Preparation of PVP-coated copper oxide nanosheets as antibacterial and antifungal agents

Abstract

Copper oxide (CuO) nanosheets synthesized in polyvinylpyrrolidone (PVP) were characterized with respect to antimicrobial activity by quick precipitation method. Different sizes and shapes of CuO nanosheets were obtained by simple variations of PVP concentrations. The x-ray diffraction results revealed the formation of pure-phase CuO with monoclinic structure. Transmission electron microscopy analysis showed that the average ratio of length to width of these nanosheets increased with increasing PVP concentrations. Due to the quantum size effect, CuO nanosheets exhibit a blue shift in the ultraviolet-visible spectra. Field emission scanning electron microscopy results showed that as the concentration of PVP increased, well-defined morphologies were formed on the surface of the products. Energy dispersive analysis of x-ray clearly confirmed the presence of Cu and O with an atomic ratio of 1:1. Fourier transform infrared spectroscopy results showed that C5O in PVP coordinated with CuO and formed a protective layer. The mechanism of the reaction was also discussed. CuO nanosheets in suspension showed activity against a range of bacterial pathogens and fungi with minimum bactericidal concentrations (MBCs) ranging from 100 to 5000 lg/mL. The extent of the inhibition zones and the MBCs was found to be size-dependent.

Single Nanoparticle to 3D Supercage: Framing for an Artificial Enzyme System

“…Before the reaction, a protective layer of PVP is generated by mixing PVP with Cu(OH) 2 NPs in order to control the reaction rate. 14 With addition of the copper–ammonia complex ([Cu(H 2 O) 6 ] 2+ + n NH 3 ·H 2 O ⇌ [Cu(NH 3 ) n ] 2+ + ( n + 6)H 2 O, NH 3 ·H 2 O ⇌ NH 4 + + OH − ), Cu 2+ ions ([Cu(H 2 O) 6 ] 2+ ) on the surface of the amorphous Cu(OH) 2 NPs (Figure S1) first coordinate with NH 3 ·H 2 O to generate [Cu(NH 3 ) n ] 2+ (Figure 4a). [Cu(NH 3 ) n ] 2+ tends to coordinate in a square planar manner with OH − , 15 leading to an extended complex chain structure on the particle surface, i.e., [Cu(NH 3 ) n ] 2+ → [Cu(NH 3 ) n −1 (OH)] + → [Cu(NH 3 ) n −2 (OH) 2 ] → … → [Cu(OH) n ] ( n −2)− (Figure 4b).…”

Fabrication of ultrathin Zn(OH)2 nanosheets as drug carriers

“…(1) Before the reaction, PVP was mixed with Cu nanowires, and the adsorbed PVP molecules later acted as a passivating layer to control the dissolution rate of Cu nanowires. 11 (2) Upon addition of ZnCl 2 solution, several coordination reactions occurred. First, the hydrolysis product of ZnCl 2 (ZnCl 2 + H 2 O ⇌ H[Zn(OH)Cl 2 ) slowly reacted with Cu and oxygen to form a soluble Cu[Zn(OH)Cl 2 ] complex (4Cu + O 2 + 4H[Zn(OH)Cl 2 ] ⇌ 4Cu[Zn(OH)Cl 2 ] + 2H 2 O, 2Cu + + ½O 2 + H 2 O → 2Cu 2+ +2OH ‒ ) (see standard electrode potentials , ESI) by strong interaction between Cu + and [Zn(OH)Cl 2 ] − .…”

Surface Charge Driven Growth of Eight-Branched Cu2O Crystals

“…[3][4][5] Due to its unique and interesting magnetic and optical properties, Cu2O has been widely studied due to its potential applications in a huge range of fields such as catalysis, 6,7 gas sensing 8 and the conversion of solar energy into chemical or electrical energy [9][10][11] as well as having been at the centre of research into the Bose-Einstein condensation of excitons. 12 Cu2O has been shown to exhibit a wide variety of morphologies such as thin films, 13,14 nanorod arrays, 15 nanospheres or nanocubes [16][17][18] and even hollow crystals. 19,20 Since the suitability of Cu2O for its various applications is so highly dependent on its morphology and microstructure, 21 an array of different and often complicated techniques have been utilised to attempt to control the shapes and sizes of Cu2O crystals.…”

“…Shahmiri et al 14 reported the use of PVP to synthesise PVP-coated copper oxide, CuO, nanosheets via a quick precipitation method for use as antibacterial and antifungal agents. In their mechanism, a Cu 2+ /PVP matrix formed rapidly as an intermediate step in the formation of CuO.…”