Search Results (80)

The slurry aluminizing process is widely employed to enhance the oxidation and corrosion resistance of nickel-based superalloys used in high-temperature environments such as gas turbines and aerospace engines. This study investigates the effects of the concentration of Al vapors in the reactor chamber and the initial slurry layer thickness on the microstructure, chemical composition, and phase composition of aluminide coatings. Coatings were manufactured on Ni-based superalloy substrates using CrAl powders as an aluminum source and chloride- and fluoride-based activator salts. The effect of the initial thickness of the slurry layer was studied by varying the amount of deposited slurry in terms of mg_slurry/cm²_sample (with constant mg_slurry/cm³_chamber). The microstructure and phase composition of the produced aluminide coatings were evaluated by SEM, EDS, and XRD analysis. Slurry thickness can affect concentration gradients during diffusion, and the best results were obtained with an initial slurry amount of 100 mg_slurry/cm²_sample. The effect of the Al vapor phase in the reaction chamber was then investigated by varying the mg_slurry/cm³_chamber ratio while keeping the slurry layer thickness constant at 100 mg_slurry/cm²_sample. This parameter influences the amount of Al at the substrate surface before the onset of solid-state diffusion, and the best results were obtained for a 6.50 mg_slurry/cm³_chamber ratio with the formation of 80 µm coatings (excluding the interdiffusion zone) with a β-NiAl phase throughout the thickness. To validate process flexibility, the same parameters were successfully applied to produce platinum-modified aluminides with a bi-phasic ζ-PtAl2 and β-(Ni,Pt)Al microstructure. Full article

Neurodegenerative diseases (NDDs), including Alzheimer’s disease (AD) and Parkinson’s disease (PD), are characterized by progressive neuronal dysfunction and loss and represent a significant global health challenge. Oxidative stress, neuroinflammation, and neurotransmitter dysregulation, particularly affecting acetylcholine (ACh) and monoamines, are key hallmarks of these conditions. The current therapeutic strategies targeting cholinergic and monoaminergic systems have some limitations, highlighting the need for novel approaches. Metallodrugs, especially ruthenium and platinum complexes, are gaining attention for their therapeutic use. Among metal complexes, gold(I) and silver(I) N-heterocyclic carbene (NHC) complexes exhibit several biological activities, but their application in NDDs, particularly as monoamine oxidase (MAO) inhibitors, remains largely unexplored. To advance the understanding of this field, we designed, synthesized, and evaluated the biological activity of a new series of Au(I) and Ag(I) complexes stabilized by NHC ligands and bearing a carboxylate salt of tert-butyloxycarbonyl (Boc)-N-protected proline as an anionic ligand. Through in silico and in vitro studies, we assessed their potential as acetylcholinesterase (AChE) and MAO inhibitors, as well as their antioxidant and anti-inflammatory properties, aiming to contribute to the development of potential novel therapeutic agents for NDD management. Full article

An efficient protocol was developed for the microwave-mediated metallation of 5-(4-methoxycarbonylphenyl)-10,15,20-tris(pentafluorophenyl)porphyrin (P1) with bis(benzonitrile)platinum dichloride salt and subsequent 1,3-dipolar cycloaddition of the resulting PtP1 with an azomethine ylide to give two isomeric metallochlorins: PtC1 (main isomer) and PtC3. The methyl ester group of metalloporphyrin PtP1 and metallochlorin PtC1 was successfully hydrolysed in an alkaline medium to yield the corresponding derivatives PtP2 and PtC2 in moderate-to-good yields. As a proof of concept of the reactivity of the carboxy group in PtP2 and PtC2, these compounds were conjugated with a hydroxylated derivative of indomethacin, a known potent non-steroidal anti-inflammatory, obtaining the conjugates PtP2-Ind and PtC2-Ind. The obtained platinum(II) porphyrins and chlorins were characterized by UV-Vis, NMR spectroscopy and mass spectrometry. The structure of PtP1 was also confirmed by X-ray crystallography. Singlet oxygen generation studies were carried out, as well as theoretical calculations, which demonstrated that the prepared Pt(II) complexes can be considered potential photosensitizers for PDT. Full article

Noble metals are widely recognized for their ability to catalyze the electro-oxidation of organic compounds, with smaller particle sizes significantly enhancing electrocatalytic activity. In this study, catalytic electrodes decorated with atomic-level platinum and Pt-Au clusters were fabricated using cyclic atomic-metal electrodeposition. The interactions between the iminium (protonated imine) groups in emeraldine salt polyaniline (PANI) and metal chloride complexes in the electrolyte enabled precise control over the cluster size and composition. The electrocatalytic activity of these electrodes for propanol oxidation was systematically evaluated using cyclic voltammetry (CV). Notably, PANI electrodes decorated with odd-numbered atomic-level Pt clusters exhibited higher peak oxidation currents compared to even-numbered clusters, revealing a unique even–odd effect. For atomic-level Pt-Au clusters, the catalytic activity was significantly influenced by the sequence of Pt and Au deposition, with PANI-Au₁Pt₃ achieving the highest catalytic activity (35.34 mA/cm²). Bi-metallic clusters consistently outperformed mono-metallic clusters, and clusters containing only one Pt atom demonstrated superior catalytic activity. These findings provide valuable insights into the design of high-performance catalytic electrodes by leveraging atomic-level control of the cluster size, composition, and deposition sequence, paving the way for advanced applications in electrochemical sensors. Full article

Deep eutectic solvents (DESs) are environmentally friendly solvents formed by combining hydrogen bond donors and acceptors, resulting in a eutectic mixture with a lower melting point than the individual components. While there is extensive research on the electrochemical synthesis of platinum nanoparticles in DESs, to the best of our knowledge, there are no studies on the chemical reactivity of platinum(II) complexes in these systems. This study investigates the simple model reaction between K₂PtCl₄ and ethylenediamine (en), exploring the behaviour in DES environment, to optimize the synthesis of simple cisplatin-like platinum compounds with the potential objective of improving the traditional methods, decreasing the number of steps required for obtaining target compounds and reducing chemical waste. The reactions were performed in two hydrophilic DESs: choline chloride:glycerol 1:2 (glyceline, GL) and choline chloride:ethylene glycol 1:2 (ethaline, EG). The experiments, conducted in a 70% (v/v) DES and 30% 1:1 H₂O/D₂O mixture to allow for direct NMR analysis, revealed that en quickly formed [PtCl₂(en)], which further reacted to produce [Pt(en)₂]Cl₂. Reaction products were characterised by 1D (¹H and ¹⁹⁵Pt{¹H}) and 2D ([¹H,¹³C]-HSQC and [¹H,¹⁵N]-HSQC) NMR experiments. The discolouration of solutions, due to the consumption of K₂PtCl₄, and the precipitation of the purple Magnus salt [Pt(en)₂][PtCl₄] occurred over time. The main observed difference between the two solvent mixtures was the slower reactivity in glyceline, due to the much higher viscosity of the solution. Diffusion-ordered spectroscopy (DOSY) indicated lower water mobility in DES mixtures than pure water, with the reaction products closely associated with DES molecules. Full article

Nanozymes, exemplified by metal nanoparticles, have shown promise in the fields of biological diagnostics and therapeutics. However, their practical application is often hindered by aggregation or deactivation in complex biological systems. Here, we develop a DNA-engineered nanozyme coating to preserve the peroxidase-like catalytic activity of platinum nanoparticles in complex biological environments. We employed thiol-modified single-stranded DNA to coat the platinum nanoparticles through metal–sulfur interaction. We found that the negatively charged DNA coating prevents the aggregation of platinum nanoparticles in high-salt environments. Moreover, the DNA coating functions as a molecular sieve, inhibiting non-specific protein adsorption while preserving substrate access to the catalytic interface, thus sustaining high peroxidase-like catalytic activity in serum. As a proof of concept, we demonstrate miRNA detection in serum samples with a detection limit of 1 fM. This approach offers a versatile strategy for molecular diagnostics of nanozymes in complex biological environments. Full article

Metallic Pd/Ni gauzes, located downstream of the Pt/Rh ammonia oxidation catalyst nets in the Ostwald process, is the current technology for capturing volatile gas phase platinum and rhodium species lost from the Pt/Rh combustion catalyst through evaporation. In this screening study, we explore four oxide families, ABO₃ perovskites, (ABO₃)_n(AO) Ruddlesden–Popper (RP) phases, AO rock salt, and A₂O₃ sesquioxide type oxides, as alternative materials for platinum capture. It was found that all the tested nickelates, LaNiO₃, NdNiO₃, La₂NiO₄, and La₄Ni₃O₁₀, captured platinum well and formed A₂NiPtO₆. In contrast, La_0.85Sr_0.15FeO₃, LaFeO₃, and LaCoO₃ did not capture platinum. CaO, SrO, and Nd₂O₃ formed low-dimensional platinates such as Ca_xPt₃O₄, Sr₄PtO₆, and a newly discovered neodymium platinate, Nd_10.67Pt₄O₂₄. Gd₂O₃ did not capture platinum in bench-scale experiments in dry air, but did, however, seem to capture platinum under pilot plant conditions, likely due to the co-capture of Co lost from the N₂O abatement catalyst. The catalytic activity of both oxides and platinum-containing products were studied, toward NO_x and N₂O decomposition. None of the oxides showed significant activity toward NO_x decomposition, and all showed activity toward N₂O decomposition, but to different extents. An overall assessment of the screened oxides with respect to potential use in industrial Ostwald conditions is provided. All tested oxides except CaO and SrO withstood industrial conditions. From our assessments, the nickelates and A₂O₃ (A = Nd, Gd) stand out as superior oxides for platinum capture. Full article

Developing non-noble metal catalysts that exhibit oxygen reduction reaction (ORR) activity comparable to or exceeding that of platinum-based catalysts remains a significant challenge. This research presents the successful fabrication of novel cobalt-nitrogen (Co-N) catalysts through a straightforward one-step synthesis method. This method involves stirring a mixture of cobalt (II) nitrate, polyhexamethylene guanidine (PHMG) as a nitrogen source, and carbon spheres at ambient temperature. By varying the mass ratio of PHMG to cobalt salt, three distinct catalyst formulations were produced. The catalyst with an optimal PHMG-to-cobalt nitrate ratio of 2:1 (Co-PHMG-2@C) exhibited exceptional electrocatalytic activity for the oxygen reduction reaction (ORR) in alkaline electrolytes. This catalyst demonstrated a high onset potential of 0.97 V and a half-wave potential of 0.82 V versus the reversible hydrogen electrode (RHE), favorably comparable to those of the benchmark Pt/C catalyst (1.02 V vs. RHE). Furthermore, Co-PHMG-2@C displayed superior stability and resistance to methanol poisoning. The scalability of this synthesis technique offers a promising pathway for cost-effective and environmentally friendly production of carbon nanomaterials for applications in fuel cells and other electrochemical energy devices. Full article

Developing an efficient recycling route for spent single-use medical devices is essential for recovering precious metals. The proposed complete hydrometallurgical route goes through the initial pyrolysis and acid digestion steps, expanding upon our previous relevant work in the field, followed by solvent extraction, stripping, and precipitation procedures. In this study, a complete hydrometallurgical process was developed for the recovery of gold, platinum, iridium, and tantalum, separating them from other metals, i.e., from iron, chromium, and nickel, also present in the examined medical devices, i.e., (i) diagnostic electrophysiology catheters, containing gold, (ii) diagnostic guide wires, containing platinum and iridium alloys, and (iii) self-expanding stents, containing tantalum. This study reports the experimental results of selecting an efficient extractant, stripping, and precipitation agent, along with the effects of key factors that influence each consecutive step of the process, i.e., agent concentration, aqueous to organic phase ratio, contact time, and pH, using simulated metal solutions and also applying the obtained optimal conditions to the treatment of real sample solutions. For the selective separation of gold, Aliquat 336 was used to extract it in the organic phase; it was then stripped using a thiourea solution and precipitated by utilizing an iron sulfate (II) solution and proper pH adjustment. The selective separation of platinum was achieved by using Aliquat 336 for the organic phase extraction and a perchlorate acid solution for stripping it back into the aqueous solution and adding a sodium bromate solution to precipitate it. Due to the similar chemical behavior, the selective recovery of iridium followed the same processes as that of platinum, and the separation between them was achieved through selective precipitation, as heating the solution and adjusting the pH value resulted in the selective precipitation of iridium. Lastly, the selective recovery of tantalum consists of extraction by using Alamine 336, then stripping it back to the aqueous phase by using sodium chloride, and precipitation by using potassium salt solution and proper pH adjustment. A total recovery of 88% for Au, 86% for Pt, 84% for Ir, and 80% for Ta was obtained, thus achieving a high uptake of precious metals from the examined real spent/waste samples. Full article

In this paper, platinum nanoparticles with a size of less than 50 nm were rapidly and successfully synthesized in low-temperature molten salt using a microwave method. The morphology and structure of the product were characterized by SEM, TEM, EDX, XRD, etc. The TEM and SEM results showed that the prepared product was a nanostructure with concave and uniform size. The EDX result indicated that the product was pure Pt, and the XRD pattern showed that the diffraction peaks of the product were consistent with the standard spectrum of platinum. The obtained Pt/C nanoparticles exhibited remarkable electrochemical performance in a formic acid catalytic oxidation reaction (FAOR), with a peak mass current density of 502.00 mA·mg⁻¹_Pt and primarily following the direct catalytic oxidation pathway. In addition, in the chronoamperometry test, after 24 h, the mass-specific activity value of the Pt concave NPs/C catalyst (10.91 mA·mg⁻¹_Pt) was approximately 4.5 times that of Pt/C (JM) (2.35 mA·mg⁻¹_Pt). The Pt/C NPs exhibited much higher formic acid catalytic activity and stability than commercial Pt/C. The microwave method can be extended to the preparation of platinum-based alloys as well as other catalysts. Full article

Although their efficacy has been well-established in Oncology, the use of platinum salts remains limited due to the occurrence of acute kidney injury (AKI). Caffeine has been suggested as a potential pathophysiological actor of platinum-salt-induced AKI, through its hemodynamic effects. This work aims to study the association between caffeine consumption and the risk of platinum-salt-induced AKI, based on both clinical and experimental data. The clinical study involved a single-center prospective cohort study including all consecutive thoracic cancer patients receiving a first-line platinum-salt (cisplatin or carboplatin) chemotherapy between January 2017 and December 2018. The association between daily caffeine consumption (assessed by a validated auto-questionnaire) and the risk of platinum-salt induced AKI or death was estimated by cause-specific Cox proportional hazards models adjusted for several known confounders. Cellular viability, relative renal NGAL expression and/or BUN levels were assessed in models of renal tubular cells and mice co-exposed to cisplatin and increasing doses of caffeine. Overall, 108 patients were included (mean age 61.7 years, 65% men, 80% tobacco users), among whom 34 (31.5%) experienced a platinum-salt-induced AKI (67% Grade 1) over a 6-month median follow-up. The group of high-caffeine consumption (≥386 mg/day) had a two-fold higher hazard of AKI (adjusted HR [95% CI], 2.19 [1.05; 4.57]), without any significant association with mortality. These results are consistent with experimental data confirming enhanced cisplatin-related nephrotoxicity in the presence of increasing doses of caffeine, in both in vitro and in vivo models. Overall, this study suggests a potentially deleterious effect of high doses of daily caffeine consumption on the risk of platinum-salt-related AKI, in both clinical and experimental settings. Full article

Platinum and taxane chemotherapy is associated with the risk of hypersensitivity reactions (HSRs), which may require switching to less effective treatments. Desensitization to platinum and taxane HSRs can be used to complete chemotherapy according to the standard regimen. Therefore, we aimed to investigate the current management of HSRs to platinum and/or taxane chemotherapy in patients with gynecologic cancers. We conducted an online cross-sectional survey among gynecological and medical oncologists consisting of 33 questions. A total of 144 respondents completed the survey, and 133 respondents were included in the final analysis. Most participants were gynecologic oncologists (43.6%) and medical oncologists (33.8%), and 77.4% (n = 103) were involved in chemotherapy treatment. More than 73% of participants experienced >5 HSRs to platinum and taxane per year. Premedication and a new attempt with platinum or taxane chemotherapy were used in 84.8% and 92.5% of Grade 1–2 HSRs to platinum and taxane, respectively. In contrast, desensitization was used in 49.4% and 41.8% of Grade 3–4 HSRs to platinum and taxane, respectively. Most participants strongly emphasized the need to standardize the management of platinum and taxane HSRs in gynecologic cancer. Our study showed that HSRs in gynecologic cancer are common, but management is variable and the use of desensitization is low. In addition, the need for guidance on the management of platinum- and taxane-induced HSRs in gynecologic cancer was highlighted. Full article

This paper presents a detailed study of a titanium–platinum thin film-based electrode preparation and its practical application in the electrooxidation of cyanides to help protect our environment. The novel electrochemical deposition process of Pt on nearly atomically smooth magnetron-sputtered Ti film has been used to prepare a highly effective glass|Ti|Pt composite electrode with high catalytic activity for the electrooxidation of cyanide ions. The composite electrode exhibits over a 90% electrical current efficiency in the cyanide electrooxidation process and can be used for the decontamination of highly concentrated KCN solutions (up to 0.1 M) without any chemical additives. A high current efficiency (70%) of Pt thin film deposition on a glass|Ti electrode was achieved using a potentiostatic double-pulse method. Fast Fourier transform electrochemical impedance spectroscopy revealed the oxidation kinetics for cyanide ions at the electrode. The glass|Ti electrode was prepared using the magnetron sputtering technique, which allows us to fabricate electrodes of any shape suitable for any electrochemical cell or electroplating bath. Meanwhile, electrochemical deposition of Pt on the glass|Ti electrode is an efficient and environmentally friendly method, since various salts of Pt and/or Pt-containing wastes can be used for electrodeposition instead of pure Pt, which is more expensive. Full article

Epithelial ovarian cancer (EOC) is the leading cause of death from gynecological cancers in Western countries. High-Grade Serous Ovarian Carcinoma (HGSOC) accounts for 60–70% of EOC and is the most aggressive subtype. Reduced PTPN13 expression levels have been previously correlated with worse prognosis in HGSOC. However, PTPN13’s exact role and mechanism of action in these tumors remained to be investigated. To elucidate PTPN13’s role in HGSOC aggressiveness, we used isogenic PTPN13-overexpressing clones of the OVCAR-8 cell line, which poorly expresses PTPN13, and also PTPN13 CRISPR/Cas9-mediated knockout/knockdown clones of the KURAMOCHI cell line, which strongly expresses PTPN13. We investigated their migratory and invasive capacity using a wound healing assay, their mesenchymal-epithelial transition (EMT) status using microscopy and RT-qPCR, and their sensitivity to chemotherapeutic drugs used for HGSOC. We found that (i) PTPN13 knockout/knockdown increased migration and invasion in KURAMOCHI cells that also displayed a more mesenchymal phenotype and increased expression of the SLUG, SNAIL, ZEB-1, and ZEB-2 EMT master genes; and (ii) PTPN13 expression increased the platinum sensitivity of HGSOC cells. These results suggest that PTPN13 might be a predictive marker of response to platinum salts in HGSOC. Full article

The development of efficient, reliable, and sensitive dopamine detection methods has attracted much attention. In this paper, vancomycin-stabilized platinum nanoparticles (Van-Pt_n NPs, n = 0.5, 1, 2) were prepared by the biological template method, where n represented the molar ratio of vancomycin to Pt. The results show that Van-Pt₂ NPs had oxidase-like activity and peroxidase-like activity, and the mechanism was due to the generation of reactive oxygen ¹O₂ and OH. Van-Pt₂ NPs exhibited good temperature stability, storage stability, and salt solution stability. Furthermore, Van-Pt₂ NPs had almost no cytotoxicity to A549 cells. More importantly, the colorimetric detection of DA in human serum samples was performed based on the oxidase-like activity of Van-Pt₂ NPs. The linear range of DA detection was 10–700 μM, and the detection limit was 0.854 μM. This study establishes a rapid and reliable method for the detection of dopamine and extends the application of biosynthetic nanoparticles in the field of biosensing. Full article