Controllable phyto-synthesised copper nanoparticles for antioxidant and label-free colorimetric iron detection purposes

Abstract

ABSTRACT Eco-friendly and sustainable synthesis of copper nanoparticles (CuNPs) using the aqueous leaf extract of Manilkara zapota L. and its application as a colorimetric sensor for detection of Fe(II) and Fe(III) ions is reported in this work. At first, the influence of key parameters on the formation of nanoparticles has been investigated. The optimal conditions were determined to be: pH = 11.0, the quantity of the leaf extract = 10.0 mL, copper precursor concentration = 0.5 mM, Temprature = 60 ℃, and incubation time = 30 min. The as-prepared CuNPs were characterised by various analytical techniques such as UV-Vis, TEM, XRD, XPS, and FTIR. The synthesised nanoparticles are amorphous in nature, spherical in shape with a size between 22 to 45 nm. Furthermore, the antioxidant potential of synthesised CuNPs was evaluated using Ferric-Reducing Antioxidant Power (FRAP) assay. Finally, a colorimetric method was described for the determination of Fe(II) and Fe(III) with high sensitivity and selectivity based on the CuNPs which leads to the red-shift of the absorption. Under the optimised conditions, the presented sensor showed a linear relationship over a concentration range of 10.0 μM to 270.0 μM with a LOD of 3.3 μM for both iron ions. Hence, this study has shown a great potential for the development of a cost-effective and selective colorimetric sensor utilising phytogenic CuNPs in the determination of iron ions using UV-Vis spectroscopy.