Antibacterial and antibiofilm properties of yttrium fluoride nanoparticles

Abstract

Antibiotic resistance has prompted the search for new agents that can inhibit bacterial growth. Moreover, colonization of abiotic surfaces by microorganisms and the formation of biofilms is a major cause of infections associated with medical implants, resulting in prolonged hospitalization periods and patient mortality. In this study we describe a water-based synthesis of yttrium fluoride (YF₃) nanoparticles (NPs) using sonochemistry. The sonochemical irradiation of an aqueous solution of yttrium (III) acetate tetrahydrate [Y(Ac)₃ · (H₂O)₄], containing acidic HF as the fluorine ion source, yielded nanocrystalline needle-shaped YF₃ particles. The obtained NPs were characterized by scanning electron microscopy and X-ray elemental analysis. NP crystallinity was confirmed by electron and powder X-ray diffractions. YF₃ NPs showed antibacterial properties against two common bacterial pathogens (Escherichia coli and Staphylococcus aureus) at a μg/mL range. We were also able to demonstrate that antimicrobial activity was dependent on NP size. In addition, catheters were surface modified with YF₃ NPs using a one-step synthesis and coating process. The coating procedure yielded a homogeneous YF₃ NP layer on the catheter, as analyzed by scanning electron microscopy and energy dispersive spectroscopy. These YF₃ NP-modified catheters were investigated for their ability to restrict bacterial biofilm formation. The YF₃ NP-coated catheters were able to significantly reduce bacterial colonization compared to the uncoated surface. Taken together, our results highlight the potential to further develop the concept of utilizing these metal fluoride NPs as novel antimicrobial and antibiofilm agents, taking advantage of their low solubility and providing extended protection.

Keywords:

• yttrium fluoride
• nanoparticles
• biofilms
• antibacterial
• catheter
• sterile surfaces

Acknowledgments

This research was carried out as part of the activities of the KAMIN project financed by the Israeli Ministry of Industry, Trade and Labor to EB. This research was carried out as part of the activities of the NOVO Consortium. NOVO, is an investigatory project of the Seventh European Commission Program, HEALTH.2011.2.3.1-5 (Contract No 278402) to AG. This research is part of the requirements for a PhD thesis for JL at Bar-Ilan University. We confirm that the manuscript has been read and approved by all named authors and that there are no other persons who satisfied the criteria for authorship. We further confirm that the order of authors listed in the manuscript has been approved by all of us.

Disclosure

We confirm that there are no known conflicts of interest associated with this publication and there has been no significant financial support for this work that could have influenced its outcome.

Supplementary figures

Figure S1 Growth curves (A) and biofilm formation (B) of Escherichia coli and Staphylococcus aureus exposed to fluorine (100 μg/mL) and yttrium ions (100 μg/mL) for 24 hours at 37°C.

Notes: Untreated bacteria served as a control. Error bars represent the standard deviation of three independent experiments conducted in triplicate.

Abbreviation: OD₅₉₅, optical density at 595 nm.

Figure S2 Antimicrobial effect of MgF₂ NPs. Growth curves of (A) Escherichia coli and (B) Staphylococcus aureus exposed to variable concentrations (0.0001 to 1 mg/mL) of MgF₂ NP solutions for 24 hours at 37°C.

Notes: Untreated bacteria served as a control. Error bars represent the standard deviation of three independent experiments conducted in triplicate.

Abbreviations: MgF₂, magnesium fluoride; OD₅₉₅, optical density at 595 nm; NPs, nanoparticles.