Search Results (440)

Background/Objectives: Research on noble metal nanoparticles (NPs) has increased over the past three decades, with advancements in synthesis techniques refining their physicochemical characteristics, including size, shape, and surface chemistry. Bimetallic NPs (BNPs) offer synergistic properties contributed by both metals. Gold (Au) and palladium (Pd) NPs possess low toxicity, high biocompatibility and loading, ease of synthesis and surface modification. Doxorubicin (DOX) and 5-fluorouracil (5-FU) are potent chemotherapeutic drugs but are rapidly metabolised in the body, producing severe side effects, limiting their use. Hence, innovative strategies to mitigate this is needed. Methods: In this study, AuPd NPs in a core-shell formation were chemically synthesized. The AuPd NPs were conjugated to 5-FU and DOX-encapsulated CS complexes and decorated with the targeting moiety transferrin (Tf). Results: Transmission electron microscopy and nanoparticle tracking analysis confirmed that the BNPs were spherical, with an average size of 73.4 nm. Functionalized BNPs were able to encapsulate more than 70% of 5-FU and DOX, resulting in a controlled drug release profile at pH 4.2. Cytotoxicity levels in human cancer cells, HeLa (cervical carcinoma) and MCF-7 (breast adenocarcinoma), as well as in non-cancer HEK293 (embryonic kidney) cells, revealed that the Tf-targeted nanocomplexes were HeLa cell-specific, with no significant cytotoxicity in the HEK293 cells. Tf-mediated cellular uptake was confirmed by receptor competition studies in the HeLa cells. Apoptosis and oxidative stress analysis confirmed cell death by apoptosis, consistent with the action of 5-FU and DOX. Conclusions: This study highlighted the potential of this BNP-nanocomplex as a suitable vehicle for drug delivery. Full article

Metal nanoparticles (NPs) with enzyme-mimicking activities, known as nanozymes, are being actively explored for biomedical and analytical applications. Enhancing their catalytic activity and metal utilization efficiency is crucial for advancing these technologies. Here, we report an aqueous-phase, room-temperature synthesis of tetra-metallic Au@Ag-Pd-Pt NPs that exhibit superior peroxidase-like activity compared to their mono-, bi-, and trimetallic counterparts. The synthesis involves a sequential, seed-mediated approach comprising the formation of Au NP seeds, the overgrowth of a Ag shell, and the galvanic replacement of Ag with Pd and Pt ions. We systematically investigated the effects of the Au core diameter (15, 40, 55 nm), Ag precursor concentration (50–400 µM), and the Pd-to-Pt ratio on the optical and catalytic properties. By changing the particle composition, we were able to tune the absorbance maximum from 520 nm to 650 nm while maintaining high extinction coefficients (10⁹–10¹⁰ M⁻¹cm⁻¹) comparable to that of the initial Au nanoparticles. Mapping of chemical element distributions in the nanoscale range confirmed a core–shell–shell architecture with surface-enriched Pd and Pt. This structure ensures the surface-exposed localization of catalytically active atoms, yielding a more than 10-fold improvement in specific peroxidase-like activity while utilizing up to two orders of magnitude less Pt and Pd than bimetallic particles. The synthesized NPs thus combine high catalytic activity with tunable optical properties, making them promising multifunctional labels for biosensing. Full article

The development of hydrogen energy is advancing rapidly, while the progress of hydrogen sensors has been relatively lagging behind and cannot meet the stringent performance requirements of hydrogen energy applications. WO₃ has attracted significant attention due to its highly complementary optical and electrical responses to hydrogen. In this study, hydrogen-sensitive WO₃ thin films characterized by vertically aligned crystallites were fabricated by modulating the substrate temperature and oxygen pressure during pulsed laser deposition. Building upon this foundation, a comprehensive investigation into surface modification strategies for enhancing sensitivity was undertaken. The surface modifications encompassed eight distinct metals and four different metal oxides. Among the metal-modified samples, palladium (Pd) Pd exhibited a markedly enhanced electrical response, defined as the ratio of the resistance in hydrogen-free air to that in hydrogen, of 1022, corresponding to ~45 times higher than the value of 22.4 achieved for Pt-modified films and 120 times higher than the value of 8.4 for Au-modified films. In addition, Pd/WO₃ films showed a measurable optical transmittance change of 9.7%, while all other metal-modified samples exhibited negligible optical responses (<1%). This enhancement is attributable to the catalytic and electronic sensitisation effects of Pd. Conversely, metals such as platinum (Pt), gold (Au), and silver (Ag) elicited negligible optical responses, suggesting minimal catalytic activity. The electrical response in these cases was primarily governed by electronic sensitization effects related to the work function of the metal, with higher work function values correlating with more pronounced sensitization. Regarding metal oxide modifications, the sensitization effect was more substantial when the disparity in work function between the oxide and WO₃ was greater, and this enhancement was found to be independent of the charge carrier type of the modifying oxide. These results offer significant insights into the design principles underlying high-performance WO₃-based hydrogen sensors and underscore the pivotal influence of surface modification in governing their sensing characteristics. Full article

The biomarker carcinoembryonic antigen (CEA) plays an important role in the diagnosis and monitoring of cancer, like breast, surveillance, colon, and liver cancer. The highly sensitive surface plasmon resonance (SPR) sensor presented in this work uses two-dimensional (2D) materials: BP/graphene, and the franckeite layer integrated in a Kretschmann configuration. The sensor structure, which includes a copper (Cu) layer and a CaF₂ prism, is intended to detect CEA in aqueous solutions with high accuracy. The proposed sensor’s performance was assessed using the transfer matrix method (TMM), with particular attention paid to important metrics like sensitivity, figure of merit (FoM), detection accuracy (DA), and penetration depth (PD). The proposed sensor achieved a sensitivity of 307.50 deg/RIU and a FoM of 61.62/RIU at a R_min value of 4.20 × 10⁻⁵ a.u. at a 40 nm Cu thickness, operating at a wavelength of 633 nm. The maximum sensitivity of 348.07 deg/RIU was achieved at 47 nm Cu thickness with BP layer, while the graphene layer yielded maximum sensitivity of 314.32 deg/RIU at the same Cu thickness. The results show that adding 2D layered materials to symmetric SPR sensors greatly improves detection performance, providing a promising foundation for the detection of clinical biomarkers in the future. Full article

In this work, the photocatalytic reduction of CO₂ was innovatively tested with the simultaneous removal and mineralization of a textile contaminant, methylene blue (MB), which acts as a sacrificial agent. The process was carried out in a flow regime under atmospheric conditions, using a liquid-phase photoreactor under UVA illumination with a duration of 24 h per test. Two commercial TiO₂-based photocatalysts, P25 and P90 from Evonik, were used and surface modified through the photodeposition of metallic nanoparticles of Pt, Au, and Pd, as they did not show gas-phase products from CO₂ reduction on their own. The optimal pH was 5, the decreasing order of activity by metal was Pt > Au > Pd, and the optimal MB concentration was 20 ppm. The major products were CH₄ and H₂ in the gas phase. The presence of CH₄ was only detected in the presence of a CO₂ flow. In the liquid phase, carboxylic acids were also detected in small amounts, and in the test, 100 ppm of MB ethanol was additionally detected. A 100% degradation of MB and 72.5% mineralization was achieved under the conditions of highest CH₄ production (20 ppm MB at pH 5 with 4 g·L⁻¹ P25-0.70%Pt). Full article

The ethanol oxidation reaction (EOR) is a key process for direct ethanol fuel cells (DEFCs), offering a high-energy-density and carbon-neutral pathway for sustainable energy conversion. However, the practical implementation of DEFCs is significantly hindered by the EOR due to its sluggish kinetics, complex multi-electron transfer pathways, and severe catalyst poisoning by carbonaceous intermediates. This review provides a comprehensive and mechanistically grounded overview of recent advances in EOR electrocatalysts, with a particular emphasis on the structure–activity relationships of noble metals (Pt, Pd, Rh, Au) and non-noble metals. The effects of catalyst composition, surface structure, and electronic configuration on C–C bond cleavage efficiency, product selectivity (C1 vs. C2), and CO tolerance are critically evaluated. Special attention is given to the mechanistic distinctions among different metal systems, highlighting how these factors influence reaction pathways and catalytic behavior. Key performance-enhancing strategies—including alloying, nanostructuring, surface defect engineering, and support interactions—are systematically discussed, with mechanistic insights supported by in situ characterization and theoretical modeling. Finally, this review identifies major challenges and emerging opportunities, outlining rational design principles for next-generation EOR catalysts that integrate high activity, durability, and scalability for real-world DEFC applications. Full article

Precious metals play an important role in various fields, from industry to jewelry and finance. In the industrial field, it is often necessary to know their mechanical properties. Micro-hardness measurement is a suitable test. In this type of test, the results are usually influenced by the Indentation Size Effect (ISE). The paper addresses the problem of micro-hardness measurement and the subsequent interpretation of the measured values using Meyer’s index n, the PSR method, and the Hays–Kendall approach in order to determine the true, test-load-independent micro-hardness values of gold, silver, palladium, and platinum. The tester Hanemann (manufactured by Carl Zeiss, Jena, Germany) was used to measure micro-hardness. The loads applied during the micro-hardness test were between 0.09807 N and 0.9807 N. Investment precious metals with a declared purity of at least 99.95% were used for the measurements. Palladium and silver have a Meyer index close to the validity of Kick’s law, with neutral ISE. Gold and platinum show a slightly “normal” ISE. This may be the influence of the previous deformation of the sample. Full article

To reduce energy consumption in buildings and to maintain comfortable conditions, lighting equipment that includes light-emitting diode (LED) lamps and lighting management equipment is utilised. In this study, integrated circuits detached from lighting equipment were characterised for the presence of precious metals (silver, gold, palladium, and platinum). Their digestion was carried out with HNO₃ and aqua regia solution on a hot plate and characterised using inductively coupled plasma optical emission spectroscopy (ICP-OES). The concentration of each element as a function of the type and origin of the integrated circuits varied as follows: silver, 652–3876 mg/kg; gold, 0–993 mg/kg; palladium, 0–74 mg/kg; and platinum was detected at a concentration below the quantification limit. These results indicate the need for selective removal and separate recycling processes for integrated circuits from the lighting equipment. Full article

Indium oxide-based gas sensors have been proven to be a promising material for detecting nitrogen dioxide (NO₂) gas because of its wide bandgap and stability. In this paper, the enhancement mechanism for the sensitivity of indium oxide NO₂ gas sensors was systematically investigated using density functional theory (DFT) calculations and experimental validation with noble metals like Au, Ag, Pt, Pd, and Cu. We have fabricated a GaN nanowire-based NO₂ gas sensor functionalized with In₂O₃ and decorated with noble metals using a standard fabrication technique. Experimental tests showed that Au/In₂O₃ sensors exhibited the highest response of 38.9% followed by bare In₂O₃ with 10% for 10 ppm NO₂ at room temperature. The sensing properties were mainly attributed to a spillover effect or catalytic performance of Au with In₂O₃. The adsorption energies, charge transfers, and band gap confirm the enhanced sensing capability of Au-decorated Indium oxide for a NO₂ gas sensor. Full article

Environmental contamination is a critical global concern, primarily due to detrimental greenhouse gas (GHG) emissions, especially carbon dioxide (CO₂), which significantly contribute to climate change. Moreover, the presence of harmful heavy metals like Ni, Cd, Cu, Hg, and Pb in soil and water ecosystems has led to poor water quality. Noble metal nanoparticles (MNPs), for instance, Pd, Ag, Pt, and Au, have emerged as promising solutions for addressing environmental pollution. However, the practical utilization of MNPs faces challenges as they tend to aggregate and lose stability. To overcome this issue, the reverse double-solvent method (RDSM) was utilized to synthesis melamine-based porous polyaminals (POPs) as a supportive material for the in situ growing of silver nanoparticles (Ag NPs). The porous structure of melamine-based porous polyaminals, featuring aminal-linked (-HN-C-NH-) and triazine groups, provides excellent binding sites for capturing Ag⁺ ions, thereby improving the dispersion and stability of the nanoparticles. The resulting material exhibited ultrafine particle sizes for Ag NPs, and the incorporation of Ag NPs within the porous polyaminals demonstrated a high surface area (~279 m²/g) and total pore volume (1.21 cm³/g), encompassing micropores and mesopores. Additionally, the Ag NPs@POPs showcased significant capacity for CO₂ capture (2.99 mmol/g at 273 K and 1 bar) and effectively removed Cu (II), with a remarkable removal efficiency of 99.04%. The nitrogen-rich porous polyaminals offer promising prospects for immobilizing and encapsulating Ag nanoparticles, making them outstanding adsorbents for selectively capturing carbon dioxide and removing metal ions. Pursuing this approach holds immense potential for various environmental applications. Full article

To investigate how sweating–drying processing affects the components, antioxidant activity, and hepatoprotective mechanisms of Eucommia ulmoides (EUB) against acute liver injury (ALI), this study constructed a “processing–active components–ALI targets” network. Eight processed EUB samples were analyzed using HPLC fingerprinting, multi-assay antioxidant tests (DPPH/ABTS·+/pyrogallol), network pharmacology, and molecular docking. Sweating–drying significantly altered EUB’s chemical profile, with HPLC fingerprint similarities ranging from 0.715 to 1.000, the lowest being for FG4 (40 °C dried after sweating) and FD (freeze-dried after sweating). Key components (chlorogenic acid (CA), pinoresinol diglucoside (PDG), aucubin (AU), geniposidic acid (GPA)) varied: XS (sun-dried) had the highest CA/PDG, while FG4 showed increased AU/GPA. FY (shade-dried after sweating) exhibited the strongest free radical scavenging (DPPH/ABTS·+/pyrogallol IC₅₀ = 0.828, 0.134, 14.200 mg/mL), which correlated with CA/PDG/liriodendrin (PD) synergy. Network pharmacology identified 205 EUB-ALI intersection targets (core: TNF, PTGS2, GAPDH) and the AGE-RAGE pathway; molecular docking confirmed strong CA/PDG binding to GAPDH/PTGS2. This study clarifies how processing regulates EUB’s components and their links to antioxidant and hepatoprotective effects, providing scientific support for EUB’s clinical application against ALI. Full article

Excessive use of antibiotics can lead to antibiotic resistance, posing a significant threat to human health and the environment. Chloramphenicol (CAP), once widely used, has been banned in many regions for over 20 years due to its toxicity. Detecting CAP residues in food products is crucial for regulating safe use and preventing unnecessary antibiotic exposure. Electrochemical sensors are low-cost, sensitive, and easily detect CAP. This paper reviews recent research on electrochemical sensors for CAP detection, with a focus on the materials and fabrication techniques employed. The sensors are evaluated based on key performance parameters, including limit of detection, sensitivity, linear range, selectivity, and the ability to perform simultaneous detection. Specifically, we highlight the use of metal and carbon-based electrode modifications, including gold nanoparticles (AuNPs), nickel–cobalt (Ni-Co) hollow nano boxes, platinum–palladium (Pt-Pd), graphene (Gr), and covalent organic frameworks (COFs), as well as molecularly imprinted polymers (MIPs) such as polyaniline (PANI) and poly(o-phenylenediamine) (P(o-PD)). The mechanisms by which these modifications enhance CAP detection are discussed, including improved conductivity, increased surface-to-volume ratio, and enhanced binding site availability. The reviewed sensors demonstrated promising results, with some exhibiting high selectivity and sensitivity, and the effective detection of CAP in complex sample matrices. This review aims to support the development of next-generation sensors for antibiotic monitoring and contribute to global efforts to combat antibiotic resistance. Full article

This review examines the emerging role of manganese-based nanoparticles (Mn-NPs) in detecting heavy metal pollutants in environmental matrices. Heavy metals such as cadmium, lead, zinc, and copper pose serious environmental and health concerns due to their tendency to persist in ecosystems and accumulate in living organisms. As a result, there is a growing need for reliable methods to detect and remove these pollutants. Manganese nanoparticles offer unique advantages that scientists could consider as replacing other metal nanoparticles, which may be more expensive or more toxic. The physicochemical properties of Mn-NPs—including their multiple oxidation states, magnetic susceptibility, catalytic capabilities, and semiconductor conductivity—enable the development of multi-modal sensing platforms with exceptional sensitivity and selectivity. While Mn-NPs exhibit inherently low electrical conductivity, strategies such as transition metal doping and the formation of composites with conductive materials have successfully addressed this limitation. Compared to noble metal nanoparticles (Au, Ag, Pd) and other base metal nanoparticles (Bi, Fe₃O₄), Mn-NPs demonstrate competitive performance without the drawbacks of high cost, complex synthesis, poor distribution control, or significant aggregation. Preliminary studies retrieved from the Scopus database highlight promising applications of manganese-based nanomaterials in electrochemical sensing of heavy metals, with recent developments showing detection limits in the sub-ppb range. Future research directions should focus on addressing challenges related to scalability, cost-effectiveness, and integration with existing water treatment infrastructure to accelerate the transition from laboratory findings to practical environmental applications. Full article

The Jinbaoshan Pt-Pd deposit is China’s largest independent PGM deposit. However, the deposit has not been utilized until now because of the low grade of precious metals, the complex mineral composition, and, notably, the presence of precious metals in the microgranular material disseminated to other minerals. Its high MgO content, in particular, is regarded as a challenge for efficiently recovering precious metals via mature pyrometallurgical methods. In this research, the feasibility of a smelting process to recover precious metals from Jinbaoshan Pt-Pd concentrates at a conventional smelting temperature (1350 °C) with the addition of iron ore as a metal collector and SiO₂ and CaO as fluxes was verified on the basis of thermodynamic slag design and experimental analyses. Under the optimal conditions of 100 g of the Pt-Pd concentrates, 32.5 g of SiO₂, 7.5 g of CaO, and 30 g of iron ore at 1350 °C for 1 h, the extraction efficiencies of Au, Pt, and Pd were 94.66%, 96.75%, and 97.28%, respectively. This strategy enables the rapid collection of PGMs from Jinbaoshan Pt-Pd concentrates at the conventional temperature within a short time and minimizes the use of fluxes and collectors, contributing to energy and cost conservation. Full article

In a previous article, an estimation procedure for calculating the liquidus and solidus lines of binary equilibrium phase diagrams was presented. In this article, keeping the thermodynamic basics, the estimation method for the approximate calculation of the liquidus and solidus surfaces of ternary phase diagrams was further developed. It is shown that the procedure has a hierarchical structure, and the ternary functions contain the binary functions. The applicability of the method is checked by calculating the liquidus and solidus surfaces of the Ag-Au-Pd isomorphous ternary equilibrium phase diagram. The application of each level of the developed four-level procedure depends on the data available and the aim. It is shown that in the case of a concentration range close to the base alloy pure element, the liquidus and solidus surfaces of the ternary equilibrium phase diagram can be calculated from the liquidus and solidus functions of the binary equilibrium phase diagrams with a few K errors, which is 0.2 at% at 10 K/at% slope. The equilibrium phase diagrams were available in graphical form, so the data obtained via digitalisation of the diagrams for the calculations was used. The functions describe the slope of the surfaces, and the approximate method developed for the calculation of the partition ratios is also shown. Full article