Magnetic nanoparticle-based sensors for MRI have been accelerated to a timescale of seconds using densely-functionalized particles of small size. Parameters that increase response rates also result in large nuclear magnetic relaxation rate and light scattering changes, allowing signals to be detected almost immediately after changes in calcium concentration.United States. National Institutes of Health (DP2-OD2114)United States. National Institutes of Health (R01-DA28299)United States. National Institutes of Health (R01-NS76462
