title: Cytotoxicity of Ultrasmall Gold Nanoparticles on Planktonic and Biofilm Encapsulated Gram-Positive Staphylococci.
abstract: The emergence of multidrug resistant bacteria, especially biofilm-associated Staphylococci, urgently requires novel antimicrobial agents. The antibacterial activity of ultrasmall gold nanoparticles (AuNPs) is tested against two gram positive: S. aureus and S. epidermidis and two gram negative: Escherichia coli and Pseudomonas aeruginosa strains. Ultrasmall AuNPs with core diameters of 0.8 and 1.4 nm and a triphenylphosphine-monosulfonate shell (Au0.8MS and Au1.4MS) both have minimum inhibitory concentration (MIC) and minimum bactericidal concentration of 25 × 10(-6) m [Au]. Disc agar diffusion test demonstrates greater bactericidal activity of the Au0.8MS nanoparticles over Au1.4MS. In contrast, thiol-stabilized AuNPs with a diameter of 1.9 nm (AuroVist) cause no significant toxicity in any of the bacterial strains. Ultrasmall AuNPs cause a near 5 log bacterial growth reduction in the first 5 h of exposure, and incomplete recovery after 21 h. Bacteria show marked membrane blebbing and lysis in biofilm-associated bacteria treated with ultrasmall AuNP. Importantly, a twofold MIC dosage of Au0.8MS and Au1.4MS each cause around 80%-90% reduction in the viability of Staphylococci enveloped in biofilms. Altogether, this study demonstrates potential therapeutic activity of ultrasmall AuNPs as an effective treatment option against staphylococcal infections.
authors.affiliation: Helmholtz-Institute for Biomedical Engineering-Biointerface Laboratory, RWTH Aachen University, Germany.|Laboratory for Biomaterials, Materials Research Centre, Interdisciplinary Bio-Engineering Program, Indian Institute of Science, Bangalore, 560012, India.
authors.forename: Sunil Kumar
authors.initials: SK
authors.lastname: Boda
authors.affiliation: Institute of Inorganic Chemistry, RWTH Aachen University, Germany.
authors.forename: Janine
authors.initials: J
authors.lastname: Broda
authors.affiliation: Institute of Inorganic Chemistry, RWTH Aachen University, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Schiefer
authors.affiliation: Medical Microbiology, RWTH Aachen University, Germany.
authors.forename: Josefine
authors.initials: J
authors.lastname: Weber-Heynemann
authors.affiliation: Electron Microscopy Facility, Medical Faculty, RWTH Aachen University, Germany.
authors.forename: Mareike
authors.initials: M
authors.lastname: Hoss
authors.affiliation: Institute of Inorganic Chemistry, RWTH Aachen University, Germany.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Simon
authors.affiliation: Laboratory for Biomaterials, Materials Research Centre, Interdisciplinary Bio-Engineering Program, Indian Institute of Science, Bangalore, 560012, India.
authors.forename: Bikramjit
authors.initials: B
authors.lastname: Basu
authors.affiliation: Helmholtz-Institute for Biomedical Engineering-Biointerface Laboratory, RWTH Aachen University, Germany.
authors.forename: Willi
authors.initials: W
authors.lastname: Jahnen-Dechent
mesh_terms: D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000737:chemistry; D018441:Biofilms / Q000187:drug effects / Q000254:growth & development*; D002470:Cell Survival / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D006046:Gold / Q000008:administration & dosage* / Q000737:chemistry; D008422:Materials Testing; D053768:Metal Nanoparticles / Q000008:administration & dosage* / Q000737:chemistry / Q000648:ultrastructure*; D010316:Particle Size; D010933:Plankton / Q000187:drug effects / Q000502:physiology*; D013210:Staphylococcus / Q000187:drug effects / Q000502:physiology*
chemical_list: D000900:Anti-Bacterial Agents; D006046:Gold
keywords: antibiotics; biofilms; gold nanoparticles; staphylococci; toxicity