Light-harvesting ytterbium(III)-porphyrinate-BODIPY conjugates: synthesis, excitation-energy transfer, and two-photon-induced near-infrared-emission studies

Robust antibacterial activity of rare-earth ions on planktonic and biofilm bacteria

Bacterial infections pose a serious threat to human health, with emerging antibiotic resistance, necessitating the development of new antibacterial agents. Cu2+and Ag+are widely recognized antibacterial agents with a low propensity for inducing bacterial resistance; however, their considerable cytotoxicity constrains their clinical applications. Rare-earth ions, owing to their unique electronic layer structure, hold promise as promising alternatives. However, their antibacterial efficacy and biocompatibility relative to conventional antibacterial agents remain underexplored, and the variations in activity across different rare-earth ions remain unclear. Here, we systematically evaluate the antibacterial activity of five rare-earth ions (Yb3+, Gd3+, Sm3+, Tb3+, and La3+) againstStaphylococcus aureusandPseudomonas aeruginosa, benchmarked against well-established antibacterial agents (Cu2+, Ag+) and the antibiotic norfloxacin. Cytotoxicity is also assessed via live/dead staining of fibroblasts after 24 h rare-earth ion exposure. Our findings reveal that rare-earth ions require higher concentrations to match the antibacterial effects of traditional agents but offer the advantage of significantly lower cytotoxicity. In particular, Gd3+demonstrates potent bactericidal efficacy against both planktonic and biofilm bacteria, while maintaining the lowest cytotoxicity toward mammalian cells. Moreover, the tested rare-earth ions also exhibited excellent antifungal activity againstCandida albicans. This study provides a critical empirical framework to guide the selection of rare-earth ions for biomedical applications, offering a strategic direction for the development of novel antimicrobial agents.

Applications of rare earth elements in cancer: Evidence mapping and scientometric analysis

Cancer is one of the most important public health issues worldwide. Radiation therapy (XRT), chemotherapy, and targeted therapy are some of the main types of cancer therapy. Metals are used extensively in cancer diagnosis and therapy, and rare earth elements occupy an important niche in these areas. In recent years, an increasing number of studies have focused on the application of lanthanides in cancer diagnosis and therapy. However, no research has analyzed the current status and future trends of lanthanides in treating cancer. We downloaded data from publications from the Web of Science Core Collection. We used VOSviewer 1.16.16 software and Excel 2016 to analyze literature information, including publication years, journals, countries, institutes, authors, keywords, and co-cited references. A total of 7,849 publications were identified. The first study on the association of rare earth elements with cancer was published in 1945. However, before 1979, the number of publications per year was no more than 10. After 1980, the number of yearly publications increased. The United States was the most productive country (2,726, 34.73%), and the institution with the most frequent contributions was the Chinese Academy of Sciences (211, 2.69%). We observed close collaboration between countries and between institutes. The 7,839 publications were published in 1,579 journals, and Radiology was both the most productive journal (183, 2.33%) and cited journal (5,863 citations). A total of 33,987 authors investigated rare earth elements and cancer. Only 0.45% of the authors published more than 10 publications, and 79.07% of the authors published only one publication. Of the top 10 high-yield authors, seven were from developed countries and three were from China. However, among the top 10 co-cited authors, there was only one high-yield author. The main research topics in the application of lanthanide complex-doped nanomaterials in the diagnosis and treatment of cancer include magnetic resonance imaging contrast agents, photodynamic therapy, anticancer drug delivery, the efficacy and safety of yttrium-90 radioimmunotherapy and chemoembolization for the treatment of HCC, gadolinium magnetic resonance imaging (MRI) contrast agent for cancer diagnosis, and cerium oxide nanoparticles. In recent years, especially since 2016, the research frontiers are emerging in cerium oxide nanoparticles and photodynamic therapy. Studies related to the application of rare earth elements and cancer have significantly increased over the past 20 years. The United States contributed the most articles in the field, followed by China and Germany, and cooperation among countries was frequent. The Chinese Academy of Sciencess, Northwestern University, and Stanford University were the three most productive institutions, and cooperation among institutions was frequent. Many high-quality journals have published relevant research, but there are few highly productive journals.

Coordination-Directed Self-Assembly of Functional Polynuclear Lanthanide Supramolecular Architectures

Lanthanide supramolecular chemistry is a fast growing and intriguing research field due to the unique photophysical, magnetic, and coordination properties of lanthanide ions (Ln^III). Compared with the intensively investigated mononuclear Ln-complexes, polymetallic lanthanide supramolecular assemblies offer more structural superiority and functional advantages. In recent decades, significant progress has been made in polynuclear lanthanide supramolecules, varying from structural evolution to luminescent and magnetic functional materials. This review summarizes the design principles in ligand-induced coordination-driven self-assembly of polynuclear Ln-structures and intends to offer guidance for the construction of more elegant Ln-based architectures and optimization of their functional performances. Design principles concerning the water solubility and chirality of the lanthanide-organic assemblies that are vital in extending their applications are emphasized. The strategies for improving the luminescent properties and the applications in up-conversion, host-guest chemistry, luminescent sensing, and catalysis have been summarized. Magnetic materials based on supramolecular assembled lanthanide architectures are given in an individual section and are classified based on their structural features. Challenges remaining and perspective directions in this field are also briefly discussed.

Novel DBMBF2-BODIPY dyads connected via a flexible linker: synthesis and photophysical properties

Novel BODIPY and DBMBF2 dyads connected via a flexible trisiloxane linker were synthesized and their photophysical properties were investigated.

Lanthanide-tetrapyrrole complexes: synthesis, redox chemistry, photophysical properties, and photonic applications

Tetrapyrrole derivatives such as porphyrins, phthalocyanines, naphthalocyanines, and porpholactones, are highly stable macrocyclic compounds that play important roles in many phenomena linked to the development of life. Their complexes with lanthanides are known for more than 60 years and present breath-taking properties such as a range of easily accessible redox states leading to photo- and electro-chromism, paramagnetism, large non-linear optical parameters, and remarkable light emission in the visible and near-infrared (NIR) ranges. They are at the centre of many applications with an increasing focus on their ability to generate singlet oxygen for photodynamic therapy coupled with bioimaging and biosensing properties. This review first describes the synthetic paths leading to lanthanide-tetrapyrrole complexes together with their structures. The initial synthetic protocols were plagued by low yields and long reaction times; they have now been replaced with much more efficient and faster routes, thanks to the stunning advances in synthetic organic chemistry, so that quite complex multinuclear edifices are presently routinely obtained. Aspects such as redox properties, sensitization of NIR-emitting lanthanide ions, and non-linear optical properties are then presented. The spectacular improvements in the quantum yield and brightness of Yb^III-containing tetrapyrrole complexes achieved in the past five years are representative of the vitality of the field and open welcome opportunities for the bio-applications described in the last section. Perspectives for the field are vast and exciting as new derivatizations of the macrocycles may lead to sensitization of other Ln^III NIR-emitting ions with luminescence in the NIR-II and NIR-III biological windows, while conjugation with peptides and aptamers opens the way for lanthanide-tetrapyrrole theranostics.

Halogen-Bonded BODIPY Frameworks with Tunable Optical Features*

The ability to tune the optical features of BODIPY materials in the solid state is essential for their photorelated application and requires efficient control of the crystal packing. In this study, such control of BODIPY supramolecular assemblies was achieved by deliberate design and synthesis of a BODIPY containing a strong halogen-bond (XB) acceptor (-NO₂ ) and donor (I, Br) to mediate XB interactions. The di-halogenated structures formed isostructural mono-coordinate motif B3, B4 (1D tubular structure) and symmetric bifurcated motif B4-II (1D zigzag chains structure) through N-O⋅⋅⋅I, Br XB interactions. These XB interactions promote singlet-to-triplet intersystem crossing and triplet-to-singlet reverse intersystem crossing due to partial delocalization of oxygen electrons onto Br and I, which leads to unexpected fluorescence enhancement of B4-II. Finally, the indirect optical band gaps of B3, B4 and B4-II were amenable to tuning in the range of 1.85-2.50  eV by XB-driven crystal packings.

Thermodynamic and Spectroscopic Studies of the Complexes Formed in Tartaric Acid and Lanthanide(III) Ions Binary Systems

Binary complexes of tartaric acid with lanthanide(III) ions were investigated. The studies have been performed in aqueous solution using the potentiometric method with computer analysis of the data for detection of the complexes set, determination of the stability constants of these compounds. The mode of the coordination of complexes found was determined using spectroscopy, which shows: Infrared, circular dichroism, ultraviolet, visible as well as luminescence spectroscopy. The overall stability constants of the complexes as well as the equilibrium constants of the reaction were determined. Analysis of the equilibrium constants of the reactions and spectroscopic data allowed the effectiveness of the carboxyl groups in the process of complex formation.

A conjugated porphyrin as a red-light sensitizer for near-infrared emission of ytterbium(iii) ion

A conjugated porphyrin with broader absorption in the visible region was synthesized for sensitizing the near-infrared emission of ytterbium(iii) ions.

Research Progress of Near-Infrared Fluorescence Immunoassay

Near-infrared fluorescence probes (NIFPs) have been widely used in immunoassay, bio-imaging and medical diagnosis. We review the basic principles of near-infrared fluorescence and near-infrared detection technology, and summarize structures, properties and characteristics of NIFPs (i.e., cyanines, xanthenes fluorescent dyes, phthalocyanines, porphyrin derivates, single-walled carbon nanotubes (SWCNTs), quantum dots and rare earth compounds). We next analyze applications of NIFPs in immunoassays, and prospect the application potential of lateral flow assay (LFA) in rapid detection of pathogens. At present, our team intends to establish a new platform that has highly sensitive NIFPs combined with portable and simple immunochromatographic test strips (ICTSs) for rapid detection of food-borne viruses. This will provide technical support for rapid detection on the port.

Recent Trends Concerning Upconversion Nanoparticles and Near-IR Emissive Lanthanide Materials in the Context of Forensic Applications

Upconversion nanoparticles (UCNPs) are materials that, upon absorbing multiple photons of low energy (e.g. infrared radiation), subsequently emit a single photon of higher energy, typically within the visible spectrum. The physics of these materials have been the subject of detailed investigations driven by the potential application of these materials as medical imaging devices. One largely overlooked application of UCNPs is forensic science, wherein the ability to produce visible light from infrared light sources would result in a new generation of fingerprint powders that circumvent background interference which can be encountered with visible and ultraviolet light sources. Using lower energy, infrared radiation would simultaneously improve the safety of forensic practitioners who often employ light sources in less than ideal locations. This review article covers the development of UCNPs, the use of infrared radiation to visualise fingerprints by the forensic sciences, and the potential benefits of applying UCNP materials over current approaches.

Enhanced luminescence and tunable magnetic properties of lanthanide coordination polymers based on fluorine substitution and phenanthroline ligand

Lanthanide coordination polymers with F-substituted carboxylate tectonics and phenanthroline ligands exhibit emission from the visible to near-infrared region with long lifetime. Dy(iii) compounds show temperature dependent and field induced single molecule magnetism.

Highly luminescent, biocompatible ytterbium(iii) complexes as near-infrared fluorophores for living cell imaging

We report three synthetic methods to prepare biocompatible Yb³⁺ complexes, which displayed high NIR luminescence with quantum yields up to 13% in aqueous media. This renders β-fluorinated Yb³⁺ porphyrinoids a new class of NIR probes for living cell imaging including time-resolved fluorescence lifetime imaging.

Herein, we report the design and synthesis of biocompatible Yb³⁺ complexes for near-infrared (NIR) living cell imaging. Upon excitation at either the visible (Soret band) or red region (Q band), these β-fluorinated Yb³⁺ complexes display high NIR luminescence (quantum yields up to 23% and 13% in dimethyl sulfoxide and water, respectively) and have higher stabilities and prolonged decay lifetimes (up to 249 μs) compared to the β-non-fluorinated counterparts. This renders the β-fluorinated Yb³⁺ complexes as a new class of biological optical probes in both steady-state imaging and time-resolved fluorescence lifetime imaging (FLIM). NIR confocal fluorescence images showed strong and specific intracellular Yb³⁺ luminescence signals when the biocompatible Yb³⁺ complexes were uptaken into the living cells. Importantly, FLIM measurements showed an intracellular lifetime distribution between 100 and 200 μs, allowing an effective discrimination from cell autofluorescence, and afforded high signal-to-noise ratios as firstly demonstrated in the NIR region. These results demonstrated the prospects of NIR lanthanide complexes as biological probes for NIR steady-state fluorescence and time-resolved fluorescence lifetime imaging.

K+-Induced in situ self-assembly of near-infrared luminescent membrane material armored with bigger Yb(iii) complex crystallites

A semi-rigid ligand could capture effectively Yb³⁺ ions to form a stable Yb³⁺ complex and provide a potential cavity to accommodate alkali metal ions.

Ameliorated synthetic methodology for crystalline lanthanoid–metalloporphyrin open frameworks based on a multitopic octacarboxy-porphyrin scaffold: structural, gas sorption and photophysical properties

A novel synthetic methodology has been applied to obtain sizeable single crystals of wide-pore porphyrin-based MOFs.

π-Extended diketopyrrolopyrrole–porphyrin arrays: one- and two-photon photophysical investigations and theoretical studies

Diketopyrrolopyrrole–porphyrin conjugates show remarkable NIR emission properties, high two-photon absorption cross-sections and significant singlet oxygen production efficiency.

Two-photon multiplexing bio-imaging using a combination of Eu- and Tb-bioprobes

Two europium and terbium luminescent bio-probes whose luminescence can be sensitized by a two-photon sensitisation process have been designed and the proof-of-concept of biphotonic multiplexing experiment is described.

Near-infrared fluorescent probes in cancer imaging and therapy: an emerging field

Near-infrared fluorescence (NIRF) imaging is an attractive modality for early cancer detection with high sensitivity and multi-detection capability. Due to convenient modification by conjugating with moieties of interests, NIRF probes are ideal candidates for cancer targeted imaging. Additionally, the combinatory application of NIRF imaging and other imaging modalities that can delineate anatomical structures extends fluorometric determination of biomedical information. Moreover, nanoparticles loaded with NIRF dyes and anticancer agents contribute to the synergistic management of cancer, which integrates the advantage of imaging and therapeutic functions to achieve the ultimate goal of simultaneous diagnosis and treatment. Appropriate probe design with targeting moieties can retain the original properties of NIRF and pharmacokinetics. In recent years, great efforts have been made to develop new NIRF probes with better photostability and strong fluorescence emission, leading to the discovery of numerous novel NIRF probes with fine photophysical properties. Some of these probes exhibit tumoricidal activities upon light radiation, which holds great promise in photothermal therapy, photodynamic therapy, and photoimmunotherapy. This review aims to provide a timely and concise update on emerging NIRF dyes and multifunctional agents. Their potential uses as agents for cancer specific imaging, lymph node mapping, and therapeutics are included. Recent advances of NIRF dyes in clinical use are also summarized.

Design, synthesis and photophysical studies of dipyrromethene-based materials: insights into their applications in organic photovoltaic devices

This review article presents the most recent developments in the use of materials based on dipyrromethene (DPM) and azadipyrromethenes (ADPM) for organic photovoltaic (OPV) applications. These chromophores and their corresponding BF2-chelated derivatives BODIPY and aza-BODIPY, respectively, are well known for fluorescence-based applications but are relatively new in the field of photovoltaic research. This review examines the variety of relevant designs, synthetic methodologies and photophysical studies related to materials that incorporate these porphyrinoid-related dyes in their architecture. The main idea is to inspire readers to explore new avenues in the design of next generation small-molecule and bulk-heterojunction solar cell (BHJSC) OPV materials based on DPM chromophores. The main concepts are briefly explained, along with the main challenges that are to be resolved in order to take full advantage of solar energy.

Highly emitting near-infrared lanthanide "encapsulated sandwich" metallacrown complexes with excitation shifted toward lower energy

Near-infrared (NIR) luminescent lanthanide complexes hold great promise for practical applications, as their optical properties have several complementary advantages over organic fluorophores and semiconductor nanoparticles. The fundamental challenge for lanthanide luminescence is their sensitization through suitable chromophores. The use of the metallacrown (MC) motif is an innovative strategy to arrange several organic sensitizers at a well-controlled distance from a lanthanide cation. Herein we report a series of lanthanide “encapsulated sandwich” MC complexes of the form Ln3+ [12-MC(Zn(II),quinHA)-4]2[24-MC(Zn(II),quinHA)-8] (Ln3+ [Zn(II)MC(quinHA)]) in which the MC framework is formed by the self-assembly of Zn2+ ions and tetradentate chromophoric ligands based on quinaldichydroxamic acid (quinHA). A first-generation of luminescent MCs was presented previously but was limited due to excitation wavelengths in the UV. We report here that through the design of the chromophore of the MC assembly, we have significantly shifted the absorption wavelength toward lower energy (450 nm). In addition to this near-visible inter- and/or intraligand charge transfer absorption, Ln3+ [Zn(II)MC(quinHA)] exhibits remarkably high quantum yields, long luminescence lifetimes (CD3OD; Yb3+, QLn(L) = 2.88(2)%, τobs = 150.7(2) μs; Nd3+, QLn(L) = 1.35(1)%, τobs = 4.11(3) μs; Er3+, QLn(L) = 3.60(6)·10–2%, τobs = 11.40(3) μs), and excellent photostability. Quantum yields of Nd3+ and Er3+ MCs in the solid state and in deuterated solvents, upon excitation at low energy, are the highest values among NIR-emitting lanthanide complexes containing C–H bonds. The versatility of the MC strategy allows modifications in the excitation wavelength and absorptivity through the appropriate design of the ligand sensitizer, providing a highly efficient platform with tunable properties.

Millisecond lifetime imaging with a europium complex using a commercial confocal microscope under one or two-photon excitation

We demonstrate that a commercial confocal microscope can perform time-gated and long lifetime imaging in the μs to ms range under classical one photon or nonlinear two photon excitation.

Simultaneous enhanced diagnosis and photodynamic therapy of photosensitizer-doped perylene nanoparticles via doping, fluorescence resonance energy transfer, and antenna effect

We demonstrate a new strategy for preparing photosensitizer-doped perylene nanoparticles via doping, fluorescence resonance energy transfer, and antenna effect for simultaneous enhanced diagnosis and photodynamic therapy.

Synthesis of conjugated BODIPYs via the Wittig reaction

A Wittig reaction was employed to synthesize conjugated BODIPYs in high yields by treating formylated BODIPYs with alkyl/aryl ylides under simple room temperature conditions. Treatment of 3,5-diformyl BODIPYs or α-formyl 3-pyrrolyl BODIPY with different alkyl/aryl ylides in CH2Cl2 at room temperature for 2 h followed by straightforward column chromatographic purification on silica afforded conjugated BODIPYs in ~65-90% yields. This is an alternate method to Knoevenagel and Heck reactions which have been used to synthesize such conjugated BODIPYs. The method works very efficiently, and we prepared 12 substituted BODIPYs including cholesterol-substituted BODIPYs to demonstrate the versatility of the reaction. The spectral, electrochemical, and fluorescence properties of these conjugated BODIPYs are also described.