In vitro assessment of Ag2O nanoparticles toxicity against Gram-positive and Gram-negative bacteria.

In view of antibiotic resistance among pathogens, the present study is to address the toxicity of Ag2O nanoparticles against the Gram-positive and Gram-negative bacteria through in vitro assays. The preliminary screening by agar diffusion assay confirms the antibacterial activity of Ag2O nanoparticles against all the test bacteria. Comparative antibacterial activity of Ag2O nanoparticles and respective antibiotics reveals their broad range of activity and lower inhibitory dose against the used bacterial strains. Further, they can inhibit E. coli with an effective dose of 0.036 mg/ml within 1 h of exposure time as determined by luciferin based ATP assay. Moreover, the Ag2O nanoparticles exhibit higher antibacterial efficacy against Gram-negative bacteria than Gram-positive bacteria, as revealed by their MIC & MBC values. Therefore, Ag2O nanoparticles pave the way for a new generation of antibacterial agents against the emerging multidrug resistant pathogens.

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.