Lanthanide Oxide Nanoparticles Research Articles

Sensitization of Europium Oxide Nanoparticles Enhances Signal-to-Noise over Autofluorescence with Time-Gated Luminescence Detection.

Clinical translation of nanoparticle-based therapeutics has been limited, and a lack of preclinical delivery characterization is partly to blame, limiting our understanding of the mechanisms of failure. The improvement of the preclinical delivery assessment requires nanoparticles with higher detectability. This work focused on the exploration of several aromatic carboxylic ligands (terephthalic acid, quinaldic acid, and kynurenic acid) for the sensitization of europium oxide nanoparticles with a long emission lifetime to overcome cellular autofluorescence, a key confounder of detection in luminescence-based bioimaging. A facile one-pot synthesis and ligand exchange process generated and sensitized ultrasmall Eu2O3 cores. As reflected in the emission spectra and lifetimes, ligand binding yielded unique coordination environments around Eu3+. Then, the efficacy of sensitization was tested against the autofluorescence provided by tissue lysate. Normal (simultaneous excite-read) measurements showed integrated signal improvements over autofluorescence of 2.2-, 3.9-, and 14.0-fold for EuTA, EuQA, and EuKA, respectively. In time-gated mode, the improvements over autofluorescence were more dramatic with fold differences of 75-, 89-, and 108-fold for EuTA, EuQA, and EuKA, respectively. The investigation of novel sensitizers expands the breadth of the field of sensitized lanthanide oxide nanoparticles, and the signal enhancement observed with sensitization and time-gating supports the utility of the generated samples for future bioimaging applications.

Lanthanide Oxide Nanoparticles for Environmental Remediation: A Review

The lanthanide oxide nanoparticles were used for the removal of pollutants towards environmental remediation. The enhanced properties and effectiveness of nanotechnology based materials makes them particularly suitable contender in detection of pollutants. The used particles synthesized by facile and easy method with additional standard modification. The origin of pollutants, their toxicity and influential effect of respective pollutants on the environment, humans and ecological system studied in details. The prepared nanoparticles as highly efficient probes, with novel methodology utilized for detection and removal of pollutants. The easy, cost effective and efficient technologies were performed for sensing of these pollutants. This article deals with mainly detection of pollutants present in water, air and soil by using nanomaterial. Further, these nanoparticle is utilized in degradation of various types of pollutants present in the environment.

Molecularly Targeted Lanthanide Nanoparticles for Cancer Theranostic Applications

Injectable colloidal solutions of lanthanide oxides (nanoparticles between 10 and 100 nm in size) have demonstrated high biocompatibility and no toxicity when the nanoparticulate units are functionalized with specific biomolecules that molecularly target various proteins in the tumor microenvironment. Among the proteins successfully targeted by functionalized lanthanide nanoparticles are folic receptors, fibroblast activation protein (FAP), gastrin-releasing peptide receptor (GRP-R), prostate-specific membrane antigen (PSMA), and integrins associated with tumor neovasculature. Lutetium, samarium, europium, holmium, and terbium, either as lanthanide oxide nanoparticles or as nanoparticles doped with lanthanide ions, have demonstrated their theranostic potential through their ability to generate molecular images by magnetic resonance, nuclear, optical, or computed tomography imaging. Likewise, photodynamic therapy, targeted radiotherapy (neutron-activated nanoparticles), drug delivery guidance, and image-guided tumor therapy are some examples of their potential therapeutic applications. This review provides an overview of cancer theranostics based on lanthanide nanoparticles coated with specific peptides, ligands, and proteins targeting the tumor microenvironment.

Unsupervised Learning-Based WSN Clustering for Efficient Environmental Pollution Monitoring.

Wireless Sensor Networks (WSNs) have been adopted in various environmental pollution monitoring applications. As an important environmental field, water quality monitoring is a vital process to ensure the sustainable, important feeding of and as a life-maintaining source for many living creatures. To conduct this process efficiently, the integration of lightweight machine learning technologies can extend its efficacy and accuracy. WSNs often suffer from energy-limited devices and resource-affected operations, thus constraining WSNs' lifetime and capability. Energy-efficient clustering protocols have been introduced to tackle this challenge. The low-energy adaptive clustering hierarchy (LEACH) protocol is widely used due to its simplicity and ability to manage large datasets and prolong network lifetime. In this paper, we investigate and present a modified LEACH-based clustering algorithm in conjunction with a K-means data clustering approach to enable efficient decision making based on water-quality-monitoring-related operations. This study is operated based on the experimental measurements of lanthanide oxide nanoparticles, selected as cerium oxide nanoparticles (ceria NPs), as an active sensing host for the optical detection of hydrogen peroxide pollutants via a fluorescence quenching mechanism. A mathematical model is proposed for the K-means LEACH-based clustering algorithm for WSNs to analyze the quality monitoring process in water, where various levels of pollutants exist. The simulation results show the efficacy of our modified K-means-based hierarchical data clustering and routing in prolonging network lifetime when operated in static and dynamic contexts.

Luminescent lanthanide oxides nanoparticles with a surface agent acting as a sensitiser

This work describes a series of lanthanide oxide nanoparticles, Nd2O3, Sm2O3, Eu2O3, TbO1.81, and Dy2O3 (Ln2O3-NPs) synthesised using a modified Polyol method. These oxides exhibit small particle sizes ranging from 5 nm to 20 nm, according to HRTEM micrographs, and crystallise into a cubic phase with an I213 space group. We employed deprotonated 2,3-dihydroxyquinoxaline (L2−) as a capping agent and sensitiser for nanoparticle luminescence. Spectroscopic results indicate that L2− is an excellent antenna. This work presents photoluminescence and absorption spectra of the Ln2O3 NPs, naked and with the capping agent. We also include the emission spectra at low temperatures (200 K and 100 K) and variable pressure for which a significant Stark level splitting was observed in the case of Sm2O3-L2- NPs. This splitting agrees with a D3 site symmetry for the samarium ion, being low symmetry. All compounds exhibit excellent luminescence properties; further studies may determine their possible use as optical sensors.

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

Recent progress in functionalized lanthanide oxide (Ln2O3) 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. Recently, nanoparticle-based MRI contrast agents have become a hot research topic in biomedical imaging due to their high performance, easy surface functionalization, and low toxicity. Among them, functionalized Ln2O3 nanoparticles are applicable as MRI contrast agents for tumor-targeting and nontumor-targeting imaging and image-guided tumor therapy. Primarily, Gd2O3 nanoparticles have been intensively investigated as tumor-targeting T1 MRI contrast agents. T2 MRI is also possible due to the appreciable paramagnetic moments of Ln2O3 nanoparticles (Ln = Dy, Ho, and Tb) at room temperature arising from the nonzero orbital motion of 4f electrons. In addition, Ln2O3 nanoparticles are eligible as X-ray computed tomography contrast agents because of their high X-ray attenuation power. Since nanoparticle toxicity is of great concern, recent toxicity studies on Ln2O3 nanoparticles are also discussed.

Prediction of Thermal Behavior of Polycarbonate/Cerium Oxide Composite Films

AbstractThermal effects in polycarbonate (PC) induced by lanthanide oxide nanoparticles (NPs) dispersed by blending were studied using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). DSC data proved the occurrence of solvent‐induced crystallization of polymer doped with cerium oxide (ceria). TGA was performed to predict PC flammability properties in composites with 5–15 wt % ceria NPs at various heating rates. Decomposition was represented by first‐order reactions and the Arrhenius equation. A model was formulated for thin samples subject to uniform heat irradiation, which is based on PC softening and decomposition into several products. This is an attempt to predict composite film burning behavior assuming constant heat transmission to samples.

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

Polyacrylic acid (PAA)-coated lanthanide oxide (Ln2O3) nanoparticles (NPs) (Ln = Tb and Ho) with high colloidal stability and good biocompatibility were synthesized, characterized, and investigated as a new class of negative (T2) magnetic resonance imaging (MRI) contrast agents at high MR fields. Their r2 values were appreciable at a 3.0 T MR field and higher at a 9.4 T MR field, whereas their r1 values were negligible at all MR fields, indicating their exclusive induction of T2 relaxations with negligible induction of T1 relaxations. Their effectiveness as T2 MRI contrast agents at high MR fields was confirmed from strong negative contrast enhancements in in vivo T2 MR images at a 9.4 T MR field after intravenous administration into mice tails.

Ultrasmall Europium, Gadolinium, and Dysprosium Oxide Nanoparticles: Polyol Synthesis, Properties, and Biomedical Imaging Applications.

Imaging agents are crucial in diagnosing diseases. Ultrasmall lanthanide oxide (Ln2O3) nanoparticles (NPs) (Ln = Eu, Gd, and Dy) are promising materials as high-performance imaging agents because of their excellent magnetic, optical, and X-ray attenuation properties which can be applied as magnetic resonance imaging (MRI), fluorescence imaging (FI), and X-ray computed tomography (CT) agents, respectively. Ultrasmall Ln2O3 NPs (Ln = Eu, Gd, and Dy) are reviewed here. The reviewed topics include polyol synthesis, characterization, properties, and biomedical imaging applications of ultrasmall Ln2O3 NPs. Recently published papers were used as bibliographic databases. A polyol method is a simple and efficient one-pot synthesis for preparing ultrasmall Ln2O3 NPs. Ligand-coated ultrasmall Ln2O3 NPs have good colloidal stability, biocompatibility, and renal excretion ability suitable for in vivo imaging applications. Ultrasmall Eu2O3 NPs display photoluminescence in the red region suitable for use as FI agents. Ultrasmall Gd2O3 NPs have r1 values higher than those of commercial molecular contrast agents and r2/r1 ratios close to 1, which make them eligible for use as T1 MRI contrast agents. Ultrasmall Dy2O3 NPs exhibit high r2 and negligible r1 values, which make them suitable for use as T2 MRI contrast agents. All ultrasmall Ln2O3 NPs have high X-ray attenuation powers which make them suitable for use as CT contrast agents. Unmixed, mixed, or doped ultrasmall Ln2O3 NPs with different Ln are extremely useful for in vivo imaging applications in MRI, CT, FI, MRI-CT, MRI-FI, CT-FI, and MRI-CT-FI.

Synthesis and Biochemical Evaluation of Samarium-153 Oxide Nanoparticles Functionalized with iPSMA-Bombesin Heterodimeric Peptide.

Developments in the design of lanthanide oxide nanoparticles (NPs) have unleashed a wide variety of biomedical applications. Several types of hepatic cancer cells overexpress two proteins: the gastrin-releasing peptide receptor (GRPr), which specifically recognizes the bombesin (BN) peptide, and the prostate-specific membrane antigen (PSMA), which specifically binds to several peptides that inhibit its activity (iPSMA). This research synthesized and physicochemically characterized Sm₂O₃ nanoparticles functionalized with the iPSMA-BN heterodimeric peptide and studied the effects on their structural, biochemical and preclinical properties after activation by neutron irradiation for possible use in molecular dual-targeted radiotherapy of hepatocellular carcinoma. The Sm₂O₃ NPs were synthesized by the precipitation-calcination method and functionalized with iPSMA-BN peptide using the DOTA macrocycle as a linking agent. Analysis of physicochemical characterization via TEM, EDS, XRD, UV-Vis, FT-IR, DSL, and zeta potential results showed the formation of Sm₂O₃-iPSMA-BN NPs (94.23 ± 5.98 nm), and their physicochemical properties were not affected after neutron activation. The nanosystem showed a high affinity with respect to PSMA and GRPr in HepG2 cells ( Kd = 6.6 ± 1.6 nM) and GRPr in PC3 cells ( Kd = 10.6 ± 1.9 nM). 153Sm₂O₃-iPSMA-BN NPs exhibited radioluminescent properties, making possible in vivo optical imaging of their biodistribution in mice. The results obtained from this research support further preclinical studies designed to evaluate the dosimetry and therapeutic efficacy of 153Sm₂O₃-iPSMA-BN nanoparticles for in vivo imaging and molecular dual-targeted radiotherapy of liver tumors overexpressing PSMA and/or GRPr proteins.

Mixed Lanthanide Oxide Nanoparticles Coated with Alginate-Polydopamine as Multifunctional Nanovehicles for Dual Modality: Targeted Imaging and Chemotherapy.

Integrating anticancer drugs and diagnostic agents in a polymer nanosystem is an emerging and promising strategy for improving cancer treatment. However, the development of multifunctional nanoparticles (NPs) for an "all-in-one" platform characterized by specific targeting, therapeutic efficiency, and imaging feedback remains an unmet clinical need. In this study, pH-responsive mixed-lanthanide-based multifunctional NPs were fabricated based on simple metal-ligand interactions for simultaneous cancer cell imaging and drug delivery. We investigated two new systems of alginate-polydopamine complexed with either terbium/europium or dysprosium/erbium oxide NPs (Tb/Eu@AlgPDA or Dy/Er@AlgPDA NPs). Tb/Eu@AlgPDA NPs were then functionalized with the tumor-targeting ligand folic acid (FA) and loaded with the anticancer drug doxorubicin (DOX) to form FA-Tb/Eu@AlgPDA-DOX NPs. Using such systems, the mussel-inspired property of PDA was introduced to improve tumor targetability and penetration, in addition to active targeting (via FA-folate receptor interactions). Determining the photoluminescence efficiency showed that the Tb/Eu@AlgPDA system was superior to the Dy/Er@AlgPDA system, presenting intense and sharp emission peaks on the fluorescence spectra. In addition, compared to Dy/Er@AlgPDA NPs (82.4%), Tb/Eu@AlgPDA NPs exhibited negligible cytotoxicity with >93.3% HeLa cell viability found in MTT assays at NP concentrations of up to 0.50 mg/mL and high biocompatibility when incubated with zebrafish (Danio rerio) embryos and larvae. The FA-Tb/Eu@AlgPDA-DOX system exhibited a pH-responsive and sustained drug-release pattern. In a spheroid model of HeLa cells, the FA-Tb/Eu@AlgPDA-DOX system showed a better penetration efficiency and spheroid growth-inhibitory effect than free DOX. After incubation with zebrafish embryos, the FA-Tb/Eu@AlgPDA-DOX system also showed improved antitumor efficacies versus the other experimental groups in HeLa tumor cell xenografted zebrafish. Therefore, our results suggested that FA-Tb/Eu@AlgPDA-DOX NPs are promising multifunctional nanocarriers with therapeutic capacity for tumor targeting and penetration.

Study of the Electrochemical Mechanisms That Control the Electrode Reaction and Degradation of La0.6Sr0.4Co0.8Fe0.2O3- δ cathodes Impregnated with Oxide Nanoparticles

Reducing fuel cells degradation and cathode polarization losses are currently two of the most important challenges in order to achieve more efficient and cost competitive SOFC's. One strategy has been to reduce operation temperatures to the range between 600 ºC and 800 ºC (IT-SOFC), which reduces degradation rates but increases activation over potentials as a consequence (mainly the cathode reaction overpotential, due to the high activation energy of oxygen reduction reaction -ORR-). Several approaches have been taken to counteract this problem and recently, promising results [1] have been obtained by modifying the electrodes surface using the impregnation technique. This technique consists of synthesizing catalyst nanoparticles on the electrode surface through a liquid solution-based process [2, 3]. In this work we show the results obtained when decorating La0.6Sr0.4Co0.8Fe0.2O3-δ -LSCF- cathodes with lanthanide oxides (CeOx, Ce1-yGdyOx, PrOx) nanoparticles after its impregnation with nitrate solutions. All systems were characterized using SEM, TEM and XRD, where spatially homogeneous and monodisperse size distributions were observed (See Figure 1a and 1b, where a cathode with and without nanoparticles is shown, respectively). Figure 1c presents the Nyquist plot of Electrochemical Impedance Spectroscopy (EIS) measurements at 600 ºC. These measurements showed that when impregnating with lanthanide oxide nanoparticles the cathode polarization resistance at 600ºC was reduced from 0.6 Ωcm2 for plain LSCF to 0.32, 0.2 and 0.08 Ωcm2 for LSCF decorated with Ce0.8Gd0.2O2, CeO2 and PrO2 oxide nanoparticles, respectively. The reduction due to the Pr oxide impregnation allows, in principle, a decrease of 100 ºC (from 700ºC to 600ºC) of the cathode's operation temperature, which could be considered as a candidate for low temperature SOFC (LT-SOFC)[4].Figure 1. a) plain LSCF b) GDC impregnated LSCF c) Nyquist plots measured at 600 ºC of plain LSCF and LSCF impregnated with CeO2, GDC and PrO2.The EIS measurements as a function of temperature and oxygen partial pressure enable the proposal of a mechanism for the oxygen reduction reaction and an explanation about the effect of lanthanide oxides nanoparticles decoration. For example, when impregnating with GDC nanoparticles the impregnation is observed to modify the surface resistance of the ORR in the cathode’s surface but leaves the O2- ion conduction resistance in bulk LSCF unmodified [5]. Finally, the EIS measurements as a function of time during the aging of the samples exposed for periods between 300 h and 500 h to the operation temperatures was observed to produce an irreversible degradation (melting) of the impregnated nanoparticles.

Potential fluorescence and magnetic resonance imaging modality using mixed lanthanide oxide nanoparticles.

Imaging is a very important technique in the diagnosis and treatment of cancer diseases. This study developed a dual modality (fluorescence/MR) imaging technique for cancer cell lines (HeLa) and T2-weighted phantom imaging by using a mixed lanthanide (Dy/Er/Tb) oxide nanoparticles. To further enhance the solubility, stability and biocompatibility of mixed lanthanide oxide, the nanoparticles were coated with folic acid as well as G4.5 PAMAM dendrimer. The coated nanoparticles were then compared, the later with results demonstrating pronounced effects in both T2 weighted phantom MR and fluorescence imaging of the cancer cell lines. Imaging enhancement was attributed to a synergistic effect of the fluorescent properties and higher water solubility of the PAMAM dendrimer when compared to the folic acid. Besides, mixed lanthanides of Dy and Tb were used for T2 weighted MR imaging, while mixed lanthanides of Er and Tb were used for fluorescence imaging in the near infrared and visible regions, and were synthesized in the facile composition control. Hence, the mixed lanthanide oxides are packed together, and stable, which is used to facilitate biomedical imaging in vitro. To conclude, the G4.5 PAMAM dendrimer coated mixed lanthanide oxide nanoparticles will be used for dual-modality (fluorescence/MR imaging) cancer cell line detection in both in vitro and in vivo study.

A general method for preparing lanthanide oxide nanoparticles via thermal decomposition of lanthanide(III) complexes with 1-hydroxy-2-naphthoic acid and hydrazine ligands

Six new lanthanide(III) complexes (i.e., [Ln(L)2(NA)1.5]·3H2O, where Ln=La(III), Pr(III), Nd(III), Sm(III), Gd(III), and Ce(III) and L and NA indicate N2H4 and C10H6(1-O)(2-COO), respectively) with 1-hydroxy-2-naphthoic acid [C10H6(1-O)(2-COOH)] and hydrazine (N2H4) as co-ligands were characterized by elemental, FTIR, UV-visible, and XRD techniques. In the FT-IR spectra, the N-N stretching frequency in the range of 981–949cm−1 demonstrates evidence of the presence of coordinated N2H4, indicating the bidentate bridging nature of hydrazine in the complexes. These complexes show symmetric and asymmetric COO− stretching from 1444 to 1441cm−1 and 1582 to 1557cm−1, respectively, indicating bidentate coordination. TG-DTA studies revealed that the compounds underwent endothermic dehydration from 98 to 110°C. This was followed by the exothermic decomposition of oxalate intermediates to yield the respective metal oxides as the end products. From SEM images, the average size of the metal oxide particles prepared by thermal decomposition of the complexes was determined to be 39–42nm. The powder X-ray and SEM coupled with energy dispersive X-ray (EDX) studies revealed the presence of the respective nano-sized metal oxides. The kinetic parameters of the decomposition of the complexes were calculated using the Coats-Redfern equation.

Synthesis, Magnetic Properties, Map Images, and Water Proton Relaxivities of D-Glucuronic Acid Coated Ln2O3 Nanoparticles (Ln = Ho and Er).

T2 MRI contrast agents cannot be synthesized by using molecules but nanoparticles because appreciable magnetic moments at room temperature are needed. Recently, some of lanthanide (Ln) oxide nanoparticles have shown decent magnetic moments at room temperature and even at ultrasmall particle diameters. In this study, we explored D-glucuronic acid coated Ln2O3 nanoparticles (Ln = Ho and Er) with ultrasmall particle diameters. They showed decent magnetic moments at room temperature and as a result, appreciable transverse water proton relaxivities (r2s) at 1.5 tesla MR field. Clear dose-dependent contrast enhancements in R2 map images were observed in both samples. These results showed that D-glucuronic acid coated Ln2O3 nanoparticles (Ln = Ho and Er) would be potential T2 MRI contrast agents at high MR fields.

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. Gd3+ (8S7/2) 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 Dy3+ (6H15/2) 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 Gd3+ and Dy3+ 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. The D-glucuronic acid coated GDO nanoparticles (davg = 1.0 nm) showed large r1 and r2 values (r2/r1 ≈ 6.6) and as a result clear dose-dependent contrast enhancements in R1 and R2 map images. Finally, the dual-mode imaging capability of the nanoparticles was confirmed by obtaining in vivo T1 and T2 MR images.

Newly fabricated magnetic lanthanide oxides core-shell nanoparticles in phosphoproteomics.

Metal oxides show high selectivity and sensitivity toward mass spectrometry based enrichment strategies. Phosphopeptides/phosphoproteins enrichment from biological samples is cumbersome because of their low abundance. Phosphopeptides are of interest in enzymes and phosphorylation pathways which lead to the clinical links of a disease. Magnetic core-shell lanthanide oxide nanoparticles (Fe3O4@SiO2-La2O3 and Fe3O4@SiO2-Sm2O3) are fabricated, characterized by SEM, FTIR, and EDX and employed in the enrichment of phosphopeptides. The nanoparticles enrich phosphopeptides from casein variants, nonfat milk, egg yolk, human serum and HeLa cell extract. The materials and enrichment protocols are designed in a way that there are almost no nonspecific bindings. The selectivity is achieved up to 1:8500 using β-casein/BSA mixture and sensitivity down to 1 atto-mole. Batch-to-batch reproducibility is high with the reuse of core-shell nanoparticles up to four cycles. The enrichment followed by MALDI-MS analyses is carried out for the identification of phosphopeptides from serum digest and HeLa cell extract. Characteristic phosphopeptides of phosphoproteins are identified from human serum after the enrichment, which have the diagnostic potential toward prostate cancer. Thus, the lanthanide based magnetic core-shell materials offer a highly selective and sensitive workflow in phosphoproteomics.

Multi-modal imaging and cancer therapy using lanthanide oxide nanoparticles: current status and perspectives.

Biomedical imaging is an essential tool for diagnosis and therapy of diseases such as cancers. It is likely true that medicine has developed with biomedical imaging methods. Sensitivity and resolution of biomedical imaging methods can be improved with imaging agents. Furthermore, it will be ideal if imaging agents could be also used as therapeutic agents. Therefore, one dose can be used for both diagnosis and therapy of diseases (i.e., theragnosis). This will simplify medical treatment of diseases, and will be also a benefit to patients. Mixed (Ln(1x)Ln(2y)O3, x + y = 2) or unmixed (Ln2O3) lanthanide (Ln) oxide nanoparticles (Ln = Eu, Gd, Dy, Tb, Ho, Er) are potential multi-modal imaging and cancer therapeutic agents. The lanthanides have a variety of magnetic and optical properties, useful for magnetic resonance imaging (MRI) and fluorescent imaging (FI), respectively. They also highly attenuate X-ray beam, useful for X-ray computed tomography (CT). In addition gadolinium-157 ((157)Gd) has the highest thermal neutron capture cross section among stable radionuclides, useful for gadolinium neutron capture therapy (GdNCT). Therefore, mixed or unmixed lanthanide oxide nanoparticles can be used for multi-modal imaging methods (i.e., MRI-FI, MRI-CT, CT-FI, and MRICT- FI) and cancer therapy (i.e., GdNCT). Since mixed or unmixed lanthanide oxide nanoparticles are single-phase and solid-state, they can be easily synthesized, and are compact and robust, which will be beneficial to biomedical applications. In this review physical properties of the lanthanides, synthesis, characterizations, multi-modal imagings, and cancer therapy of mixed and unmixed lanthanide oxide nanoparticles are discussed.

Ordered Nanoporous Silica Modified with Nanoparticles of Lanthanide Oxides

Lanthanide oxide nanoparticles were encapsulated inside of pores of highly ordered periodic silica of SBA15 type with hexagonal symmetry. The magnetic properties of such nanoperticles were investigated. The structural characterization using the SAXS, XANES, XRD, and N2 adsorption measurements showed the presence of lanthanide oxides of Ln2O3 type (Ln=La, Pr, Nd, Gd, Eu), with the size of about 5 nm, incorporated in nanoporous channel system. Their magnetic properties, studied by SQUID apparatus, showed the weak antiferromagnetic ordering at 2 K in the nanocomposites Gd2O3@SBA15, Pr2O3@SBA15 and Nd2O3@SBA15. This behaviour of the nanoparticles is caused by blocking process of magnetic moments, which at 300 K exhibit the superparamagnetism, evidenced from ZFC/FC magnetization.

Water-soluble d-glucuronic acid coated ultrasmall mixed Ln/Mn (Ln = Gd and Dy) oxide nanoparticles and their application to magnetic resonance imaging.

Ultrasmall lanthanide oxide nanoparticles are promising materials as new magnetic resonance imaging (MRI) contrast agents because of their appreciable longitudinal (r1) or transverse (r2) water proton relaxivities at ultrasmall particle diameters. Two systems of d-glucuronic acid coated ultrasmall Ln/Mn (Ln = Gd and Dy) oxide nanoparticles with an average particle diameter of 2.0 nm were explored. The d-glucuronic acid coated ultrasmall Gd/Mn oxide nanoparticles showed strong positive contrast enhancements in 1.5 tesla T1 MR images while the d-glucuronic acid coated ultrasmall Dy/Mn oxide nanoparticles showed appreciable negative contrast enhancements in 1.5 tesla T2 MR images, proving their potential as T1 and T2 MRI contrast agents, respectively.