Poly-l-lysine-modified reduced graphene oxide stabilizes the copper nanoparticles with higher water-solubility and long-term additively antibacterial activity

In order to improve the water-solubility and long-term antibacterial activity of copper nanoparticles (CuNPs), a poly-l-lysine-modified reduced graphene oxide (PLL–rGO) was used as the carrier of CuNPs, and a poly-l-lysine/reduced graphene oxide/copper nanoparticles (PLL–rGO–CuNPs) hybrid was prepared by anchoring the CuNPs on the reduced graphene oxide surface. The novel PLL–rGO–CuNPs hybrid was characterized and the antibacterial activity of it on gram-negative Escherichia coli and Gram-positive Staphylococcus aureus was tested. Such a hybrid showed additively antibacterial activity, and the CuNPs on PLL–rGO were more stable than those on polyvinyl pyrrolidone, resulting in long-term additively antibacterial effect. Meanwhile, this hybrid showed excellent water-solubility, suggesting great potential application in microbial control.

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► PLL–rGO–CuNPs dispersion was found to remain stable for more than 3 months.
► The solubility of PLL–rGO–CuNPs could reach up to 1.4 mg/mL.
► The PLL–rGO–CuNPs showed long-term additively antibacterial effect.
► PLL–rGO–CuNPs could play a role by disrupting the ion concentrations of intracellular fluid.