Curcuma longa debranched starch assisted synthesis of cerium oxide nanoparticles and its antioxidant, anticancer, antimicrobial, and anti-biofilm activities

Nowadays, there is a growing emphasis on eco-friendly methods for synthesizing metal nanoparticles (NPs), that avoid chemical processes and the production of harmful substances. In this study, we present a novel green approach for preparing cerium oxide nanodots (CeO₂NPs) using Curcuma longa debranched starch as a reducing and capping agent via the sol-gel method. The prepared CeO₂NPs were characterized using various techniques, including UV-vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and zeta potential (ζ). An absorption peak of the particles at 315 nm was detected in the UV-Vis spectrum. Spherical CeO₂NPs were observed by SEM and TEM with a 2-4 nm NP range. Energy-dispersive X-ray spectroscopy (EDX) analysis showed that the Ce, oxygen and carbon contents were 68.33 wt%, 25.59 wt and 6.07 wt%, respectively. The CeO₂NPs exhibited antioxidant activity with an IC⁵⁰ value of 3.2 ± 0.23 µg/mL, and 3.66 ± 0.18 µg/mL for DPPH and ABTS free radical scavenging assays, respectively. Furthermore, CeO₂NPs exhibited antibacterial activity against Corynebacterium diphtheriae, Klebsiella pneumoniae, Salmonella typhi, and Escherichia coli and antibiofilm activity against Corynebacterium diphtheriae and Escherichia coli. The in vitro cytotoxicity of CeO₂NPs against HepG2 cells (IC⁵⁰ of 178 ± 14 µg/mL) was dose-dependent as evaluated using the MTT assay. These results collectively suggest the diverse functions of CeO₂NPs, showcasing their potential as antioxidants, anticancer and antibacterial agents, and their usefulness in biomedical applications.