Water-Soluble MnO Nanocolloid for a Molecular T₁ MR Imaging: A Facile One-Pot Synthesis, In vivo T₁ MR Images, and Account for Relaxivities

Abstract

A facile one-pot synthesis of a water-soluble MnO nanocolloid (i.e., D-glucuronic acid-coated MnO nanoparticle) is presented. The MnO nanoparticle in the MnO nanocolloid was coated with a biocompatible and hydrophilic D-glucuronic acid, and its particle diameter was nearly monodisperse and ranged from 2 to 3 nm. The average hydrodynamic diameter of the MnO nanocolloid was estimated to be 5 nm. The MnO nanoparticle was nearly paramagnetic down to T=3 K. The MnO nanocolloid showed a high longitudinal water proton relaxivity of r1=7.02 s(-1) mM(-1) with the r2/r1 ratio of 6.83 due to five unpaired S-state electrons of Mn(II) ion (S=5/2) as well as a high surface to volume ratio of the MnO nanoparticle. High contrast in vivo T1 MR images were obtained for various organs, showing the capability of the MnO nanocolloid as a sensitive T1 MRI contrast agent. The suggested three key-parameters which control the r1 and r2 relaxivities of nanocolloids (i.e., the S value of a metal ion, the spin structure, and the surface to volume ratio of a nanoparticle) successfully accounted for the observed r1 and r2 relaxivities of the MnO nanocolloid.

Iron Oxide-Based Nanostructures for MRI and Magnetic Hyperthermia

“…This includes the design of nanoparticles by modification of shape, such as polyhedral [88], nanocubes [89], superparamagnetic colloidal nanocrystals [90] and multiple magnetite nanocrystals [41]; and the use of manganese nanoparticles [91], cobalt nanoparticles [92] and quantum dot-capped magnetite nanorings [93], among others.…”

Nanoparticles in Biomedical Applications and Their Safety Concerns

“…These MnO nanoparticles were also used to demonstrate feasibility of cell labeling and in vivo MRI tracking. (Baek, Park et al 2010) However, under existing MnO based nanoparticle systems, the contrast is weak and the duration of signal is short for the long time in vivo MRI tracking. Therefore, it is required the further development of the MnO based contrast agent with high relaxivities and improved cellular uptake to stem cells which is more difficult to label due to the lack of substantial phgocytic capacity.…”

Functionalized nanomaterials: their use as contrast agents in bioimaging: mono- and multimodal approaches

“…Transition metal oxide (MnO) NPs have recently been developed by various groups for T 1 -contrast imaging of brain tumors, [71] in addition to the liver and kidney [58,72]. Hollow MnO NPs could also carry drug molecules in their cavities for simultaneous imaging and therapy applications [73].…”