Inhibition of Bacterial Growth by the Exfoliated Clays and Observation of Physical Capturing Mechanism

We observed unexpected antimicrobial behavior from the silicate platelets, prepared from the exfoliation of natural clays, for a broad spectrum of microorganisms. The antimicrobial properties are attributed to the unique structure of the exfoliated platelets, which possess an average dimension of 80 nm x 80 nm x 1 nm and polyvalent ionic charges (ca. 18 000 sodium ions/platelet) on the surface of ultrathin platelets. The thin shape and ionic character of the silicates enables them to physically adhere to microbe surfaces and be directly observed by scanning electron microscopy. The nanometer-sized thin silicates with the uniquely combined features of large surface areas and polyvalent charges have potential uses for biomedical treatments.