Magnetite nanoparticles functionalized propolis extract as nano-antibiotics against methicillin resistant strains of Staphylococcus aureus

Due to their ability to penetrate planktonic and biofilm organized bacteria , nano-antimicrobial agents have been perceived, in recent years, in almost every domain of life especially in health care for the control of infectious diseases. Magnetite nanoparticles (MNPs) have been evaluated for inhibiting microbial growth and bioﬁlm formation. The aim of this study was to evaluate the effect of Moroccan propolis extract functionalized magnetite nanoparticles as nanoantibiotics against methicillin resistant Staphylococcus aureus (MRSA) growth. Chemical composition of propolis was established by pyrolysis GC-MS method. The fabricated nanostructure was characterized by X-ray Diffraction, Transmission Electron Microscopy, and Fourier Transform-Infrared Spectroscopy. FTIR spectroscopy data allowed to confirm functionalization of the MNPs upon contact with oleic acid (OA). Further functionalization with either propolis extract or chloramphenicol was also confirmed by observation of the corresponding FTIR spectra. When both components were added together to OA-functionalized MNPs, the presence of the former is clear whereas that of the latter is less evident, although possible. The use of MNPs functionalized with propolis and chloramphenicol (positive control) at MIC value against methicillin susceptible S. aureus (MSSA) and MRSA strains inhibited the bacterial growth. After the treatment with functionalized MNPs the cells showed disruption of the cell wall as assessed by transmission electron microscopy (TEM). The use of the combination of propolis and the chloramphenicol antibiotic in free form at minimum inhibitory concentration largely impaired both MSSA and MRSA strains, after 2 h of treatment no viable cells of MRSA 2 and MRSA 16 were recovered.