Crumpled Aluminum Hydroxide Nanostructures as a Microenvironment Dysregulation Agent for Cancer Treatment.

Owing to their unique physicochemical properties, nanomaterials have become a focus of multidisciplinary research efforts including investigations of their interactions with tumor cells and stromal compartment of tumor microenvironment (TME) toward the development of next-generation anticancer therapies. Here, we report that agglomerates of radially assembled Al hydroxide crumpled nanosheets exhibit anticancer activity due to their selective adsorption properties and positive charge. This effect was demonstrated in vitro by decreased proliferation and viability of tumor cells, and further confirmed in two murine cancer models. Moreover, Al hydroxide nanosheets almost completely inhibited the growth of murine melanoma in vivo in combination with a minimally effective dose of doxorubicin. Our direct molecular dynamics simulation demonstrated that Al hydroxide nanosheets can cause significant ion imbalance in the living cell perimembranous space through the selective adsorption of extracellular anionic species. This approach to TME dysregulation could lay the foundation for development of novel anticancer therapy strategies.

Micron- and Nanosized Alloy Particles Made by Electric Explosion of W/Cu-Zn and W/Cu/Ni-Cr Intertwined Wires for 3D Extrusion Feedstock.

A novel approach to electric explosion of intertwined wires to obtain homogeneous powder mixtures intended for preparing feedstock for extrusion 3D printing has been applied. The powder were composed of spherical micron- and nano-sized W/Cu particles in-situ alloyed by Zn and Ni during electric explosion of intertwined dissimilar metal wires is offered. The mean particle size measured by micron-sized particles was not more than 20 µm. The average number size of these particles was 3 µm and it was dependent on the energy input. The powders contained phases such as α-W, ß-W/W3O as well as FCC α-Cu(Zn) and α-Cu(Ni) solid solutions with the crystalline lattice parameters 3.629 and 3.61 A, respectively.

Mathematical modeling of high-energy materials rheological behavior in 3D printing technology.

In this paper, a mathematical model of the extrusion process in 3D printing of high-energy composites is studied. These composites are formed from polymer binder and powder with bimodal particles obtained by electric explosion technique. The main difficulty of extrusion 3D printing method is primarily linked to the high viscosity of utilized material, especially one with high concentration of particles. In this case, the viscosity of the initial mixture depends on the pressure, temperature and concentration of the filler, as well as on the particle dispersion. Under certain conditions the ignition of high-energy material in the nozzle is possible, thus the search for optimal printing parameters based on the mathematical modeling and the following experimental verification are the main purposes of the current work.

New PMMA-Based Hydroxyapatite/ZnFe2O4/ZnO Composite with Antibacterial Performance and Low Toxicity.

Polymethylmethacrylate (PMMA) is the most commonly used bone void filler in orthopedic surgery. However, the biocompatibility and radiopacity of PMMA are insufficient for such applications. In addition to insufficient biocompatibility, the microbial infection of medical implants is one of the frequent causes of failure in bone reconstruction. In the present work, the preparation of a novel PMMA-based hydroxyapatite/ZnFe2O4/ZnO composite with heterophase ZnFe2O4/ZnO NPs as an antimicrobial agent was described. ZnFe2O4/ZnO nanoparticles were produced using the electrical explosion of zinc and iron twisted wires in an oxygen-containing atmosphere. This simple, highly productive, and inexpensive nanoparticle fabrication approach could be readily adapted to different applications. From the findings, the presented composite material showed significant antibacterial activity (more than 99% reduction) against P. aeruginosa, S. aureus, and MRSA, and 100% antifungal activity against C. albicans, as a result of the combined use of both ZnO and ZnFe2O4. The composite showed excellent biocompatibility against the sensitive fibroblast cell line 3T3. The more-than-70% cell viability was observed after 1-3 days incubation of the sample. The developed composite material could be a potential material for the fabrication of 3D-printed implants.

Antibacterial Activity and Cytocompatibility of Electrospun PLGA Scaffolds Surface-Modified by Pulsed DC Magnetron Co-Sputtering of Copper and Titanium.

Biocompatible poly(lactide-co-glycolide) scaffolds fabricated via electrospinning are having promising properties as implants for the regeneration of fast-growing tissues, which are able to degrade in the body. The hereby-presented research work investigates the surface modification of these scaffolds in order to improve antibacterial properties of this type of scaffolds, as it can increase their application possibilities in medicine. Therefore, the scaffolds were surface-modified by means of pulsed direct current magnetron co-sputtering of copper and titanium targets in an inert atmosphere of argon. In order to obtain different amounts of copper and titanium in the resulting coatings, three different surface-modified scaffold samples were produced by changing the magnetron sputtering process parameters. The success of the antibacterial properties' improvement was tested with the methicillin-resistant bacterium Staphylococcus aureus. In addition, the resulting cell toxicity of the surface modification by copper and titanium was examined using mouse embryonic and human gingival fibroblasts. As a result, the scaffold samples surface-modified with the highest copper to titanium ratio show the best antibacterial properties and no toxicity against mouse fibroblasts, but have a toxic effect to human gingival fibroblasts. The scaffold samples with the lowest copper to titanium ratio display no antibacterial effect and toxicity. The optimal poly(lactide-co-glycolide) scaffold sample is surface-modified with a medium ratio of copper and titanium that has antibacterial properties and is non-toxic to both cell cultures.

Antibacterial Calcium Phosphate Coatings for Biomedical Applications Fabricated via Micro-Arc Oxidation.

A promising method for improving the functional properties of calcium-phosphate coatings is the incorporation of various antibacterial additives into their structure. The microbial contamination of a superficial wound is inevitable, even if the rules of asepsis and antisepsis are optimally applied. One of the main problems is that bacteria often become resistant to antibiotics over time. However, this does not apply to certain elements, chemical compounds and drugs with antimicrobial properties. In this study, the fabrication and properties of zinc-containing calcium-phosphate coatings that were formed via micro-arc oxidation from three different electrolyte solutions are investigated. The first electrolyte is based on calcium oxide, the second on hydroxyapatite and the third on calcium acetate. By adding zinc oxide to the three electrolyte solutions, antibacterial properties of the coatings are achieved. Although the same amount of zinc oxide has been added to each electrolyte solution, the zinc concentration in the coatings obtained vary greatly. Furthermore, this study investigates the morphology, structure and chemical composition of the coatings. The antibacterial properties of the zinc-containing coatings were tested toward three strains of bacteria-Staphylococcus aureus, methicillin-resistant Staphylococcus aureus and Pseudomonas aeruginosa. Coatings of calcium acetate and zinc oxide contained the highest amount of zinc and displayed the highest zinc release. Moreover, coatings containing hydroxyapatite and zinc oxide show the highest antibacterial activity toward Pseudomonas aeruginosa, and coatings containing calcium acetate and zinc oxide show the highest antibacterial activities toward Staphylococcus aureus and methicillin-resistant Staphylococcus aureus.

Synthesis of novel hierarchical micro/nanostructures AlOOH/AlFe and their application for As(V) removal.

Hierarchical micro/nanostructured composites, which contain iron and/or its (hydr)oxides, demonstrate high rate and capacity of arsenic adsorption. The main objective of this paper is the use of novel low toxicity AlOOH/AlFe hierarchical micro/nanostructures for arsenic removal. AlOOH/AlFe composite was obtained by simple water oxidation in mild conditions using AlFe bimetallic nanopowder as a precursor. AlFe bimetallic nanopowder was produced by electrical explosive of two twisted wires in argon atmosphere. The productivity of the electrical explosion assembly was 50 g/h, with the consumption of the electrical energy was 75 kW·h/kg. AlFe bimetallic nanoparticles were chemically active and interacted with water at 60 °C. This nanocomposite AlOOH/AlFe is low cost and adsorbs more than 200 mg/g As(V) from its aqueous solution. AlOOH/AlFe composite has flower-like morphology and specific surface area 247.1 m2/g. The phase composition of nanostructures is present AlOOH boehmite and AlFe intermetallic compound. AlOOH/AlFe composite was not previously used for this. The flower-shape AlOOH morphology not only facilitated deliverability, but increased the As(V) sorption capacity by up to 200 mg/g. The adsorption kinetics has been found to be described by a pseudo-second-order equation of Lagergren and Weber-Morris models while the experimental adsorption isotherm is closest to the Freundlich model. This indicates the energy heterogeneity of the adsorbent surface and multilayer adsorption. The use of non-toxic nanostructures opens up new options to treat water affected by arsenic pollution.

Controlled Oxidation of Cobalt Nanoparticles to Obtain Co/CoO/Co3O4 Composites with Different Co Content.

The paper studies patterns of interaction of electroexplosive Co nanoparticles with air oxygen during heating. The characteristics of Co nanoparticles and composite Co/CoO/Co3O4 nanoparticles formed as a result of oxidation were studied using transmission electron microscopy, X-ray phase analysis, thermogravimetric analysis, differential scanning calorimetry, and vibrating sample magnetometry. It was established that nanoparticles with similar morphology in the form of hollow spheres with different content of Co, CoO, and Co3O4 can be produced by varying oxidation temperatures. The influence of the composition of composite nanoparticles on their magnetic characteristics is shown.

Preparation and Properties of Iron Nanoparticle-Based Macroporous Scaffolds for Biodegradable Implants.

Fe-based scaffolds are of particular interest in the technology of biodegradable implants due to their high mechanical properties and biocompatibility. In the present work, using an electroexplosive Fe nanopowder and NaCl particles 100-200 µm in size as a porogen, scaffolds with a porosity of about 70 ± 0.8% were obtained. The effect of the sintering temperature on the structure, composition, and mechanical characteristics of the scaffolds was considered. The optimum parameters of the sintering process were determined, allowing us to obtain samples characterized by plastic deformation and a yield strength of up to 16.2 MPa. The degradation of the scaffolds sintered at 1000 and 1100 °C in 0.9 wt.% NaCl solution for 28 days resulted in a decrease in their strength by 23% and 17%, respectively.

Review of the Problems of Additive Manufacturing of Nanostructured High-Energy Materials.

This article dwells upon the additive manufacturing of high-energy materials (HEM) with regards to the problems of this technology's development. This work is aimed at identifying and describing the main problems currently arising in the use of AM for nanostructured high-energy materials and gives an idea of the valuable opportunities that it provides in the hope of promoting further development in this area. Original approaches are proposed for solving one of the main problems in the production of nanostructured HEM-safety and viscosity reduction of the polymer-nanopowder system. Studies have shown an almost complete degree of deagglomeration of microencapsulated aluminum powders. Such powders have the potential to create new systems for safe 3D printing using high-energy materials.

Preparation of Nano/Micro Bimodal Aluminum Powder by Electrical Explosion of Wires.

Electrical explosion of aluminum wires has been shown to be a versatile method for the preparation of bimodal nano/micro powders. The energy input into the wire has been found to determine the relative content of fine and coarse particles in bimodal aluminum powders. The use of aluminum bimodal powders has been shown to be promising for the development of high flowability feedstocks for metal injection molding and material extrusion additive manufacturing.

Preparation and Characterization of Al/HTPB Composite for High Energetic Materials.

Nanosized Al (nAl) powders offer increased reactivity than the conventional micron-sized counterpart, thanks to their reduced size and increased specific surface area. While desirable from the combustion viewpoint, this high reactivity comes at the cost of difficult handling and implementation of the nanosized powders in preparations. The coating with hydroxyl-terminated polybutadiene (HTPB) is proposed to improve powder handling and ease of use of nAl and to limit its sensitivity to aging. The nAl/HTPB composite can be an intermediate product for the subsequent manufacturing of mixed high-energy materials while maintaining the qualities and advantages of nAl. In this work, experimental studies of the high-energy mixture nAl/HTPB are carried out. The investigated materials include two composites: nAl (90 wt.%) + HTPB (10 wt.%) and nAl (80 wt.%) + HTPB (20 wt.%). Thermogravimetric analysis (TGA) is performed from 30 to 1000 °C at slow heating rate (10 °C/min) in inert (Ar) and oxidizing (air) environment. The combustion characteristics of propellant formulations loaded with conventional and HTPB-coated nAl are analyzed and discussed. Results show the increased burning rate performance of nAl/HTPB-loaded propellants over the counterpart loaded with micron-sized Al.

Hierarchical γ-alumina: From Pure Phase to Nanocomposites.

Recent advances in nanotechnology make it possible to create nanomaterials based on γ-alumina with novel hierarchical structure and physicochemical properties. Hierarchical γ-alumina can be synthesized using chemical or physical methods. The nanostructures based on γ-alumina exhibit unique properties, which are utilized in the design of efficient applications. These superior properties are often due to their hierarchical organizations from the nanosize scale to the macroscopic level. The present review is devoted to the contemporary state of the studies on the methods to produce hierarchical γ-alumina. We tried to summarize herein the literature data on the methods of synthesis of hierarchical γ-AlOOH and γ-Al2O3 with controlled morphology and the application of these methods for the synthesis of hierarchical γ-AlOOH and γ-Al2O3 nanocomposites.

Effect of Cold-Sintering Parameters on Structure, Density, and Topology of Fe-Cu Nanocomposites.

The design of advanced nanostructured materials with predetermined physical properties requires knowledge of the relationship between these properties and the internal structure of the material at the nanoscale, as well as the dependence of the internal structure on the production (synthesis) parameters. This work is the first report of computer-aided analysis of high pressure consolidation (cold sintering) of bimetallic nanoparticles of two immiscible (Fe and Cu) metals using the embedded atom method (EAM). A detailed study of the effect of cold sintering parameters on the internal structure and properties of bulk Fe-Cu nanocomposites was conducted within the limitations of the numerical model. The variation of estimated density and bulk porosity as a function of Fe-to-Cu ratio and consolidation pressure was found in good agreement with the experimental data. For the first time, topological analysis using Minkowski functionals was applied to characterize the internal structure of a bimetallic nanocomposite. The dependence of topological invariants on input processing parameters was described for various components and structural phases. The model presented allows formalizing the relationship between the internal structure and properties of the studied nanocomposites. Based on the obtained topological invariants and Hadwiger's theorem we propose a new tool for computer-aided design of bimetallic Fe-Cu nanocomposites.

Hardening of Additive Manufactured 316L Stainless Steel by Using Bimodal Powder Containing Nanoscale Fraction.

The particle size distribution significantly affects the material properties of the additively manufactured parts. In this work, the influence of bimodal powder containing nano- and micro-scale particles on microstructure and materials properties is studied. Moreover, to study the effect of the protective atmosphere, the test samples were additively manufactured from 316L stainless steel powder in argon and nitrogen. The samples fabricated from the bimodal powder demonstrate a finer subgrain structure, regardless of protective atmospheres and an increase in the Vickers microhardness, which is in accordance with the Hall-Petch relation. The porosity analysis revealed the deterioration in the quality of as-built parts due to the poor powder flowability. The surface roughness of fabricated samples was the same regardless of the powder feedstock materials used and protective atmospheres. The results suggest that the improvement of mechanical properties is achieved by adding a nano-dispersed fraction, which dramatically increases the total surface area, thereby contributing to the nitrogen absorption by the material.

Synthesis and Applications of Bimetallic Nanoparticles of Immiscible Elements.

BACKGROUND: Recent advances in nanotechnology make it possible to create nanomaterials with novel microstructure and unique physicochemical properties. Different structures of nanoparticles of immiscible elements can be synthesized using chemical, mechanochemical or physical methods. The present review is devoted to contemporary state of the studies on the methods to produce bimetallic nanoparticles formed of immiscible metals. METHODS: We undertook a structured search of bibliographic databases for peer-reviewed research literature using a focused review question and inclusion/exclusion criteria. The quality of retrieved papers was appraised using standard tools. RESULTS: Ninety-six papers were included in the review. Taking into account a large number of works in this field of the studies in the present review we are going to consider general methods of producing BMINPs with diverse structures: core-shell (twenty one papers), nanoalloys (twenty papers), Januslike (sixteen papers). The field of BMINPs application was described in seventeen articles. In the part Current & Future Developments the perspectives on the usage of bulk materials produced by BMINPs consolidation are discussed. CONCLUSION: As can be seen from this review, ideal bimetallic nanoparticles synthesis methods are not developed by now. The existence of different routes to nanoparticles synthesis and their unique properties confirm the importance promoted awareness of potential benefits of nanoparticles in different applications. The reviewed patents emphasized the importance of bimetallic nanoparticles and their application in various fields as well.

Investigation of differences between nanosecond electropulse and electrohydraulic methods of lithotripsy: a comparative in vitro study of efficacy.

PURPOSE: To compare the effectiveness of novel nanosecond electropulse lithotripsy with standard electrohydraulic lithotripsy to demonstrate and authenticate their differences because both modalities appear to be similar. MATERIALS AND METHODS: An in vitro fragmentation study was conducted using cuboid BegoStone phantoms, which mimic hard and soft stones, based on an established model. Three different stone sizes were used in the testing having volumes of 100, 256, and 320 mm(3). A nanosecond electropulse lithotripter (NEPL) and an electrohydraulic lithotripter (EHL) were operated using a range of probe sizes at comparable energy settings and pulse rates with the objective of obtaining a stone fragment <2 mm. To compare the efficacy of these two lithotripters, the number of pulses needed for stone phantom fragmentation was recorded according to probe size and energy setting, which were then converted into units of cumulative energy. RESULTS: The results clearly demonstrated that, for all operating modes and stone phantom types, the NEPL device needs much less cumulative energy and thus fewer pulses and consequently less time to achieve stone fragmentation than the EHL device. The disparity in the results is explained by the dissimilar mechanisms at work in the compared lithotripters during destruction of the stone. The electropulse stone disintegration mechanism transfers energy directly into the stone because of discharge penetration into a solid body. This contrasts with the electrohydraulic mechanism in EHL in which energy is transferred through the liquid medium, which also creates a damaging shockwave. CONCLUSIONS: The findings demonstrate that, for all operating modes and stone types, the NEPL device needs much less cumulative energy and thus fewer pulses for stone fragmentation than the EHL device. The disparity in the results is explained by the dissimilar mechanisms at work in the compared lithotripters during destruction of the stone.

Retrograde endoscopic lithotripsy using the innovative nanosecond electropulse method.

PURPOSE: The purpose of this clinical study is to assess the safety and efficiency of a novel lithotripsy method for endoscopic treatment of urinary stones throughout the urinary tract via semi-rigid and flexible endoscopes. This new method is based on the transfer of nanosecond high voltage electric pulses to the stones through flexible probes of various sizes. METHODS: The study involved 879 patients aged 19-88 with renal, ureter and bladder calculi. Gender distribution: 46.3% female and 53.7% male. The prospective single-arm study took place at three centers. The goal of the clinical study was to evaluate the safety and efficacy of a novel lithotripsy method. All treatments were performed retrograde transurethrally. A variety of probes were used for stone fragmentation at different locations. Auxiliary treatments and adverse events were recorded as per protocol. Statistical analysis was conducted using SPSS software. RESULTS: Nanosecond electropulse lithotripsy (NEPL) was found to be technically feasible for all patients with stones located in the kidney, UPJ, ureter and bladder. It requires only a few dozen pulses to disintegrate stones while causing only minor stone migration. The overall stone-free rate in the study was 96%. The average time required for executing the entire procedure was 45±28 min. The overwhelming majority of intraoperative complications occurred due to endoscopic manipulation when using a rigid ureterorenoscope and not due to lithotripsy impact. CONCLUSIONS: NEPL is a new, efficient and safe method for urinary stone disintegration that can be used throughout the urinary tract using rigid and flexible endoscopes. Intraoperative complications of the NEPL procedure do not exceed the percentage of adverse effects observed in other lithotripsy methods. The main advantages of relatively low-cost NEPL are fast stone fragmentation requiring only a few dozen pulses to disintegrate stones, tissue safety and availability of highly flexible probes for treating stones in the lower pole through a flexible ureterorenoscope.