New mechanistic approach of inorganic palladium toxicity: impairment in mitochondrial electron transfer

A highly sensitive and selective fluorescent probe for rapid detection and intracellular imaging of Pd(II)

A novel near-infrared fluorescent probe (SWJT-13) for detecting Pd2+ ions was designed and synthesized using 3-bromopropargyne group as a recognition site. SWJT-13 can detect Pd2+ ions specifically, which can be quickly recognized by naked eye under natural light. SWJT-13 has a large Stokes shift (155 nm) with LOD of 10.5 nM. The mechanism was verified by 1H NMR, MS, and Gaussian calculations. In addition, the detection of Pd2+ ions by the probe was studied in HeLa cells.

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 development of folate-functionalised palladium nanoparticles for folate receptor targeting in breast cancer cells

Folate receptor-targeted therapy has excellent prospects for the treatment of breast cancer. A non-toxic concentration of folate-conjugated palladium-based nanoparticles was used to target the overexpressed folate receptor on breast cancer cells. The folate-conjugated nanoparticles were tailored to accumulate selectively in cancer cells relative to normal cells via the folate receptor. The MDA-MB-231, MDA-MB-468, MCF-7 breast cancer cell lines, and MCF-10A normal cell lines were used in the study. Qualitative and quantitative analysis of nanoparticle cellular uptake and accumulation was conducted using transmission electron microscopy and inductively coupled plasma-optical emission spectroscopy. The findings proved that folate-conjugated palladium nanoparticles successfully and preferentially accumulated in breast cancer cells. We conclude that folate-conjugated palladium nanoparticles can be potentially used to target breast cancer cells for radiopharmaceutical applications.

Colorimetric Paper-Based Analytical Devices (PADs) Backed by Chemometrics for Pd(II) Detection

This paper presents the development of cheap and selective Paper-based Analytical Devices (PADs) for selective Pd(II) determination from very acidic aqueous solutions. The PADs were obtained by impregnating two cm-side squares of filter paper with an azoic ligand, (2-(tetrazolylazo)-1,8 dihydroxy naphthalene-3,6,-disulphonic acid), termed TazoC. The so-obtained orange TazoC-PADs interact quickly with Pd(II) in aqueous solutions by forming a complex purple-blue-colored already at pH lower than 2. The dye complexes no other metal ions at such an acidic media, making TazoC-PADs highly selective to Pd(II) detection. Besides, at higher pH values, other cations, for example, Cu(II) and Ni(II), can interact with TazoC through the formation of stable and pink-magenta-colored complexes; however, it is possible to quantify Pd(II) in the presence of other cations using a multivariate approach. To this end, UV-vis spectra of the TazoC-PADs after equilibration with the metal ions solutions were registered in the 300-800 nm wavelength range. By applying Partial Least Square regression (PLS), the whole UV-vis spectra of the TazoC-PADs were related to the Pd(II) concentrations both when present alone in solution and also in the presence of Cu(II) and Ni(II). Tailored PLS models obtained with matrix-matched standard solutions correctly predicted Pd(II) concentrations in unknown samples and tap water spiked with the metal cation, making the method promising for quick and economical sensing of Pd(II).

Kinetic Aspects of Suzuki Cross-Coupling Using Ligandless Pd Nanoparticles Embedded in Aromatic Polymeric Matrix

During the last decades, palladium nanoparticles (Pd(0) NPs) and Pd(II) compounds were shown to be attractive catalysts for fine organic synthesis. Nanostructured Pd(0) or Pd(II) catalysts have a relatively low environmental impact, but, at the same time, they are indispensable for such processes as Suzuki cross-coupling. This paper describes the preparation of Pd(0) or Pd(II) supported/embedded in hyper-cross-linked polystyrene (HPS) and compares their activity in Suzuki cross-coupling between phenylboronic acid and 4-bromoanisole. Obviously, the palladium charge (Pd(0) ↔ Pd(II)) changes continuously during the reaction catalytic cycle. It would seem that the use of the starting palladium in the form of Pd(0) or Pd(II) should not affect the reaction’s kinetic laws for both catalysts, but their special individuality is manifested between them. Nanoparticulate Pd(0) catalysts are stable during the reaction. In contrast, catalysts based on Pd(II) are extremely active in the initial period of the reaction, but then the “hot form” of the catalyst is rapidly converted into the form of Pd(0), whose activity is identical to that of the preliminarily reduced catalyst. This work discusses the possible nature of this phenomenon. A mathematical model for Suzuki cross-coupling reaction was suggested that was able to adequately describe experimental data. The level of reliability (R2) of the correlation between the experimental and calculated data was R2 = 0.97–0.99.

Imaging mitochondrial palladium species in living cells with a NIR iridium(III) complex

The wide use of palladium (Pd) raises the concern about environmental pollution and human diseases, evoking the need for the development of detection methods for Pd species. However, the development of near-infrared (NIR) luminescence probes for subcellular Pd species remains challenging. In this work, we presented a NIR iridium(III) complex-based luminescence probe for the detection of Pd⁰ species through incorporating an allyl group and amino group into the N^N ligand. We found that the probe was capable of detecting Pd⁰ species with a limit of detection (LOD) of 0.5 μM. Importantly, cell imaging experiments showed that the probe is applicable for visualizing mitochondrial Pd⁰ ions in living cells, which are also suitable for Pd(II) species. To the best of our knowledge, this is the first NIR luminescence imaging probe for the detection of mitochondria Pd species in living cells, paving the way for studying subcellular distributions and related toxicity analysis of exogenous Pd species in living cells.

Correlation between coenzyme Q10 content and the nutrient sensors in AKI induced by Hemiscorpius lepturus envenomation

Introduction: Acute kidney injury (AKI) may have a negative effect on mitochondrial hemostasis and bioenergetics as well as coenzyme Q₁₀ (CoQ₁₀) content. PGC-1α, AMPK, sirtuin 1 (Sirt1), and Sirt3, as the key metabolic regulators under nutritional stress, stimulate energy production via mitochondrial biogenesis during AKI. However, no report is available on the relationship between CoQ₁₀ level and nutrient sensors in the pathophysiology of AKI caused by Hemiscorpius lepturus scorpion envenomation. Methods: Three doses of venoms (1, 5, and 10 mg/kg) were administered by subcutaneous (SC) injection to male albino mice. The animals were sacrificed 1 day or 7 days after administration of venom and their kidneys were collected to analyze gene expression involved in AKI, nutrient sensors, and apoptosis signaling activation by real-time polymerase chain reaction (PCR) and the measurement of CoQ₁₀ level using the High-performance liquid chromatography (HPLC) method. Results: The data indicated a significant decrease in CoQ₁₀ level after the administration of venom in 5 and 10 mg/kg. In addition, 1 day after the treatment, a significant over-expression of Sirt1 (5 and 10 mg/kg) was observed compared with normal mice. Overexpression of Sirt3 occurred 1 day and 7 days after treatment only at the dose of 5.0 mg/kg of venom. Furthermore, over-expression of AMPK as an important mitochondrial energetic sensor happened 1 day and 7 days after the injection of venom (5 mg/kg) (P < 0.01). The significant increase in the gene expression of caspase-9 and 3 after the injection of venom (5 and 10 mg/kg) confirmed the role of cell death signaling. Conclusion: The venom-induced energy-sensing pathways have a key role in gene expression of PGC-1α, AMPK, Sirt3, and CoQ₁₀ content after venom-induced AKI.

Hybrid Pd-Nanoparticles within Polymeric Network in Selective Hydrogenation of Alkynols: Influence of Support Porosity

This work is addressing the selective hydrogenation of alkynols over hybrid catalysts containing Pd-nanoparticles, within newly synthesized hyper-cross-linked polystyrenes (HPS). Alkynols containing C₅, C₁₀, and C₂₀ with a terminal triple bond, which are structural analogues or direct semi-products of fragrant substances and fat-soluble vitamins, have been studied. Selective hydrogenation was carried out in a batch mode (ambient hydrogen pressure, at 90 °C, in toluene solvent), using hybrid Pd catalysts with low metal content (less than 0.2 wt.%). The microporous and mesoporous HPS were both synthesized and used as supports in order to address the influence of porosity. Synthesized catalysts were shown to be active and selective: in the case of C₅, hydrogenation selectivity to the target product was more than 95%, at close to complete alkynol conversion. Mesoporous catalysts have shown some advantages in hydrogenation of long-chain alkynols.

A detailed theoretical investigation to unravel the molecular mechanism of the ligand-free copper-catalyzed Suzuki cross-coupling reaction

The Suzuki-Miyaura coupling (SMC) represents a very efficacious method for constructing C-C bonds in organic synthesis. The ligand-free variants of SMC have been grabbing attention these days. Despite this momentousness, the mechanistic details of the ligand-free variants are scant in the literature. Herein, we have carried out a detailed mechanistic investigation into the ligand-free Cu-catalyzed SMC of unsaturated organic halides with aryl boronic acid with the aid of density functional theory (DFT) calculations employing the conductor-like polarizable continuum model (CPCM) method. The present study elucidates that in the absence of ancillary ligands on the metal, the substrates, base, and solvent molecules could act as pseudo-ancillary ligands to facilitate the cross-coupling reaction. The investigation further revealed that unsaturated halides like alkynyl halides/vinyl halides could act as good ancillary ligands for copper by forming a Cu-π intermediate and promoting a facile transmetalation process. However, regarding the oxidative addition and reductive elimination steps, a concerted pathway is observed contrary to Pd catalyzed Suzuki coupling, owing to the instability of Cu(III) species and the favourability of Csp²-Csp bond formation. In the whole set of mechanisms explored, oxidative addition/oxidative nucleophilic substitution was the rate-determining step in all the cases. A thermodynamically stable π-coordinated intermediate species where the substrate and base molecule are coordinated to the metal center is identified as the rate-determining species for the ligand-free Suzuki cross-coupling reaction. The presence of the aforesaid intermediate increases the energy span and consequently the activation barrier for the rate-determining step. This study unveiled a theoretical rationale for the high-temperature requirement in the ligand-free Cu-catalyzed SMC reaction.

A highly sensitive sensor for colorimetric detection of palladium(II) in lysosomes and its applications

Considering the scarcity of palladium ion probes with subcellular organelle targeting, especially probes with near-infrared (NIR) emission wavelength fluorophores, our group has been working to overcome this problem and looking forward to providing potential practical tools for exploring the toxicity of palladium ions at the subcellular level. In this paper, a novel colorimetric and NIR fluorescent probe, BHCy-Pd, for the specific detection of palladium ions (Pd²⁺) in lysosomes via an internal charge-transfer (ICT) mechanism was designed and synthesized. As expected, BHCy-Pd exhibited a rapid, selective, and sensitive response for palladium with an ultralow limit of detection at 5.9 nM, accompanied by a distinct color change from purple to blue. Furthermore, BHCy-Pd can be made into a simple test strip for rapid and easy detection of Pd²⁺ in practical applications. Importantly, BHCy-Pd is capable of specific distribution in lysosomes, and thus can detect Pd²⁺ in real-time, thereby providing a potential tool for studying the cytotoxicity of Pd²⁺ ions at the subcellular level.

Qiangji Jianli Decoction Alleviates Hydrogen Peroxide-Induced Mitochondrial Dysfunction via Regulating Mitochondrial Dynamics and Biogenesis in L6 Myoblasts

Oxidative stress can cause the excessive generation of reactive oxygen species (ROS) and has various adverse effects on muscular mitochondria. Qiangji Jianli decoction (QJJLD) is an effective traditional Chinese medicine (TCM) that is widely applied to improve muscle weakness, and it has active constituents that prevent mitochondrial dysfunction. To investigate the protective mechanism of QJJLD against hydrogen peroxide- (H2O2-) mediated mitochondrial dysfunction in L6 myoblasts. Cell viability was determined with MTT assay. Mitochondrial ultrastructure was detected by transmission electron microscope (TEM). ROS and mitochondrial membrane potential (MMP) were analyzed by fluorescence microscope and flow cytometry. The superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) activity, and malondialdehyde (MDA) level were determined by WST-1, TBA, and DTNB methods, respectively. The mRNA and protein levels were measured by quantitative real-time PCR (qRT-PCR) and Western blot. The cell viability was decreased, and the cellular ROS level was increased when L6 myoblasts were exposed to H2O2. After treatment with QJJLD-containing serum, the SOD and GSH-Px activities were increased. MDA level was decreased concurrently. ROS level was decreased while respiratory chain complex activity and ATP content were increased in L6 myoblasts. MMP loss was attenuated. Mitochondrial ultrastructure was also improved. Simultaneously, the protein expressions of p-AMPK, PGC-1α, NRF1, and TFAM were upregulated. The mRNA and protein expressions of Mfn1/2 and Opa1 were also upregulated while Drp1 and Fis1 were downregulated. These results suggest that QJJLD may alleviate mitochondrial dysfunction through the regulation of mitochondrial dynamics and biogenesis, the inhibition of ROS generation, and the promotion of mitochondrial energy metabolism.

Clozapine attenuates mitochondrial dysfunction, inflammatory gene expression, and behavioral abnormalities in an animal model of schizophrenia

Beyond abnormalities in the neurotransmitter hypothesis, recent evidence suggests that mitochondrial dysfunction and immune-inflammatory responses contribute to the pathophysiology of schizophrenia. The prefrontal cortex (PFC) undergoes maturation and development during adolescence, which is a critical time window in life that is vulnerable to environmental adversities and the development of psychiatric disorders such as schizophrenia. Applying eight weeks of post-weaning social isolation stress (PWSI) to rats, as an animal model of schizophrenia, we decided to investigate the effects of PWSI on the mitochondrial function and expression of immune-inflammatory genes in the PFC of normal and stressed rats. To do this, control and PWSI rats were divided into treatment (clozapine; CLZ, 2.5 mg/kg/day for 28 days) and non-treatment sub-groups. Our results showed PWSI caused schizophrenic-like behaviors in rats and induced mitochondrial dysfunction as well as upregulation of genes associated with innate immunity in the PFC. Chronic treatment with CLZ attenuated the effects of PWSI on behavioral abnormalities, mitochondrial dysfunction, and immune-inflammatory responses in the PFC of rats. These results may advance our understanding about the mechanism of action of CLZ that targets mitochondrial dysfunction and immune-inflammatory responses as factors involved in the pathophysiology of schizophrenia.

Fabrication and characterization of ternary sepiolite/g-C3N4/Pd composites for improvement of photocatalytic degradation of ciprofloxacin under visible light irradiation

The development of high-quality photocatalytic materials for the degradation of organic pollutants under visible light irradiation is a vital field of research. In the present study, a composite of natural sepiolite clay and synthetic graphitic carbon nitride (CN) mixed with dispersed palladium nanoparticles was developed for the efficient photocatalytic degradation of ciprofloxacin (CIP) under visible light irradiation. The sepiolite, CN, and composite materials were characterized by several techniques. The sepiolite/CN composite (SC30%) displayed superior activity than pristine sepiolite and CN, resulted from the generation of new electron trap states in the interfacial contract between sepiolite and CN to suppress the charge recombination of CN. Furthermore, the well-dispersed of 1 wt% Pd-nanoparticles in the SC30% composite collectively enhanced CIP degradation by avoiding the recombination of photogenerated electrons and holes. Additionally, the electron trap states on the surface of all samples were studied using novel reversed double-beam photoacoustic spectroscopy to understand electron transfer in the composites related to the photocatalytic degradation mechanism of CIP. The developed sepiolite/CN/Pd(0) composite can act as a potential catalyst for the degradation of organic pollutants in wastewater under visible light irradiation.

Genetically modified Pichia pastoris, a powerful resistant factory for gold and palladium bioleaching and nanostructure heavy metal biosynthesis

A metal-resistant engineered Pichia pastoris was developed here to fulfil the metal bioleaching in aqueous conditions. Parent and recombinant yeasts were grown in YPD medium containing different concentrations of ion metals. XRD, electron microscopy and particle size analyser were used for the characterisation and the nanoparticle analyses. The nanoparticle production kinetics were studied by ICP-OES. The cytotoxicity of nanoparticles was assayed against human cell lines. Media colours changed to a range from purplish-brown to grey during early fermentation stages. The maximum biosorption capacities were recorded 81.23 and 493.35 mg/g for gold and palladium in batch conditions, respectively. Various physical investigations proved monodispersed spherical nanoparticles around 100 nm in size. Pure palladium nanoparticles and PdCl₂ represented the least cytotoxic potency towards T47D and EPG85.257 cells. The results demonstrated that the genetically modified yeast is a cost-effective, high-throughput, robust, and facile system for metal biosorption.

Palladium-Mediated Cleavage of Proteins with Thiazolidine-Modified Backbone in Live Cells

Chemical protein synthesis and biorthogonal modification chemistries allow production of unique proteins for a range of biological studies. Bond-forming reactions for site-selective protein labeling are commonly used in these endeavors. Selective bond-cleavage reactions, however, are much less explored and still pose a great challenge. In addition, most of studies with modified proteins prepared by either total synthesis or semisynthesis have been applied mainly for in vitro experiments with very limited extension to live cells. Reported here is an approach for studying uniquely modified proteins containing a traceless cell delivery unit and palladium-based cleavable element for chemical activation, and monitoring the effect of these proteins in live cells. This approach is demonstrated for the synthesis of a caged ubiquitin-aldehyde, which was decaged for the inhibition of deubiquitinases in live cells.

Pd(II) complexes with N-heteroaromatic hydrazone ligands: Anticancer activity, in silico and experimental target identification

Anticancer activity of Pd complexes 1-5 with bidentate N-heteroaromatic hydrazone ligands was investigated on human acute monocytic leukemia (THP-1; cells in a suspension) and human mammary adenocarcinoma (MCF-7; two-dimensional layer and three-dimensional spheroid tumor model) cell lines. For the Pd(II) complexes with condensation products of ethyl hydrazainoacetate and quinoline-8-carboxaldehyde (complex 1) and 2-formylpyridine (complex 3), for which apoptosis was determined as a mechanism of anticancer activity, further investigation revealed that they arrest the cell cycle in G0/G1 phase, induce generation of reactive oxygen species and inhibit Topoisomerase I in vitro. In silico studies corroborate experimental findings that these complexes show topoisomerase inhibition activity in the micromolar range and indicate binding to a DNA's minor groove as another potential target. Based on the results obtained by circular dichroism and fluorescence spectroscopy measurements, the most active complexes are suitable to be delivered to a blood stream via human serum albumin.

Melatonin Ameliorates Busulfan-Induced Spermatogonial Stem Cell Oxidative Apoptosis in Mouse Testes

AIMS

Many men endure immunosuppressive or anticancer treatments that contain alkylating agents before the age of sexual maturity, especially the increasing number of preadolescent males who undergo busulfan treatment for myeloablative conditioning before hematopoietic stem cell transplantation. Before sperm production, there are no sperm available for cryopreservation. Thus, it is necessary to identify a solution to ameliorate the busulfan-induced damage of spermatogonial stem cells (SSCs).

RESULTS

In this study, we demonstrated that melatonin relieved the previously described SSC loss and apoptosis in mouse testes. Melatonin increased the expression of manganese superoxide dismutase (MnSOD), which regulated the production of busulfan-induced reactive oxygen species (ROS). Moreover, melatonin promoted sirtuin type 1 (SIRT1) expression. SIRT1 participated in the deacetylation of p53, which promotes p53 ubiquitin degradation. Decreased concentrations of deacetylated p53 resulted in spermatogonial cell resistance to apoptosis. Acute T cell leukemia cell assay demonstrated that melatonin does not affect busulfan-induced cancer cell apoptosis and ROS.

INNOVATION

The current evidence suggests that melatonin may alleviate the side effects of alkylating drugs, such as busulfan.

CONCLUSION

Melatonin promoted MnSOD and SIRT1 expression, which successfully ameliorated busulfan-induced SSC apoptosis caused by high concentrations of ROS and p53. Antioxid. Redox Signal. 28, 385-400.

High-Precision Photothermal Ablation Using Biocompatible Palladium Nanoparticles and Laser Scanning Microscopy

Herein, we report a straightforward method for the scalable preparation of Pd nanoparticles (Pd-NPs) with reduced inherent cytotoxicity and high photothermal conversion capacity. These Pd-NPs are rapidly taken up by cells and able to kill labeled cancer cells upon short exposure to near-infrared (NIR) light. Following cell treatment with Pd-NPs, ablated areas were patterned with high precision by laser scanning microscopy, allowing one to perform cell migration assays with unprecedented accuracy. Using coherent Raman microscopy, cells containing Pd-NPs were simultaneously ablated and imaged. This novel methodology was combined with intravital imaging to mediate microablation of cancerous tissue in tumor xenografts in mice.

Effective Adsorption of Precious Metal Palladium over Polyethyleneimine-Functionalized Alumina Nanopowder and Its Reusability as a Catalyst for Energy and Environmental Applications

Palladium is one of the widely used precious metals toward catalysis, energy, and environmental applications. Efficient recovery and reusability of palladium from the spent catalysts is not only highly desirable for sustainable industrial processing but also for preventing environmental contamination. Here, we present a facile citrate-mediated amine functionalization of alumina nanopowder (AO) in aqueous medium. The surface functionalization is probed using infrared (IR), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis, surface area, and zeta potential measurements. The amine-functionalized sorbent is thoroughly studied for its vital palladium-sorption parameters such as amount of adsorbent, pH, adsorption capacity, thermodynamics, and kinetics. The palladium adsorption over amine-functionalized AO is further characterized with X-ray diffraction and XPS. IR analysis of palladium adsorbed over polyethyleneimine is performed to elucidate the mechanistic insight on the role of nitrogen in capturing palladium. The amine-functionalized sorbent after adsorbing palladium is studied for the catalytic reduction of 4-nitrophenol and Cr(VI) and hydrogen generation from ammonia borane, which demonstrated its excellent catalytic activity and reusability toward energy and environmental applications. The environmentally benign materials and all-aqueous reactions employed in this work demonstrate the potential of the strategy for efficient and economical industrial transformations and waste-stream management.