Chemical Synthesis of Copper Nanospheres and Nanocubes and Their Antibacterial Activity Against Escherichia coli and Enterococcus sp.

Abstract

Abstract:The interest in synthesising inorganic nanomaterials for biological applications has increased in recent years, especially for antibacterial purposes. In the present study, spherical and cube-shaped copper nanoparticles were synthesised by a chemical reduction method and their efficacy as antimicrobial agents against both Gram-negative (Escherichia coli) and Gram-positive (Enterococcus sp) organisms investigated. The nanoparticles were characterised using ultra-violet/visible spectroscopy, scanning electron microscopy, energydispersive spectroscopy and x-ray diffraction. Copper nanocubes were found to be more antimicrobial when compared with copper nanospheres and it is postulated that whilst both sets of nanoparticles have similar total surface areas, the different shapes have different active facets and surface energies, which may lead to differing bactericidal behaviour.

Antimicrobial Metal Nanomaterials: From Passive to Stimuli‐Activated Applications

“…In addition to size, the shape of the nanoparticles can also influence their intrinsic properties, for example, photocatalytic properties can be affected, largely through enhanced surface area while plasmonic properties are influenced by the nanomaterials shape which affects the relative lengths along which the electron cloud can resonate and hence the specific wave function. [ 73 ] With improvements in nanotechnology and fabrication processes, a diverse array of nanoscale shapes have been constructed, such as: nanoparticles, [ 74 ] nanodots, [ 75 ] nanocubes, [ 76,77 ] nanorods, [ 78,79 ] nanoshells, [ 80 ] nanocages, [ 81 ] nanostars, [ 82 ] nanoflowers, [ 83 ] nanoeggs, [ 84 ] nanopopcorn, [ 85 ] and numerous other 2D materials. [ 86,87 ] Figure shows a variety of commonly investigated nanomaterials, along with experimentally obtained images of example nanomaterials with the corresponding shape.…”

“…This renewed interest coincides with significant breakthroughs in the understanding, fabrication and characterization of sub‐micron‐sized materials. A wide range of nanomaterials have been demonstrated to possess antimicrobial effects, including iron (III) oxide, [ 106 ] zinc oxide, [ 107 ] magnesium oxide, [ 108 ] silver, [ 67,109 ] gold, [ 110 ] copper [ 45,77 ] and copper oxide, [ 111 ] calcium oxide, [ 41 ] titanium dioxide [ 112 ] and cadmium oxide [ 113 ] among others. [ 41,42,87,114,115 ] Successful antimicrobial activity has been demonstrated utilizing an equally wide array of shapes (Figure 2).…”

Towards advanced wound regeneration

“…The physical shape of the nano-metal is an important factor, affecting its ability to interact with the bacterial membrane, as well as the generation of ROS. A variety of shapes can be formed, including nanocubes [35][36][37], nanospheres [37,38], flat nanosheets [39], nanorods [40][41][42], nanoclusters [43][44][45] and nanoprisms [46] which all produce different levels of antibacterial effect. Alshareef et al, tested the antibacterial efficacy of copper nanospheres and nanocubes against the gram-negative strain Escherichia coli and the gram-positive strain Enterococcus sp.…”

“…Alshareef et al, tested the antibacterial efficacy of copper nanospheres and nanocubes against the gram-negative strain Escherichia coli and the gram-positive strain Enterococcus sp. Tests demonstrated that both copper nanospheres and nanocubes were effective against both gram positive and negative strains, however the nanocube morphology had the greatest antimicrobial effect, which suggests that the cubic profile resulted in higher levels of reactivity against the bacterial strains [37]. Zhang et al created a composite nanosheet comprising of polydopamine-graphene nanosheet-nanosilver, for antibacterial testing against gram-negative Escherichia coli and gram-positive B. subtilis.…”

Antimicrobial Biodegradable Food Packaging Based on Chitosan and Metal/Metal-Oxide Bio-Nanocomposites: A Review

“…Some examples of organic antimicrobial agents include quaternary ammonium salts, halogenated compounds, organic acids, and phenols; natural materials are based on materials such as chitosan and chitin [ 22 ]. Inorganic antimicrobial agents, including metals and metal ions, metal oxide nanoparticles including TiO 2 [ 43 ], ZnO [ 44 ], silver [ 45 ], gold [ 46 ], magnesium oxide [ 47 , 48 ] copper [ 49 ], copper oxide [ 50 ], iron (III) oxide [ 51 ], and CaO [ 52 ], have attracted considerable interest in food packaging researches due to their stability, especially under the different conditions imposed in food packaging [ 53 , 54 ].…”