Antimicrobial activity of organically modified nano-clays

• Published in: Journal of nanoscience and nanotechnology Vol. 8; no. 11; p. 5818
• Main Authors: Hong, Seek-In, Rhim, Jong-Whan
• Format: Journal Article
• Language: English
• Published: United States 01.11.2008
• Subjects: Aluminum Silicates - administration & dosage; Aluminum Silicates - chemistry; Anti-Bacterial Agents - administration & dosage; Anti-Bacterial Agents - chemistry; Bacterial Physiological Phenomena - drug effects; Cell Survival - drug effects; Clay; Crystallization - methods; Macromolecular Substances - chemistry; Materials Testing; Molecular Conformation; Nanomedicine - methods; Nanostructures - administration & dosage; Nanostructures - chemistry; Nanostructures - ultrastructure; Particle Size; Surface Properties; Titanium - chemistry
• ISSN: 1533-4880
• DOI: 10.1166/jnn.2008.248

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.