Oleic acid-coated iron oxide nanoparticles for enhanced magnetomotive ultrasound and photoacoustic imaging in oil-based phantoms

Phantoms play a crucial role in quality control for clinical ultrasound imaging. To evaluate the efficacy of nanoparticles as contrast agents, researchers often use phantoms made from materials such as gelatin, agar, and various polymers. However, the hydrophobic surface of oleic acid–coated iron oxide nanoparticles (OA-IONPs) limit their dispersion in aqueous environments, thereby restricting their application in conventional imaging phantoms and clinical settings. In this study, we synthesized monodisperse OA-IONPs (12–14 nm) using the thermal decomposition method, characterized them, and evaluated their performance in an oil-based phantom using magnetomotive ultrasound (MMUS) and photoacoustic (PA) imaging. The results demonstrate that OA-IONPs embedded in oil-based phantoms can serve as effective contrast agents, yielding signal-to-noise ratio (SNR) of approximately 11.3  dB in PA imaging and a displacement of 4.8  µm in MMUS at a nanoparticle concentration of 1.5  mg/mL. These findings may contribute to the development of enhanced synthesis strategies and the advancement of biomedical imaging technologies.