Biocompatible Fe3O4 increases the efficacy of amoxicillin delivery against Gram-positive and Gram-negative bacteria

Abstract

This paper reports the synthesis and characterization of amoxicillin- functionalized magnetite nanostructures (Fe3O4@AMO), revealing and discussing several biomedical applications of these nanomaterials. Our results proved that 10 nm Fe3O4@AMO nanoparticles does not alter the normal cell cycle progression of cultured diploid cells, and an in vivo murine model confirms that the nanostructures disperse through the host body and tend to localize in particular sites and organs. The nanoparticles were found clustered especially in the lungs, kidneys and spleen, next to the blood vessels at this level, while being totally absent in the brain and liver, suggesting that they are circulated through the blood flow and have low toxicity. Fe3O4@AMO has the ability to be easily circulated through the body and optimizations may be done so these nanostructures cluster to a specific target region. Functionalized magnetite nanostructures proved a great antimicrobial effect, being active against both the Gram positive pathogen S. aureus and the Gram negative pathogen E. coli. The fabricated nanostructures significantly reduced the minimum inhibitory concentration (MIC) of the active drug. This result has a great practical relevance, since the functionalized nanostructures may be used for decreasing the therapeutic doses which usually manifest great severe side effects, when administrated in high doses. Fe3O4@AMO represents also a suitable approach for the development of new alternative strategies for improving the activity of therapeutic agents by targeted delivery and controlled release.

Figure 1

XRD patterns of Fe₃O₄@AMO and control Fe₃O_4.

Figure 2

TEM images (a,b), HR-TEM image (c) and SAED pattern (d) of magnetite nanoparticles coated with amoxicillin (Fe3O4@AMO).

Figure 3

DLS histogram (a) and zeta potential distribution (b) of the Fe₃O₄@AMO nanoparticles.

Figure 4

Thermogravimetric curves for magnetite nanoparticles with and without amoxicillin.

Figure 5

Flow cytometry results revealing the cell cycle progression of HCT8 cultured cells after the treatment for 24 h with the Fe₃O₄@AMO nanostructures. K = control HCT8 culture (untreated), Fe₃O₄ = HCT8 cultures grown in the presence of 1 mg/mL Fe₃O₄; Fe₃O₄@AMO = HCT8 cultures grown in the presence of 1 mg/mL Fe₃O₄@AMO. p < 0.5, based on One Way ANOVA test.

Figure 6

Graphic representation of the MTT results obtained by analyzing endothelial cells grown in the presence of tested Fe₃O₄@AMO for 24, 48 and 72 h.

Figure 7

Fluorescence microscopy images of endothelial cells grown in the presence of Fe₃O₄@AMO (a) and in standard conditions (b) at 5 days of incubation.

Figure 8

MIC values obtained for the nanoparticles functionalized with antibiotics against S. aureus ATCC 29213, as compared with control MIC values, represented by plain antibiotic solutions, ** p < 0.05.

Figure 9

MIC values obtained for the nanoparticles functionalized with antibiotics against E. coli ATCC 25922, as compared with control MIC values, represented by plain antibiotic solutions. *** p < 0.01.

Figure 10

The effect of Fe₃O₄@AMO on S. aureus adherence at the inert substrata after 24 h of incubation.

Figure 11

The effect of Fe₃O₄@AMO on E. coli adherence at the inert substrata after 24 h of incubation.

Figure 12

Transversal sections through different mice organs (A = brain, B = liver, C = lung, D = kidney, E = spleen) in untreated control (1) and after the treatment with the obtained magnetite nanoparticles for 48 h (2); ×400 magnification.