Extending the Excitation Wavelength of Potential Photosensitizers via Appendage of a Kinetically Stable Terbium(III) Macrocyclic Complex for Applications in Photodynamic Therapy

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.

Effects of Europium Complex on Thermal and Photoluminescence Properties of Polyurethane-Europium Materials

A europium complex with double bonds was synthesized with crotonic acid as the ligand and a europium ion as the center ion. Then, the obtained europium complex was added to synthesized poly(urethane-acrylate) macromonomers to prepare the bonded polyurethane-europium materials by the polymerization of the double bonds in the complex and the poly(urethane-acrylate) macromonomers. The prepared polyurethane-europium materials had high transparency, good thermal stability and good fluorescence. The storage moduli of polyurethane-europium materials are obviously higher than those of pure polyurethane. Polyurethane-europium materials exhibit bright red light with good monochromaticity. The light transmittance of the material decreases slightly with increases in the europium complex content, but the luminescence intensity gradually increases. In particular, polyurethane-europium materials possess a long luminescence lifetime, which has potential applications for optical display instruments.

Luminescent Lanthanide Complexes for Effective Oxygen-Sensing and Singlet Oxygen Generation

Oxygen quantification using luminescence has attracted considerable attention in various fields, including environmental monitoring and clinical analysis. Among the reported luminophores, trivalent lanthanide complexes have displayed characteristic narrow emission bands with high brightness. This bright emission is based on photo-sensitized energy transfer via organic triplet states. The organic triplet states in lanthanide complexes effectively react with the triplet oxygen, enabling oxygen quantification by lanthanide luminescence. Some Tb^III and Eu^III complexes with slow deactivation processes have also formed the excited state equilibrium, thus resulting in the emission-lifetime based oxygen sensing property. The combination of Tb^III /Eu^III emission, Eu^III /Sm^III emission, Eu^III /ligand phosphorescence, and ligand fluorescence/ligand phosphorescence provide the ratiometric oxygen-sensing properties. Moreover, the reaction generates singlet oxygen species which exhibit numerous applications in the photo-medical field. The ligands with large π-conjugated aromatic systems, such as porphyrin, phthalocyanine, and polyaromatic compounds, induces highly efficient oxygen generation. The combination of effective luminescence with singlet-oxygen generation by the lanthanide complexes render them suitable for photo-driven theranostics. This review summarizes the research progress of lanthanide complexes with efficient oxygen-sensing and singlet-oxygen generation properties.

Tuning the photophysical properties of luminescent lanthanide complexes through regioselective antenna fluorination

Carbostyrils monofluorinated in the 3, 5, or 6 positions were synthesised from olefinic precursors via a photochemical isomerisation-cyclisation route, and incorporated into octadentate cyclen triacetate ligands that formed luminescent complexes...

Recent Strategies to Develop Innovative Photosensitizers for Enhanced Photodynamic Therapy

This review presents a robust strategy to design photosensitizers (PSs) for various species. Photodynamic therapy (PDT) is a photochemical-based treatment approach that involves the use of light combined with a light-activated chemical, referred to as a PS. Attractively, PDT is one of the alternatives to conventional cancer treatment due to its noninvasive nature, high cure rates, and low side effects. PSs play an important factor in photoinduced reactive oxygen species (ROS) generation. Although the concept of photosensitizer-based photodynamic therapy has been widely adopted for clinical trials and bioimaging, until now, to our surprise, there has been no relevant review article on rational designs of organic PSs for PDT. Furthermore, most of published review articles in PDT focused on nanomaterials and nanotechnology based on traditional PSs. Therefore, this review aimed at reporting recent strategies to develop innovative organic photosensitizers for enhanced photodynamic therapy, with each example described in detail instead of providing only a general overview, as is typically done in previous reviews of PDT, to provide intuitive, vivid, and specific insights to the readers.

High anticancer activity and apoptosis- and autophagy-inducing properties of novel lanthanide(III) complexes bearing 8-hydroxyquinoline-N-oxide and 1,10-phenanthroline

In the quest for rare earth metal complexes with enhanced cancer chemotherapeutic properties, the discovery of seven lanthanide(iii) complexes bearing 8-hydroxyquinoline-N-oxide (NQ) and 1,10-phenanthroline (phen) ligands, i.e., [SmIII(NQ)(phen)(H2O)Cl2] (Ln1), [EuII(NQ)(phen)(H2O)Cl2] (Ln2), [GdIII(NQ)(phen)(H2O)Cl2] (Ln3), [DyIII(NQ)(phen)(H2O)Cl2] (Ln4), [HoIII(NQ)(phen)(H2O)Cl2] (Ln5), [ErIII(NQ)(phen)(H2O)Cl2] (Ln6), and [YbIII(NQ)(phen)(H2O)Cl2] (Ln7), as potential anticancer drugs is described. Complexes Ln1-Ln7 exhibit high antiproliferative activity against cisplatin-resistant A549/DDP cells (IC50 = 0.025-0.097 μM) and low toxicity to normal HL-7702 cells. Moreover, complex Ln1, and to a lesser extent Ln7, can upregulate the expression of LC3 and Beclin1 and downregulate p62 to induce apoptosis in cisplatin-resistant A549/DDP cell lines, which is related to the cell autophagy-inducing properties of Ln1 and Ln7. Furthermore, in vivo assays suggest that Ln1 significantly inhibits A549/DDP xenograft tumor growth (56.5%). These results indicate that lanthanide(iii) complex Ln1 is a promising candidate as an anticancer drug against cisplatin-resistant A549/DDP cells.

Increased Lipophilicity of Halogenated Ruthenium(II) Polypyridyl Complexes Leads to Decreased Phototoxicity in vitro when Used as Photosensitizers for Photodynamic Therapy

In the fight against cancer, photodynamic therapy is generating great interest thanks to its ability to selectively kill cancer cells without harming healthy tissues. In this field, ruthenium(II) polypyridyl complexes, and more specifically, complexes with dipyrido[3,2-a:2',3'-c]phenazine (dppz) as a ligand are of particular interest due to their DNA-binding and photocleaving properties. However, ruthenium(II) polypyridyl complexes can sometimes suffer from low lipophilicity, which hampers cellular internalisation through passive diffusion. In this study, four new [Ru(dppz-X₂ )₃ ]²⁺ complexes (X=H, F, Cl, Br, I) were synthesized and their lipophilicity (logP), cytotoxicity and phototoxicity on cancerous and noncancerous cell lines were assessed. This study shows that, counterintuitively, the phototoxicity of these complexes decreases as their lipophilicity increases; this could be due solely to the atomic radius of the halogen substituents.

Photo-physical, theoretical and photo-cytotoxic evaluation of a new class of lanthanide(iii)–curcumin/diketone complexes for PDT application

Improved ISC in La(iii) complex of curcumin, on activation with visible light, has resulted in high yield of ¹O₂ in HeLa/MCF-7 cells, leading to the oxidative stress which was responsible for remarkable caspase 3/7-dependent apoptotic photocytotoxicity.

Antimicrobial effects of photodynamic therapy

The microorganisms that cause infections are increasing their resistance to antibiotics. In this context, alternative treatments are necessary. The antimicrobial photodynamic therapy (aPDT) is a therapeutic modality based on photosensitizing molecules that end up generating reactive oxygen species that induce the destruction of the target cells when are irradiated with light of a suitable wavelength and at a proper dose. The cells targeted by aPDT are all types of microorganisms (bacteria, fungi and parasites) including viruses and has been proven effective against representative members of all of them. In the field of dermatology, aPDT has been tested with promising results in different infections such as chronic ulcers, acne, onychomycosis and other cutaneous mycoses, as well as in leishmaniasis. Therefore, it is presented as a possible treatment option against the agents that cause skin and/or mucous infections.

Honeycomb-patterned porous films fabricated via self-organization of Tb complex-loaded amphiphilic copolymers

Amphiphilic copolymers, poly(styrene)-block-Tb complex (PS-b-Tb complex), were synthesized by reversible addition fragmentation chain transfer (RAFT) polymerization. The honeycomb structured porous films were fabricated via dropping the PS-b-Tb complex copolymer solutions on glass substrates by the breath figures method (BFM). The structure and composition of the amphiphilic copolymer PS-b-Tb complex were confirmed by gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FT-IR) and ¹H nuclear magnetic resonance spectroscopy (¹H NMR). The surface morphology and elemental mapping of the highly ordered porous films were investigated by field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDX) and laser scanning confocal microscopy (LSCM). The results indicated that the solvent type and copolymer concentration can affect the surface morphology of the porous films. The average diameter of the pores in the porous films decreased with the polymer concentration and the molecular weight of the copolymers increased. The FESEM-EDX analysis further verified that the hydrophilic groups (Tb complex groups) were mainly distributed at the pore wall, instead of at the outer surface layer of the films, which was consistent with the LSCM results.

Amphiphilic copolymers PS-b-Tb complex were synthesized by RAFT polymerization, the honeycomb structured porous films were fabricated via BFM, the hydrophilic groups (Tb complex groups) were mainly distributed at the pore wall.