Immobilization of Ib-M2 peptide on core@shell nanostructures based on SPION nanoparticles and their antibacterial activity against Escherichia coli O157:H7

Antimicrobial peptides arise as a very promising alternative for the treatment of infections generated by pathogenic microorganisms. The Ib-M2 antimicrobial peptide turns out to be a very promising candidate for these types of applications. However, it is required to evaluate immobilization systems that give peptides greater stability and activity in order to be used in biological systems. Given the above, this paper reports the preparation of superparamagnetic iron oxide nanoparticles (SPIONs) coated with chitosan in order to immobilize the Ib-M2 antimicrobial peptide. Structural properties of SPIONs were studied by DLS, SEM, XRD, FT-IR, XPS and the magnetic properties were evaluated by vibrating-sample magnetometer technique. The antimicrobial activity of the Ib-M2/SPIONs@Chi bioconjugate obtained was evaluated against Escherichia coli O157:H7 by determining the minimum inhibitory concentration (MIC). Results show that the SPIONs obtained have particle size between 10 and 15 nm with a magnetite-type structure which was confirmed by FT-IR and XPS. Characterization of magnetic properties evidences a superparamagnetic behavior of nanoparticles obtained. MIC results showed that Ib-M2/SPIONs@Chi bioconjugate exhibit a comparable or higher activity against E. coli in comparison with the free Ib-M2 peptide. These results show that the bioconjugate obtained can be considered for use in biomedical applications.