Adherence of amino acids funtionalized iron oxide nanoparticles on bacterial models E. coli and B. subtilis

Magnetic iron oxides nanoparticles (NPs) functionalized with lysine (Lys) and arginine (Arg) was obtained by following chemical co-precipitation route in basic medium. The synthesis was performed by mixing ferrous chloride... [ view full abstract ]

Magnetic iron oxides nanoparticles (NPs) functionalized with lysine (Lys) and arginine (Arg) was obtained by following chemical co-precipitation route in basic medium. The synthesis was performed by mixing ferrous chloride (FeCl2 • 4H2O), ferric chloride (FeCl3 • 6H2O) and the specific amino acid in a molar ratio of 1: 2: 0.5, respectively. High pH sample was washed several times with distilled water to reach a pH similar to distilled water (Ph=7) after the synthesis process, part of the NPs obtained was dried. The dried samples were characterized by X-ray diffraction (XRD), Mössbauer spectroscopy (MS), infrared Fourier transform spectroscopy (F-TIR) and zeta potential (ζ). Of the measurements of XRD and MS was obtained that the samples are magnetic nanoparticles (core -shell) of magnetite and maghemite of about 9 nm in diameter. Of the F-TIR and zeta potential measures was obtained that the amino acids Lys and Arg were correctly functionalized at magnetic nanoparticles, referred to herein as M@Lys and M@Arg. 

In order to demonstrate the capture and adhesion of the nanoparticles to the bacteria, scanning electron microscopy (SEM) was performed. The obtained visualizations of both bacteria show that they are coated by the magnetic particles. In addition, M@Lys (B. subtilis) were cultured to verify the inhibition of growth measured by colony forming units (CFU), the concentrations of M@Lys used were 1.75x102 g/mL and 0.875x102 g/mL, After the confrontation obtained efficiencies of 75.63% and 98.75% respectively for the third dilution. While for the fourth dilution efficiencies were 90% and 98.57% respectively were obtained for each concentration of nanoparticles. Hinting that a high efficiency of bacterial capture at very low concentrations of NPs, which gives us a tool to capture nanobiotechnology bacteria in liquid cultures with application to capture them in wastewater. Based on our results we concluded that NPs functionalized with the amino acids Lys and Arg adhere to the bacteria efficiently in low concentrations. 

Keywords: iron oxides, nanoparticles, maghemite, E. coli, B. subtilis, functionalization, SEM, UFC.