Core–shell fabrication of an extra‐antimicrobial magnetic agent with synergistic effect of substrate ligand to increase the antimicrobial activity of Ag nanoclusters

In this work, a novel antimicrobial agent is synthesized. The metal‐chelating ligand EDTA is incorporated into silver nanoparticles to form a new cluster system which is enhanced in its efficacy to eliminate bacteria. Magnetic nanoparticles of Fe3O4 were layer‐by‐layer coated with aminopropyltriethoxysilane, linked‐EDTA, and silver nanoclusters (Fe3O4@APTES–EDTA@Ag), respectively. All steps of nanocomposite preparation were characterized by the TEM, field emission scanning electron microscope, X‐ray diffraction, Brunauer–Emmett–Teller, Vibrating Sample Magnetometer, and Fourier transform infrared. A sequential nucleophilic reaction applied for layer‐by‐layer fabrication of these antimicrobial units which could maintain the functionality of linked‐EDTA as EDTA chelator. The linked‐EDTA sequesters Ca2+ and Mg2+ ions effectively, thereby removing these metallic ions which are necessary for cell‐wall stability, growth, and survival of the bacteria. The antimicrobial activity of silver nanocomposite was qualified by disk diffusion method and quantified by measuring the minimum inhibitory concentration and minimum bactericidal concentration against some Gram‐positive and Gram‐negative bacteria. The results show that the mean value of inhibition zone (mm) of Fe3O4@APTES–EDTA@Ag and Ag+ against tested bacteria is significantly different by Student's T‐Test (P