Nanopartículas Janus formadas pela deposição da multicamada Ag/NiFe/Ag sobre microesferas de SiO2

Abstract

The main focus of this work is the synthesis and characterization of Janus nanoparticles SiO2 (face 1)/Ag/Ni80Fe20/Ag trilayer (face 2) for application in magnetic hyperthermia and extrusion of bacteria. SiO2 microspheres (side 1) with a diameter of 500 nm were deposited on a Si(100) substrate using the spin coating technique. the face 2 (trilayer) was deposited by the magnetron sputtering on the substrate with the microspheres, resulting in JANUS particles. The particles were removed from the substrate using ultrasound. The thickness of the Ag layer was held constant (5 nm) and the thickness of the Ni80Fe20 varied from 10 nm to 50 nm. Scanning electron microscopy, as well as transmission, confirmed the formation of the intended JANUS particles. From the magnetic point of view, the particle hysteresis cycles are characteristic of a magnetically soft material. The particle with a 30 nm thick Ni80Fe20 layer, the state of vortices was observed in low magnetic fields. The magnetic hyperthermia experiment was unsuccessful, since silica has a much higher density than water and even glycerin, so that the particles precipitated, making the measurement unfeasible. The silver surface was effective for sterilize bacteria E coli strains 25922 and DH5α and S. aureus strains 29213 and MU50. In future work, it is intended to do new bacteria sterilization tests should be carried out combining, in a systematic way, the effects of silver, of sterilants that can be added to the porous surface of silica and the movement that can be generated in the particles and, consequently, on the bacteria through alternating magnetic fields.