Controllable phyto-synthesis of cupric oxide nanoparticles by aqueous extract of Capparis spinosa (caper) leaves and application in iron sensing

We demonstrate here for the first time a one step and efficient phytosynthesis of cupric oxide nanoparticles (CuO NPs) using easily available Capparis spinosa leaf extract as a bio-reductant and bio-stabilizer at room temperature without the addition of any harmful and expensive reagent and solvents. The effect of pH of the reaction, the leaf extract quantity, concentrations of the copper precursor, temperature, and reaction time were also studied in order to control over the particle size and stability. The synthesized CuO NPs at the optimum condition was characterized through UV-Vis spectroscopy, TEM and FT-IR spectroscopy. The surface plasmon resonance (SPR) of the biosynthesized CuO NPs centered at lambda(max) 408. The FT-IR analysis demonstrates the role of phyto-compounds in the capping of the formed nanoparticles. TEM images clarified the spherical shape of the as-prepared nanoparticles with 21 to 58 nm in size and XRD analysis clarified the monoclinic phase of formed CuO NPs. Also, as a novel work, we display a colorimetric detection ability of as-synthesized CuO NPs (without surface functionalization or modification) respect to Fe2+ and Fe3+ in aqueous solution. Under the optimized conditions, a good linear relationship (R-2 = 0.9954, R-2 = 0.9903 for Fe2+ and Fe3+, respectively) were obtained between the absorbance at 500 nm and the concentration of iron ions with a limit of quantification 0.084 ppm and 0.12 ppm for Fe2+ and Fe3+, respectively. A remarkable feature of this first reported the colorimetric detection of iron ions based on the green synthesized CuO NPs is a simple and fast operation with high selectivity to Fe2+ and Fe3+ over other tested metal ions.