BIOSYNTHESIS AND CHARACTERIZATION OF COPPER OXIDE NANOPARTICLES

Ecological approaches regarding the synthesis of metal oxide nanoparticles have attracted special attention, due to their ability to prevent environmental contamination, but also to improve the quality of life and human well-being. CuO NPs began to be intensively used due to their physical and chemical properties, becoming effective in many biomedical, industrial, agricultural, and environmental applications, etc. In this paper, we report the use of the natural extract of Echinacea leaves [Echinacea purples] for the biosynthesis of copper oxide nanoparticles, and copper nitrate [Cu(NO₃)₂ 3H₂O] as a metal precursor salt. The applicability of natural extracts is given by phytochemical compounds (e.g. phenols, flavonoids, carboxylic acids, terpenoids, tannins, etc.), which act as reducing and capping agents for the formation of CuO NPs. The morphology of the oxide nanoparticles is influenced by: the reducing potential of the bioactive compounds determined by the type and amount of extract, the concentration and the ratio of the main raw materials, the pH of the solution, the process temperature, etc. The synthesized CuO was investigated using FTIR si RAMAN spectroscopy, X-ray diffraction, FESEM microscopy, and EDX analysis. The FTIR spectra confirm the presence of the Cu-O bond through the appearance of the characteristic peak at 480 cm^-1, but also the presence of the functional groups characteristic of the biomolecules present in the plant extracts used. The RAMAN spectra indicate peaks at 272 and 610 cm^-1, which are characteristic bands for CuO. The XRD diffractogram indicates the formation of a monoclinic crystalline structure by the appearance of distinctive peaks corresponding to (110), (002), and (111), planes, with an average crystallite size of 15 nm. The SEM images highlight the formation of spherical particles with dimensions below 40 nm. The EDX spectrum confirms the presence of the peaks attributed to (C) and (O) atoms, without other impurities. Due to the small size, morphology, and precise elemental composition of CuO NPs, this approach allows the synthesis of biomaterials with applicability in the development of antibacterial agents and biosensors.