Shape dependent physical mutilation and lethal effects of silver nanoparticles on bacteria.

In this report, spherical silver nanoparticle (AgNP-sp) and rod-shaped silver nanoparticle (AgNR) were prepared by chemical reduction method and their antibacterial activity against various Gram-positive and Gram-negative bacteria had been evaluated for their efficiency. Minimal inhibitory concentration (MIC) tests were conducted to study the antibacterial properties, and substantiated with killing kinetics of silver nanoparticles (AgNPs). The study revealed that both AgNP-sp and AgNRs are good antibacterial candidates. Bacterial sensitivity to nanoparticles (NPs) was found to vary depending on microbial species. Disc diffusion studies revealed the greater effectiveness of AgNP-sp and AgNR against Klebsiella pneumoniae AWD5 at the doses of 249 and 392 µg. The dose dependent activities of prepared NPs were also observed on the batch studies of disc diffusion and MIC with various strains. The optical and morphological structures of NPs were analyzed by UV-visible, XRD, FE-SEM and TEM. Further, FESEM of bacterial culture treated with AgNPs confirmed antibacterial activity of NPs by showing rupture of bacterial cell wall. Also, the genome of test organism was found to have CusCFBA and CusRS operons. The killing kinetics confirmed that the death rate of K. pneumoniae was higher against AgNP-sp as compared to AgNR.

Potential of Vinca rosea extracts in modulating trace element profile: a chemopreventive approach.

Diethylnitrosamine (DEN) was used as cancer-inducing agent in the experimental animals. Vinca rosea extract was supplemented with the drinking water as a chemopreventive agent. After 4 wk of treatment, animals were sacrificed and livers were excised. Nuclei and mitochondria were separated by differential centrifugation. The proton-induced X-ray emission technique has been used as the analytical method. Elemental analysis were performed for whole liver, nuclei, and mitochondria.V. rosea plant parts were also analyzed for elemental contents. Treatment with DEN caused an increase of Ni, Zn, and Cr levels in the whole liver and nuclei. There is an increase in Fe concentration in the liver, although the level decreased in mitochondria. The concentrations of Br and Ca were unchanged in the liver as a whole, but there were substantial increases of Br in nuclei and mitochondria, whereas Ca levels depleted drastically in these two organelles. Vinca extracts were effective in reverting the changes in the elemental concentration in the hepatic tissue as a whole, but were not that effective at subcellular levels.