pH and temperature influences on eco-friendly synthesized copper oxide nanoparticles using clove extract for brain cancer treatment

• Synthesis of copper oxide nanoparticles by environmentally friendly green sol–gel method. • Exploring the effect of solution pH, reaction temperature, and calcination on the properties of the nanoparticles. • Solution pH significantly controls the crystalline structure of the as-synthesized product. • Very low IC50 values for Brain cancer treatment using the selected NPs in the dark condition. Brain cancer remains one of the most challenging and life-threatening diseases, demanding innovative and effective treatment strategies. In the paper, CuO nanoparticles are synthesized by the environmentally friendly green sol–gel method and proposed for addressing the challenge related to required non-invasive brain cancer treatment. For a comprehensive study, copper oxide nanoparticles are synthesized using clove extract at various solution pH and under two different reaction temperatures of 50 °C and 80 °C. All the samples are comprehensively characterized before and after the calcination process at 500 °C. Structural characterizations reveal that the crystalline structure and chemical composition of the as-synthesized samples are pH-dependent, while all calcined samples have an identical crystalline phase with similar chemical composition at different pH and synthesis temperatures. The morphologies of the as-synthesized samples are two-dimensional flake-like, while they transform to spherical nanoparticles after the calcination process. Also, the nanoparticles have direct and indirect bandgaps ranging from 1.53 to 2.96 eV and 1.23 to 1.87 eV, indicating the significant effects of the studied parameters on the optical properties of the produced nanoparticles. The therapeutic potentials of selective CuO nanoparticles in brain cancer treatment (C6 glioma cell line) are investigated in vitro and in dark conditions using the MTT assay. The results demonstrate the promising efficiency of green sol–gel synthesized CuO nanoparticles in brain cancer treatment, with significantly low IC50 values (14.96, 50.27, and 23.38 µg/mL for 48 h) under dark conditions, which is promising for effective non-invasive brain cancer treatment.