Antibacterial Activity of Positively and Negatively Charged Hematite (α-Fe2O3) Nanoparticles to Escherichia coli, Staphylococcus aureus and Vibrio fischeri

Nanomaterials

Krisjanis Smits¹  Liga Bikse¹  Merilin Rosenberg²  Maarja Otsus²  Imbi Kurvet²  Mariliis Sihtmäe²  Anne Kahru²  Kaja Kasemets²  Andris Šutka³  Svetlana Vihodceva³ 

[1] Institute of Solid State Physics, University of Latvia, Kengaraga 8, LV-1063 Riga, Latvia;Laboratory of Environmental Toxicology, National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, 12618 Tallinn, Estonia;Research Laboratory of Functional Materials Technologies, Faculty of Materials Science and Applied Chemistry, Riga Technical University, Paula Valdena 3/7, LV-1048 Riga, Latvia;

关键词: hematite;    α-Fe₂O₃ nanoparticles;    hydrothermal synthesis;    surface charge;    antibacterial;    nano-bio interactions;   

DOI  :  10.3390/nano11030652

来源: DOAJ

【 摘 要 】

In the current study, the antibacterial activity of positively and negatively charged spherical hematite (α-Fe₂O₃) nanoparticles (NPs) with primary size of 45 and 70 nm was evaluated against clinically relevant bacteria Escherichia coli (gram-negative) and Staphylococcus aureus (gram-positive) as well as against naturally bioluminescent bacteria Vibrio fischeri (an ecotoxicological model organism). α-Fe₂O₃ NPs were synthesized using a simple green hydrothermal method and the surface charge was altered via citrate coating. To minimize the interference of testing environment with NP’s physic-chemical properties, E. coli and S. aureus were exposed to NPs in deionized water for 30 min and 24 h, covering concentrations from 1 to 1000 mg/L. The growth inhibition was evaluated following the postexposure colony-forming ability of bacteria on toxicant-free agar plates. The positively charged α-Fe₂O₃ at concentrations from 100 mg/L upwards showed inhibitory activity towards E. coli already after 30 min of contact. Extending the exposure to 24 h caused total inhibition of growth at 100 mg/L. Bactericidal activity of positively charged hematite NPs against S. aureus was not observed up to 1000 mg/L. Differently from positively charged hematite NPs, negatively charged citrate-coated α-Fe₂O₃ NPs did not exhibit any antibacterial activity against E. coli and S. aureus even at 1000 mg/L. Confocal laser scanning microscopy and flow cytometer analysis showed that bacteria were more tightly associated with positively charged α-Fe₂O₃ NPs than with negatively charged citrate-coated α-Fe₂O₃ NPs. Moreover, the observed associations were more evident in the case of E. coli than S. aureus, being coherent with the toxicity results. Vibrio fischeri bioluminescence inhibition assays (exposure medium 2% NaCl) and colony forming ability on agar plates showed no (eco)toxicity of α-Fe₂O₃ (EC₅₀ and MBC > 1000 mg/L).

【 授权许可】

Unknown