Lanthanide based inorganic phosphates and biological nucleotides sensor

Antenna effect-modulated luminescent lanthanide complexes for biological sensing

With the discovery and further exploitation of the antenna effect, the optical properties of luminescent lanthanide complexes (LLCs) have been greatly improved. Antenna effect-modulated LLCs exhibit long luminescence lifetimes, large Stokes shifts, narrow emission spectra, pure chromaticity, and high photostability. Meanwhile, LLCs have garnered considerable attention in recent years and are widely used as biosensors in the fields of food safety, environmental monitoring, clinical diagnosis, and drug analysis. In this review, we first systematically review the design of antenna effect-modulated LLC sensors, including the construction principle of antenna effect in LLCs and the selection of antenna ligands. Secondly, the classification of antenna ligands was discussed in detail. Thirdly, biological sensing applications of antenna effect-modulated LLCs in the past three years are described in terms of the role of LLCs in fluorescence sensors and electrochemiluminescence sensors. Finally, we also discussed the challenges and emerging opportunities of antenna effect-modulated LLCs in future sensing applications.

Tailoring Nanomaterial Cross-Linkers through Lanthanide-Ligand Pairs: Guidance for Fine-Tuning the Structures and Properties of Luminescent Nanocomposite Hydrogels

Integrating luminescent nanomaterials into hydrogels provides unique optical properties and improves their mechanical features for various applications. It is challenging but highly desirable to develop a versatile luminescent nanocomposite hydrogel system with tunable structures and properties to expand the potential uses of luminescent materials. Here, multiple amine-functionalized lanthanide-containing hydroxyapatites are synthesized as tailored nanomaterial cross-linkers to interact with polydextran aldehyde through imine bonds. The microstructure, gelation time, luminescence, rheological behavior, mechanical properties, thermal stability, degradation, and swelling capability of the luminescent lanthanide-containing nanocomposite hydrogels are systematically investigated. This study reveals that the strong binding affinity between surface metal ions and capping ligands of the nanomaterial cross-linkers contributes to the densest network and the highest mechanical properties of the nanocomposite hydrogels. In addition, these nanocomposite hydrogels possess dynamic features of self-healing, shear-thinning, and injectability, improving their suitability for advanced applications. The luminescent lanthanide-containing nanocomposite lyophilized hydrogels are also demonstrated in the differentiation of volatile organic compounds. Taken together, the adjustable microstructures and characteristics of this lanthanide-containing nanocomposite hydrogel system highlight its potential for offering guidance in producing diverse luminescent materials with definable performances across various fields.

Combination Diagnostics In Vivo: Dual-Mode Ultrasound/NIR Fluorescence Imaging with Neodymium- and Thulium-Doped Graphene Quantum Dots

The combination of two biomedical imaging techniques, fluorescence and ultrasound imaging, can uniquely offer enhanced anatomical visualization, sensitivity, and specificity necessary for improved diagnostic accuracy in detecting small tumors, tracing therapeutic delivery, and guiding biopsies. This work aims to harness the advantages of highly deterministic fluorescence imaging and deeply penetrating ultrasound diagnostics in neodymium- and thulium-doped graphene quantum dot (Nd-NGQD and Tm-NGQD) ultrasound/near-infrared (NIR) fluorescence contrast agents. These biocompatible nanostructures are tested for dual-mode fluorescence/ultrasound imaging in vivo in live sedated BALB/c mice as well as in animal organs. Injected intravenously (IV), Tm-NGQDs and Nd-NGQDs exhibit ultrasound enhancement and NIR fluorescence in the liver, spleen, and kidneys. The best agreement is achieved between the two techniques in the liver at 12 h for Tm-NGQDs and in the liver at 24 h, in the spleen at 6 h, and in the kidneys at 12 h for Nd-NGQDs, suggesting the optimal timeline for imaging. IP-injected Nd-NGQDs demonstrate a greater consistency between ultrasound enhancement and NIR fluorescence within 1-48 h time points in all imaged organs. Metal-doped GQD contrast agents developed for the first time in this work hold significant promise for dual-mode ultrasound-fluorescence imaging, paving the way for improved diagnostics and therapeutic monitoring.

Strategic enhancement of collagen detection using lanthanide-functionalized collagen targeted peptides

Monitoring collagen denaturation is crucial for diagnosing collagen-related diseases such as tumors and fibrosis. Herein, we have developed specific probes to detect denatured collagen (d-Col) and collagen I (Col I), utilizing peptide probes with sequences (GOP)10 and HVWMQAP, targeting at d-Col and Col I, respectively. These peptides were conjugated with 1,10-phenanthroline-5-carboxylic Acid (Phen), forming Phen-Ahx-(GOP)10 and Phen-Ahx-HVWMQAP. Phen acts as both an antenna sensitizer and a chelator, coordinating with Terbium (III) and Europium (III) ions via its nitrogen atom, facilitating fluorescent emission in green and red, respectively. The investigation demonstrated that Tb3+ interacts with three (GOP)10 peptide units through Phen, while Eu3+ connects with four units of Ahx-HVWMQAP peptides. Additionally, it is important to note that the structure of the peptides remains unchanged after chelating with the lanthanide ions, maintaining their integrity throughout the process. These probes have effectively demonstrated their ability to bind to specific collagen types with selectivity, enabling accurate identification of their presence. The excellent binding of these probes is due to the branched structure of the formed lanthanide-peptide complexes. A dose-dependent linear association was observed in the binding of Eu-[Phen-Ahx-HVWMQAP]4 to Col I, with concentration levels ranging from 0.5 to 100 μM and a minimal detectable concentration of 0.113 μM. We anticipate that our developed probes will improve understanding of collagen remodeling and provide opportunities for the diagnosis of collagen-associated diseases.

A Multifaceted Luminescent Europium(III) Probe for the Discrimination of Nucleoside Phosphates and Detection of Organophosphate Nerve Agents

The nucleotides play multiple fundamental roles that are essential in biochemical enzymatic reactions and signaling pathways. Many diseases are closely associated with their dysregulation. Therefore, reliable and sensitive optical probes to discriminate various nucleotides are essential in biochemistry, drug discovery, and disease diagnosis. Furthermore, developing reliable, easy-to-use optical sensors for extremely toxic organophosphonates/nerve-agents is critical to counter public health threats. Luminescent lanthanide(III) complexes have emerged as promising optical bioprobes owing to intraconfigurational f → f transitions. Herein, we present strategically designed Eu(III) probes: [Eu(THC)(X)3]Cl (Eu.1) and [Eu(TBC)(X)3]Cl/Br (Eu.2) containing pentadentate terpyridine dicarboxylates: 4'-(3,4,5-trihydroxyphenyl)-[2,2':6',2″-terpyridine]-6,6″-dicarboxylic acid (THC) and 4'-phenyl-[2,2':6',2″-terpyridine]-6,6″-dicarboxylic acid (TBC) and X = solvent. The Eu.1 probe is systematically evaluated for discrimination of various NPs and as a luminescent chemodosimetric probe for diethyl chlorophosphate (DCP) as a G-series nerve agent mimic. The time-delayed luminescence is used for discrimination between various adenine-based NPs under physiological conditions. The Eu.1 probe shows high affinity and selectivity for ADP enabling continuous monitoring of the ADP/ATP ratio in a simulated enzymatic reaction. Additionally, Eu.1 acted as a chemodosimetric probe for DCP. The interaction produces a change in the sensitization pathway, enhancing the Eu(III)-based luminescence with a ppb level of detection of DCP (LOD = 758 ppb). Our innovative approach expands applications of lanthanide luminescence for probing nucleotides and the detection of lethal nerve agents.

Luminescent Lanthanide Infinite Coordination Polymers for Ratiometric Sensing Applications

Ratiometric lanthanide coordination polymers (Ln-CPs) are advanced materials that combine the unique optical properties of lanthanide ions (e.g., Eu3+, Tb3+, Ce3+) with the structural flexibility and tunability of coordination polymers. These materials are widely used in biological and chemical sensing, environmental monitoring, and medical diagnostics due to their narrow-band emission, long fluorescence lifetimes, and excellent resistance to photobleaching. This review focuses on the composition, sensing mechanisms, and applications of ratiometric Ln-CPs. The ratiometric fluorescence mechanism relies on two distinct emission bands, which provides a self-calibrating, reliable, and precise method for detection. The relative intensity ratio between these bands varies with the concentration of the target analyte, enabling real-time monitoring and minimizing environmental interference. This ratiometric approach is particularly suitable for detecting trace analytes and for use in complex environments where factors like background noise, temperature fluctuations, and light intensity variations may affect the results. Finally, we outline future research directions for improving the design and synthesis of ratiometric Ln-CPs, such as incorporating long-lifetime reference luminescent molecules, exploring near-infrared emission systems, and developing up-conversion or two-photon luminescent materials. Progress in these areas could significantly broaden the scope of ratiometric Ln-CP applications, especially in biosensing, environmental monitoring, and other advanced fields.

MR Imaging Reveals Dynamic Aggregation of Multivalent Glycoconjugates in Aqueous Solution

Glycoconjugates forming from the conjugation of carbohydrates to other biomolecules, such as proteins, lipids, or other carbohydrates, are essential components of mammalian cells and are involved in numerous biological processes. Due to the capability of sugars to form multiple hydrogen bonds, many synthetic glycoconjugates are desirable biocompatible platforms for imaging, diagnostics, drugs, and supramolecular self-assemblies. Herein, we present a multimeric galactose functionalized paramagnetic gadolinium (Gd(III)) chelate that displays spontaneous dynamic aggregation in aqueous conditions. The dynamic aggregation of the Gd(III) complex was shown by the concentration-dependent magnetic resonance (MR) relaxation measurements, nuclear magnetic resonance dispersion (NMRD) analysis, and dynamic light scattering (DLS). Notably, these data showed a nonlinear relationship between magnetic resonance relaxation rate and concentrations (0.03-1.35 mM), and a large DLS hydrodynamic radius was observed in the high-concentration solutions. MR phantom images were acquired to visualize real-time dynamic aggregation behaviors in aqueous solutions. The in situ visualization of the dynamic self-assembling process of multivalent glycoconjugates has rarely been reported.

Specific smart sensing of electron-rich antibiotics or histidine improves the antenna effect, luminescence, and photodynamic sterilization capabilities of lanthanide polyoxometalates

Excessive discharge of antibiotics seriously threatens human health and is thus a global public health problem. This highlights the urgent need to develop intelligent sensing materials for specific antibiotics that are highly visual, fast, convenient, and inexpensive. Herein, two reverse α-octamolybdate polyoxometalates (POMs; Mo8) were used to chelate lanthanide ions to obtain lanthanide POMs (LnPOMs; LnMo16; Ln = Eu, Sm, Tb, Gd) with highly sensitive smart photoresponses to specific antibiotics (ofloxacin [OFN], norfloxacin [NOR], enrofloxacin [ENR], and oxytetracycline [OTC]) and histidine (His) with luminescence turn-on. Specific antibiotics and His, which has an electron-rich structure, can efficiently enhance the antenna effect, thereby greatly improving the luminescence of EuMo16. Surprisingly, OFN and NOR both enhanced the luminescence of Eu(III) ions and Mo8, whereas ENR and OTC only enhanced the luminescence of Eu(III) ions, showing a differentiated sensitization effect. More notably, the combination of POMs and Ln(III) ions enhanced the ability of LnPOMs to produce reactive oxygen species under light irradiation, and these LnPOMs showed significant sterilization effects on Escherichia coli and Staphylococcus aureus. To our knowledge, this is the first time electron-rich antibiotics or amino acids were used to enhance the luminescence of LnPOMs, achieving luminescence-enhanced photoresponse to specific antibiotics and amino acids.

Neodymium-Facilitated Visualization of Extreme Phosphate Accumulation in Fibroblast Filopodia: Implications for Intercellular and Cell-Matrix Interactions

A comprehensive understanding of intercellular and cell-matrix interactions is essential for advancing our knowledge of cell biology. Existing techniques, such as fluorescence microscopy and electron microscopy, face limitations in resolution and sample preparation. Supravital lanthanoid staining provides new opportunities for detailed visualization of cellular metabolism and intercellular interactions. This study aims to describe the structure, elemental chemical, and probable origin of zones of extreme lanthanoid (neodymium) accumulation that form during preparation for scanning electron microscopy (SEM) analysis in corneal fibroblasts filopodia. The results identified three morphological patterns of neodymium staining in fibroblast filopodia, each exhibiting asymmetric staining within a thin, sharp, and extremely bright barrier zone, located perpendicular to the filopodia axis. Semi-quantitative chemical analyses showed neodymium-labeled non-linear phosphorus distribution within filopodia, potentially indicating varying phosphate anion concentrations and extreme phosphate accumulation at a physical or physicochemical barrier. Phosphorus zones labeled with neodymium did not correspond to mitochondrial clusters. During apoptosis, the number of filopodia with extreme and asymmetric phosphorus accumulation increases. Supravital lanthanoid staining coupled with SEM allows detailed visualization of intercellular and cell-matrix interactions with high contrast and resolution. These results enhance our understanding of phosphate anion accumulation and transfer mechanisms in cells under normal conditions and during apoptosis.

Transition Metal Complexes with Appended Benzimidazole Groups for Sensing Dihydrogenphosphate

Four new complexes [Ru(bpy)2(bbib)](PF6)2, [Ru(phen)2(bbib)](PF6)2, [Re(CO)3(bbib)(py)](PF6) and [Ir(ppy)2(bbib)](PF6) [where bbib=4,4'-bis(benzimidazol-2-yl)-2,2'-bipyridine] have been prepared and their photophysical properties determined. Their behaviour has been studied with a variety of anions in acetonitrile, DMSO and 10 % aquated DMSO. Acetate and dihydrogenphosphate demonstrate a redshift in the bbib ligand associated absorptions suggesting that the ligand is strongly interacting with these anions. The 3MLCT emissive state is sensitive to the introduction of small quantities of anion (sub-stoichiometric quantities) and significant quenching is typically observed with acetate, although this is less pronounced in the presence of water. The emissive behaviour with dihydrogenphosphate is variable, showing systematic changes as anion concentration increases with several distinct interactions evident. 1H- and 31P-NMR titrations in a 10 % D2O-DMSO-D6 mixture suggest that with dihydrogenphosphate, the imidazole group is able to act as both a proton acceptor and donor. It appears that all four complexes can form a {[complex]2-H2PO4} "dimer", a one-to-one species (which the X-ray crystallography study suggests is dimeric in the solid-state), and a complex with a combined bis(dihydrogenphosphate) complex anion. The speciation relies on complex equilibria dependent on several factors including the complex charge, the hydrophobicity of the associated ligands, and the solvent.

Selective pyrophosphate detection via metal complexes

Pyrophosphate (PPi) anions are crucial in numerous biological and ecological processes involved in energy conversion, enzymatic reactions, and metabolic regulation along with adenosine. They are also significant biological markers for various processes related to diseases. Fluorescent PPi sensors would enable visual and/or biological detection in convenient settings. However, the current availability of commercial sensors has been limited to costly enzymes that are not compatible for imaging. Sensor development has also encountered challenges such as poor selectivity and stability, and limited practical applications. In this review, we analyze the situation of PPi sensing via commercial kits and focus on sensors that use metal complexes. We address their designs, sensing mechanisms, selectivities and detection limits. Finally, we discuss limitations and perspectives for PPi detection and imaging.

Innovative lanthanide complexes: Shaping the future of cancer/ tumor chemotherapy

Developing new therapeutic and diagnostic metals and metal complexes is a stunning example of how inorganic chemistry is rapidly becoming an essential part of modern medicine. More study of bio-coordination chemistry is needed to improve the design of compounds with fewer harmful side effects. Metal-containing drugs are widely utilized in the treatment of cancer. Platinum complexes are effective against some cancers, but new coordination compounds are being created with improved pharmacological properties and a broader spectrum of anticancer action. The coordination complexes of the 15 lanthanides or rare earth elements in the periodic table are crucial for diagnosing and treating cancer. Understanding and treating cancer requires the detection of binding lanthanide (III) ions or complexes to DNA and breaking DNA by these complexes. Current advances in lanthanide-based coordination complexes as anticancer treatments over the past five years are discussed in this study.

A simple synthesis method of microsphere immunochromatographic test strip for time-resolved luminescence detection of folic acid

Folic acid (FA) is an ingredient that must be added to infant milk powder to avoid potential defects. Rapid, sensitive and reliable detection methods are needed to determined FA addition levels. Thus, this study established a microsphere immunochromatographic test strip for time-resolved luminescence detection (TRLM-ICTS) based on carboxyl-functionalized time-resolved luminescent microspheres (Eu-TRLMs) prepared by a one-step method as fluorescent markers for the immediate quantitative detection of FA in milk powder. Eu-TRLMs prepared by the one-step method showed good dispersion, high stability and strong fluorescence intensity, which is improving the sensitivity of TRLM-ICTS. In the performance evaluation of TRLM-ICTS, the detection limit was 0.487 ng mL^-1, the recovery rate was 97.3-105 %, and the actual sample detection results were in line with those of UPLC-MS/MS. TRLM-ICTS has the advantages of rapid, high sensitivity and strong specificity and could as a practical quantitative detection method for the detection of FA in milk powder.

Design and Application of Electrochemical Sensors with Metal-Organic Frameworks as the Electrode Materials or Signal Tags

Metal-organic frameworks (MOFs) with fascinating chemical and physical properties have attracted immense interest from researchers regarding the construction of electrochemical sensors. In this work, we review the most recent advancements of MOF-based electrochemical sensors for the detection of electroactive small molecules and biological macromolecules (e.g., DNA, proteins, and enzymes). The types and functions of MOF-based nanomaterials in terms of the design of electrochemical sensors are also discussed. Furthermore, the limitations and challenges of MOF-based electrochemical sensing devices are explored. This work should be invaluable for the development of MOF-based advanced sensing platforms.

A 2-fold interpenetrated zinc–organic framework with Lewis basic triazole sites: luminescence sensing of Fe3+ and Cr2O72−, and warm white-light emission by encapsulated Ln3+ ions

A 2-fold interpenetrated Zn-MOF with Lewis basic triazole sites shows selective luminescence sensing of Fe3+ and Cr2O72− and tunable white-light emission by encapsulated Ln3+ ions.