Effects of Synthetic Procedures and Postsynthesis Incubation pH on Size, Shape, and Antibacterial Activity of Copper (I) Oxide Nanoparticles

Abstract

Copper (I) oxide nanoparticles (Cu2O NP) were synthesized by reducing CuSO4 with glucose in the presence of polyvinyl alcohol as a capping agent. We used three different synthetic procedures with a fast reaction (procedure 1p), a fast-then-slow reaction (procedure 2p), and a slow-then-fast reaction (procedure 3p). The reaction rates were controlled by changing the temperature and the speed of adding reagents. The synthesized Cu2O NP were subsequently incubated for 24 h in a pH 6 solution (Cu2O NP6) or a pH 8 solution (Cu2O NP8) at 5°C. XRD and SEM images analysis revealed that the 1p procedure produced smaller NP, while the 2p procedure produced larger but more uniform NP. The 3p procedure produced the largest NP with a higher size variation. The 24-hour acidic postsynthesis incubation resulted in an etching effect, which reduced the size and size variation of Cu2O NP6. To evaluate the antibacterial activity, E. coli suspensions were mixed with the obtained Cu2O NP (32, 96, or 160 ppm) for different time intervals (1 or 24 h) and then grown on Petri dishes at 37°C for 24 h. Higher doses, smaller sizes of Cu2O NP, and longer contact times with the bacterial suspension resulted in higher inactivation efficiencies. Cu2O NP6 showed higher antibacterial effects at low doses, possibly due to the etching effect and the positive surface charge. Increasing the Cu2O doses from 32 to 96 and 160 ppm noticeably increased the antibacterial effect of the Cu2O NP8, but not significantly for Cu2O NP6. We suggested that the Cu2O NP6 suffered from agglomeration at high doses due to their high surface activity and low surface charges.

Evolution of Structural and Optical Properties of Cuprous Oxide Particles for Visible Light Absorption

“…From the in-situ temperature results, it can be guaranteed that the phase composition of the samples is maintained up to a temperature of 280 °C. This could be beneficial for its potential use as a light-absorbing material for solar cells as well as its antibacterial properties [23,24] since the particles maintain the Cu 2 O phase in a more significant proportion and without any changes.…”

“…Cuprous oxide is used in electrodes for lithium-ion batteries, photochemical cells, hydrogen production, sensors, photocatalysts, supercapacitors, magnetic storage, and water splitting [15][16][17][18][19][20][21], as well as a bactericide, colorant, and additive for corrosion-proof coatings [22][23][24]. Various methods have been developed to obtain Cu 2 O, such as the water bath method, the SILAR (Successive Ionic Layer Absorption and Reaction) method, the polyol method, chemical reduction, and sol-gel [4,10,17,[25][26][27][28][29][30][31][32]; however, some of these methods require special equipment [17,27,28], catalysts, organic additives, or expensive surfactants [25,31,32].…”

“…The use of glucose as a reducing agent has the advantage of being environmentally friendly, resulting in green chemical synthesis. Besides, glucose is cheap and highly selective in producing Cu 2 O [24,33], and its use is suitable for the development of Cu 2 O particles with different morphologies like spheres, cubes, beveled cubes, octahedrons, flower shapes, nanowires, nanorods, hierarchical structures, cages, and hollow structures [17,25,34,35] by changing the temperature, pH, reagents, solvents, reaction times, and surfactants control [36][37][38][39][40][41][42][43].…”

Antibacterial Filtration Using Polyethylene Terephthalate Filters Coated with Copper Nanoparticles

“…The highest antibacterial effect of the 10 min filter was due to the nature of nanoparticles on the filter surface: Cu 2 O possesses higher antibacterial potency than CuO nanoparticles [4,[23][24][25]. When the time of Cu 2+ reduction increased to 20 and 45 min, the antibacterial effect of the filter decreased (Figure 10(a)) because Cu 2 O was gradually converted to Cu, which was then quickly oxidized in the air to CuO with lower antibacterial potency.…”

“…However, the high cost of silver is its main disadvantage. Copper and copper oxide nanoparticles have lower production cost and relatively high antimicrobial effects on a wide range of microorganisms and thus can be used to replace silver nanoparticles in antimicrobial applications [4][5][6]. The antimicrobial effects of metal and metal nanoparticles generally are attributed to their small sizes, high surface-to-volume ratios, and the ability to release metal ions into solution.…”