We studied the structural and antimicrobial properties of copper oxide nanoparticles (CuO NPs) synthesized by a very simple precipitation technique. Copper (II) acetate was used as a precursor and sodium hydroxide as a reducing agent. X-ray diffraction patter (XRD) pattern showed the crystalline nature of CuO NPs. Field emission scanning electron microscope (FESEM) and field emission transmission electron microscope (FETEM) demonstrated the morphology of CuO NPs. The average diameter of CuO NPs calculated by TEM and XRD was around 23 nm. Energy dispersive X-ray spectroscopy (EDS) spectrum and XRD pattern suggested that prepared CuO NPs were highly pure. CuO NPs showed excellent antimicrobial activity against various bacterial strains (
Metal oxide nanoparticles (NPs) have been receiving considerable attention for their potential applications in optoelectronics, nanodevices, nanoelectronics, nanosensors, information storage, and catalysis. Among various metal oxide NPs, CuO has attracted particular attention because it is the simplest member of the family of copper compounds and shows a range of useful physical properties such as high temperature superconductivity, electron correlation effects, and spin dynamics [
Microbial contamination of air, water, and soil due to different types of microorganisms creates problems in living conditions and is a serious issue in health care. Due to the spread of antibiotic resistant infections, interest in alternative antimicrobial agents, such as small antibiotics, cationic polymers, metal NPs, and antimicrobial peptides have been rising [
CuO NPs were synthesized by aqueous precipitation method using copper (II) acetate [Cu(CH3COO)2·H2O)] (98%, Sigma-Aldrich) as a precursor and sodium hydroxide (NaOH) as a reducing agent. In brief, 0.2 M copper (II) acetate solution (600 mL) and glacial acetic acid (CH3COOH) (2 mL) were added into a round-bottomed flask and heated to boiling under magnetic stirring. Then, 30 mL of 6 M NaOH solution was poured into the flask. The colour of the solution turned from blue to black immediately, and a black suspension formed simultaneously. The reaction was carried out under stirring and boiling for 2.5 h. The mixture was cooled to room temperature and centrifuged. Then, a wet CuO precipitate was obtained. The precipitates were filtered and washed with distilled water and absolute ethanol for several times. The resulting product was dried (at 60°C for 6 h) to obtain the dry powder of CuO NPs. The yield of prepared CuO NPs was 52%.
The crystalline nature of CuO NPs was carried out by XRD. The XRD pattern of CuO nanopowder was acquired at room temperature with the help of a PANalytical X’Pert X-ray diffractometer equipped with an Ni filtered using Cu K
Seven human gram negative bacteria
The minimum inhibitory concentration (MIC) was determined based on a broth microdilution method as described elsewhere [
Antimicrobial data represented are mean ± SD of three identical experiments made in six replicates. Statistical analysis conducted using the Prism software (GraphPad Software Inc.).
Figure
XRD pattern of CuO NPs.
(a) FESEM image of CuO NPs and (b) FETEM image of CuO NPs.
EDS profile of CuO NPs and inset shows high resolution TEM of the same.
Antimicrobial activity of CuO NPs was analyzed against various bacterial strains
(a) Well diffusion assay of CuO NPs against various bacterial strains and (b) MIC of CuO NPs for various bacterial strains. PC: positive control (streptomycin 150
Highly pure CuO NPs was prepared by a simple precipitation method. XRD spectrum revealed that CuO NPs were monoclinic crystals with space group C2/c. FESEM and FETEM showed the morphology of CuO NPs. The average TEM diameter of CuO NPs was around 23 nm that agreed fairly well with XRD data. CuO NPs showed excellent antimicrobial activity against eight bacterial strains. Consequently, CuO NPs have potential for external uses as antibacterial agents in surface coatings on various substrates to prevent microorganisms from attaching, colonizing, spreading, and forming biofilms in indwelling medical devices. This study suggests that mechanisms of antimicrobial response of CuO NPs in different species of bacterial should be further investigated.
We declare that we have no conflict of interests.
The authors extend their appreciation to the Deanship of Scientific Research at King Saud University for funding this work through research group no. RGP-VPP-308.