Design of Macromolecular Contrast Agents for Magnetic Resonance Imaging
Magnetic resonance imaging (MRI) has emerged as one of the most powerful and widely used technique for noninvasive clinical diagnosis owing to its high degree of soft tissue contrast, spatial resolution, and depth of penetration. MRI contrast is determined by the relaxation times (T1, spin–lattice relaxation and T2, spin–spin relaxation) of in vivo water protons. According to the density and nature of the biological tissue, different contrasts can be observed. To increase the contrast and the signal-to-noise ratio, contrast agents are usually administered to patients. These contrast agents can change the water relation in their surrounding by shortening T1 or increasing T2, resulting hyperintense signals. The contrast agents are generally based on either iron oxide nanoparticles (providing negative contrast in T2-weighted images) or complexes of lanthanide metals (mostly containing gadolinium ions, providing positive contrast in T1-weighted images). The Australian Centre of Nanomedicine designs the next generation of contrast agents by using nanotechnology. To achieve this aim, new functionalized iron oxide nanoparticles coated with biocompatible polymers are investigated. In contrast to conventional contrast agents, these nanoparticle contrast agents can be easily functionalized with therapeutic molecules, which can facilitate the accumulation of these agents in specific tissue. By using this approach, a lower dose on contrast agents can be used.
Magnetic Layered Double Hydroxide Nanoparticles as Dualmode Magnetic Resonance Imaging Contrast Agent
Magnetic resonance imaging (MRI) is currently one of the most powerful non-invasive molecular imaging techniques for cancer diagnosis by providing anatomical images of tissues and organs with excellent spatial resolutions. The diagnostic capabilities of MR imaging can be greatly improved by introducing exogenous contrast agents (T1 or T2 weighted contrast agents) to enhance target tissue contrast through altering the relaxation time of nearby water protons. Dual-mode MR imaging has been explored to address the issues on single-mode MR imaging by combining T1 and T2 weighted contrast agent into one nano-platform. The project aims to develop a new dual-mode MRI contrast agent with high selectivity, superb relaxivity and desirable biocompatibility.