Nano-enabled, antimicrobial toothbrushes – How physical and chemical properties relate to antibacterial capabilities

• Published in: Journal of hazardous materials 2020-09, Vol.396, p.122445, Article 122445
• Main Authors: Johnson, Clayton R., Tran, Mia Nhu, Michelitsch, Lisa-Marie, Abraham, Simi, Hu, Jinglin, Gray, Kimberly A., Hartmann, Erica M.
• Format: Article
• Language: English
• Subjects: Anti-Bacterial Agents - pharmacology; Anti-Infective Agents; Antimicrobial; Consumer products; Equipment Design; Humans; Microscopy; Nanoparticles; Release; Toothbrush; Toothbrushing
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2020.122445

[Display omitted] •The antimicrobial bristles contained particulate Ag and Zn that ranged from approximately 50 to 100 nm in size.•The antimicrobial bristles contained on average 9.3 μg Ag and 3522.0 μg Zn per toothbrush.•Antimicrobial bristles released Ag and Zn during simulated brushing.•The majority of Ag and Zn release occurred in the first 10 min of brushing.•The bristle antimicrobial properties are affected by toothbrush use and are microbial species dependent. Over the past two decades, Ag and Zn nanoparticles have been integrated into various consumer products as a biocide. While some nano-enabled consumer products have been shown to have antibacterial properties, their antibacterial efficacy as well as the human and environmental health outcomes are not fully known. In this study, we examine a nanoparticle-enabled product that also serves as a conduit for human exposure to bacteria: toothbrushes. We utilize a combination of chemical analyses, laboratory experiments, and microscopy to characterize the nano-enabled toothbrush bristles. Our analysis showed the majority of measured Ag and Zn particles ranged from approximately 50 to 100 nm in size and were located on the surface and within bristles. During simulated brushing, antimicrobial bristles released both Ag and Zn, the majority of which was released in particulate form. While our results demonstrate that antimicrobial bristles have enhanced bactericidal properties compared to control samples, we also show that the surface topography influences nanoparticle retention, microbial adhesion, and bactericidal activity. We thus conclude that Ag or Zn content alone is insufficient to predict antimicrobial properties, which are further governed by the bioavailability of Ag or Zn at the bristle surface.