In-vitro catalytic, antimicrobial and antioxidant activities of bioengineered copper quantum dots using Mangifera indica (L.) leaf extract

Abstract

A simple green chemistry route has been developed for the synthesis of copper (Cu) quantum dots (QDs) from copper sulfate using leaf extract of Mangifera indica (L.) with assessment of their catalytic, antibacterial and antioxidant activities. The impact of quantities of leaf extract, concentrations of copper sulfate, incubation temperature, pH and reaction time were investigated so as to attain regulation on the QDs particle size and stability. The bio-fabrication of Cu QDs was studied by employing UV–Visible (UV–Vis) spectrophotometry at wavelength (λmax) 338 nm. Fourier-Transform Infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDS), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) along with Selected Area Electron Diffraction (SAED) as well as X-Ray Diffractometer (XRD) were employed to characterize the morphology as well as structure of Cu QDs. The FTIR spectra depicted polyphenolic compound ‘mangiferin’ as major phytochemical from M. indica leaf extract that functioned as reducing, capping and stabilizing agent during Cu QDs fabrication. Highly stable spherical Cu QDs with very narrow size distributions (4–7 nm) have been observed. These Cu QDs revealed distinctive catalytic activity (against the reduction of anthropogenic prominent contaminant methylene blue for environment protection), potent antimicrobial activity (against Escherichia coli KT45/45A and Staphylococcus aureus KT68) and free radical scavenging activity. These studies established that M. indica leaf extract is a cost-effective promising green material for producing Cu QDs with multi-applications as catalyst, antibacterial and antioxidant agents.