Relaxation of biofunctionalized magnetic nanoparticles in ultra-low magnetic fields

Abstract

In this work, the spin-spin relaxation rate, 1/T2, and spin-lattice relaxation rate, 1/T1, of protons' spins induced by biofunctionalized magnetic nanoparticles and ferrofluids are investigated using a high-Tc superconducting quantum interference device-detected magnetometer in ultra-low fields. The biofunctionalized magnetic nanoparticles are the anti-human C-reactive protein (antiCRP) coated onto dextran-coated superparamagnetic iron oxides Fe3O4, which is labeled as Fe3O4-antiCRP. The ferrofluids are dextran-coated iron oxides. It was found that both 1/T2 and 1/T1 of protons in Fe3O4-antiCRP are enhanced by the presence of magnetic nanoparticles. Additionally, both the 1/T1 and 1/T2 of Fe3O4-antiCRP are close to that of ferrofluids, which are dextran-coated Fe3O4 dispersed in phosphate buffer saline. Characterizing the relaxation of Fe3O4-antiCRP can be useful for biomedical applications. © 2013 American Institute of Physics.