Nanostructured materials for magnetic biosensing

Background: Magnetic nanoparticles (MNPs) are at the leading edge of the field of biomedical applications and magnetic biosensing. Methods: MNPs were fabricated by electrophysical methods of the laser target evaporation (LTE) and spark discharge with electrodynamic acceleration of plasma jumpers (SD). Synthesis of polyacrylamide hydrogel was done in the presence of Fe2O3 MNPs in different concentrations obtained by LTE. [FeNi/Ti](3)/Cu[Ti/FeNi](3)/Ti multilayers for giant magnetoimpedance (GMI) based sensitive elements were prepared by rf-sputtering for testing a biosensor prototype. Results: Iron oxide MNPs, ferrofluids, ferrofluids contacting with biological systems, synthetic ferrogels mimicking natural tissues - are the steps of the discussed in this work development of bionanomaterials. Thorough the structural and magnetic studies of a multilayered sensitive element, MNPs and ferrogels insure the complete characterization of biosensor prototype. The GMI responses were carefully evaluated in initial state and in the presence of ferrogel with known concentration of MNPs. SD MNPs had the smallest 5-8 nm size. This nanomaterial was characterized by large internal strains of the order of 25 x 10(-3), which can play an important role for the interaction with different biosystems. Conclusions: Iron oxide MNPs were fabricated by LTE and SD methods. SD MNPs had the smallest 5-8 nm size and large internal strains of the order of 25 x 10(-3). Designed GMI biosensor prototype allowed precise evaluation of the stray field of the MNPs present in the ferrogel by evaluating the systematic changes of the GMI in a 20-400 MHz frequency range. (C) 2016 Elsevier B.V. All rights reserved.