Synthesis of Copper Nanoparticles and its Antibacterial Activity against Escherichia coli

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 g, 0.3 g 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 MIC (minimum inhibitory concentration) and MBC (minimum bactericidal concentration) tests, cytoplasmic leakage and ROS (reactive oxygen species) 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. CuNPs - microorganism interaction induces oxidative stress generated by ROS (reactive oxygen species). Leakage of cytoplasmic components, loss of membrane permeability and ROS generation are the primary causes of CuNPs induced bacterial cell death. As-synthesized CuNPs exhibiting promising antibacterial activities and could be a promising candidate for novel antibacterial agents.

Nanomaterials and microbes' interactions: a contemporary overview

Use of nanomaterials in the field of science and technology includes different fields in food industry, medicine, agriculture and cosmetics. Nanoparticle-based sensors have wide range of applications in food industry for identification and detection of chemical contaminants, pathogenic bacteria, toxins and fungal toxins from food materials with high specificity and sensitivity. Nanoparticle-microbe interactions play a significant role in disease treatment in the form of antimicrobial agents. The inhibitory mechanism of nanoparticles against different bacteria and fungi includes release of metal ions that interacts with cellular components through various pathways including reactive oxygen species (ROS) generation, pore formation in cell membranes, cell wall damage, DNA damage, and cell cycle arrest and ultimately inhibits the growth of cells. Nanoparticle-based therapies are growing to study the therapeutic treatments of plant diseases and to prevent the growth of phytopathogens leading to the growing utilization of engineered nanomaterials. Hence, with this background, the present review focuses thoroughly on detailed actions and responses of nanomaterials against different bacteria and fungi as well as food sensing and storage.

Production, characterization and antibacterial activity of silver nanoparticles produced by Fusarium oxysporum and monitoring of protein-ligand interaction through in-silico approaches

The present study envisages biological production of silver nanoparticles using Fusarium oxysporum and in-silico identification of the antibacterial activity of the nanoparticles using protein-ligand interaction studies. The morphology of the nanoparticles was variable, with majority of them spherical in the size range 1-50 nm. For in-silico studies, two microorganisms, Escherichia coli and Pseudomonas aeruginosa were selected and metal docking was carried out using the licensed software SYBYL X 1.1.1. The ligand docked deeply into the binding pockets of the outer membrane proteins (OMPs) of both E. coli and P. aeruginosa. The results showed that silver may prove to be a strong antibacterial agent against both the pathogens, with the antibacterial action of silver being greater in the case of P. aeruginosa. The results obtained through in-silico studies were further validated by in-vitro approaches on both solid and liquid media to confirm the results obtained by in-silico analysis. The corroboration of in-silico and in-vitro results amply demonstrates the immense antibacterial potential of silver nanoparticles against the selected pathogens.

Preparation of cellulose composites with in situ generated copper nanoparticles using leaf extract and their properties

In the present work, copper nanoparticles (CuNPs) were in situ generated in cellulose matrix using Ocimum sanctum leaf extract as a reducing agent and aq. CuSO4 solution by diffusion process. Some CuNPs were also formed outside the film in the solution which were separated and viewed by Transmission electron microscope and Scanning electron microscope (SEM). The composite films showed good antibacterial activity against Escherichia coli bacteria when the CuNPs were generated using higher concentrated aq. CuSO4 solutions. The cellulose, matrix and the composite films were characterized by Fourier transform infrared spectroscopic, X-ray diffraction, thermogravimetric analysis and SEM techniques. The tensile strength of the composite films was lower than that of the matrix but still higher than the conventional polymers like polyethylene and polypropylene used for packaging applications. These biodegradable composite films can be considered for packaging and medical applications.