MXenes with ordered triatomic-layer borate polyanion terminations.

Surface terminations profoundly influence the intrinsic properties of MXenes, but existing terminations are limited to monoatomic layers or simple groups, showing disordered arrangements and inferior stability. Here we present the synthesis of MXenes with triatomic-layer borate polyanion terminations (OBO terminations) through a flux-assisted eutectic molten etching approach. During the synthesis, Lewis acidic salts act as the etching agent to obtain the MXene backbone, while borax generates BO2- species, which cap the MXene surface with an O-B-O configuration. In contrast to conventional chlorine/oxygen-terminated Nb2C with localized charge transport, OBO-terminated Nb2C features band transport described by the Drude model, exhibiting a 15-fold increase in electrical conductivity and a 10-fold improvement in charge mobility at the d.c. limit. This transition is attributed to surface ordering that effectively mitigates charge carrier backscattering and trapping. Additionally, OBO terminations provide Ti3C2 MXene with substantially enriched Li+-hosting sites and thereby a large charge-storage capacity of 420 mAh g-1. Our findings illustrate the potential of intricate termination configurations in MXenes and their applications for (opto)electronics and energy storage.

Combustion Synthesis of Functionalized Carbonated Boron Nitride Nanoparticles and Their Potential Application in Boron Neutron Capture Therapy.

In this research, we developed boron-rich nanoparticles that can be used for boron neutron capture therapy as potential carriers for boron delivery to cancerous tissues. Functionalized carbonated boron nitride nanostructures (CBNs) were successfully synthesized in self-propagating combustion waves in mixtures of high-nitrogen explosives and boron compounds. The products' composition, morphology, and structural features were investigated using Fourier transform infrared spectroscopy, powder X-ray diffraction, low-temperature nitrogen sorption analysis, thermogravimetric analysis, high-resolution scanning electron microscopy, and high-resolution transmission electron microscopy. The extreme conditions prevailing in combustion waves favor the formation of nanosized CBN hollow grains with highly disordered structures that are properly functionalized on the surface and inside the particles. Therefore, they are characterized by high porosity and good dispersibility in water, which are necessary for medical applications. During biological tests, a concentration-dependent effect of the obtained boron nitride preparations on the viability of normal and neoplastic cells was demonstrated. Moreover, the assessment of the degree of binding of fluorescently labeled nanoparticles to selected cells confirmed the relationships between the cell types and the concentration of the preparation at different incubation time points.

Lack of cytotoxic and genotoxic effects of mPEG-silane coated iron(III) oxide nanoparticles doped with magnesium despite cellular uptake in cancerous and noncancerous lung cells.

Cytotoxic and genotoxic effects of novel mPEG-silane coated iron(III) oxide nanoparticles doped with magnesium (Mg0.1-γ-Fe2O3(mPEG-silane)0.5) have been investigated on human adenocarcinomic alveolar basal epithelial (A549) and human normal bronchial epithelial (BEAS-2B) cells. In the studies several molecular and cellular targets addressing to cell membrane, cytoplasm organelles and nucleus components were served as toxicological endpoints. The as-synthesized nanoparticles were found to be stable in the cell culture media and were examined for different concentration and exposure times. No cytotoxicity of the tested nanoparticles was found although these nanoparticles slightly increased reactive oxygen species in both cell types studied. Mg0.1-γ-Fe2O3(mPEG-silane)0.5 nanoparticles did not produce any DNA strand breaks and oxidative DNA damages in A549 and BEAS-2B cells. Different concentration of Mg0.1-γ-Fe2O3(mPEG-silane)0.5 nanoparticles and different incubation time did not affect cell migration. The lung cancer cells' uptake of the nanoparticles was more effective than in normal lung cells. Altogether, the results evidence that mPEG-silane coated iron(III) oxide nanoparticles doped with magnesium do not elucidate any deleterious effects on human normal and cancerous lung cells despite cellular uptake of these nanoparticles. Therefore, it seems reasonable to conclude that these novel biocompatible nanoparticles are promising candidates for further development towards medical applications.

Removal of doxorubicin hydrochloride and crystal violet from aqueous solutions using spray-dried niobium oxide coated with chitosan-activated carbon: Experimental and DFT calculations.

Spray-dried niobium oxide coated with chitosan-activated carbon (NIC) was synthesized and used to remove doxorubicin hydrochloride and crystal violet from aqueous solutions under different parameters such as solution pH (2, 4, 6, and 8), contact time (1 to 9 h), initial concentration (20 to 200 mg L-1), and competing ions (0.1 M of CaCl2 and NaCl). The addition of 5 % chitosan-activated carbon to the matrix of niobium oxide slightly increased the specific surface area from 26 to 30 m2 g-1, with the introduction of a carboxylic functional group. This led to an increase in the amount of adsorbed doxorubicin hydrochloride (DOH) from 30 to 44 mg g-1 and that of crystal violet (CV) from 15 to 32 mg g-1 from the initial respective 100 mg L-1 at pH 8. The data from the concentration study fitted into Liu isotherm having adsorption capacity of 128 and 57 mg g-1 for DOH and CV respectively, while pseudo first and second order are more suitable for adsorption kinetics. The additional functional groups on the IR spectrum of NIC after the adsorption of DOH and CV confirmed the interaction between NIC and the adsorbates' molecules. The mechanism of adsorption was supported by DFT calculations.

Extracellular Vesicles as Next-Generation Biomarkers in Lung Cancer Patients: A Case Report on Adenocarcinoma and Squamous Cell Carcinoma.

Extracellular vesicles (EVs) released from primary cell lines, originating from resected tissues during biopsies in patients with non-small cell lung cancer (NSCLC) revealing adenocarcinoma and squamous cell carcinoma subtypes, were examined for membrane proteomic fingerprints using a proximity barcoding assay. All the collected EVs expressed canonical tetraspanins (CD9, CD63, and CD81) highly coexpressed with molecules such as lysosome-associated membrane protein-1 (LAMP1-CD107a), sialomucin core protein 24 (CD164), Raph blood group (CD151), and integrins (ITGB1 and ITGA2). This representation of the protein molecules on the EV surface may provide valuable information on NSCLC subtypes and offer new diagnostic opportunities as next-generation biomarkers in personalized oncology.

Nanofiber-Supported Palladium Nanocubes-Toward Highly Active and Reusable Catalyst.

Electrospun nanofibers were used to support palladium nanocubes, resulting in a highly active, stable, and reusable catalyst. The system proposed herein offers significant advantages compared to catalysts in the form of nanoparticles suspension. The porous, solvent permeable structure of the nanofiber mat ensures uniform and stable time distribution of palladium nanoparticles; preventing coalescence and allowing multiple use of the catalyst. The proposed cross-linked poly(vinyl alcohol) nanofiber mat loaded with Pd nanocubes during the nanofiber preparation step is a macroscopic structure of intrinsically nanostructural character of the catalyst that can be easily transferred between different solutions without compromising its effectiveness in consecutive cycles. Thus, obtained system was characterized with high catalytic activity as tested on a model example of 4-nitrophenol (4-NP) reduction by NaBH4 to 4-aminophenol (4-AP). It is shown that loading nanofibers with Pd nanocubes during electrospinning resulted in a significantly more stable system compared to surface modification of obtained nanofibers with nanocube suspension.

Comparative studies on the cytotoxic effects induced by iron oxide nanoparticles in cancerous and noncancerous human lung cells subjected to an alternating magnetic field.

The cytotoxic effects of water-based ferrofluids composed of iron oxide nanoparticles, including magnetite (Fe3O4) and maghemite (γ-Fe2O3), ranging from 15 to 100 nm, were examined on various lung cancer cells including adenocarcinomic human alveolar basal epithelial cells (A549), nonsmall lung squamous cell carcinoma (H1703), small cell lung cancer cells (DMS 114), and normal bronchial epithelial cells (BEAS-2B). The cytotoxic effect was evaluated both with and without exposure to an alternating magnetic field (AMF). The studies revealed that neither AMF nor iron oxide nanoparticles when tested individually, produced cytotoxic effects on either cancerous or noncancerous cells. However, when applied together, they led to a significant decrease in cell viability and proliferative capacity due to the enhanced effects of magnetic fluid hyperthermia (MFH). The most pronounced effects were found for maghemite (<50 nm) when subjected to an AMF. Notably, A549 cells exhibited the highest resistance to the proposed hyperthermia treatment. BEAS-2B cells demonstrated susceptibility to magnetized iron oxide nanoparticles, similar to the response observed in lung cancer cells. The studies provide evidence that MFH is a promising strategy as a standalone treatment for different types of lung cancer cells. Nevertheless, to prevent any MFH-triggered adverse effects on normal lung cells, targeted magnetic ferrofluids should be designed.

Nanostars in Highly Si-Doped GaN.

Understanding the relation between surface morphology during epitaxy of GaN:Si and its electrical properties is important from both the fundamental and application perspectives. This work evidences the formation of nanostars in highly doped GaN:Si layers with doping level ranging from 5 × 1019 to 1 × 1020 cm-3 grown by plasma-assisted molecular beam epitaxy (PAMBE). Nanostars are 50-nm-wide platelets arranged in six-fold symmetry around the [0001] axis and have different electrical properties from the surrounding layer. Nanostars are formed in highly doped GaN:Si layers due to the enhanced growth rate along the a-direction ⟨112̅0⟩. Then, the hexagonal-shaped growth spirals, typically observed in GaN grown on GaN/sapphire templates, develop distinct arms that extend in the a-direction ⟨112̅0⟩. The nanostar surface morphology is reflected in the inhomogeneity of electrical properties at the nanoscale as evidenced in this work. Complementary techniques such as electrochemical etching (ECE), atomic force microscopy (AFM), and scanning spreading resistance microscopy (SSRM) are used to link the morphology and conductivity variations across the surface. Additionally, transmission electron microscopy (TEM) studies with high spatial resolution composition mapping by energy-dispersive X-ray spectroscopy (EDX) confirmed about 10% lower incorporation of Si in the hillock arms than in the layer. However, the lower Si content in the nanostars cannot solely be responsible for the fact that they are not etched in ECE. The compensation mechanism in the nanostars observed in GaN:Si is discussed to be an additional contribution to the local decrease in conductivity at the nanoscale.

Nano-bio interactions of upconversion nanoparticles at subcellular level: biodistribution and cytotoxicity.

Background: Modern medicine requires intensive research to find new diagnostic and therapeutic solutions. Recently, upconverting nanoparticles (UCNPs) doped with lanthanide ions have attracted significant attention. Methods: The efficient internalization of UCNPs by cells was confirmed, and their precise cellular localization was determined by electron microscopy and confocal studies. Results: UCNPs colocalized only with specific organelles, such as early endosomes, late endosomes and lysosomes. Furthermore, experiments with chemical inhibitors confirmed the involvement of endocytosis in UCNPs internalization and helped select several mechanisms involved in internalization. Exposure to selected UCNPs concentrations did not show significant cytotoxicity, induction of oxidative stress or ultrastructural changes in cells. Conclusion: This study suggests that UCNPs offer new diagnostic options for biomedical infrared imaging.

Ionic Nickel Embedded in Ceria with High Specific CO2 Methanation Activity.

CO2 hydrogenation to methane is gaining increasing interest as one of the most promising ways to store intermittent renewable energy in the form of chemical fuels. Ni particles supported on CeO2 represent a highly efficient, stable and inexpensive catalyst for this reaction. Herein, Ni-doped CeO2 nanoparticles were tested for CO2 methanation showing an extremely high Ni mass-specific activity and CH4 selectivity. Operando characterization reveals that this performance is tightly associated with ionic Νi and Ce3+ surface sites, while formation of metallic Ni does not seem to considerably promote the reaction. Theoretical calculations confirmed the stability of interstitial ionic Ni sites on ceria surfaces and highlighted the role of Ce-O frustrated Lewis pair (FLP), Ni-O classical Lewis pair (CLP) and Ni-Ce pair sites to the activation of H2 and CO2 molecules. To a large extent, the theoretical predictions were validated by in situ spectroscopy under H2 and CO2 : H2 gaseous environments.

Application of biocompatible and ultrastable superparamagnetic iron(III) oxide nanoparticles doped with magnesium for efficient magnetic fluid hyperthermia in lung cancer cells.

Magnetic fluid hyperthermia (MFH) is a promising therapeutic strategy that targets malignant tissues by heating to 40-43 °C using magnetic nanoparticles (MNPs) subjected to an alternating magnetic field (AMF). In this study, novel magnetic iron(III) oxide nanoparticles doped with magnesium (Mg0.1-γ-Fe2O3(mPEG-silane)0.5) were synthesized, and their structural, chemical, and magnetic properties were analyzed using the following techniques: Fourier-transform infrared spectroscopy, Raman spectroscopy, vibrating magnetometer analysis, powder X-ray diffraction, inductively coupled plasma mass spectrometry, scanning electron microscopy, high-resolution transmission electron microscopy, and energy-dispersive X-ray spectroscopy. The as-synthesized MNPs were used as water ferrofluids for MFH under an AMF in two calorimetric setups, namely phantom and lung cancer cell (A549) models. The as-synthesized MNPs were hexagonal or rhombohedral shaped, with an average size of 27 nm. They showed a typical soft ferromagnetic behavior based on the hysteresis profile, with a magnetic saturation of 70 emu g-1 and remnant magnetization of 1.6 emu g-1. In phantom studies, the ferrofluid (3.0 mg mL-1) exposed to an AMF (18.3 kA m-1, 110.1 kHz) heated up extremely quickly, reaching more than 90 °C in the first 10 min of magnetization. In cell studies, the ferrofluid (0.25 mg mL-1) under an AMF (16.7 kA m-1, 110.1 kHz) showed a slight increase in temperature within the first 12 min, reaching a peak of ca. 43-45 °C, which was stable up to the end of the AMF exposure (45 min). Under these conditions, a pronounced cytotoxic effect on the lung cancer cells was observed (viability ca. 15-20%). No such deleterious effects were observed when the cells were treated with MNPs only without an AMF. Specific absorption rate (SAR) measurements were performed using three mathematical approaches, namely the initial slope method, the corrected slope method, and the Box-Lucas method, which ranged from ca. 429 to 596 W g-1 for phantom and cell studies. Iron(III) oxide MNPs doped with magnesium were found to be candidates for MFH in lung cancer treatments.

Co nanoparticles supported on mixed magnesium-lanthanum oxides: effect of calcium and barium addition on ammonia synthesis catalyst performance.

The synthesis of ammonia in the Haber-Bosch process produces millions of tons of ammonia annually needed for producing fertilisers required to feed the growing population. Although this process has been optimised extensively, it still accounts for about 2% of global energy consumption. It is, therefore, desirable to develop an efficient ammonia synthesis catalyst. Over the last decades, many attempts have been made to improve the ammonia synthesis catalyst efficiency under mild conditions. Here, we studied the effect of adding Ca and Ba to the cobalt ammonia synthesis catalyst. The combination of the different experimental results allows concluding that Ca served as an inactive additive, whereas Ba served as an electronic promoter. The Ca addition did not change the textural, structural, and chemisorptive properties of the Ca-doped Co catalyst. On the other hand, the Ba addition had a major effect on the nature of active Co sites. It contributed to the formation of new active sites for hydrogen and nitrogen adsorption and dissociation. Barium addition also contributed to the generation of new basic sites, particularly the strong ones. These unique characteristics were ascribed to the formation of Co(core)-BaO(shell) structures. It is likely that the donation of electrons from BaO to N2 via Co markedly promoted ammonia synthesis. This catalyst exhibited ammonia synthesis activity 4 times higher than that of the undoped Co catalyst and 2 times higher than that of the industrial Fe catalysts under identical conditions.

Exosomes derived from lung cancer cells: Isolation, characterization, and stability studies.

Recent advances in nanomedicine have paved the way for developing targeted drug delivery systems. Nanoscale exosomes are present in almost every body fluid and represent a novel mechanism of intercellular communication. Because of their membrane origin, they easily fuse with cells, acting as a natural delivery system and maintaining the bioactivity and immunotolerance of cells. To develop a reconstitutable exosome-based drug candidate for clinical applications, quality assurance by preserving its physical and biological properties during storage is necessary. Therefore, this study aimed to determine the best storage conditions for exosomes derived from lung cancer cells (A549). This study established that the phosphate-buffered saline buffer enriched with 25 mM trehalose is an optimal cryoprotectant for A549-derived exosomes stored at -80°C. Under these conditions, the concentration, size distribution, zeta potential, and total cargo protein levels of the preserved exosomes remained constant.

Vanadium oxide nanorods as an electrode material for solid state supercapacitor.

The electrochemical properties of metal oxides are very attractive and fascinating in general, making them a potential candidate for supercapacitor application. Vanadium oxide is of particular interest because it possesses a variety of valence states and is also cost effective with low toxicity and a wide voltage window. In the present study, vanadium oxide nanorods were synthesized using a modified sol-gel technique at low temperature. Surface morphology and crystallinity studies were carried out by using scanning electron microscopy, transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy analysis. To the best of our knowledge, the as-prepared nanorods were tested with magnesium ion based polymer gel electrolyte for the first time. The prepared supercapacitor cell exhibits high capacitance values of the order of ~ 141.8 F g-1 with power density of ~ 2.3 kW kg-1 and energy density of ~ 19.1 Wh kg-1. The cells show excellent rate capability and good cycling stability.

On the effect of metal loading on the performance of Co catalysts supported on mixed MgO-La2O3 oxides for ammonia synthesis.

Synthesis of ammonia from nitrogen and hydrogen is one of the largest manmade chemical processes, with annual production reaching 170 million tons. The Haber-Bosch process is the main industrial method for producing ammonia, which proceeds at high temperatures (400-600 °C) and pressures (20-40 MPa) using an iron-based catalyst. It is thus highly desirable to develop new catalysts with sufficient activity and stability under mild conditions. In this work, we report cobalt catalysts supported on magnesium-lanthanum mixed oxide with different Co loading amounts synthesised via a simple wet impregnation method. We have found a clear relationship between the ammonia synthesis rate and the Co loading amount. Specifically, the NH3 synthesis rate increased on increasing cobalt loading and reached a maximum at 40 wt% Co deposition. A further increase in Co loading did not change the activity significantly. Interestingly, the surface-specific activity (TOF) remained almost unchanged regardless of the Co loading amount in the catalysts. It revealed that the resultant ammonia synthesis rate over the studied catalysts did not depend on the size and structure of Co nanoparticles but strongly on the Co loading amount. Finally, it is believed that the use of this type of catalyst will be a starting point toward energy-efficient ammonia production.

Topological surface currents accessed through reversible hydrogenation of the three-dimensional bulk.

Hydrogen, the smallest and most abundant element in nature, can be efficiently incorporated within a solid and drastically modify its electronic and structural state. In most semiconductors interstitial hydrogen binds to defects and is known to be amphoteric, namely it can act either as a donor (H+) or an acceptor (H-) of charge, nearly always counteracting the prevailing conductivity type. Here we demonstrate that hydrogenation resolves an outstanding challenge in chalcogenide classes of three-dimensional (3D) topological insulators and magnets - the control of intrinsic bulk conduction that denies access to quantum surface transport, imposing severe thickness limits on the bulk. With electrons donated by a reversible binding of H+ ions to Te(Se) chalcogens, carrier densities are reduced by over 1020cm-3, allowing tuning the Fermi level into the bulk bandgap to enter surface/edge current channels without altering carrier mobility or the bandstructure. The hydrogen-tuned topological nanostructures are stable at room temperature and tunable disregarding bulk size, opening a breadth of device platforms for harnessing emergent topological states.

The Role of the Built-In Electric Field in Recombination Processes of GaN/AlGaN Quantum Wells: Temperature- and Pressure-Dependent Study of Polar and Non-Polar Structures.

In this paper, we present a comparative analysis of the optical properties of non-polar and polar GaN/AlGaN multi-quantum well (MQW) structures by time-resolved photoluminescence (TRPL) and pressure-dependent studies. The lack of internal electric fields across the non-polar structures results in an improved electron and hole wavefunction overlap with respect to the polar structures. Therefore, the radiative recombination presents shorter decay times, independent of the well width. On the contrary, the presence of electric fields in the polar structures reduces the emission energy and the wavefunction overlap, which leads to a strong decrease in the recombination rate when increasing the well width. Taking into account the different energy dependences of radiative recombination in non-polar and polar structures of the same geometry, and assuming that non-radiative processes are energy independent, we attempted to explain the 'S-shape' behavior of the PL energy observed in polar GaN/AlGaN QWs, and its absence in non-polar structures. This approach has been applied previously to InGaN/GaN structures, showing that the interplay of radiative and non-radiative recombination processes can justify the 'S-shape' in polar InGaN/GaN MQWs. Our results show that the differences in the energy dependences of radiative and non-radiative recombination processes cannot explain the 'S-shape' behavior by itself, and localization effects due to the QW width fluctuation are also important. Additionally, the influence of the electric field on the pressure behavior of the investigated structures was studied, revealing different pressure dependences of the PL energy in non-polar and polar MQWs. Non-polar MQWs generally follow the pressure dependence of the GaN bandgap. In contrast, the pressure coefficients of the PL energy in polar QWs are highly reduced with respect to those of the bulk GaN, which is due to the hydrostatic-pressure-induced increase in the piezoelectric field in quantum structures and the nonlinear behavior of the piezoelectric constant.

Optical and structural properties of europium doped Y-Al-O compounds grown by microwave driven hydrothermal technique.

Perovskites, garnets, monoclinic forms, and lately also oxyhydroxides doped with rare-earth ions have been drawn large attention due to their beneficial optical and photovoltaic properties. In this work, we have shown that several forms of crystals from Y-Al-O family can be synthesized using microwave driven hydrothermal technique using different pH and post-growth annealing at different temperatures. The structural and optical properties of these crystals were investigated as a function of hydrothermal crystallization conditions. For this purpose, x-ray diffraction, scanning electron microscopy, energy-dispersive x-ray spectroscopy, transmission electron microscopy, photoluminescence, and photoluminescence excitation studies were performed. All the structures have been doped with Eu3+ions which are known as a local symmetry sensor because various symmetries generate different crystal fields and thus affect their luminescence spectra. The optical properties of the obtained nanoparticles in correlation with their structure and chemical composition are discussed.

Mesoporous silica nanoparticles containing copper or silver synthesized with a new metal source: Determination of their structure parameters and cytotoxic and irritating effects.

One of the potential implementation of mesoporous silica nanomaterials (MSNs) is their use in biomedical applications as adsorbents or carriers of various bioactive substances. In this study, we attempted to fabricate silica nanomaterials containing copper and silver that were introduced into the MSN matrix, for the first time using oxalate compounds as a metal source. The syntheses were carried out using hydrothermal and impregnation methods. Structure studies revealed that the obtained nanoparticles were of a spheroidal shape and most had diameters in the range 200-500 nm. Silver and copper were found to be grouped into clusters in most samples, except in copper-decorated MSNs prepared with the impregnation method, which had an even distribution of metal atoms throughout the volume of the granule. An evaluation of the cytotoxic and irritating effects revealed that the preferred candidates for potential future applications in medicine or cosmetology among materials obtained with the presented method are the copper-conjugated MSNs.

STEM Tomography of Au Helical Assemblies.

Composite, helical nanostructures formed using cooperative interactions of liquid crystals and Au nanoparticles were studied using a scanning transmission electron microscopy (STEM) mode. The investigated helical assemblies exhibit long-range hierarchical order across length scales, as a result of the crystallization (freezing) directed growth mechanism of nanoparticle-coated twisted nanoribbons and their ability to form organized bundles. Here, STEM methods were used to reproduce the 3D structure of the Au nanoparticle double helix.