Search Results (33)

This work is devoted to the study of the effect of small Bi additives on the functional properties of Pdx:Bi/Al₂O₃ catalysts in the selective oxidation of glucose to gluconic acid. The catalysts obtained by the joint impregnation method were characterized (TEM) by high dispersion of bimetallic nanoparticles with a median diameter of 4–5 nm. The structure of the Pd-Bi solid solution was confirmed via XPS and showed a change in the valence state of Pd and Bi depending on the Bi content, as well as the fraction of the oxidized state of Bi. TPR-H₂ revealed various forms of Pd, including PdO and mixed Pd-O-Bi structures. The Pd10:Bi1/Al₂O₃ catalyst demonstrated the highest efficiency (77.2% glucose conversion, 96% sodium gluconate selectivity), which is due to the optimal ratio between Pd and Bi, ensuring the stabilization of metallic Pd and preventing its oxidation. Full article

Chemical sensors, relying on electrical conductance changes in a gas-sensitive material due to the surrounding gas, have the (dis-)advantage of reacting with multiple target gases and humidity. In this work, we report CMOS-integrated SnO₂ thin film-based gas sensors, which are functionalized with mono-, bi-, and trimetallic nanoparticles (NPs) to optimize the sensor performance. The spray pyrolysis technology was used to deposit the metal oxide sensing layer on top of a CMOS-fabricated micro-hotplate (µhp), and magnetron sputtering inert-gas condensation was employed to functionalize the sensing layer with metallic NPs, Ag-, Pd-, and Ru-NPs, and all combinations thereof were used as catalysts to improve the sensor response to carbon monoxide and to suppress the cross-sensitivity toward humidity. The focus of this work is the detection of toxic carbon monoxide and a specific hydrocarbon mixture (HC_mix) in a concentration range of 5–50 ppm at different temperatures and humidity levels. The use of CMOS chips ensures low-power, integrated sensors, ready to apply in cell phones, watches, etc., for air quality-monitoring purposes. Full article

We demonstrate the systematic optimization of SnO₂-based thin-film chemical sensors by using mono-, bi- and tri metallic nanoparticles (NPs) composed of Ag, Pd, and Ru, which are deposited via magnetron sputtering inert gas condensation. The ultrathin SnO₂ films are integrated on CMOS-based micro-hotplate devices, where each chip contains 16 sensor devices in total. We found that the response of the sensor device can be significantly tuned to specific target gases, such as CO and VOCs, by using various types of NPs. Full article

Stable palladium (II) complexes, incorporating a double (N-benzoylthiourea) arrangement bonded to a complex heterocyclic scaffold, are used as precursors of catalytic species able to promote Suzuki–Miyaura, Mizoroki–Heck, Hiyama, Buchwald–Hartwig, Hirao and Sonogashira–Hagihara cross-coupling transformations in water. These sustainable processes are chemoselective and very versatile. The nanoparticles responsible for these catalytic reactions were analyzed and studied. Their usefulness is demonstrated after several tests and analyses. The heterogeneous character of this species in water was also confirmed. Full article

Surface-modified nanoplate-shaped thermoelectric materials can achieve good thermoelectric performance. Herein, single-crystalline Bi₂Te₃ nanoplates with regular hexagonal shapes were prepared via solvothermal techniques. Surface modification was performed to deposit different metals onto the nanoplates using electroless deposition. Nanoparticle-shaped tin (Sn) and layer-shaped palladium (Pd) formed on the Bi₂Te₃ nanoplates via electroless deposition. For the sequential deposition of Sn and Pd, the surface morphology was mostly the same as that of the Sn-Bi₂Te₃ nanoplates. To assess the thermoelectric properties of the nanoplates as closely as possible, they were compressed into thin bulk shapes at 300 K. The Sn-Bi₂Te₃ and Sn/Pd-Bi₂Te₃ nanoplates exhibited the lowest lattice thermal conductivity of 1.1 W/(m·K), indicating that nanoparticle-shaped Sn facilitated the scattering of phonons. By contrast, the Pd-Bi₂Te₃ nanoplates exhibited the highest electrical conductivity. Thus, the highest power factor (15 μW/(m∙K²)) and dimensionless ZT (32 × 10⁻³) were obtained for the Pd-Bi₂Te₃ nanoplates. These thermoelectric properties were not as high as those of the sintered Bi₂Te₃ samples; however, this study revealed the effect of different metal depositions on Bi₂Te₃ nanoplates for improving thermoelectric performance. These findings offer venues for improving thermoelectric performance by sintering nanoplates deposited with appropriate metals. Full article

Palladium–bismuth nanomaterials are used in various chemical applications such detectors, electrodes, and catalysts. Pd-Bi catalysts are attracting widespread interest because these catalysts enable the production of valuable products quickly and efficiently, and are environmentally friendly. However, the composition of the catalyst can have a significant impact on its catalytic performance. In this work, we identified a correlation between the composition of the catalyst and its efficiency in converting glucose into sodium gluconate. It was found that the conversion decreases with increasing bismuth content. The most active catalyst was the 0.35Bi:Pd sample with a lower bismuth content (glucose conversion of 57%). TEM, SEM, EXAFS, and XANES methods were used to describe, in detail, the surface properties of the xBi:Pd/Al₂O₃ catalyst samples. The increase in particle size with increasing bismuth content, observed in the TEM micrographs, was associated with the low melting point of bismuth (271 °C). The SEM method showed that palladium and bismuth particles were uniformly distributed over the surface of the support in close proximity to each other, which allowed us to conclude that an alloy of non-stoichiometric composition was formed. The EXAFS and XANES methods established that bismuth was located on the surface of the nanoparticle predominantly in an oxidized state. Full article

Two bis-(imidazolium–vanillylidene)-(R,R)-diaminocyclohexane ligands (H₂(VAN)₂dach, H₂L_1,2) and their Pd(II) complexes (PdL₁ and PdL₂) were successfully synthesized and structurally characterized using microanalytical and spectral methods. Subsequently, to target the development of new effective and safe anti-breast cancer chemotherapeutic agents, these complexes were encapsulated by lipid nanoparticles (LNPs) to formulate (PdL₁LNP and PdL₂LNP), which are physicochemically and morphologically characterized. PdL₁LNP and PdL₂LNP significantly cause DNA fragmentation in MCF-7 cells, while trastuzumab has a 10% damaging activity. Additionally, the encapsulated Pd_1,2LNPs complexes activated the apoptotic mechanisms through the upregulated P53 with p < 0.001 and p < 0.05, respectively. The apoptotic activity may be triggered through the activity mechanism of the Pd_1,2LNPs in the inhibitory actions against the FGFR2/FGF2 axis on the gene level with p < 0.001 and the Her2/neu with p < 0.05 and p < 0.01. All these aspects have triggered the activity of the PdL₁LNP and PdL₂LNP to downregulate TGFβ1 by p < 0.01 for both complexes. In conclusion, LNP-encapsulated Pd(II) complexes can be employed as anti-cancer drugs with additional benefits in regulating the signal mechanisms of the apoptotic mechanisms among breast cancer cells with chemotherapeutic-safe actions. Full article

The C-3 modification of 1H-indazole has produced active pharmaceuticals for the treatment of cancer and HIV. But, so far, this transformation has seemed less available, due to the lack of efficient C-C bond formation at the less reactive C-3 position. In this work, a series of silica gel-supported PdO₂ nanoparticles of 25–66 nm size were prepared by ball milling silica gel with divalent palladium precursors, and then employed as catalysts for the Suzuki–Miyaura cross-coupling of 1H-indazole derivative with phenylboronic acid. All the synthesized catalysts showed much higher cross-coupling yields than their palladium precursors, and could also be reused three times without losing high activity and selectivity in a toluene/water/ethanol mixed solvent. Although the palladium precursors showed an order of activity of PdCl₂(dppf, 1,1′-bis(diphenylphosphino)ferrocene) > PdCl₂(dtbpf, 1,1′-bis(di-tert-butylphosphino)ferrocene) > Pd(OAc, acetate)₂, the synthesized catalysts showed an order of C1 (from Pd(OAc)₂) > C3 (from PdCl₂(dtbpf)) > C2 (from PdCl₂(dppf)), which conformed to the orders of BET (Brunauer–Emmett–Teller) surface areas and acidities of these catalysts. Notably, the most inexpensive Pd(OAc)₂ can be used as a palladium precursor for the synthesis of the best catalyst through simple ball milling. This work provides a highly active and inexpensive series of catalysts for C-3 modification of 1H-indazole, which are significant for the large-scale production of 1H-indazole-based pharmaceuticals. Full article

X-ray computed tomography (CT) contrast agents offer extremely valuable tools and techniques in diagnostics via contrast enhancements. Heavy metal-based nanoparticles (NPs) can provide high contrast in CT images due to the high density of heavy metal atoms with high X-ray attenuation coefficients that exceed that of iodine (I), which is currently used in hydrophilic organic CT contrast agents. Nontoxicity and colloidal stability are vital characteristics in designing heavy metal-based NPs as CT contrast agents. In addition, a small particle size is desirable for in vivo renal excretion. In vitro phantom imaging studies have been performed to obtain X-ray attenuation efficiency, which is a critical parameter for CT contrast agents, and the imaging performance of CT contrast agents has been demonstrated via in vivo experiments. In this review, we focus on the in vitro and in vivo studies of various heavy metal-based NPs in pure metallic or chemical forms, including Au, Pt, Pd, Ag, Ce, Gd, Dy, Ho, Yb, Ta, W, and Bi, and provide an outlook on their use as high-performance CT contrast agents. Full article

To date, there is no cure for Parkinson’s disease (PD). There is a pressing need for anti-neurodegenerative therapeutics that can slow or halt PD progression by targeting underlying disease mechanisms. Specifically, preventing the build-up of alpha-synuclein (αSyn) and its aggregated and mutated forms is a key therapeutic target. In this study, an adeno-associated viral vector loaded with the A53T gene mutation was used to induce rapid αSyn-associated PD pathogenesis in C57BL/6 mice. We tested the ability of a novel therapeutic, a single chain fragment variable (scFv) antibody with specificity only for pathologic forms of αSyn, to protect against αSyn-induced neurodegeneration, after unilateral viral vector injection in the substantia nigra. Additionally, polyanhydride nanoparticles, which provide sustained release of therapeutics with dose-sparing properties, were used as a delivery platform for the scFv. Through bi-weekly behavioral assessments and across multiple post-mortem immunochemical analyses, we found that the scFv-based therapies allowed the mice to recover motor activity and reduce overall αSyn expression in the substantia nigra. In summary, these novel scFv-based therapies, which are specific exclusively for pathological aggregates of αSyn, show early promise in blocking PD progression in a surrogate mouse PD model. Full article

The rational regulation of catalyst active sites at atomic scale is a key approach to unveil the relationship between structure and catalytic performance. Herein, we reported a strategy for the controllable deposition of Bi on Pd nanocubes (Pd NCs) in the priority order from corners to edges and then to facets (Pd NCs@Bi). The spherical aberration-corrected scanning transmission electron microscopy (ac-STEM) results indicated that Bi₂O₃ with an amorphous structure covers the specific sites of Pd NCs. When only the corners and edges of the Pd NCs were covered, the supported Pd NCs@Bi catalyst exhibited an optimal trade-off between high conversion and selectivity in the hydrogenation of acetylene to ethylene under ethylene-rich conditions (99.7% C₂H₂ conversion and 94.3% C₂H₄ selectivity at 170 °C) with remarkable long-term stability. According to the H₂-TPR and C₂H₄-TPD measurements, the moderate hydrogen dissociation and the weak ethylene adsorption are responsible for this excellent catalytic performance. Following these results, the selectively Bi-deposited Pd nanoparticle catalysts showed incredible acetylene hydrogenation performance, which provides a feasible perspective to design and develop highly selective hydrogenation catalysts for industrial applications. Full article

Aerobic oxidation of bio-sourced 2,5-bis(hydroxymethyl)furan (BHMF) to 2, 5-furandicarboxylic acid (FDCA), a renewable and green alternative to petroleum-derived terephthalic acid (TPA), is of great significance in green chemicals production. Herein, hierarchical porous bowl-like nitrogen-rich (nitrated) carbon-supported bimetallic Au-Pd nanocatalysts (Au_mPd_n/ N-BN_xC) with different nitrogen content and bimetal nanoparticle sizes were developed and employed for the highly efficient aerobic oxidation of BHMF to FDCA in sodium carbonate aqueous solution. The reaction pathway for catalytic oxidation of BHMF went through the steps of BHMF→HMF→HMFCA→FFCA→FDCA. Kinetics studies showed that the activation energies of BHMF, HMF, HMFCA, and FFCA were 58.1 kJ·moL⁻¹, 39.1 kJ·moL⁻¹, 129.2 kJ·moL⁻¹, and 56.3 kJ·moL⁻¹, respectively, indicating that the oxidation of intermediate HMFCA to FFCA was the rate-determining step. ESR tests proved that the active species was a superoxide radical. Owing to the synergy between the nitrogen-rich carbon support and bimetallic Au-Pd nanoparticles, the Au₁Pd₁/N-BN₂C nanocatalysts exhibited BHMF conversion of 100% and FDCA yield of 95.8% under optimal reaction conditions. Furthermore, the nanocatalysts showed good stability and reusability. This work provides a versatile strategy for the design of heterogeneous catalysts for the highly efficient production of FDCA from BHMF. Full article

Cationic surfactants carry antimicrobial activity, based on their interaction and disruption of cell membranes. Nonetheless, their intrinsic toxicity limits their applicability. To overcome this issue, a feasible strategy consists of using solid nanoparticles to improve their delivery. The zein nanoparticles were loaded with four cationic arginine-based surfactants: one single chain Nα-lauroyl-arginine (LAM) and three Gemini surfactants Nα Nω-Bis (Nα-lauroyl-arginine) α, ω—diamide) (C₃(LA)₂, C₆(LA)₂ and C₉(LA)₂). Blank and loaded zein nanoparticles were characterized in terms of size, polydispersity and zeta potential. Furthermore, the antimicrobial activity against bacteria and yeasts and the hemolytic activity were investigated and compared to the surfactants in a solution. Nanoparticles were found to be monodisperse, presenting a size of between 180–341 nm, a pdI of <0.2 and a positive zeta potential of between +13 and +53 mV, remaining stable over 365 days. The nanoencapsulation maintained the antimicrobial activity as unaltered, while the extensive hemolytic activity found for the surfactants in a solution was reduced drastically. Nuclear Magnetic Ressonance (NMR), molecular docking and monolayer findings indicated that zein entraps the surfactants, interfering in the surfactant–membrane interactions. Accordingly, the nanoepcasulation of arginine surfactants improved their selectivity, while the cationic charges were free to attack and destroy bacteria and fungi; the aliphatic chains were not available to disrupt the cellular membranes. Full article

Pt-nanoparticle (NP)-alloyed Sn-58Bi solders were reacted with electroless nickel-immersion gold (ENIG) and electroless nickel-electroless palladium-immersion gold (ENEPIG) surface finishes. We investigated formation of intermetallic compounds (IMCs) and their diffusion barrier properties at reaction interfaces as functions of Pt NP content in the composite solders and duration of solid-state aging at 100 °C. At Sn-58Bi-xPt/ENIG interfaces, typical Ni₃Sn₄/Ni₃P(P-rich layer) microstructure was formed. With the large consumption of the Ni-P layer, the Ni-P and Cu layers were intermixed and Cu atoms spread over the composite solder after 500 h of aging. By contrast, a (Pd,Ni)Sn₄/thin Ni₃Sn₄ microstructure was observed at the Sn-58Bi-xPt/ENEPIG interfaces. The (Pd,Ni)Sn₄ IMC effectively suppressed the consumption of the Ni-P layer and Ni₃Sn₄ growth, functioning as a good diffusion barrier. Therefore, the Sn-58Bi-xPt/ENEPIG joint survived 500 h of aging without microstructural degradation. Based on the experimental results and analysis of this study, Sn-58Bi-0.05Pt/ENEPIG is suggested as the optimum combination for future low-temperature soldering systems. Full article

Synthesis of 2,5-bis(hydroxymethyl)furan (BHMF) by selective 5-hydroxymethylfurfural (HMF) hydrogenation is ecofriendly and industrially important since HMF is obtained from renewable sources, and BHMF is a raw material used for production of biodegradable polymers. Four copper-based catalysts were prepared by incipient wetness impregnation (Cu/SiO₂-I, Cu/Al₂O₃-I), precipitation–deposition (Cu/SiO₂-PD) and coprecipitation (CuMgAl), and then tested in the liquid-phase hydrogenation of HMF. Metallic phases with large copper particles were obtained by incipient wetness impregnation, while precipitation methods gave highly dispersed metal copper nanoparticles. The pattern found for the concentration and strength of surface acid sites was: CuMgAl > Cu/Al₂O₃-I > Cu/SiO₂-PD > Cu/SiO₂-I. The copper-based catalysts active in HMF hydrogenation are all highly selective to BHMF, but the intrinsic activity and stability depend on metallic copper dispersion and support nature. The catalyst stability becomes poorer in the cases that the metallic phase is formed by large copper particles or interacts with high-acidity supports. Therefore, the catalyst with the highest activity, BHMF yield and stability was Cu/SiO₂-PD. Furthermore, it was found that Cu/SiO₂-PD is reusable in the selective liquid-phase HMF hydrogenation after being submitted to a two-step thermal treatment: (1) calcination under air flow at 673 K; (2) reduction under H₂ flow at 523 K. Full article