Microscale ZnO with controllable crystal morphology as a platform to study antibacterial action on <i>Staphylococcus aureus</i>

Reeks, John; Ali, Iman; Moss, William J.; Davis, Eric S.; McGillivray, Shauna M.; Strzhemechny, Yuri M.

doi:10.1116/6.0000957

Cited by 4 publications

(11 citation statements)

References 27 publications

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“…We find that nanoscale particles exhibit an MIC at ca. 2.5 mg/mL, which is comparable to the MIC previously reported for our hydrothermally grown ZnO microparticles [29]. It should be noted that those results do not indicate differences detectable at this stage in antibacterial action for samples of different synthesis origins and morphological nature.…”

Section: Morphologysupporting

confidence: 88%

“…As previously reported [29], we employed the hydrothermal growth technique to produce ZnO MPs of tunable size and morphology to probe the influence of ZnO surface polarity on the underlying antibacterial behavior of ZnO at the micro and nanoscale. The synthesized MPs, in conjunction with commercial NPs, were then used in antibacterial assays and underwent optoelectronic characterization.…”

Section: Resultsmentioning

confidence: 99%

“…Studies into this phenomenon indicate that the latter may be more likely. Previous work has shown that for Staphylococcus aureus (S. aureus), ZnO microparticles (MPs) far too large to be internalized by the bacteria, demonstrated cytotoxic efficacy comparable to those at the nanoscale [29]. These studies indicate that cell internalization of ZnO is not a driving force in the observed antibacterial behavior, pointing to other mechanisms that scale with particle size [29,30].…”

Section: Introductionmentioning

confidence: 92%

“…Commercial ZnO NPs (with the average size < 100 nm) were provided by Sigma Aldrich (SA, St. Louis, MO, USA) and Zochem Inc (Dickson, TN, USA). MPs were synthesized in-house using a bottom-up hydrothermal growth method previously described in [29] as follows. ZnO microcrystals were grown from a D.I.…”

Section: Zno Synthesismentioning

confidence: 99%

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Influence of Surface Properties and Microbial Growth Media on Antibacterial Action of ZnO

et al. 2022

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Nano- and microscale ZnO demonstrate robust antibacterial action, although the driving mechanisms remain undetermined. In this study for commercial ZnO nano-powders and home-grown ZnO microparticles of varying morphologies we probe the response to bacterial growth media in isolation and with Staphylococcus aureus bacteria. ZnO microparticles are synthesized via a controllable hydrothermal method and subjected to biological assays with varying microbial environments. Changes in the optoelectronic, structural and chemical properties of these crystals before and after such exposure are characterized utilizing temperature-dependent photoluminescence spectroscopy, scanning electron microscopy and energy-dispersive X-ray spectroscopy. This is done to evaluate the impact of surface-surface interactions in antibacterial assays and the role ZnO surface and morphological properties play in these processes. In our experiments various bacterial environments are employed to elucidate the effects of media interactions on the cytotoxic efficacy of ZnO. In particular, minimum inhibitory concentration assays with Staphylococcus aureus reveal that microscale particles exhibit antibacterial efficacy comparable to that of the nano-powders, indicating that intra-bacterial internalization is not necessary for antimicrobial action. In our studies we determine that the nature of structural and optoelectronic changes in ZnO depends on both the media type and the presence (or absence) of bacteria in these media. Further evidence is provided to support significant cytotoxicity in the absence of particle internalization in bacteria, further highlighting the role of surface and media interactions in this process.

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Section: Morphologysupporting

confidence: 88%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 92%

Section: Zno Synthesismentioning

confidence: 99%

See 2 more Smart Citations

Influence of Surface Properties and Microbial Growth Media on Antibacterial Action of ZnO

et al. 2022

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“…Such experiments are of interest as they allow for the elucidation of the surface-specific responses of ZnO to bacteria and the local environment. The usage of ZnO MPs serves to control for internalization effects which are not thought to be a driving force in the observed bacterial growth inhibition [ 23 ]. Exposure of ZnO MPs to PBS in isolation allows for differentiation of interactions at the surface between bacteria and the media.…”

Section: Introductionmentioning

confidence: 99%

Surface Photovoltage Response of ZnO to Phosphate-Buffered Saline Solution with and without Presence of Staphylococcus aureus

et al. 2023

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Nano- and microscale zinc oxide (ZnO) exhibits significant potential as a novel antibacterial agent in biomedical applications. However, the uncertainty regarding the underlying mechanisms of the observed antimicrobial action inhibits the realization of this potential. Particularly, the nature of interactions at the free crystalline surface and the influence of the local bacterial environment remains unclear. In this investigation, we utilize ZnO particles synthesized via tunable hydrothermal growth method as a platform to elucidate the effects of interactions with phosphate-rich environments and differentiate them from those with bacteria. This is achieved using the time- and energy-dependent surface photovoltage (SPV) to monitor modifications of the surface electronic structure and surface charge dynamics of the ZnO particles due to these interactions. It is found that there exists a dramatic change in the SPV transients after exposure to phosphate-rich environments. It also presents differences in the sub-bandgap surface electronic structure after these exposures. It can be suggested that these phenomena are a consequence of phosphate adsorption at surface traps corresponding to zinc deficiency defects. This effect is shown to be suppressed in the presence of Staphylococcus aureus bacteria. Our results support the previously proposed model of the competitive nature of interactions between S. aureus and aqueous phosphates with the free surface of ZnO and bring greater clarity to the effects of phosphate-rich environments on bacterial growth inhibition of ZnO.

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Zinc oxide nanoparticles mediate bacterial toxicity in Mueller-Hinton Broth via Zn2+

Caron,

Ali,

Delgado

et al. 2024

Front. Microbiol.

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As antibiotic resistance increases and antibiotic development dwindles, new antimicrobial agents are needed. Recent advances in nanoscale engineering have increased interest in metal oxide nanoparticles, particularly zinc oxide nanoparticles, as antimicrobial agents. Zinc oxide nanoparticles are promising due to their broad-spectrum antibacterial activity and low production cost. Despite many studies demonstrating the effectiveness of zinc oxide nanoparticles, the antibacterial mechanism is still unknown. Previous work has implicated the role of reactive oxygen species such as hydrogen peroxide, physical damage of the cell envelope, and/or release of toxic Zn2+ ions as possible mechanisms of action. To evaluate the role of these proposed methods, we assessed the susceptibility of S. aureus mutant strains, ΔkatA and ΔmprF, to zinc oxide nanoparticles of approximately 50 nm in size. These assays demonstrated that hydrogen peroxide and electrostatic interactions are not crucial for mediating zinc oxide nanoparticle toxicity. Instead, we found that Zn2+ accumulates in Mueller-Hinton Broth over time and that removal of Zn2+ through chelation reverses this toxicity. Furthermore, we found that the physical separation of zinc oxide nanoparticles and bacterial cells using a semi-permeable membrane still allows for growth inhibition. We concluded that soluble Zn2+ is the primary mechanism by which zinc oxide nanoparticles mediate toxicity in Mueller-Hinton Broth. Future work investigating how factors such as particle morphology (e.g., size, polarity, surface defects) and media contribute to Zn2+ dissolution could allow for the synthesis of zinc oxide nanoparticles that possess chemical and morphological properties best suited for antibacterial efficacy.

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Microscale ZnO with controllable crystal morphology as a platform to study antibacterial action on Staphylococcus aureus

Cited by 4 publications

References 27 publications

Influence of Surface Properties and Microbial Growth Media on Antibacterial Action of ZnO

Influence of Surface Properties and Microbial Growth Media on Antibacterial Action of ZnO

Surface Photovoltage Response of ZnO to Phosphate-Buffered Saline Solution with and without Presence of Staphylococcus aureus

Zinc oxide nanoparticles mediate bacterial toxicity in Mueller-Hinton Broth via Zn2+

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