Microbubbles with surface coated by superparamagnetic iron oxide nanoparticles

► We report synthesis method of microbubbles (MBs) with SPIO nanoparticles on surfaces. ► SPIO-coated MBs preserve superparamagnetic properties better than SPIO-embedded MBs. ► SPIO-coated MBs have better ultrasound contrast than MBs without SPIO. ► SPIO-coated MBs have better MRI contrast than SPIO-embedded MBs.