD patterns of the magnetite/silica nanocomposites.

Figure 4

FTIR spectra of the magnetite/silica nanocomposites.

Figure 5

(a) SEM images, (b) EDX spectra, and (c) particle size distributions of the samples FS1, FS2, FS3, and FS4. The SiKa, OKa, FeKa, FeLa, FeKb, and FeKesc represent the elemental contents (Si, O, and Fe) of the magnetite/silica nanocomposites.

Figure 6

Hysteresis curves of the magnetite, silica, and magnetite/silica nanocomposites.

Figure 7

Fitted hysteresis curves of the samples (a) magnetite, (b) FS1, (c) FS2, (c) FS2, (d) FS3, (d) FS3, and (e) FS4. The circles represent the magnetization data, and the solid lines represent the fitting model using the Langevin equation.

Figure 8

Mechanisms of cell damage by nanoparticles.

Figure 9

Inhibition zone diameter of the magnetite/silica nanocomposites.

Figure 10

Dox loading profiles of the magnetite/silica nanocomposites.

Figure 11

Cumulative drug release profiles of the magnetite/silica nanocomposites.