Clustered ultra-small iron oxide nanoparticles as potential T/Tdual-modal magnetic resonance imaging contrast agents and application to tumor model.

Many studies have been conducted on the use of ultra-small iron oxide nanoparticles (USIONs) (d < 3 nm) as potential positive magnetic resonance imaging (MRI)-contrast agents (CAs); however, there is dearth of research on clustered USIONs. In this study, nearly monodispersed clustered USIONs were synthesized using a simple two-step one-pot polyol method. First, USIONs (d = 2.

Ultrasmall cerium oxide nanoparticles as highly sensitive X-ray contrast agents and their antioxidant effect.

Owing to their theranostic properties, cerium oxide (CeO) nanoparticles have attracted considerable attention for their key applications in nanomedicine. In this study, ultrasmall CeO nanoparticles (particle diameter = 1-3 nm) as X-ray contrast agents with an antioxidant effect were investigated for the first time. The nanoparticles were coated with hydrophilic and biocompatible poly(acrylic acid) (PAA) and poly(acrylic acid--maleic acid) (PAAMA) to ensure satisfactory colloidal stability in aqueous media and low cellular toxicity.

Core-Shell FeO@C Nanoparticles as Highly Effective T Magnetic Resonance Imaging Contrast Agents: In Vitro and In Vivo Studies.

Magnetite nanoparticles (FeO NPs) have been intensively investigated because of their potential biomedical applications due to their high saturation magnetization. In this study, core-shell FeO@C NPs (core = FeO NPs and shell = amorphous carbons, d = 35.1 nm) were synthesized in an aqueous solution.

Production, surface modification, physicochemical properties, biocompatibility, and bioimaging applications of nanodiamonds.

Nanodiamonds (ND) are chemically inert and stable owing to their sp covalent bonding structure, but their surface sp graphitic carbons can be easily homogenized with diverse functional groups oxidation, reduction, hydrogenation, amination, and halogenation. Further surface conjugation of NDs with hydrophilic ligands can boost their colloidal stability and functionality. In addition, NDs are non-toxic as they are made of carbons.

Heavy Metal-Based Nanoparticles as High-Performance X-ray Computed Tomography Contrast Agents.

X-ray computed tomography (CT) contrast agents offer extremely valuable tools and techniques in diagnostics via contrast enhancements. Heavy metal-based nanoparticles (NPs) can provide high contrast in CT images due to the high density of heavy metal atoms with high X-ray attenuation coefficients that exceed that of iodine (I), which is currently used in hydrophilic organic CT contrast agents. Nontoxicity and colloidal stability are vital characteristics in designing heavy metal-based NPs as CT contrast agents.

High-Quantum-Yield Ultrasmall LnO (Ln = Eu, Tb, or Dy) Nanoparticle Colloids in Aqueous Media Obtained via Photosensitization.

Fluorescent nanoparticles used in biomedical applications should be stable in their colloidal form in aqueous media and possess a high quantum yield (QY). We report ultrasmall LnO (Ln = Eu, Tb, or Dy) nanoparticle colloids with high QYs in aqueous media. The nanoparticles are grafted with hydrophilic and biocompatible poly(acrylic acid) (PAA) to ensure colloidal stability and biocompatibility and with organic photosensitizer 2,6-pyridinedicarboxylic acid (PDA) for achieving a high QY.

Magnetic Nanoparticle-Based High-Performance Positive and Negative Magnetic Resonance Imaging Contrast Agents.

In recent decades, magnetic nanoparticles (MNPs) have attracted considerable research interest as versatile substances for various biomedical applications, particularly as contrast agents in magnetic resonance imaging (MRI). Depending on their composition and particle size, most MNPs are either paramagnetic or superparamagnetic. The unique, advanced magnetic properties of MNPs, such as appreciable paramagnetic or strong superparamagnetic moments at room temperature, along with their large surface area, easy surface functionalization, and the ability to offer stronger contrast enhancements in MRI, make them superior to molecular MRI contrast agents.

Facile Synthesis and X-ray Attenuation Properties of Ultrasmall Platinum Nanoparticles Grafted with Three Types of Hydrophilic Polymers.

Ultrasmall platinum nanoparticles (Pt-NPs) grafted with three types of hydrophilic and biocompatible polymers, i.e., poly(acrylic acid), poly(acrylic acid-co-maleic acid), and poly(methyl vinyl ether-alt-maleic acid) were synthesized using a one-pot polyol method.

Mono and Multiple Tumor-Targeting Ligand-Coated Ultrasmall Gadolinium Oxide Nanoparticles: Enhanced Tumor Imaging and Blood Circulation.

Hydrophilic and biocompatible PAA-coated ultrasmall GdO nanoparticles (d = 1.7 nm) were synthesized and conjugated with tumor-targeting ligands, i.e.

Polyethylenimine-Coated Ultrasmall Holmium Oxide Nanoparticles: Synthesis, Characterization, Cytotoxicities, and Water Proton Spin Relaxivities.

Water proton spin relaxivities, colloidal stability, and biocompatibility of nanoparticle magnetic resonance imaging (MRI) contrast agents depend on surface-coating ligands. In this study, hydrophilic and biocompatible polyethylenimines (PEIs) of different sizes (M = 1200 and 60,000 amu) were used as surface-coating ligands for ultrasmall holmium oxide (HoO) nanoparticles. The synthesized PEI1200- and PEI60000-coated ultrasmall HoO nanoparticles, with an average particle diameter of 2.

Enhanced Tumor Imaging Using Glucosamine-Conjugated Polyacrylic Acid-Coated Ultrasmall Gadolinium Oxide Nanoparticles in Magnetic Resonance Imaging.

Owing to a higher demand for glucosamine (GlcN) in metabolic processes in tumor cells than in normal cells (i.e., GlcN effects), tumor imaging in magnetic resonance imaging (MRI) can be highly improved using GlcN-conjugated MRI contrast agents.

Gadolinium Neutron Capture Therapy (GdNCT) Agents from Molecular to Nano: Current Status and Perspectives.

Gd (natural abundance = 15.7%) has the highest thermal neutron capture cross section (σ) of 254,000 barns (1 barn = 10 m) among stable (nonradioactive) isotopes in the periodic table. Another stable isotope, Gd (natural abundance = 14.

Functionalized Lanthanide Oxide Nanoparticles for Tumor Targeting, Medical Imaging, and Therapy.

Recent progress in functionalized lanthanide oxide (LnO) nanoparticles for tumor targeting, medical imaging, and therapy is reviewed. Among the medical imaging techniques, magnetic resonance imaging (MRI) is an important noninvasive imaging tool for tumor diagnosis due to its high spatial resolution and excellent imaging contrast, especially when contrast agents are used. However, commercially available low-molecular-weight MRI contrast agents exhibit several shortcomings, such as nonspecificity for the tissue of interest and rapid excretion in vivo.

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

Polyacrylic acid (PAA)-coated lanthanide oxide (LnO) nanoparticles (NPs) (Ln = Tb and Ho) with high colloidal stability and good biocompatibility were synthesized, characterized, and investigated as a new class of negative (T) magnetic resonance imaging (MRI) contrast agents at high MR fields. Their r values were appreciable at a 3.0 T MR field and higher at a 9.

Chitosan Oligosaccharide Lactate-Coated Ultrasmall Gadolinium Oxide Nanoparticles: Synthesis, Cytotoxicity, and Relaxometric Properties.

In this study, hydrophilic and biocompatible chitosan oligosaccharide lactate (COL)-coated ultra-small gadolinium oxide nanoparticles (NPs) were synthesized through a one-pot polyol method and characterized by various experimental techniques. The cellular cytotoxicity assay indicated that the COL-coated gadolinium oxide NPs were non-toxic up to 500 M Gd. In addition, their water proton spin relaxivities (i.

Hydrophilic Biocompatible Poly(Acrylic Acid-co-Maleic Acid) Polymer as a Surface-Coating Ligand of Ultrasmall GdO Nanoparticles to Obtain a High r Value and T MR Images.

The water proton spin relaxivity, colloidal stability, and biocompatibility of nanoparticle-based magnetic resonance imaging (MRI) contrast agents depend on the surface-coating ligands. Here, poly(acrylic acid-co-maleic acid) (PAAMA) (M = ~3000 amu) is explored as a surface-coating ligand of ultrasmall gadolinium oxide (GdO) nanoparticles. Owing to the numerous carboxylic groups in PAAMA, which allow its strong conjugation with the nanoparticle surfaces and the attraction of abundant water molecules to the nanoparticles, the synthesized PAAMA-coated ultrasmall GdO nanoparticles (d = 1.

New Class of Efficient T Magnetic Resonance Imaging Contrast Agent: Carbon-Coated Paramagnetic Dysprosium Oxide Nanoparticles.

Nanoparticles are considered potential candidates for a new class of magnetic resonance imaging (MRI) contrast agents. Negative MRI contrast agents require high magnetic moments. However, if nanoparticles can exclusively induce transverse water proton spin relaxation with negligible induction of longitudinal water proton spin relaxation, they may provide negative contrast MR images despite having low magnetic moments, thus acting as an efficient T MRI contrast agent.

In Vivo Positive Magnetic Resonance Imaging Applications of Poly(methyl vinyl ether-alt-maleic acid)-coated Ultra-small Paramagnetic Gadolinium Oxide Nanoparticles.

The study of ultra-small paramagnetic gadolinium oxide (GdO) nanoparticles (NPs) as in vivo positive (T) magnetic resonance imaging (MRI) contrast agents is one of the most attractive fields in nanomedicine. The performance of the GdO NP imaging agents depends on the surface-coating materials. In this study, poly(methyl vinyl ether-alt-maleic acid) (PMVEMA) was used as a surface-coating polymer.

Relaxometric, Optical and Cell Viability Properties of D-Glucuronic Acid Coated Cr₂O₃ Nanoparticles.

D-glucuronic acid-coated ultrasmall chromium oxide (Cr2O3) nanoparticles were synthesized by a one-pot polyol method and their relaxometric and optical properties were investigated. The as-synthesized D-glucuronic acid-coated nanoparticles were amorphous owing to ultrasmall particle diameters (davg = 2.0 nm), whereas orthorhombic Cr2O3 nanoparticles with two size groups (davg = 3.

Longitudinal Water Proton Relaxivity and In Vivo T₁ MR Images of Mixed Zn(II)/Gd(III) Oxide Nanoparticles.

Mixed Zn(II)/Gd(III) oxide nanoparticles (~8 mole%Zn) with d(avg) of 2.1 nm were synthesized. The D-glucuronic acid coated Zn(II)/Gd(III) oxide nanoparticles showed a longitudinal water proton relaxivity (r₁) of 12.

Magnetic resonance imaging, gadolinium neutron capture therapy, and tumor cell detection using ultrasmall GdO nanoparticles coated with polyacrylic acid-rhodamine B as a multifunctional tumor theragnostic agent.

Monodisperse and ultrasmall gadolinium oxide (GdO) nanoparticle colloids ( = 1.5 nm) (nanoparticle colloid = nanoparticle coated with hydrophilic ligand) were synthesized and their performance as a multifunctional tumor theragnostic agent was investigated. The aqueous ultrasmall nanoparticle colloidal suspension was stable and non-toxic owing to hydrophilic polyacrylic acid (PAA) coating that was partly conjugated with rhodamine B (Rho) for an additional functionalization (mole ratio of PAA : Rho = 5 : 1).

Stable and non-toxic ultrasmall gadolinium oxide nanoparticle colloids (coating material = polyacrylic acid) as high-performance magnetic resonance imaging contrast agents.

For use as positive ( ) magnetic resonance imaging contrast agents (MRI-CAs), gadolinium oxide (GdO) nanoparticle colloids ( nanoparticles coated with hydrophilic ligands) should be stable, non-toxic, and ultrasmall in particle diameter for renal excretion. In addition, they should have a high longitudinal water proton relaxivity ( ) and / ratio that is close to one ( = transverse water proton relaxivity) for high-performance. In this study, we report ultrasmall GdO nanoparticle colloids [coating material = polyacrylic acid, = ∼5100 Da] satisfying these conditions.

Dual-mode T1 and T2 magnetic resonance imaging contrast agent based on ultrasmall mixed gadolinium-dysprosium oxide nanoparticles: synthesis, characterization, and in vivo application.

A new type of dual-mode T1 and T2 magnetic resonance imaging (MRI) contrast agent based on mixed lanthanide oxide nanoparticles was synthesized. Gd(3+) ((8)S7/2) plays an important role in T1 MRI contrast agents because of its large electron spin magnetic moment resulting from its seven unpaired 4f-electrons, and Dy(3+) ((6)H15/2) has the potential to be used in T2 MRI contrast agents because of its very large total electron magnetic moment: among lanthanide oxide nanoparticles, Dy2O3 nanoparticles have the largest magnetic moments at room temperature. Using these properties of Gd(3+) and Dy(3+) and their oxide nanoparticles, ultrasmall mixed gadolinium-dysprosium oxide (GDO) nanoparticles were synthesized and their potential to act as a dual-mode T1 and T2 MRI contrast agent was investigated in vitro and in vivo.