title: Antimicrobial activity of organically modified nano-clays.
abstract: Antimicrobial activity of three kinds of commercially available montmorillonite nano-clays including a naturally occurring one (Cloisite Na+) and two organically modified ones (Cloisite 20A and Cloisite 30B) against four representative pathogenic bacteria (two Gram-positive ones such as Staphylococcus aureus and Listeria monocytogenes, and two Gram-negative ones such as Salmonella typhimurium and E. coli O157:H7) was investigated. Antimicrobial activity was found to be dependent on the type of nano-clay and microorganisms tested. Among the nano-clays tested, Cloisite 30B showed the highest antibacterial activity followed by Cloisite 20A, however, the unmodified montmorillonite (Cloisite Na+) did not show any antibacterial activity. Especially, Cloisite 30B inactivated Gram-positive bacteria completely within an hour of incubation and inactivated Gram-negative bacteria by more than 2-3 log cycles after 8 hours incubation. SEM and TEM images of cell structure indicated that the organically modified nano-clay caused rupture of cell membrane and inactivation of the bacteria. This finding of antimicrobial activity of the organo-clay would open a new opportunity to develop polymer nanocomposites with additional functionality, i.e., antimicrobial function.
authors.affiliation: Korea Food Research Institute, 516 Baekhyun-dong, Bundang-gu, Seongnam-si, 463-746 Kyonggi-do, Korea.
authors.forename: Seek-In
authors.initials: SI
authors.lastname: Hong
authors.forename: Jong-Whan
authors.initials: JW
authors.lastname: Rhim
mesh_terms: D000538:Aluminum Silicates / Q000008:administration & dosage* / Q000737:chemistry; D000900:Anti-Bacterial Agents / Q000008:administration & dosage* / Q000737:chemistry; D018407:Bacterial Physiological Phenomena / Q000187:drug effects*; D002470:Cell Survival / Q000187:drug effects; D000077215:Clay; D003460:Crystallization / Q000379:methods; D046911:Macromolecular Substances / Q000737:chemistry; D008422:Materials Testing; D008968:Molecular Conformation; D050997:Nanomedicine / Q000379:methods*; D049329:Nanostructures / Q000008:administration & dosage* / Q000737:chemistry* / Q000648:ultrastructure; D010316:Particle Size; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry*
chemical_list: D000538:Aluminum Silicates; D000900:Anti-Bacterial Agents; D046911:Macromolecular Substances; C009495:titanium dioxide; D014025:Titanium; D000077215:Clay