Paramagnetic inorganic nanoparticles as T₁MRI contrast agents

Abstract

Magnetic resonance imaging (MRI) is one of the most powerful molecular imaging techniques and can noninvasively visualize and quantify biological processes within the living organisms. The introduction of exogenous contrast agents has allowed specific visualization of biological targets as well as enhanced the sensitivity of MRI. Recently, paramagnetic inorganic nanoparticles showing positive T(1) contrast effect have been investigated as T(1) MRI contrast agents. Since the first trials of spherical nanoparticles of manganese oxide and gadolinium oxide, inorganic nanoparticles of various compositions and shapes have been used for in vivo and in vitro MRI because of their distinct signal enhancement in MR images. However, for clinical applications, important and complex issues such as safety and efficiency should be investigated by active research encompassing multiple disciplines, including chemistry, biology, biomedical engineering, and medicine.

Iron Oxide Based Nanoparticles for Multimodal Imaging and Magnetoresponsive Therapy

“…Such extremely small iron oxide nanoparticles (ESIONs) have been recently investigated as T 1 contrast agents. 24,97 The high r 1 relaxivity of 4.78 mM −1 s −1 and low r 2 /r 1 ratio of 3.67 indicate that they have the potential as effective positive contrast agents.…”

Copper Oxide Nanoparticles Stimulate Cytotoxicity and Apoptosis in Glial Cancer Cell Line

“…To 100 ml of distilled water, we added 0.25 g of CuSO 4 and then 5 g of polyvinyl pyrrolidone K30 (PVP-K30) and was dissolved in this solution. For reduction of CuO, 0.25 g NaBH 4 was poured into the solution.…”

“…Inorganic NPs consisting of metal oxides have been manufactured on a large scale for applications in medicine like drug delivery, bio-sensing, cell imaging and cancer therapy in organs such as brain which is protected by specialized brain barrier. [1][2][3][4] Chemotherapeutic researches based on the use of metals for new anti-cancer drugs with the potential of being less toxic and exhibiting more anti-proliferative activity against tumors have been developed. 5 NPs in comparison to large biological molecules (enzymes, receptors, etc.)…”

Nanoparticles for Molecular Imaging

“…[231][232][233][234] Among them, SPIONs-based contrast agents are currently the frontrunners as T2 contrast agents as shown in Table III, because of their high magnetic susceptibility, high saturation magnetization and super-paramagnetic properties. SPIONs have been demonstrated to significantly improve the sensitivity of T2-weighted MRI even at low concentrations, where the typical relaxivity of SPIONs are R2 of 100 mM −1 s −1 and R1 of 30 mM −1 s −1 (R2/R1 > 3) measured at 37 C and 0.47 T. 4 The relaxivity of SPIONs are influenced by several parameters including particle size, composition, concentration of particles within a given imaging voxel, and data acquisition parameters.…”