d‐Glucuronic Acid‐Coated Ultrasmall Paramagnetic Ln₂O₃ (Ln = Tb, Dy, and Ho) Nanoparticles: Magnetic Properties, Water Proton Relaxivities, and Fluorescence Properties

Abstract

Many of the lanthanide‐based nanoparticles are valuable in magnetic resonance imaging (MRI) because they have excellent magnetic properties that make them suitable for MRI contrast agents, while some of them have additional optical properties and thus can serve as fluorescence imaging (FI) agents as well. Herein, we synthesized d‐glucuronic acid‐coated ultrasmall Ln2O3 (Ln = Tb, Dy, and Ho) nanoparticles with average diameters of ∼ 2 nm. All the nanoparticles showed unsaturated but appreciable magnetization of ∼ 4 emu/g at an applied field of 1.8 T at room temperature, and consequently, high transverse water proton relaxivities (r2) of ∼ 7 s–1 mm–1 at 1.5 T, ∼ 35 s–1 mm–1 at 3.0 T, and ∼ 55 s–1 mm–1 at 9.4 T with negligible longitudinal water proton relaxivities (r1), thus being eligible for use as T2 MRI contrast agents at high MR fields. In addition, d‐glucuronic acid‐coated ultrasmall Tb2O3 nanoparticles exhibited fluorescence in the green region, useful for dual‐modal imaging.

Synthesis, Characterizations, and 9.4 Tesla T2 MR Images of Polyacrylic Acid-Coated Terbium(III) and Holmium(III) Oxide Nanoparticles

“…The model suggests that r 2 ∝ M NP 2 , in which M NP (in emu/NP) is a magnetic moment per NP [20][21][22]. The M NP values of the Ln 2 O 3 NPs are appreciable at room temperature, as can be noticed from their M values in Figure 6, explaining the observed appreciable r 2 values at 3.0 T. In addition, the enhanced r 2 values of the NPs at 9.4 T were due to their higher M NP values at 9.4 T because the paramagnetic NP samples were far from saturation (Figure 6 [49] of the D-glucuronic acid-coated Ln 2 O 3 NPs at the similar core particle diameters and the r 2 values of the PAA-coated Ln 2 O 3 NPs were smaller than those [49] of the D-glucuronic acid-coated Ln 2 O 3 NPs. These surface-coating ligand effects are schematically explained in Figure 9.…”

“…PAA-coated Ln 2 O 3 (Ln = Tb and Ho) NPs were synthesized through the one-pot polyol method (Figure 1). Compared to D-glucuronic acid as a surface-coating ligand [49], PAA enhanced the colloidal stability as well as biocompatibility of the NPs.…”

Facile Synthesis of Holmium-Based Nanoparticles as a CT and MRI Dual-Modal Imaging for Cancer Diagnosis

“…Tb, Ho, and Dy are the elements with the largest magnetic moments in the periodic table and can cause considerable transverse relaxation of hydrogen protons in free water. Thus, Tb, Ho, and Dy-based materials are the best choices for ultra-high field T 2 CAs ( 33 – 36 ). Against the background of continuous pursuit of ultra-high field intensity MRI, research on MRI CAs based on large magnetic moment elements is likely to experience rapid growth in the near future.…”

A Novel Strong Cyan Luminescence Emission of Tb2O3 Particles

“…Besides, their functional properties are highly dependent upon crystallite size, composition, morphology, shape, size, precursor molarity, production method [4] [6] [7][1] [8]. Among them, terbium oxide (Tb 2 O 3 ) materials are used widely in many areas such as magnetooptical [9] [10] [11] [12], optical application [13] [1] [6] [14] [15] [16] [11] [17], magnetic application [3], electronic [7], optoelectronic devices [18], MRI contrast agents [19], electrochemical applications [6]. They can be synthesized by solvothermal [17], hydrothermal [20], precipitation [6] [7], template-assisted hydrothermal [1], self-propagating high-temperature [12] [9], thermal decomposition [3], sol-gel [21] [22], magnetron sputtering [15] and metal-organic (MO) CVD [14] methods.…”