Witch-hazel-mediated hydrothermal biosynthesis of copper nanoparticles: dye removal, antibacterial potency, and anticancer synergy potential activities

Abstract

This study investigates the green synthesis of copper nanoparticles (Cu NPs) using witch-hazel extract. The successful synthesis was confirmed through various characterization methods, revealing nanoparticles with an average crystallite size of 24.2 nm by XRD. The biological preparation process via the plant extract was found to enhance the stability and encapsulation of the formed Cu NPs, as evidenced by ATR-IR analysis. Zeta potential measurements indicated high stability, with a value of −23.06 mV and a polydispersity index (PDI) of 0.33. TEM analysis showed an average particle size of 20.0 nm before methylene blue (MB) adsorption, increasing to 24.6 nm post-adsorption. The porous and cracked morphology of the Cu NPs facilitated efficient MB adsorption. Optimal adsorption conditions were identified for MB@Cu NPs. The adsorption process followed the Langmuir isotherm model, with a maximum adsorption capacity (q_L) of 46.4 mg g⁻¹. Kinetic studies supported pseudo-second-order kinetics. Thermodynamic analysis classified the adsorption as spontaneous and endothermic, indicating physical adsorption. Overall, this research highlights the potential of green synthesis methods for developing sustainable and effective adsorbents. In addition to their adsorption efficiency, the biosynthesized Cu NPs exhibited potent antibacterial activity against both Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria, with an effective concentration of 31.25 µg mL⁻¹ and enhanced inhibition observed for MB@Cu NPs. Furthermore, the nanomaterials demonstrated notable anticancer activity, with IC₅₀ values of 14.9 µg mL⁻¹ and 21.8 µg mL⁻¹ against the Caco2 and Mcf7 cell lines, respectively. The incorporation of methylene blue with Cu NPs (MB@Cu NPs) further improved the anticancer activity, as evidenced by lower IC₅₀ values of 11.5 µg mL⁻¹ and 11.6 µg mL⁻¹ against the Caco-2 and MCF-7 cell lines, respectively, compared to Cu NPs alone.