|Nuclear Magnetic Resonance (NMR) signal relaxation is influenced by aggregate formation when magnetic nanoparticles bind with target molecules. In this study, a magnetic resonance based nanosensor was developed for a clinical MRI system. The goal of this research was the detection of target polystyrene microspheres conjugation with superparamagnetic iron oxide (SPIO) nanoparticles in a rapid and highly sensitive multiplexed fashion. The binding effects would occur due to the interaction of the streptavidin coated SPIO nanoparticles with the biotinylated polystyrene microspheres (BPM). The SPIO nanoparticles were used as a proximity sensor that would augment molecular interactions. The T2 dephasing rate of nearby water molecule protons was demonstrated to be lower in the dispersed state rather than once aggregated thus providing an adjustment in transverse relaxation time, ΔT2. An optimal concentration range of the SPIO nanoparticles was shown for its greatest sensitivity at affecting T2 with any modification in the nanoparticles dispersion. By utilizing the optimal SPIO concentration, a NMR based nanosensor was developed that would identify the presence of the BPM within a solution. The SPIO nanoparticle sensor shows promise for its diagnostic capability and its portability.