Nowadays, the interest in the design of particles that combine therapy and diagnosis simultaneously to obtain a theranostic material has increased. One of the most used materials for MRI diagnosis is iron oxide, where clusters of superparamagnetic iron oxide (SPIONs) are noteworthy candidates. These particles are of high interest due to their broad range of applications, such as contrast agents, use in magnetic separation processes, and in hyperthermia therapy, among others. One of the major problems with their use is maintaining superparamagnetism while having the highest magnetization-to-particle ratio. In this work, microwave-assisted synthesis of clusters formed by SPIONs has been investigated. This synthesis strategy allows for significant reduction in the time and energy required to obtain SPION clusters. Also, the magnetization-to-particle ratio has been increased in comparison with single SPIONs. Subsequently, the clusters are coated with amorphous silica using the Stöber method, followed by mesoporous (MS) silica using the atrane method, which offers high and conformal coating homogeneity over the clusters. Surfactant extraction was done using a simple mixture of water, ethanol, and sodium chloride – avoiding the use of other organic solvents. Finally, as a proof of concept, the loading and release of a model molecule were studied to confirm that the SPION-NCs@MS presented in this work have great potential as theranostic agents.

Nanodiamonds (NDs) display several attractive features rendering them useful for medical applications such as drug delivery. However, the interactions between NDs and the immune system remain poorly understood. Here, we investigated amino-, carboxyl-, and poly(ethylene glycol) (PEG)-terminated NDs with respect to primary human immune cells. We applied cytometry by time-of-flight (CyToF) to assess the impact on peripheral blood mononuclear cells at the single-cell level, and observed an expansion of plasmacytoid dendritic cells (pDCs) which are critically involved in antiviral responses. Subsequent experiments demonstrated that the NDs were actively internalized, leading to a vigorous type I interferon response involving endosomal Toll-like receptors. ND-NH2 and ND-COOH were more potent than ND-PEG, as evidenced by using TLR reporter cell lines. Computational studies demonstrated that NDs interacted with the ligand-binding domains of TLR7 and TLR9 with high affinity though this was less pronounced for ND-PEG. NDs with varying surface functionalities were also readily taken up by macrophages. To gain further insight, we performed RNA sequencing of a monocyte-like cell line exposed to NDs, and found that the phagosome maturation pathway was significantly affected. Indeed, evidence for lysosomal hyperacidification was obtained in dendritic cells and macrophages exposed to NDs. Moreover, using a reporter cell line, NDs were found to impinge on autophagic flux. However, NDs did not affect viability of any of the cell types studied. This study has shown that NDs subvert dendritic cells leading to an antiviral-like immune response. This has implications not only for drug delivery but also for anticancer vaccines using NDs.

Thermoelectric (TE) materials can directly convert heat into electrical energy. However, they sustain costly production procedures and batch-to-batch performance variations. Therefore, developing scalable synthetic techniques for large-scale and reproducible quality TE materials is critical for advancing TE technology. This study developed a facile, high throughput, solution-chemical synthetic technique. Microwave-assisted thermolysis process, providing energy-efficient volumetric heating, was used for the synthesis of bismuth and antimony telluride (Bi2Te3, Sb2Te3). As-made materials were characterized using various techniques, including XRPD, SEM, TEM, XAS, and XPS. Detailed investigation of the local atomic structure of the synthesized Bi2Te3 and Sb2Te3 powder samples was conducted through synchrotron radiation XAS experiments. Radial distribution functions around the absorbing atoms were reconstructed using reverse Monte Carlo simulations, and effective force constants for the nearest and distant coordination shells were subsequently determined. The observed differences in the effective force constants support high anisotropy of the thermal conductivity in Bi2Te3 and Sb2Te3 in the directions along and across the quintuple layers in their crystallographic structure. The as-made materials were consolidated via Spark Plasma Sintering to evaluate thermal and electrical transport properties. The sintered TE materials exhibited low thermal conductivity, achieving the highest TE figure-of-merit values of 0.7 (573 K) and 0.9 (523 K) for n-type Bi2Te3 and p-type Sb2Te3, respectively, shifted significantly to the high-temperature region when compared to earlier reports, highlighting their potential for power generation applications. The scalable, energy- and time-efficient synthetic method developed, along with the demonstration of its potential for TE materials, opens the door for a wider application of these materials with minimal environmental impact.

Bismuth telluride-Bi2Te3 is the most promising material for harvesting thermal energy near room temperature. There are numerous works on Bi2Te3 reporting significantly different transport properties, with no clear connection to the synthetic routes used and the resultant surface chemistry of the synthesized materials. It is of utmost importance to characterize the constituent particles’ surface and interfaces to get a better understanding of their influence on the transport properties, that will significantly improve the material design starting from the synthesis step. Electrophoretic deposition (EPD) is a promising technique, enabling the formation of thick films using colloidally stabilized suspensions of pre-made nanoparticles, which can enable the study of the effect of surface chemistry, in connection to the synthetic route, on the material's transport properties. In order to explore the differences in surface chemistry and the resultant transport properties in relation to the synthetic scheme used, here we report on Bi2Te3 synthesised through two wet-chemical routes in water (Hydro-) and oil (Thermo-) as the solvents. XRD analysis showed a high phase purity of the synthesized materials. SEM analysis revealed hexagonal platelet morphology of the synthesized materials, which were then used to fabricate EPD films. Characterization of the EPD films reveal significant differences between the Hydro- and Thermo-Bi2Te3 samples, leading to about 8 times better electrical conductivity values in the Thermo-Bi2Te3. XPS analysis revealed a higher metal oxides content in the Hydro-Bi2Te3 sample, contributing to the formation of a resistive layer, thus lowering the electrical conductivity. Arrhenius plots of electrical conductivity vs inverse temperature was used for the estimation of the activation energy for conduction, revealing a higher activation energy need for the Hydro-Bi2Te3 film, in agreement with the resistive barrier oxide content. Both the samples exhibited negative Seebeck coefficient (S) in the order of 160–170 mV/K. The small difference in S of Hydro- and Themo-Bi2Te3 films was explained by the effective medium theory, revealing that the magnitude of S is linearly correlated with the surface oxide content. Based on the findings, TE materials synthesized through thermolysis route is recommended for further studies using soft treatment/processing of pre-made TE materials. EPD platform presented here is shown to clearly expose the differences in the electronic transport in connection to nanoparticle surface chemistry, proving a promising methodology for the evaluation of morphology, size and surface chemistry dependence of electronic transport for a wide range of materials.

2D titanium carbide (Ti3C2) MXenes have emerged as promising candidates for biomedical applications. However, the biological properties of these materials are poorly understood. Moreover, MXenes are prone to oxidation under ambient conditions. Here, we show that glutathione (GSH), a natural antioxidant present in millimolar concentrations in the cytosol of most cells, protects MXenes from oxidation in aqueous suspensions while preserving the biocompatibility of the material. Reactive molecular dynamics (RMD) simulations confirm that GSH protects MXenes. Moreover, we provide evidence of the intracellular biotransformation of Ti3C2 MXenes to the rutile form of TiO2, and we show that GSH tunes the transformation process, resulting in the secretion of pro-inflammatory interleukin (IL)-1β through a non-canonical, elastase-dependent pathway. These results are important because they shed new light on the biotransformation of Ti3C2 MXenes and its ramifications for cellular signaling.

One of the materials that has recently been used to remove environmental pollution from industrial effluents with photocatalytic technology is cobalt chromate (CoCr2O4) nanoparticles. An effective way to improve the photocatalytic properties of materials is to composite them with other photocatalysts to prevent recombination of electron-holes and accelerate the transfer of oxidation/reduction agents. Graphitic carbon nitride (g-C3N4) is an excellent choice due to its unique properties. In this research, CoCr2O4 and its composite with g-C3N4 (5, 10, and 15%) were synthesized by polyacrylamide gel method and characterized by X-ray diffraction, scanning electron microscopy, FTIR, UV–Vis spectroscopy techniques. The photocatalytic behavior of synthesized nanoparticles was investigated in the degradation process of methylene blue dye. The results showed that the composite samples have higher efficiency in photocatalytic activity than the pure CoCr2O4 sample. Using CoCr2O4-15 wt%g-C3N4 nanocomposite, after 80 min, methylene blue was completely degraded. The mechanism of degradation by CoCr2O4-g-C3N4 nanocomposite was the superoxide radical produced by the reaction of electrons with oxygen absorbed on the catalyst surface, as well as optically produced holes directly.

With the recent advances in thermoelectric (TE) technology, there is an increasing demand to develop thick films that would enable large-scale TE devices. Assembly of TE-films from size and morphology-controlled nano particles has been a challenging issue that can be addressed by the use of electrophoretic deposition (EPD) technique. In this work, morphology-controlled Sb2Te3 nanoparticles were synthesized through microwave assisted thermolysis, which were subsequently used for EPD of TE films on specially developed glass substrates. The electronic transport properties were measured in the temp-range of 22-45 degrees C. The as-made EPD films showed a high initial resistance, ascribed to high porosity and the presence of surface oxide/passivating layers. The impact of two types of small organic molecules-as hexanedithiol and dodecanethiol, on the electronic transport was investigated, resulting in a significant improvement in the electrical conductivity of the films. The XPS analysis suggests that the thiols bind to the surface of nanoparticles through formation of sulfides. Seebeck coefficient in the range of + 160 to + 190 & mu;V/K was measured, revealing the p-type transport through the deposited films. Finally, a power factor of about 2.5 & mu;W/K2.m was estimated the first time for p-type EPD films, revealing the potential of the developed nanoparticles and substrate, the small molecule additives and the EPD process presented in this work.

This study aimed to fabricate a glass ionomer cement/diopside (GIC/DIO) nanocomposite to improve its mechanical properties for biomaterials applications. For this purpose, diopside was synthesized using a sol-gel method. Then, for preparing the nanocomposite, 2, 4, and 6 wt% diopside were added to a glass ionomer cement (GIC). Subsequently, X-ray diffraction (XRD), differential thermal analysis (DTA), scanning electron microscopy (SEM), and Fourier transform infrared spectrophotometry (FTIR) analyses were used to characterize the synthesized diopside. Furthermore, the compressive strength, microhardness, and fracture toughness of the fabricated nanocomposite were evaluated, and a fluoride-releasing test in artificial saliva was also applied. The highest concurrent enhancements of compressive strength (1155.7 MPa), microhardness (148 HV), and fracture toughness (5.189 MPa center dot m(1/2)) were observed for the glass ionomer cement (GIC) with 4 wt% diopside nanocomposite. In addition, the results of the fluoride-releasing test showed that the amount of released fluoride from the prepared nanocomposite was slightly lower than the glass ionomer cement (GIC). Overall, the improvement in mechanical properties and optimal fluoride release of prepared nanocomposites can introduce suitable options for dental restorations under load and orthopedic implants.

The microstructure and magnetic properties of methane (CH4) heat-treated Sr-hexaferrite powders during the re-calcination process were investigated and compared with the magnetic properties of conventionally synthesized Sr-hexaferrite powder. Gradual changes in the magnetic behavior of the produced powder in each re-calcination stage were investigated using magnetization curves obtained from the vibration sample magnetometry (VSM) technique. First, the initial Sr-hexaferrite powder was prepared by the conventional route. Then the powder was heat treated in a dynamic CH4 atmosphere in previously optimized conditions (temperature: 950 degrees C, gas flow rate:15 cc min(-1) and time: 30 min), and finally, re-calcined in various temperatures from 200 to 1200 degrees C. By investigating the hysteresis loops, we found the transition temperature of soft to hard magnetic behavior to be 700 degrees C. The maximum ratio M-r/M-s was obtained at temperatures of 800-1100 degrees C. At 1100 degrees C, and despite the Sr-hexaferrite single phase, the magnetic behavior showed a multiphase behavior that was demonstrated by a kink in the hysteresis loop. Uniform magnetic behavior was observed only at 900 degrees C and 1000 degrees C. Although the ratio M-r/M-s was almost the same at these temperatures, the values of M-r and M-s at 1000 degrees C were almost double of 900 degrees C. At 1000 degrees C, the second quadrant of hysteresis curve had the maximum area. Therefore, 1000 degrees C was the optimum temperature for re-calcination after CH4 gas heat treatment in the optimized conditions. Due to the presence of a small amount of hematite soft phase at 1000 degrees C, the most probable reason for the exclusive properties of the optimized product may be the exchange coupling phenomenon between the hard Sr-hexaferrite phase and the impurity of the soft hematite phase.

The aim of the current work is to investigate the effect of SiC particle weight percent and rolling passes on Al/Cu/SiC laminated composites, fabricated by accumulative roll-bonding (ARB) and cross-accumulative roll-bonding (CARB) processes. The optical microscopy (OM) images of composites revealed that despite the good bonding of the layers, they underwent plastic instabilities as a consequence of strain hardening of the layers. However, these instabilities occurred more in ARBed composites than in composites fabricated by the CARB process. This is because in the latter process, the composites are rolled in two directions, which leads to better strain distribution. Furthermore, with an increase in passes, SiC particles were well distributed in the matrix and interfaces. The mechanical findings showed that, by increasing passes, there was a growth in the values of strengths and elongation. This behavior is believed to be related to increased work-hardening of layers, better distribution of reinforcing particles, and an enhanced bonding of interfaces at higher rolling passes. In addition, the results of thermal conductivities showed a downward trend with an increase in passes; in fact, the increased number of Al/Cu interfaces declined the heat conduction of composites.