Antibacterial activity of colloidal copper nanoparticles against Gram-negative (Escherichia coli and Proteus vulgaris) bacteria.

Antibacterial activities of as-synthesized nanoparticles have gained attention in past few years due to rapid phylogenesis of pathogens developing multi-drug resistance (MDR). Antibacterial activity of copper nanoparticles (CuNPs) on surrogate pathogenic Gram-negative bacteria Escherichia coli (MTCC no. 739) and Proteus vulgaris (MTCC no. 426) was evaluated under culture conditions. Three sets of colloidal CuNPs were synthesized by chemical reduction method with per batch yield of 0·2, 0·3 and 0·4 g. As-synthesized CuNPs possess identical plasmonic properties and have similar hydrodynamic particle sizes (11-14 nm). Antibacterial activities of CuNPs were evaluated by minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) tests, cytoplasmic leakage and reactive oxygen species (ROS) assays. MIC and MBC tests revealed dose dependence bactericidal action. Growth curves of E. coli show faster growth inhibition along with higher cytoplasmic leakage than that of P. vulgaris. This might be because of increased membrane permeability of E. coli. CuNP-microorganism interaction induces oxidative stress generated by ROS. Leakage of cytoplasmic components, loss of membrane permeability and ROS generation are the primary causes of CuNP-induced bacterial cell death. As-synthesized CuNPs exhibiting promising antibacterial activities and could be a promising candidate for novel antibacterial agents.

Effect of copper on the up-regulation/down-regulation of genes, cytotoxicity and ion dissolution for mesoporous bioactive glasses.

In the present study, copper-based (25 - x)CaO - xCuO -10P2O5 - 5B2O3 - 60SiO2 (x = 2.5, 5, 7.5, 10 mol%) mesoporous bioactive glasses (MBGs) were synthesized using the sol-gel technique with cetyltrimethyl ammonium bromide as the structure-directing agent. The live-dead cell count and cytocompatibility of MBGs for J774A.1 murine macrophages have also been investigated for different concentrations of MBGs. The ionic dissolution profile for Ca, P and Si has been evaluated in the simulated body fluid. The effect of copper content as well as the ionic dissolution products on the up-regulation and down-regulation of TGIF-2, HDAC-4, Smurf-1, mir-30c and mir-130a genes for the murine model are investigated using reverse transcription-polymerase chain reaction. Silica and calcium release follows a similar trend as followed by gene up-regulation of TGIF-2, HDAC-4 and mir-30c genes. This indicates that silica and calcium release influence gene expression.