The effect of gold and iron-oxide nanoparticles on biofilm-forming pathogens

Abstract

Microbial biofilms on biomaterial implants or devices are hard to eliminate by antibiotics due to their protection by exopolymeric substances that embed the organisms in a matrix, impenetrable for most antibiotics and immune-cells. Application of metals in their nanoparticulated form is currently considered to resolve bacterial infections. Gold and iron-oxide nanoparticles are widely used in different medical applications, but their utilisation to eradicate biofilms on biomaterials implants is novel. Here, we studied the effect of gold and iron oxide nanoparticles on Staphylococcus aureus and Pseudomonas aeruginosa biofilms. We report that biofilm growth was reduced at higher concentrations of gold and iron-oxide nanoparticles compared to absence of nanoparticles. Thus nanoparticles with appropriate concentration could show significant reduction in biofilm formation.

Figure 1

Transmission electron micrographs of (a) gold and (b) iron-oxide nanoparticles. Inset images show the synthesized nanoparticles. (b)(B) shows the magnetic property of iron-oxide nanoparticles. Bar denotes 5 nm.

Figure 2

UV-visible spectrum of (a) gold and (b) iron-oxide nanoparticles.

Figure 3

Biofilm formation of S. aureus and P. aeruginosa after 24 h of growth in the presence of gold and iron-oxide nanoparticles (0.01 mg/mL).

Figure 4

Percentage change in biofilm growth in the presence of gold nanoparticles (0.01 mg/mL, 0.05 mg/mL, 0.10 mg/mL, and 0.15 mg/mL) with respect to biofilm growth in the absence of nanoparticles (control). Error bar represents the standard deviations over three replicates, with separately cultured bacteria. #, ∗ denote significance at differences at P < 0.01 compared with 0.01 mg/mL.

Figure 5

Percentage change in biofilm growth in the presence of iron-oxide nanoparticles (0.01 mg/mL, 0.05 mg/mL, 0.10 mg/mL, and 0.15 mg/mL) with respect to biofilm growth in the absence of nanoparticles (control). Error bar represents the standard deviations over three replicates, with separately cultured bacteria. #, ∗ denote significance at differences at P < 0.01 compared with 0.01 mg/mL.