Antimicrobial organophilic montmorillonite nanoparticles: screening and detection assay

The present study presents the development of a standard protocol for detection and screening of nanoparticle(s) for their antimicrobial activity with particular reference to organophilic montmorillonite (Ommt). For this purpose, Ommt nanoparticles have been synthesized through cation exchange of commercial montmorillonite (K10) with a cetyl pyridinium bromide. The formation of Ommt has been ascertained through UV-visible, Fourier transform infrared spectroscopy, X-ray diffraction spectra, and transmission electron microscopy. Subsequently, "zone of inhibition" and "bacterial killing" assays were performed by incubating the four Gram-negative test bacteria with Ommt, to determine antimicrobial activity and reduction in colony forming unit per mL (confirmative test), respectively. The developed assay will provide an easy approach over conventional disc diffusion antibiotic sensitivity test, to study the impact of different nanoparticles against different bacterial species.