Amorphous carbon-coated nano-copper particles: Novel synthesis by Sol–Gel and carbothermal reduction method and extensive characterization

Abstract Copper nanoparticles (Cu-NPs) have attracted attention because of their wide range of applications. However, the synthesis of Cu-NPs is difficult because they are easily oxidized. This work describes a novel method of sol–gel and carbothermal reduction for the synthesis of highly stable Cu-NPs in aqueous medium using γ-polyglutamic acid (γ-PGA) as a dispersant and Tween-80 as a reducing agent. The microstructures showed the γ-PGA and Tween-80 co-synthesized Cu-NPs were nearly spherical, 25～45 nm in diameter and coated with a carbon layer. The X-ray diffraction, X-ray photoelectron spectroscopy results showed the carbon-coated Cu-NPs (C/Cu-NPs) contained zero-valent coppers with high stability against oxidation. Antibacterial and cytotoxic studies showed the C/Cu-NPs had more potent antibacterial activities and were less cytotoxic than the control CuO NPs. The study provides compelling evidence that C/Cu-NPs should find applications in biomedicine because of their stable chemical properties, good antibacterial activity and low cytotoxicity.