Biogenic synthesis, in-vitro cytotoxicity, esterase activity and interaction studies of copper oxide nanoparticles with lysozyme

Herein, we have shown the eco-friendly and low-cost synthesis of biogenic copper oxide nanoparticles (CuONPs) from Delonix regia (D. regia) leaf extract in aqueous medium. The formation of biogenic CuONPs was characterized by ultraviolet (UV)-visible, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM) as well as transmission electron microscopy (TEM). Characterization of green synthesized nanoparticles demonstrated a UV-visible peak at 273 nm. Particle size was analysed from TEM monograph in the range of 69-108 nm which validates formation of nanoparticles. The in-vitro anticancer activity was done against A549 (IC50 = 4.70 mu g/mL) and MCF7 (IC50 = 3.77 mu g/mL) cell line. The biocompatibility assay of these nanoparticles was done on HEK-293 cell line (normal non-cancerous cells). Moreover, the effect of CuONPs on the lytic activity of HEWL was evaluated against Micrococcus lysodeikticus. Further, the interaction of CuONPs with hen egg white lysozyme (HEWL) at different temperature was investigated by steady state fluorescence spectroscopy. UV-visible and far ultra violet-circular dichroism (far UV-CD) spectroscopies were also employed to study the interaction of CuONPs with HEWL. All the results supported each other and show efficient binding between HEWL and CuONPs. The fluorescence emission study revealed that CuONPs quenches the fluorescence of HEWL involving dynamic quenching. The various binding parameters and structural disparity of HEWL in the presence of synthesised CuONPs were also calculated. (C) 2021 The Authors. Published by Elsevier B.V.