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Katarzyna Niemirowicz,1,2 Izabela Swiecicka,3 Agnieszka Z Wilczewska,4 Iwona Misztalewska,4 Beata Kalska-Szostko,4 Kamil Bienias,2 Robert Bucki,1,5,6 Halina Car21Department of Microbiological and Nanobiomedical Engineering, 2Department of Experimental Pharmacology, Medical University of Bialystok, 3Department of Microbiology, 4Institute of Chemistry, University of Bialystok, Bialystok, 5Faculty of Health Sciences, Jan Kochanowski University, Kielce, Poland; 6Institute for Medicine and Engineering, University of Pennsylvania, Philadelphia, PA, USAAbstract: Superparamagnetic iron oxide nanoparticles (SPIONs) and their derivatives (aminosilane and gold-coated) have been widely investigated in numerous medical applications, including their potential to act as antibacterial drug carriers that may penetrate into bacteria cells and biofilm mass. Pseudomonas aeruginosa is a frequent cause of infection in hospitalized patients, and significant numbers of currently isolated clinical strains are resistant to standard antibiotic therapy. Here we describe the impact of three types of SPIONs on the growth of P. aeruginosa during long-term bacterial culture. Their size, structure, and physicochemical properties were determined using transmission electron microscopy, X-ray diffraction analysis, and Fourier transform infrared spectroscopy. We observed significant inhibition of P. aeruginosa growth in bacterial cultures continued over 96 hours in the presence of gold-functionalized nanoparticles (Fe3O4@Au). At the 48-hour time point, growth of P. aeruginosa, as assessed by the number of colonies grown from treated samples, showed the highest inhibition (decreased by 40%). These data provide strong evidence that Fe3O4@Au can dramatically reduce growth of P. aeruginosa and provide a platform for further study of the antibacterial activity of this nanomaterial.Keywords: antibacterial activity, Pseudomonas aeruginosa, superparamagnetic nanoparticles, iron oxides, gold-coated nanoparticles

The influence of the surface modification on the magnetism of 4–14 nm sized core and core/shell gallium ferrites obtained by different preparation methods (Massart's and thermal decomposition from acetylacetonates) was studied. The physical properties of GaxFe3-xO4 were investigated in a wide range of Ga admixtures 0 ≤ x ≤ 1.5. Ga ions location at 8a or/and 16d positions of a spinel structure depends on the synthesis method and has a pronounced effect on the superparamagnetic properties of nanoparticles. Magnetization and Mössbauer experiments show the dominant superparamagnetic contribution for the nanoparticles with x > 0.8 with the blocking temperature TB significantly below 200 K. Surface-modified nanoferrites disclosed spontaneous magnetization that does not exceed 60 emu/g. [ABSTRACT FROM AUTHOR]

We have succeeded in synthesizing orthorhombic Ga(1_X)Fe(1+X)03 (-0.05 ≤ x ≤ 0.5), hexagonal GayFe(2-y)O3 (0 ≤ y ≤1.8) and cubic Ga(1+Z)Fe(2-Z)04 (--0.1 ≤ z ≤ 0.8) nanograins of gallium ferrites using conventional precursors and an organic environment of Pechini scenario under atmosphericpressure conditions (SG method). Phase composition and homogeneity were analyzed using X-ray diffraction. Small angle neutron scattering disclosed ellipsoidal particle shapes of gallium iron oxides (GFO) crystallizing in orthorhombic (o-GFO) and hexagonal (h-GFO) symmetry and parallelepiped shapes of Ga(1+y)Fe(2-y)O4 (c-GFO) grains. Despite local agglomeration among the magnetic grains, the scanning electron microscopy and transmission electron microscopy images point to faced-elliptical shapes. The Mössbauer spectroscopy with magnetization measurements was carried out in the temperature range of 5-295 K. The analysis of gallium ferrites magnetism demonstrates that iron atoms locate with various probabilities in crystallography positions and the spontaneous magnetization preserves up to room temperature (RT). [ABSTRACT FROM AUTHOR]