Magnetofection is done through the use of super paramagnetic iron oxide nanoparticles coated with polyethylenimine.
MTSL (S-(2,2,5,5-tetramethyl-2,5-dihydro-1H-pyrrol-3-yl)methyl methanesulfonothioate) is a chemical compound which can be used as a nitroxide (amine oxide) paramagnetic spin label in protein Electron paramagnetic resonance spectroscopy experiments.
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In Nuclear magnetic resonance the introduction of the paramagnetic group increases the relaxation rate of nearby nuclei.
The voxel intensity in QSM is linearly proportional to the underlying tissue apparent magnetic susceptibility, which is useful for chemical identification and quantification of specific biomarkers including iron, calcium, gadolinium, and super paramagnetic iron oxide (SPIO) nano-particles.
Due to the changes in magnetic properties that occur from a spin transition - the complex being more diamagnetic in a LS state and more paramagnetic in a HS state - magnetic susceptibility measurements as a function of temperature are most commonly used in addition to optical spectroscopy and X-ray crystallography.
The concept of a nesting vector is illustrated in the Figure for the famous case of Cr, which transitions from a paramagnetic to SDW state at a Néel temperature of 311 K. Cr is a body-centered cubic metal whose Fermi surface features many parallel boundaries between electron pockets centered at and hole pockets at H. These large parallel regions can be spanned by the nesting wavevector shown in red.
The presence of strongly magnetic ions or particles (e.g. ferromagnetic, paramagnetic) also strongly alter T1 values and are widely used as MRI contrast agents.