Strategies for the Nuclear Delivery of Metal Complexes to Cancer Cells

An optical ratiometric approach using enantiopure luminescent metal complexes indicates changes in the average quadruplex DNA content as primary cells undergo multiple divisions

The three stereoisomers of a previously reported dinuclear ruthenium(II) complex have been quantitatively separated using cation-exchange chromatography and the individual crystal structures of the racemic pair are reported. Cell-based studies on the three stereoisomers disclosed differences in the rate of uptake of the two chiral forms of the rac diastereoisomer with the ΛΛ-enantiomer being taken up noticeably more rapidly than the ΔΔ-form. Cell viability studies reveal that the three cations show identical cytotoxicity over 24 hours, but over more extended exposure periods, the meso-ΔΛ stereoisomer becomes slightly less active. More significantly, microscopy studies revealed that although both isomers display a near infra-red "light-switch" effect associated with binding to duplex DNA on binding to chromatin in live MCF7 and L5178-R cells, only the ΛΛ enantiomer displays a distinctive, blue-shifted component associated with binding to quadruplex DNA. An analysis of the ratio of "quadruplex emission" compared to "duplex emission" for the ΛΛ-enantiomer indicated that there was a decrease in the average quadruplex DNA content within live primary cells as they undergo multiple cell divisions.

Cyclometalated Iridium(III) Schiff Base Complexes for Chemiluminogenic Bioprobes

Chemiluminogenic bioimaging has emerged as a promising paradigm due to its independence from light excitation, thereby circumventing challenges related to light penetration depth and background autofluorescence. However, the availability of effective chemiluminophores remains limited, which substantially impedes their bio-applications. Herein, we discovered for the first time that cyclometalated iridium(III) Schiff base complexes can unexpectedly generate chemiluminescence. Notably, the chemiluminescence reaction was rapid, with a half-life of only 0.86 s, significantly faster than previously reported examples. Unlike conventional chemiluminescent scaffolds, the distinguishing feature of the chemiluminogenic iridium(III) complex is its unique intramolecular imine-to-amide conversion upon reaction with reactive oxygen species (ROS). Intriguingly, the chemiluminogenicity of these complexes is not influenced by the cyclometalating ligands but is closely associated with the Schiff base ligand, allowing for tuning of the emission colors via altering the cyclometalating ligands. Additionally, we formulated one of the Schiff base complexes (1) as water-soluble chemiluminogenic nanoparticles (CLNPs) and successfully employed them as activatable chemiluminescence bioprobes for precise and rapid imaging of hypochlorite-related biological events both in vitro and in vivo. We believe that this significant finding of the development of chemiluminogenic Schiff base complexes will greatly facilitate the designing of innovative chemiluminophores for theranostic applications.

Advances in the Design of Photoactivatable Metallodrugs: Excited State Metallomics

Photoactivatable metal complexes offer the prospect of novel drugs with low side effects and new mechanisms of action to combat resistance to current therapy. We highlight recent progress in the design of platinum, ruthenium, iridium, gold and other transition metal complexes, especially for applications as anticancer and anti-infective agents. In particular, understanding excited state chemistry related to identification of the bioactive species (excited state metallomics/pharmacophores) is important. Photoactivatable metallodrugs are classified here as photocatalysts, photorelease agents and ligand-activated agents. Their activation wavelengths, cellular mechanisms of action, experimental and theoretical metallomics of excited states and photoproducts are discussed to explore new strategies for the design and investigation of photoactivatable metallodrugs. These photoactivatable metallodrugs have potential in clinical applications of Photodynamic Therapy (PDT), Photoactivated Chemotherapy (PACT) and Photothermal Therapy (PTT).

Transition Metal Complex-Loaded Nanosystems: Advances in Stimuli-Responsive Cancer Therapies

Transition metal complex-loaded nanosystems (TMCNs) represent a cutting-edge platform for stimuli (light, ultrasound)-responsive cancer therapies. These nanosystems, incorporating metals such as manganese(II), zinc(II), ruthenium(II), rhenium(I), iridium(III), and platinum(IV), significantly enhance the efficacy of light-activated therapies, including photodynamic therapy (PDT) and photothermal therapy (PTT), as well as ultrasound-activated treatments like sonodynamic therapy (SDT). TMCNs based on ruthenium(II), rhenium(I), and iridium(III) improve PDT, while manganese(II) and iridium(III) demonstrate exceptional sonosensitizing properties. In PTT, ruthenium(II) and iridium(III)-based TMCNs efficiently absorb light and generate heat. Emerging synergistic approaches that combine SDT, PTT, PDT, chemotherapy, and immunotherapy are demonstrated to be powerful strategies for precision cancer treatment. Zinc(II), ruthenium(II), iridium(III), and platinum(IV)-based TMCNs play a critical role in optimizing these therapies, enhancing tumor targeting, and reducing side effects. Furthermore, TMCNs can amplify immunotherapy by inducing immunogenic cell death, thus strengthening the immune response. These advances address key challenges such as tumor hypoxia and therapeutic resistance, opening new possibilities for innovative photosensitizer-based cancer treatments. This review highlights the latest progress in TMCNs design and applications, demonstrating their potential to revolutionize stimuli-responsive cancer therapies.

Two in one: merging photoactivated chemotherapy and photodynamic therapy to fight cancer

The growing number of cancer cases requires the development of new approaches for treatment. A therapy that has attracted the special attention of scientists is photodynamic therapy (PDT) due to its spatial and temporal resolution. However, it is accepted that this treatment methodology has limited application in cases of low cellular oxygenation, which is typical of cancerous tissues. Therefore, a strategy to overcome this drawback has been to combine this therapy with photoactivated chemotherapy (PACT), which works independently of the presence of oxygen. In this perspective, we examine compounds that act as both PDT and PACT agents and summarize their photophysical and biological characteristics.

Gene Editing with Artificial DNA Scissors

Artificial metallo-nucleases (AMNs) are small molecule DNA cleavage agents, also known as DNA molecular scissors, and represent an important class of chemotherapeutic with high clinical potential. This review provides a primary level of exploration on the concepts key to this area including an introduction to DNA structure, function, recognition, along with damage and repair mechanisms. Building on this foundation, we describe hybrid molecules where AMNs are covalently attached to directing groups that provide molecular scissors with enhanced or sequence specific DNA damaging capabilities. As this research field continues to evolve, understanding the applications of AMNs along with synthetic conjugation strategies can provide the basis for future innovations, particularly for designing new artificial gene editing systems.

Nanomaterials: leading immunogenic cell death-based cancer therapies

The field of oncology has transformed in recent years, with treatments shifting from traditional surgical resection and radiation therapy to more diverse and customized approaches, one of which is immunotherapy. ICD (immunogenic cell death) belongs to a class of regulatory cell death modalities that reactivate the immune response by facilitating the interaction between apoptotic cells and immune cells and releasing specific signaling molecules, and DAMPs (damage-associated molecular patterns). The inducers of ICD can elevate the expression of specific proteins to optimize the TME (tumor microenvironment). The use of nanotechnology has shown its unique potential. Nanomaterials, due to their tunability, targeting, and biocompatibility, have become powerful tools for drug delivery, immunomodulators, etc., and have shown significant efficacy in clinical trials. In particular, these nanomaterials can effectively activate the ICD, trigger a potent anti-tumor immune response, and maintain long-term tumor suppression. Different types of nanomaterials, such as biological cell membrane-modified nanoparticles, self-assembled nanostructures, metallic nanoparticles, mesoporous materials, and hydrogels, play their respective roles in ICD induction due to their unique structures and mechanisms of action. Therefore, this review will explore the latest advances in the application of these common nanomaterials in tumor ICD induction and discuss how they can provide new strategies and tools for cancer therapy. By gaining a deeper understanding of the mechanism of action of these nanomaterials, researchers can develop more precise and effective therapeutic approaches to improve the prognosis and quality of life of cancer patients. Moreover, these strategies hold the promise to overcome resistance to conventional therapies, minimize side effects, and lead to more personalized treatment regimens, ultimately benefiting cancer treatment.

A review on the recent advances of interaction studies of anticancer metal-based drugs with therapeutic targets, DNA and RNAs

Metal-based drugs hold promise as potent anticancer agents owing to their unique interactions with cellular targets. This review discusses recent advances in our understanding of the intricate molecular interactions of metal-based anticancer compounds with specific therapeutic targets in cancer cells. Advanced computational and experimental methodologies delineate the binding mechanisms, structural dynamics and functional outcomes of these interactions. In addition, the review sheds light on the precise modes of action of these drugs, their efficacy and the potential avenues for further optimization in cancer-treatment strategies and the development of targeted and effective metal-based therapies for combating various forms of cancer.

Carbazolyl-Modified Neutral Ir(III) Complexes for Efficient Detection of Picric Acid in Aqueous Media

Based on the electron-deficient property of picric acid (PA), two neutral Ir(III) complexes 1 and 2 modified with the electron-rich carbazolyl groups were synthesized and characterized. Both 1 and 2 exhibit aggregation-induced phosphorescence emission (AIPE) properties in THF/H2O. Among them, 2 is extremely sensitive for detecting PA with a limit of detection of 0.15 μM in THF/H2O. Furthermore, the selectivity for PA is significantly higher compared to other analytes, enabling the efficient detection of PA in four common water samples. The density functional theory calculations and the spectroscopic results confirm that the sensing mechanism is photo-induced electron transfer (PET).

Metal-Drug Coordination Nanoparticles and Hydrogels for Enhanced Delivery

Drug delivery is a key component of nanomedicine, and conventional delivery relies on the adsorption or encapsulation of drug molecules to a nanomaterial. Many delivery vehicles contain metal ions, such as metal-organic frameworks, metal oxides, transition metal dichalcogenides, MXene, and noble metal nanoparticles. These materials have a high metal content and pose potential long-term toxicity concerns leading to difficulties for clinical approval. In this review, recent developments are summarized in the use of drug molecules as ligands for metal coordination forming various nanomaterials and soft materials. In these cases, the drug-to-metal ratio is much higher than conventional adsorption-based strategies. The drug molecules are divided into small-molecule drugs, nucleic acids, and proteins. The formed hybrid materials mainly include nanoparticles and hydrogels, upon which targeting ligands can be grafted to improve efficacy and further decrease toxicity. The application of these materials for addressing cancer, viral infection, bacterial infection inflammatory bowel disease, and bone diseases is reviewed. In the end, some future directions are discussed from fundamental research, materials science, and medicine.

Unveiling the anti-echinococcal efficacy of amide-based compounds: An in-silico and in-vitro study

Cystic echinococcosis (CE) is a significant global public health concern, particularly in regions where livestock rearing is prevalent. Despite its impact on morbidity and mortality, CE has received insufficient attention compared to other neglected tropical diseases. The complexities in CE management arise from challenges in early detection, effective treatment, and parasite eradication. The present study addresses this gap by exploring innovative therapeutic approaches using amide-based compounds. In recent years, computational approaches and in-vitro studies have become prominent in neglected tropical disease drug discovery. Leveraging insights from previous studies on amide-based compounds with anti-parasitic potential, this study systematically designed, synthesized, and characterized a library of 30 amide compounds. The research integrated in-silico screening, molecular docking, and in-vitro experimentation to assess the anti-echinococcal potential of these compounds. The study identified five promising amide compounds, namely 3,5-dinitro-N-p-tolylbenzamide, N-p-tolyl-1-naphthamide, N-p-tolyl-4-(trifluoromethoxy)benzamide, 4-pentyl-N-p-tolylbenzamide, and 2,3,4,5,6-pentafluoro-N-p-tolylbenzamide, based on their docking scores. These compounds were synthesized and characterized through various spectroscopic techniques, confirming their structural integrity. The in-vitro cytotoxicity assay on HepG2 cell lines revealed varying degrees of cytotoxicity for the synthesized compounds. Notably, 4-pentyl-N-p-tolylbenzamide demonstrated the least cytotoxicity. Subsequent scolicidal activity assessments on E. granulosus protoscoleces demonstrated the potent protoscolicidal activity of N-p-tolyl-1-naphthamide, indicating its potential as an effective anti-echinococcal agent. Overall, this study presents a comprehensive exploration of amide-based compounds as potential therapeutic agents against CE. The findings contribute to the development of innovative strategies for CE treatment, addressing the urgent need for effective and safe drugs in managing this neglected tropical disease.

Nucleus-targeting DNase I self-assembly delivery system guided by pirarubicin for programmed multi-drugs release and combined anticancer therapy

The cell nucleus serves as the pivotal command center of living cells, and delivering therapeutic agents directly into the nucleus can result in highly efficient anti-tumor eradication of cancer cells. However, nucleus-targeting drug delivery is very difficult due to the presence of numerous biological barriers. Here, three antitumor drugs (DNase I, ICG: indocyanine green, and THP: pirarubicin) were sequentially triggered protein self-assembly to produce a nucleus-targeting and programmed responsive multi-drugs delivery system (DIT). DIT consisted of uniform spherical particles with a size of 282 ± 7.7 nm. The acidic microenvironment of tumors and near-infrared light could successively trigger DIT for the programmed release of three drugs, enabling targeted delivery to the tumor. THP served as a nucleus-guiding molecule and a chemotherapy drug. Through THP-guided DIT, DNase I was successfully delivered to the nucleus of tumor cells and killed them by degrading their DNA. Tumor acidic microenvironment had the ability to induce DIT, leading to the aggregation of sufficient ICG in the tumor tissues. This provided an opportunity for the photothermal therapy of ICG. Hence, three drugs were cleverly combined using a simple method to achieve multi-drugs targeted delivery and highly effective combined anticancer therapy.