The Fabrication Of Magnetic Nanoprobes And Application Studies On Magnetic Resonance Imaging

It is still a challenge to find the way to diagnose and cure disease at early time in scientific research and clinical practice. The development of biomedical imaging technology, such as computer X-ray tomography (CT), optical imaging, acoustic imaging and magnetic resonance imaging (MRI), has been widely used in clinical diagnoses such as cancer diagnose. MRI becomes to the most powerful diagnostic imaging technology due to its high-resolution, no ion radiation, and noninvasive for animal. However, high sensitive MRI imaging detection need to use the MRI contrast agents of excellent performance. Therefore, we mainly study on the synthesis of magnetic nanoprobe and its application for MRI.A facile one-pot method has been developed to prepare poly(amino acid) functionalized, water-stable, biocompatible, and superparamagnetic iron oxide nanoparticles with small diameters of～10 nm. The obtained biocompatible magnetic nanoparticles capped with polyaspartic acid (PASP) exhibit a relatively high saturation magnetization (57.1 emu/g) and a much strong magnetic resonance (MR) T2 relaxation effect with the transverse relaxivity coefficient (r2) as high as 302.6 s-1 mM-1. Interestingly, the as-prepared Fe3O4@PASP NPs are highly stable in aqueous solution and demonstrate the property of magnetic nanofluids. The high T2 effect, good water-stability, superparamagnetization, biocompatibility and bioconjugatability rendered the as-synthesized Fe3O4@PASP NPs great desirable for bioapplications such as magnetic resonance imaging (MRI), bioseparation, targeted drug delivery, and so on.For the further development of magnetic resonance contrast agents with good biocompatibility and biodegradability, we used hydrolysed a-lactalbumin as carriers and used metal cations (Ca2+ and Gd3+) to induce self-assembly of partially hydrolysed a-lactalbumin and get the nanocapsules with magnetic properties for MRI. The morphology of the nanocapsules could be affected by pH, time, and the concentrations of partially hydrolysed a-lactalbumin, Ca2+ Gd3+ and RB. It was the first time to use a-lactalbumin as a nanocarrier for Gd3+ and photosensitizer RB. These as-synthesized nanospheres present a good T1 enhanced MRI and efficient photodynamic effect with good biocompatibility. We demonstrated a facile one-step strategy to synthesize bifunctional protein nanocapsules for both magnetic resonance imaging and photodynamic therapy. Hence,it paves the way to develop new theranostics and will find great potentials in the fields of diagnosis and therapy.