Comparison of toxicity of Fe/Ni and starch-stabilized Fe/Ni nanoparticles toward Escherichia coli

•Fe/Ni NPs exhibited a stronger toxicity than the bare Fe0 NPs toward E. coli.•Starch coating alleviated the toxicity of Fe/Ni NPs, depending on starch loading.•ROS-induced oxidative stress was the primary mechanism for the toxicity of NPs.•Both Fe/Ni and starch-coated Fe/Ni NPs would lose their toxic potential over time.