Recyclable silver–magnetite nanocomposite for antibacterial application

•A facile and efficient design of magnetite surface with the use of cysteine.•These silver–magnetite nanocomposites were used in antibacterial application.•After five recycling uses, their antibacterial efficiency retained higher than 90%.•The nanocomposite had good water dispersibility with good magnetic responsiveness.

Surface modification of magnetite nanoparticle (MNP) with cysteine for efficient conjugation with silver nanoparticle (AgNP) is herein presented. This novel nanocomposite was prepared via a specific binding interaction between thiol groups of cysteine coated on the MNP and the surface of AgNP. Transmission electron microscopy indicated the formation of the nanocomposite with 18–24 nm silver nanoparticles and 8–12 nm magnetite nanoparticles. Energy dispersive spectrometry verified the presence of both Ag and Fe in the nanocomposite. After repetitive adsorption–desorption-washing process, the nanocomposite retained higher than 90% antibacterial efficiency against Escherichia coli K12 for at least five recycling cycles.

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