Synthesis, characterization and antibacterial effect of new magnetically core–shell nanocomposites

• A novel NiFe2O4@PAMA@Ag nanocomposites magnetic composite has been prepared.
• This system display potent antimicrobial activity toward some bacterial species.
• The antibacterial effect was studied by disk diffusion method.
• This composite can be easily removed from solution by magnetic decantation.

A new magnetically responsive three-component nanocomposite consisting of NiFe2O4, Poly Acrylonitrile Co Maleic Anhydride (PAMA) and nanosilver was synthesized and characterized and then its antibacterial activities were tested. For the preparation of NiFe2O4@Ag, NiFe2O4 was coated by Ag and for the synthesis of NiFe2O4@PAMA@Ag, NiFe2O4 was first covered by PAMA and then silver nanoparticles were immobilized on the surface of the PAMA shell. The nanocomposites were studied using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). The antibacterial activity of the synthesized nanocomposite against some gram positive and gram negative bacteria was studied and compared with that of naked NiFe2O4, NiFe2O4@Ag and NiFe2O4@PAMA. The NiFe2O4@PAMA@Ag had better antibacterial activity and could be readily isolated from the aqueous solution via magnetic decantation, thereby avoiding the contamination of the environment.