Recent Advances in the Use of Magnetic Nanoparticles in Bio-Imaging Applications

Early diagnosis and treatment of tumors are the most effective strategies for controlling cancer development and progression. Since the 20th century, magnetic resonance imaging (MRI) has become an important detection technology in clinical diagnosis and medical research because of its non-invasive, high-resolution, high-sensitivity, and real-time imaging advantages. Contrast-enhanced MRI can effectively distinguish not only tumors from normal tissues but also between malignant and benign tumors. It can also be used for vascular and perfusion imaging and inflammation imaging, which can effectively reduce missed diagnoses and misdiagnoses. Magnetic contrast agents as key components of nuclear magnetic imaging have great significance for accurate diagnosis. At present, great progress has been made in the design and research of contrast agents. Iron-based nanomaterials, as mature contrast agents, are the most widely used. In addition, gadolinium-based contrast agents and novel magnetic hybrid nanoparticles are also being actively utilized in MRI and multifunctional imaging. This review mainly introduces the latest research progress regarding magnetic nanomaterials for MRI and discusses the obstacles encountered in biomedical applications. Furthermore, we also focus on the development of contrast agents that can be used in the application of multimodal MRI therapy and other fields in the future.