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Developing household level drinking water disinfection unit using copper
Published in Alka Mahajan, Parul Patel, Priyanka Sharma, Technologies for Sustainable Development, 2020
Vandit R Shah, Girivyankatesh Hippargi, Jaykumar Soni
Toxic effect of copper ion on micro-organisms is known as “Oligodynamic Effect.” Previous studies on antimicrobial activity of copper have confirmed that ions are responsible for inactivation of bacteria. However, there is no clear explanation has been found for the inactivation mechanism taking place within the cells of microorganisms. Some reports suggest that metal ions bind to DNA, enzymes, and cellular proteins in the bacteria causing cell damage and death (Yamanaka, Hara, & Kudo, 2005). A recent study on the copper surface suggests that hydroxyl radicals in the solution are responsible for their lethal action(Santo, Quaranta, & Grass, 2012). Copper may inactivate bacteria by more than one mechanism(Santo, Taudte, Nies, & Grass, 2008). However, it is not known how they contribute to the actual detoxification mechanism.
Bacterial Attachment and Biofilm Formation on Biomaterials
Published in Nihal Engin Vrana, Biomaterials and Immune Response, 2018
For some biomaterials, one option is grafting/doping other metal ions capable of reduction of biofilm formation. Ions like silver, copper, bismuth and zinc are known to have oligodynamic effect (toxic effect on living organisms) on microorganisms. Silver is recognised as a powerful bacteria killer agent as it is able to bind DNA, RNA and phosphoproteins, causing a direct stop through genetic interference [185]. Moreover, silver was shown to be able to interpose bacteria metabolism through the binding of thiol groups [186] and by causing the production of reactive oxygen species [187]. Silver in nanoparticles is able to kill both Gram-negative and Gram-positive organisms [188], as demonstrated in studies involving E. coli, Enterococcus spp and S. aureus [189] and in pre-clinical in vivo studies [190].
Metal Nanoparticles: Silver
Published in Mihai V. Putz, New Frontiers in Nanochemistry, 2020
Metal nanoparticles in general and in particular silver, copper and gold nanoparticles are known to have an antibacterial activity. This property is particularly pronounced in silver nanoparticles which can be considered the best colloidal metal as a bactericide (Lansdown, 2010). The bactericidal effect of silver is known since ancient times (Lansdown, 2010). The bactericidal effect of colloidal silver is firstly due to the production and release of Ag+ ions which exert an oligodynamic effect on bacteria and protozoa. Even at high dilution, the Ag+ ions bind to the −SH groups of enzymes inhibiting their activity and also causing the denaturation of proteins. Silver also reacts with the amino-, carboxyl-, phosphate-, and imidazole-groups and diminish the activities of lactate dehydrogenase and glutathione peroxidase (Lansdown, 2010). Furthermore, silver nanoparticles may attach to the surface of membrane cell disturbing permeability and respiration function of the cell. Smaller Ag nanoparticles are more effective bactericidal that the larger nanoparticles since they can penetrate the bacterial cells and causing the disruption of the cell walls thereby causing the production of free radicals including ROS (reactive oxygen species) (Lansdown, 2010). The oligodynamic effect has been observed in living cells, algae, molds, spores, fungi, viruses, prokaryotic and eukaryotic microorganisms however silver nanoparticles are not very effective against viruses and especially against spores (Cataldo, 2014). The bactericidal properties of silver nanoparticles in both black and green tea infusions were confirmed on the Gram(–) bacterium P. Aeruginosa. Instead, the silver nanoparticles in both black and green tea infusions are not effective against the spores of B. Subtilis (Cataldo, 2014).
Green synthesis of silver nanoparticles mediated by Daucus carota L.: antiradical, antimicrobial potentials, in vitro cytotoxicity against brain glioblastoma cells
Published in Green Chemistry Letters and Reviews, 2022
Ikechukwu P. Ejidike, Hadley S. Clayton
Literature has shown that the antimicrobial activities of silver nanoparticles could be attributed to the silver (Ag) ion positive charge released from the nanoparticles, thus bringing about electrostatic attraction in the middle of the microorganism's negatively charged cell membrane and the positively charged AgNPs (3, 5, 15, 17, 34). The oligodynamic effect of silver has been reported to possess antibacterial activity against microorganisms. This is largely due to the changes on the surface of the particles causing binding affinity towards the bacterial biomolecules, which in turn induces the penetration of cells and production of reactive oxygen species (ROS), that enhances their chemical reactivity leading to the antibacterial activity of AgNPs (1, 6). Ogunsile et al. (8), MubarakAlia et al. (37), and Rotimi et al. (4), also recounted moderate bactericidal activity of pure silver nanoparticles. Antibacterial effects of Ag nanoparticles as reported by Veerasamy et al. (5) followed a dual-action phenomenon of antibacterial activity that is the anti-bacterial effect of Ag+ and membrane-disruptive outcome of the polymer subunits. A study by Rautela et al. (13) has demonstrated that AgNPs using Tectona grandis seed by green synthesis possess significant bactericidal activity against E. coli and S. Aureus.