Structure of small yttrium monoxide clusters, chemical bonding, and photoionization: threshold photoionization and density functional theory investigations

The photoionization (PI) spectra of small gas-phase yttrium monoxide clusters, YnO (n = 1-8), are investigated, and the adiabatic ionization energies are determined. The stable structures are obtained from density functional theory (DFT) calculations. The ground state structures are further confirmed by the CCSD(T) method. The PI spectra are calculated for these stable structures and are compared with the experimental PI spectra. The ground-state structures of the neutral and cation clusters are experimentally assigned with confidence on the basis of a favourable agreement between the experimental and calculated PI spectra. New structures are proposed for Y2O, Y6O, and Y8O compared to the previous literature. Y2O is a linear molecule in the ground state that was previously proposed as a C2v bent molecule. The YnO clusters become 3-dimensional from n ≥ 3. The O atom stays outside, bridging a triangular face of yttrium clusters. Chemical bonding between the yttrium and oxygen atoms is mostly ionic. The excess charge on the oxygen atom is around 1.4e-, transferred from the yttrium atoms bonded with it. Yttrium atoms are mostly covalently bonded. However, for the bigger clusters, free charges of both polarities appear on yttrium atoms that are not bonded with oxygen, indicating ionic interactions. Frontier orbitals consist of mainly delocalized 4d electrons with some 5s contributions, forming Y-Y bonding interactions, but with little contribution and zero contribution from the oxygen orbitals, regardless of the cluster size. The lost electron of YnO+ mostly comes from the 5s orbitals of all Y atoms in the cluster up to size n = 4, and then from 4d-5s hybrid orbitals from n ≥ 5, with the d contribution increasing with size. This is contrary to the previous view in the literature that photoionization occurs from a localized 4d orbital.

Donor Radii in Rare-Earth Complexes

We present a set of donor radii for the rare-earth cations obtained from the analysis of structural data available in the Cambridge Structural Database (CSD). Theoretical calculations using density functional theory (DFT) and wave function approaches (NEVPT2) demonstrate that the Ln-donor distances can be broken down into contributions of the cation and the donor atom, with the minimum in electron density (ρ) that defines the position of (3,-1) critical points corresponding well with Shannon's crystal radii (CR). Subsequent linear fits of the experimental bond distances for all rare earth cations (except Pm3+) afforded donor radii (rD) that allow for the prediction of Ln-donor distances regardless of the nature of the rare-earth cation and its oxidation state. This set of donor radii can be used to rationalize structural data and identify particularly weak or strong interactions, which has important implications in the understanding of the stability and reactivity of complexes of these metal ions. A few cases of incorrect atom assignments in X-ray structures were also identified using the derived rD values.

Transition metals in angiogenesis - A narrative review

The aim of this paper is to offer a narrative review of the literature regarding the influence of transition metals on angiogenesis, excluding lanthanides and actinides. To our knowledge there are not any reviews up to date offering such a summary, which inclined us to write this paper. Angiogenesis describes the process of blood vessel formation, which is an essential requirement for human growth and development. When the complex interplay between pro- and antiangiogenic mediators falls out of balance, angiogenesis can quickly become harmful. As it is so fundamental, both its inhibition and enhancement take part in various diseases, making it a target for therapeutic treatments. Current methods come with limitations, therefore, novel agents are constantly being researched, with metal agents offering promising results. Various transition metals have already been investigated in-depth, with studies indicating both pro- and antiangiogenic properties, respectively. The transition metals are being applied in various formulations, such as nanoparticles, complexes, or scaffold materials. Albeit the increasing attention this field is receiving, there remain many unanswered questions, mostly regarding the molecular mechanisms behind the observed effects. Notably, approximately half of all the transition metals have not yet been investigated regarding potential angiogenic effects. Considering the promising results which have already been established, it should be of great interest to begin investigating the remaining elements whilst also further analyzing the established effects.

The rare-earth yttrium induces cell apoptosis and autophagy in the male reproductive system through ROS-Ca2+-CamkII/Ampk axis

China has the world's largest reserves of rare earth elements (REEs), but widespread mining and application of REEs has led to an increased risk of potential pollution. Yttrium (Y), the first heavy REEs to be discovered, poses a substantial threat to human health. Unfortunately, little attention has been given to the impact of Y on human reproductive health. In this study, we investigated the toxic effects of YCl3 on mouse testes and four types of testicular cells, including Sertoli, Leydig, spermatogonial and spermatocyte cells. The results showed that YCl3 exposure causes substantial damage to mouse testes and induces apoptosis and autophagy, but not pyroptosis or necrosis, in testicular cells. Genome-wide gene expression analysis revealed that YCl3 induced significant changes in gene expression, with Ca2+ and mitochondria-related genes being the most significantly altered. Mechanistically, YCl3 exposure induced mitochondrial dysfunction in testicular cells, triggering the overproduction of reactive oxygen species (ROS) by impairing the Nrf2 pathway, regulating downstream Ho-1 target protein expression, and increasing Ca2+ levels to activate the CamkII/Ampk signaling pathway. Blocking ROS production or Ca2+ signaling significantly attenuates apoptosis and autophagy, while supplementation with Ca2+ reverses the suppression of apoptosis and autophagy by ROS blockade in testicular cells. Notably, apoptosis and autophagy induced by YCl3 treatment are independent of each other. Thus, our study suggests that YCl3 may impair the antioxidant stress signaling pathway and activate the calcium pathway through the ROS-Ca2+ axis, which promotes testicular cell apoptosis and autophagy independently, thus inducing testicular damage and impairing male reproductive function.

Efficient biocatalytic removal and algal detoxification of Direct Blue-15 by the hierarchically structured, high-performance, and recyclable laccase@yttrium phosphate hybrid nanostructures

From the environmental point of view, azo dye industrial effluent is a major public health concern due to its toxic, carcinogenic, and teratogenic characteristics. On the other hand, using enzyme-based technologies offers a promising systematic and controllable method for removing synthetic dyes from wastewater. In the present study, yttrium (Y3+) phosphate was applied for the synthesis of hybrid nanoparticles (HNPs) consisting of laccase as the green catalyst. When the association of HNPs was fixed by glutaraldehyde (GA), three-dimensional cubic structures with the regular arrangement were provided. GA increased the reusability of the fabricated hybrid nanostructures (HNSs) up to 32 successive cycles. About 85% of Direct Blue-15 was removed after a 4 h-treatment using laccase@YPO4•HNPs and laccase@GA@YPO4•HNSs. The azo dye removal data were well-fitted with a pseudo-second-order model for both types of the prepared HNSs. For the model freshwater green alga Raphidocelis subcapitata, the half maximal effective concentration (EC50) of the dye decreased 10- and 100-fold after the removal with laccase@YPO4•HNPs and laccase@GA@YPO4•HNSs, respectively. GA-treated HNSs (250 U L-1) inhibited the biofilm formation by approximately 78%, 82%, and 79% for Escherichia coli, Staphylococcus aureus, and Bacillus subtilis, respectively. Thus, the fabricated laccase@GA@YPO4•HNSs could be presented as a novel, efficient, and recyclable heterogeneous biocatalyst for wastewater treatment and clean-up.

Cytotoxicity and hemolysis of rare earth ions and nanoscale/bulk oxides (La, Gd, and Yb): Interaction with lipid membranes and protein corona formation

The widespread application of rare earth elements (REEs) has raised concerns about their potential release into the environment and subsequent ingestion by humans. Therefore, it is essential to evaluate the cytotoxicity of REEs. Here, we investigated the interactions between three typical REEs (La, Gd, and Yb) ions as well as their nanometer/μm-sized oxides and red blood cells (RBCs), a plausible contact target for nanoparticles when they enter the bloodstream. Hemolysis of REEs at 50-2000 μmol L^-1 was examined to simulate their cytotoxicity under medical or occupational exposure. We found that the hemolysis due to the exposure of REEs was highly dependent on their concentration, and the cytotoxicity followed the order of La³⁺ > Gd³⁺ > Yb³⁺. The cytotoxicity of REE ions (REIs) is higher than REE oxides (REOs), while nanometer-sized REO caused more hemolysis than that μm-sized REO. The production of reactive oxygen species (ROS), ROS quenching experiment, as well as the detection of lipid peroxidation, confirmed that REEs causes cell membrane rupture by ROS-related chemical oxidation. In addition, we found that the formation of a protein corona on REEs increased the steric repulsion between REEs and cell membranes, hence mitigating the cytotoxicity of REEs. The theoretical simulation indicated the favorable interaction of REEs with phospholipids and proteins. Therefore, our findings provide a mechanistic explanation for the cytotoxicity of REEs to RBCs once they have entered the blood circulation system of organisms.

Developmental immunotoxicity of maternal exposure to yttrium nitrate on BALB/c offspring mice

Yttrium is a typical heavy rare earth element with widespread use in numerous sectors. Only one previous study has indicated that yttrium has the potential to cause developmental immunotoxicity (DIT). Therefore, there remains a paucity of evidence on the DIT of yttrium. This study aimed to explore the DIT of yttrium nitrate (YN) and the self-recovery of YN-induced DIT. Dams were treated with 0, 0.2, 2, and 20 mg/kg bw/day YN by gavage during gestation and lactation. No significant changes were found in innate immunity between the control and YN-treated groups in offspring. In female offspring at postnatal day 21 (PND21), YN markedly inhibited humoral and cellular immune responses, the proliferative capacity of splenic T lymphocytes, and the expression of costimulatory molecules in splenic lymphocytes. Moreover, the inhibitory effect on cellular immunity in female offspring persisted to PND42. Unlike females, YN exposure did not change the adaptive immune responses in male offspring. Overall, maternal exposure to YN showed a strong DIT to offspring, with the lowest effective dose of 0.2 mg/kg in the current study. The toxicity of cellular immunity could persist throughout development into adulthood. There were sex-specific differences in YN-induced DIT, with females being more vulnerable.

The elements of life: A biocentric tour of the periodic table

Living systems are built from a small subset of the atomic elements, including the bulk macronutrients (C,H,N,O,P,S) and ions (Mg,K,Na,Ca) together with a small but variable set of trace elements (micronutrients). Here, we provide a global survey of how chemical elements contribute to life. We define five classes of elements: those that are (i) essential for all life, (ii) essential for many organisms in all three domains of life, (iii) essential or beneficial for many organisms in at least one domain, (iv) beneficial to at least some species, and (v) of no known beneficial use. The ability of cells to sustain life when individual elements are absent or limiting relies on complex physiological and evolutionary mechanisms (elemental economy). This survey of elemental use across the tree of life is encapsulated in a web-based, interactive periodic table that summarizes the roles chemical elements in biology and highlights corresponding mechanisms of elemental economy.

PVA-Microbubbles as a Radioembolization Platform: Formulation and the In Vitro Proof of Concept

This proof-of-concept study lays the foundations for the development of a delivery strategy for radioactive lanthanides, such as Yttrium-90, against recurrent glioblastoma. Our appealing hypothesis is that by taking advantage of the combination of biocompatible polyvinyl alcohol (PVA) microbubbles (MBs) and endovascular radiopharmaceutical infusion, a minimally invasive selective radioembolization can be achieved, which can lead to personalized treatments limiting off-target toxicities for the normal brain. The results show the successful formulation strategy that turns the ultrasound contrast PVA-shelled microbubbles into a microdevice, exhibiting good loading efficiency of Yttrium cargo by complexation with a bifunctional chelator. The selective targeting of Yttrium-loaded MBs on the glioblastoma-associated tumor endothelial cells can be unlocked by the biorecognition between the overexpressed α_Vβ₃ integrin and the ligand Cyclo(Arg-Gly-Asp-D-Phe-Lys) at the PVA microbubble surface. Hence, we show the suitability of PVA MBs as selective Y-microdevices for in situ injection via the smallest (i.e., 1.2F) neurointerventional microcatheter available on the market and the accumulation of PVA MBs on the HUVEC cell line model of integrin overexpression, thereby providing ~6 × 10^-15 moles of Y90 per HUVEC cell. We further discuss the potential impact of using such versatile PVA MBs as a new therapeutic chance for treating glioblastoma multiforme recurrence.

Bioimaging with Upconversion Nanoparticles

Bioimaging enables the spatiotemporal visualization of biological processes at various scales empowered by a range of different imaging modalities and contrast agents. Upconversion nanoparticles (UCNPs) represent a distinct type of such contrast agents with the potential to transform bioimaging due to their unique optical properties and functional design flexibilities. This review explores and discusses the opportunities, challenges, and limitations that UCNPs exhibit as bioimaging probes and highlights applications with spatial dimensions ranging from the single nanoparticle level to cellular, tissue, and whole animal imaging. We further summarized recent advancements in bioimaging applications enabled by UCNPs, including super-resolution techniques and multimodal imaging methods, and provide a perspective on the future potential of UCNP-based technologies in bioimaging research and clinical translation. This review may provide a valuable resource for researchers interested in exploring and applying UCNP-based bioimaging technologies.

In Situ Ternary Adduct Formation of Yttrium Polyaminocarboxylates Leads to Small Molecule Capture and Activation

In this work the chemistry of yttrium complexes is exploited for small molecule capture and activation. Nuclear magnetic resonance (NMR) and density functional theory (DFT) studies were used to investigate the in situ formation of solution state ternary yttrium-acetate, yttrium-bicarbonate, and yttrium-pyruvate adducts with a range of polyaminocarboxylate chelates. These studies reveal that [Y(DO3A)(H₂ O)₂ ] (H₃ DO3A - 1,4,7,10-tetraazacyclododecane-1,4,7-tricarboxylic acid) and [Y(EDTA)(H₂ O)_q ]^- (H₄ EDTA - ethylenediaminetetraacetic acid, q = 2 and 3) are able to form ternary adducts with bicarbonate and pyruvate. In the latter, unusual decarboxylation of pyruvate to form acetic acid and CO₂ was observed and further studied using SABRE-hyperpolarised ¹³ C NMR (SABRE - signal amplification by reversible exchange) to provide information about the reaction timescale and lifetime of intermediates involved in this conversion. The work presented demonstrates that yttrium complexes can capture and activate small molecules, which may lead to novel and useful applications of this metal in catalysis and medical imaging.

The Chemical Scaffold of Theranostic Radiopharmaceuticals: Radionuclide, Bifunctional Chelator, and Pharmacokinetics Modifying Linker

Therapeutic radiopharmaceuticals have been researched extensively in the last decade as a result of the growing research interest in personalized medicine to improve diagnostic accuracy and intensify intensive therapy while limiting side effects. Radiometal-based drugs are of substantial interest because of their greater versatility for clinical translation compared to non-metal radionuclides. This paper comprehensively discusses various components commonly used as chemical scaffolds to build radiopharmaceutical agents, i.e., radionuclides, pharmacokinetic-modifying linkers, and chelators, whose characteristics are explained and can be used as a guide for the researcher.

Versatile Macrocyclic Platform for the Complexation of [natY/90Y]Yttrium and Lanthanide Ions

We report a macrocyclic ligand (H₃L⁶) based on a 3,6,10,13-tetraaza-1,8(2,6)-dipyridinacyclotetradecaphane platform containing three acetate pendant arms and a benzyl group attached to the fourth nitrogen atom of the macrocycle. The X-ray structures of the YL⁶ and TbL⁶ complexes reveal nine coordination of the ligand to the metal ions through the six nitrogen atoms of the macrocycle and three oxygen atoms of the carboxylate pendants. A combination of NMR spectroscopic studies (¹H, ¹³C, and ⁸⁹Y) and DFT calculations indicated that the structure of the YL⁶ complex in the solid state is maintained in an aqueous solution. The detailed study of the emission spectra of the EuL⁶ and TbL⁶ complexes revealed Ln³⁺-centered emission with quantum yields of 7.0 and 60%, respectively. Emission lifetime measurements indicate that the ligand offers good protection of the metal ions from surrounding water molecules, preventing the coordination of water molecules. The YL⁶ complex is remarkably inert with respect to complex dissociation, with a lifetime of 1.7 h in 1 M HCl. On the other hand, complex formation is fast (∼1 min at pH 5.4, 2 × 10^–5 M). Studies using the ⁹⁰Y-nuclide confirmed fast radiolabeling since [⁹⁰Y]YL⁶ is nearly quantitatively formed (radiochemical yield (RCY) > 95) in a short time over a broad range of pH values from ca. 2.4 to 9.0. Challenging experiments in the presence of excess ethylenediaminetetraacetic acid (EDTA) and in human serum revealed good stability of the [⁹⁰Y]YL⁶ complex. All of these experiments combined suggest the potential application of H₃L⁶ derivatives as Y-based radiopharmaceuticals.

A new versatile asymmetric ligand based on an 18-membered macrocycle possessing three acetate pendant arms and a benzyl moiety provides fast complexation with both ^natY(III) and ⁹⁰Y(III), as well as slow dissociation kinetics. A detailed structural study in the solid state and in solution evidences nona coordination of the metal ion by the ligand, offering good protection from solvent water molecules. These favorable properties make this ligand an attractive candidate to develop yttrium-based radiopharmaceuticals.

Yttrium Trifluoride as a Marker of Infiltration Rate of Decalcified Root Cementum: An In Vitro Study

Research related to the development of a dental infiltrant for minimally invasive treatment of initial caries of hard dental tissues is presented. The formulation of the developed infiltrant material includes typical methacrylate monomers used in dentistry, an author’s adhesion monomer containing metronidazole, a photoinitiating system and yttrium trifluoride (YF₃). The main objective of the study was to evaluate penetration into decalcified root cementum using scanning electron microscope of an experimental preparation with the characteristics of a dental infiltrant compared to a commercial preparation with the addition of YF₃ as a contrast agent. Microscopic observations showed that YF₃ particles virtually did not penetrate deep into the root cementum—this was mainly due to the particle size of YF₃. Observations of cementum and root dentin tissue infiltration: resin tissue infiltration was visible to a depth of about 80 to 120 μm without the use of a tracer, which, due to agglomeration and particle size, remained on the cementum surface or in the resin used for inlaying. There were no differences between the degree of penetration of an experimental preparation with the characteristics of a dental infiltrant, as compared to a commercial preparation.

Capturing an elusive but critical element: Natural protein enables actinium chemistry

Actinium-based therapies could revolutionize cancer medicine but remain tantalizing due to the difficulties in studying and limited knowledge of Ac chemistry. Current efforts focus on small synthetic chelators, limiting radioisotope complexation and purification efficiencies. Here, we demonstrate a straightforward strategy to purify medically relevant radiometals, actinium(III) and yttrium(III), and probe their chemistry, using the recently discovered protein, lanmodulin. The stoichiometry, solution behavior, and formation constant of the ²²⁸Ac³⁺-lanmodulin complex and its ⁹⁰Y³⁺/^natY³⁺/^natLa³⁺ analogs were experimentally determined, representing the first actinium-protein and strongest actinide(III)-protein complex (sub-picomolar K_d) to be characterized. Lanmodulin’s unparalleled properties enable the facile purification recovery of radiometals, even in the presence of >10⁺¹⁰ equivalents of competing ions and at ultratrace levels: down to 2 femtograms ⁹⁰Y³⁺ and 40 attograms ²²⁸Ac³⁺. The lanmodulin-based approach charts a new course to study elusive isotopes and develop versatile chelating platforms for medical radiometals, both for high-value separations and potential in vivo applications.

Production of a broad palette of positron emitting radioisotopes using a low-energy cyclotron: Towards a new success story in cancer imaging?

Over the last several years, positron emission tomography (PET) has matured as an indispensable component of cancer diagnostics. Owing to the large variability observed among the cancer patients and the need to personalize individual patient's diagnosis and treatment, the need for new positron emitting radioisotopes has continued to grow. This mini review opens with a brief introduction to the criteria for radioisotope selection for PET imaging. Subsequently, positron emitting radioisotopes are categorized as: established, emerging and futuristic, based on the stages of their advancement. The production methodologies and the radiochemical separation procedures for obtaining the important radioisotopes in a form suitable for preparation of radiopharmaceuticals for PET imaging are briefly discussed.

Labeling of Hinokitiol with 90Y for Potential Radionuclide Therapy of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC), the most common form of primary liver tumors, is the fifth cancer in the world in terms of incidence, and third in terms of mortality. Despite significant advances in the treatment of HCC, its prognosis remains bleak. Transarterial radioembolization with radiolabeled microspheres and Lipiodol has demonstrated significant effectiveness. Here we present a new, simple radiolabeling of Lipiodol with Yttrium-90, for the potential treatment of HCC.

86Y PET imaging

Yttrium-86 is a non-standard positron emitter that can provide dosimetry information prior to therapy with yttrium-90 radiopharmaceuticals and be used to follow biochemical processes. In this chapter, we discuss the production, purification and applications of ⁸⁶Y for PET imaging. More specifically, ⁸⁶Y radiolabeling is highlighted and protocols to determine the radiochemical purity of ⁸⁶Y-DOTA and ⁸⁶Y-DTPA are presented.

Hyperpolarized 89Y-EDTMP complex as a chemical shift-based NMR sensor for pH at the physiological range

Yttrium (III) complexes are interesting due to the similarity of their chemistry with gadolinium complexes that are used as contrast agents in nuclear magnetic resonance (NMR) spectroscopy or imaging (MRI). While most of the paramagnetic Gd³⁺-based MRI contrast agents are T₁ or T₂ relaxation-based sensors such as Gd³⁺-complexes for zinc or pH detection, a number of diamagnetic Y³⁺-complexes rely on changes in the chemical shift for potential quantitative MRI in biological milieu. ⁸⁹Y, however, is a challenging nucleus to work with in conventional NMR or MRI due to its inherently low sensitivity and relatively long T₁ relaxation time. This insensitivity problem in ⁸⁹Y-based complexes can be circumvented with the use of dissolution dynamic nuclear polarization (DNP) which allows for several thousand-fold enhancement of the NMR or MRI signal relative to thermal equilibrium signal. Herein, we report on the feasibility of using hyperpolarized ⁸⁹Y-complexes with phosphonated open-chain ligands, ⁸⁹Y-EDTMP and ⁸⁹Y-DTPMP, as potential chemical shift-based pH NMR sensors. Our DNP-NMR data show that hyperpolarized ⁸⁹Y-DTPMP has an apparent pK_a ~ 7.01 with a 4 ppm-wide chemical shift dispersion with the signal disappearing at pH below 6.2. On the other hand, pH titration data on hyperpolarized ⁸⁹Y-EDTMP show that it has an apparent pK_a of pH 6.7 and a 16-ppm wide chemical shift dispersion at pH 5-9 range. In comparison, the previously reported hyperpolarized pH NMR sensor ⁸⁹Y-DOTP has a pK_a of 7.64 and ~ 10-ppm wide chemical shift dispersion at pH 4-9 range. Overall, our data suggest that hyperpolarized ⁸⁹Y-EDTMP is better than hyperpolarized ⁸⁹Y-DOTP in terms of pH sensing capability at the physiological range.