Revealing the Second and the Third Causes of AgNPs Property to Restore the Bacterial Susceptibility to Antibiotics.

The increase in bacterial resistance to antibiotics is a global problem for public health. In our previous works, it was shown that the application of AgNPs in cow mastitis treatment increased S. aureus and S. dysgalactiae susceptibility to 31 antibiotics due to a decrease in the bacterial efflux effect. The aim of the present work was to shed light on whether the change in adhesive and anti-lysozyme activities caused by AgNPs also contribute to the restoration of bacterial susceptibility to antibiotics. In vivo sampling was performed before and after cow mastitis treatments with antibiotics or AgNPs. The isolates were identified, and the adhesive and anti-lysozyme activities were assessed. These data were compared with the results obtained for in vitro pre-treatment of reference bacteria with AgNPs or antibiotics. The present study revealed that bacterial treatments in vitro and in vivo with AgNPs: (1) decrease the bacterial ability to adhere to cells to start an infection and (2) decrease bacterial anti-lysozyme activity, thereby enhancing the activity of lysozyme, a natural "antibiotic" present in living organisms. The obtained data contribute to the perspective of the future application of AgNPs for recovering the activity of antibiotics rapidly disappearing from the market.

Silver Nanoparticles Targeting the Drug Resistance Problem of Streptococcus dysgalactiae: Susceptibility to Antibiotics and Efflux Effect.

The present work is a continuation of our translational research focusing on the use of silver nanoparticles (AgNPs) to solve the global problem of antibiotic resistance. In vivo fieldwork was done with 300 breeding farm cows with serous mastitis. Ex vivo assays revealed that after cow treatment with the antibiotic drug Spectromast LCTM, S.dysgalactiae susceptibility to 31 antibiotics dropped by 22.9%, but after treatment with Argovit-CTM AgNPs, it was raised by 13.1%. This was explained by the fact that the percentage of isolates with an efflux effect after Spectromast LC treatment resulted in an 8% increase, while Argovit-C-treatment caused a 19% decrease. The similarity of these results to our previous results on S. aureus isolates from mastitis cows treated with the antibiotic drug Lactobay and Argovit-CTM AgNPs was shown. So, mastitis treatments with Argovit-CTM AgNPs can partially return the activity of antibiotics towards S.dysgalactiae and S. aureus, while, in contrast, treatments with antibiotic drugs such as Spectromast LC and Lactobay enhance bacterial resistance to antibiotics. The results of this work strengthen the hope that in the future the use of AgNPs as efflux pump inhibitors will recover the activity of antibiotics, and thus will preserve the wide spectrum of antibiotics on the market.

Lethal effects of silver nanoparticles on Perkinsus marinus, a protozoan oyster parasite.

Perkinsus marinus, a World Organisation for Animal Health (OIE) notifiable parasite, infects several species of oyster, including Crassostrea virginica and Crassostrea corteziensis. There is little information on possible treatments for this parasite, but the biocidal properties of silver nanoparticles (AgNP) suggest their potential use. The lethal effects of the Argovit™ formulation of AgNP was evaluated for the first time against hypnospores of P. marinus, a particularly resistant stage of the parasite that persists in the environment until favorable conditions occur for zoosporulation to be induced. Hypnospores were exposed to 1, 10 and 100 µg/mL of silver compounded in Argovit™ (corresponding to 0.009, 0.093 and 0.927 mM of Ag), to 157.47 µg/mL (0.927 mM) of silver nitrate (AgNO3) used as a positive control, and to polyvinylpyrrolidone (PVP, 1570 µg/mL) used as a vehicle control. Hypnospores in culture medium without treatment served as a negative control. Dose-dependence after 24 h of exposure to AgNP was observed. A concentration of 0.093 mM AgNP resulted in 50% mortality of P. marinus. Treatment with 0.927 mM of silver, as AgNP or AgNO3, was highly lethal, with greater than 90% mortality. Silver nanoparticles were implicated in the deformation of hypnospores. Transmission electron microscopy (TEM) revealed AgNP within the hypnospore wall and involved in the degradation of lipid droplets in the cytoplasm. AgNP were effective in a saline medium, suggesting the utility of detailed studies of the physicochemical interactions of AgNP under these conditions. These results suggest investigations of possible effect of Argovit™ formulation of AgNP against stages of the parasite like trophozoites and tomonts that develop in tissues or hemolymph of infected oysters as well as studies on its effects in the host and environment.

Nanosilver gel as an endodontic alternative against Enterococcus faecalis in an in vitro root canal system in Mexican dental specimens.

Nanotechnology has become a research area with promising results for technological innovation. Endodontics can benefit from this field of research by increasing the success rate of the treatment, which currently ranges between 86% and 98% and has varied very little over the years. One of the causes of endodontic treatment failure is based on the presence of Enterococcus faecalis. The objective of this investigation is to evaluate the antibacterial effect of a gel preparation containing silver nanoparticles (Ag-NP) against E. faecalis present in the walls of the root canal. 60 extracted human uniradicular teeth that were instrumented with Wave One Gold (Denstplay/USA) and subsequently contaminated with Enterococcus faecalis. For antibacterial evaluation, intra-canal conducting was placed, and several groups were formed: a) Ag-NP 300 ug/MI gel; b) Ag-NP 500 ug/MI gel; c) Ca (OH) 2 (Ultracal from Ultradent/USA) and the control group. They were incubated at 37°C and a sample was taken every 24 h for 7 days. The Ag-NP gel showed antimicrobial activity against E. faecalis with a value of minimum inhibitory concentration and minimum bactericidal concentration of 300 g/ml and 900 g/ml, respectively. When the Ag-NP gel was used as an intra-canal conducting drug in an in-vitro model, its antimicrobial effect at 300 g/ml and 500 g/ml was equivalent to the action of Ca(OH)2.

Silver nanoparticles enhance survival of white spot syndrome virus infected Penaeus vannamei shrimps by activation of its immunological system.

The global aquaculture has shown an impressive growth in the last decades contributing with a major part of total food fish supply. However, it also helps in the spread of diseases that in turn, causes great economic losses. The White Spot Syndrome Virus (WSSV) is one of the major viral pathogen for the shrimp aquaculture industry. Several attempts to eliminate the virus in the shrimp have been addressed without achieving a long-term effectiveness. In this work, we determine the capacity of the commercial non-toxic PVP-coated silver nanoparticles to promote the response of the immune system of WSSV-infected shrimps with or without an excess of iron ions. Our results showed that a single dose of metallic silver in the nanomolar range (111 nmol/shrimp), which is equivalent to 12 ng/mL of silver nanoparticles, produces 20% survival of treated infected shrimps. The same concentration administered in healthy shrimps do not show histological evidence of damage. The observed survival rate could be associated with the increase of almost 2-fold of LGBP expression levels compared with non-treated infected shrimps. LGBP is a key gene of shrimp immunological response and its up-regulation is most probably induced by the recognition of silver nanoparticles coating by specific pathogen-associated molecular pattern recognition proteins (PAMPs) of shrimp. Increased LGBP expression levels was observed even with a 10-fold lower dose of silver nanoparticles (1.2 ng/shrimp, 0.011 nmol of metallic silver/shrimp). The increase in LGBP expression levels was also observed even in the presence of iron ion excess, a condition that favors virus proliferation. Those results showed that a single dose of a slight amount of silver nanoparticles were capable to enhance the response of shrimp immune system without toxic effects in healthy shrimps. This response could be enhanced by administration of other doses and might represent an important alternative for the treatment of a disease that has still no cure, white spot syndrome virus.

Efficacy of silver nanoparticles against the adults and eggs of monogenean parasites of fish.

Monogeneans are a diverse group of parasites that are commonly found on fish. Some monogenean species are highly pathogenic to cultured fish. The present study aimed to determine the in vitro anthelmintic effect of silver nanoparticles (AgNPs) against adults and eggs of monogeneans in freshwater using Cichlidogyrus spp. as a model organism. We tested two types of AgNPs with different synthesis methodologies and size diameters: ARGOVIT (35 nm) and UTSA (1-3 nm) nanoparticles. Damage to the parasite tegument was observed by scanning electron microscopy. UTSA AgNPs were more effective than ARGOVIT; in both cases, there was a concentration-dependent effect. A concentration of 36 µg/L UTSA AgNPs for 1 h was 100% effective against eggs and adult parasites, causing swelling, loss of corrugations, and disruption of the parasite's tegument. This is an interesting result considering that monogenean eggs are typically tolerant to antiparasite drugs and chemical agents. To the best of our knowledge, no previous reports have assessed the effect of AgNPs on any metazoan parasites of fish. Therefore, the present work provides a basis for future research on the control of fish parasite diseases.

Potential application of silver nanoparticles to control the infectivity of Rift Valley fever virus in vitro and in vivo.

In this work we have tested the potential antiviral activity of silver nanoparticles formulated as Argovit™ against Rift Valley fever virus (RVFV). The antiviral activity of Argovit was tested on Vero cell cultures and in type-I interferon receptor deficient mice (IFNAR (-/-) mice) by two different approaches: (i) different dilutions of Argovit were added to previously infected cells or administrated to animals infected with a lethal dose of virus; (ii) virus was pre-incubated with different dilutions of Argovit before inoculation in mice or cells. Though the ability of silver nanoparticles to control an ongoing RVFV infection in the conditions tested was limited, the incubation of virus with Argovit before the infection led to a reduction of the infectivity titers both in vitro and in vivo. These results reveal the potential application of silver nanoparticles to control the infectivity of RVFV, which is an important zoonotic pathogen.

Causes of Activation and Deactivation of Modified Nanogold Catalysts during Prolonged Storage and Redox Treatments.

The catalytic properties of modified Au/TiO2 catalysts for low-temperature CO oxidation are affected by deactivation and reactivation after long-term storage and by redox treatments. The effect of these phenomena on the catalysts was studied by HRTEM, BET, SEM, FTIR CO, XPS and H2 TPR methods. The main cause for the deactivation and reactivation of catalytic properties is the variation in the electronic state of the supported gold, mainly, the proportion of singly charged ions Au⁺. The most active samples are those with the highest proportion of singly charged gold ions, while catalysts with a high content of trivalent gold ions are inactive at low-temperatures. Active states of gold, resistant to changes caused by the reaction process and storage conditions, can be stabilized by modification of the titanium oxide support with transition metals oxides. The catalyst modified with lanthanum oxide shows the highest stability and activity.

On the High Sensitivity of the Electronic States of 1 nm Gold Particles to Pretreatments and Modifiers.

In this paper, the effect of modifiers and pretreatments on the electronic states of 1 nm gold nanoparticles (AuNPs) supported on silica was systematically studied. AuNPs deposited on silica (particle size of 2-4 nm) modified with Ce, La and Fe oxides, were studied by FTIR of adsorbed CO after different redox treatments at 100, 300 and 500 °C. This study was conducted at room temperature to allow detecting the electronic states of gold, which is more likely involved in CO oxidation at the same temperature. AuNP size distribution was measured by HRTEM. It is shown that the electronic state of gold species (Aun(δ-), Au°, Aun(δ+), Au⁺) in 1 nm AuNPs is sensitive to the modifier as well as to the temperatures of redox pretreatments. Supports modified with the same additives but containing larger AuNPs (~3, 4, 5, and 7 nm) were also studied. They showed that Au° remains stable irrespective of additives and redox pretreatments, indicating no significant effect of such treatments on the electronic properties of larger AuNPs. Samples with a predominant AuNP size of 2 nm are an intermediate case between these two groups of materials.

Identification of Subnanometric Ag Species, Their Interaction with Supports and Role in Catalytic CO Oxidation.

The nature and size of the real active species of nanoparticulated metal supported catalysts is still an unresolved question. The technique of choice to measure particle sizes at the nanoscale, HRTEM, has a practical limit of 1 nm. This work is aimed to identify the catalytic role of subnanometer species and methods to detect and characterize them. In this frame, we investigated the sensitivity to redox pretreatments of Ag/Fe/TiO2, Ag/Mg/TiO2 and Ag/Ce/TiO2 catalysts in CO oxidation. The joint application of HRTEM, SR-XRD, DRS, XPS, EXAFS and XANES methods indicated that most of the silver in all samples is in the form of Ag species with size <1 nm. The differences in catalytic properties and sensitivity to pretreatments, observed for the studied Ag catalysts, could not be explained taking into account only the Ag particles whose size distribution is measured by HRTEM, but may be explained by the presence of the subnanometer Ag species, undetectable by HRTEM, and their interaction with supports. This result highlights their role as active species and the need to take them into account to understand integrally the catalysis by supported nanometals.

Use of natural mordenite to remove chromium (III) and to neutralize pH of alkaline waste waters.

The natural mordenite from Palmarito de Cauto deposit (PZ), Cuba, was studied in this work as an ion exchanger to remove Cr(3+) cations from alkaline aqueous solutions at different pH and chromium concentrations. The mordenite stability under cyclic treatment processes with alkaline solutions and its capacity to decrease the pH of the solutions was also analyzed. It was shown that PZ removes Cr(3+) ions from alkaline solutions, and it happens independently of the starting chromium concentration and the pH of the exchange solution used. This material has an important neutralizing effect on alkaline solutions, expressed in a significant pH decrease from the early stages of the treatments. For solutions with initial pH equal to 11, it decreases to a value of around seven. The stability of this material is not affected significantly after continuous cyclic treatment with NaOH solution, which shows that mordenite, in particular from Palmarito de Cauto deposit, has high stability in alkaline solutions. The results are important as they suggest that natural zeolites may be of interest in treatments of alkaline industrial waste effluents.

Nanoparticles Partially Restore Bacterial Susceptibility to Antibiotics.

The growing resistance of bacteria to antibiotics is one of the main public health problems nowadays. The influence of silver nanoparticle (AgNP) pretreatment of 220 cows with mastitis on the susceptibility of Staphylococcus epidermidis bacteria to 31 antibiotics was studied. The obtained results were compared with the previous results for Escherichia coli, Streptococcus dysgalactiae, and Staphylococcus aureus. For all four bacteria, an increase in susceptibility (9.5-21.2%) to 31 antibiotics after cow treatment with AgNPs was revealed, while after first-line antibiotic drug treatment as expected, the susceptibility decreased (11.3-27.3%). These effects were explained by (1) the increase in the contribution of isolates with efflux effect after antibiotic treatments and its decrease after AgNP treatment and (2) the changes in bacteria adhesion and anti-lysozyme activity after these treatments. The effect of the increasing antibacterial activity of antibiotics after AgNP treatment was the most pronounced in the case of E. coli and was minimal in the case of S. epidermidis. With AgNP treatment, the time of recovery decreased by 26.8-48.4% compared to the time of recovery after treatment with the first-line antibiotic drugs. The AgNP treatment allows for achieving the partial restoration of the activity of antibiotics.

New Biodegradable Copolymers Based on Betulin and Hydroxycarboxylic Acid Derivatives.

In this study, we propose an approach to the synthesis of new biodegradable polymer materials based on renewable raw feedstock (betulin) and derivatives of hydroxycarboxylic acids using a catalyst/catalytic system (γ-Al2O3, γ-Al2O3/TBHP) that is safe for health and the environment. The resulting polymers are linear thermoplastic polymers that undergo collapse upon melting in the presence of atmospheric oxygen. Moreover, these polymers demonstrate non-toxicity towards a range of Gram-positive and Gram-negative bacteria. The polycondensation of betulin with butyl lactate is particularly noteworthy.

Influence of Short-Pulse Microwave Radiation on Thermochemical Properties Aluminum Micropowder.

The thermochemical properties of Al micropowder after exposure to microwave irradiation were investigated. The Al micropowder was exposed to microwave irradiation in air with a frequency of 2.85 GHz, a power density of 8 W/cm2, and a pulse duration of 25 ns and 3 µs. The thermochemical parameters of the irradiated metal powders were determined by the method of thermal analysis at the heating in air. It was found that an increase in the duration of microwave pulses and irradiation time leads to the thermal annealing of the metal particles, and the thermal processes of melting and sintering begin to dominate over non-thermal processes. The specific thermal effect of irradiated Al micropowder oxidation increases from 7744 J/g to 10,154 J/g in comparison with the unirradiated powder. The modeling of thermal heating processes of aluminum (Al) micropowder under the action of pulsed microwave radiation has been performed. It is shown that with an increase in the duration of microwave pulses and irradiation time, a significant heating of the Al micropowder occurs, leading to its melting and sintering. The results of modeling on the action of microwave radiation on the Al micropowder were compared with experimental results.

Formation of Ag-Fe Bimetallic Nano-Species on Mordenite Depending on the Initial Ratio of Components.

The formation and properties of silver and iron nanoscale components in the Ag-Fe bimetallic system deposited on mordenite depend on several parameters during their preparation. Previously, it was shown that an important condition for optimizing nano-center properties in a bimetallic catalyst is to change the order of sequential deposition of components; the order "first Ag+, then Fe2+" was chosen as optimal. In this work, the influence of exact Ag/Fe atomic proportion on the system's physicochemical properties was studied. This ratio has been confirmed to affect the stoichiometry of the reduction-oxidation processes involving Ag+ and Fe2+, as shown by XRD, DR UV-Vis, XPS, and XAFS data, while HRTEM, SBET and TPD-NH3 show little change. However, it was found the correlation between the occurrence and amount of the Fe3+ ions incorporated into the zeolite's framework and the experimentally determined catalytic activities towards the model de-NOx reaction along the series of nanomaterials elucidated in this present paper.

Solution of the Drug Resistance Problem of Escherichia coli with Silver Nanoparticles: Efflux Effect and Susceptibility to 31 Antibiotics.

The current work is a continuation of our studies focused on the application of nanoparticles of metallic silver (AgNPs) to address the global problem of antibiotic resistance. In vivo, fieldwork was carried out with 200 breeding cows with serous mastitis. Ex vivo analyses showed that after the cow was treated with an antibiotic-containing drug DienomastTM, E. coli sensibility to 31 antibiotics decreased by 27.3%, but after treatment with AgNPs, it increased by 21.2%. This could be explained by the 8.9% increase in the portion of isolates showing an efflux effect after DienomastTM treatment, while treatment with Argovit-CTM resulted in a 16.0% drop. We verified the likeness of these results with our previous ones on S. aureus and Str. dysgalactiae isolates from mastitis cows processed with antibiotic-containing medicines and Argovit-CTM AgNPs. The obtained results contribute to the recent struggle to restore the efficiency of antibiotics and to preserve the wide range of antibiotics on the world market.

The Effect of Silver Nanoparticle Addition on Micropropagation of Apricot Cultivars (Prunus armeniaca L.) in Semisolid and Liquid Media.

Silver nanoparticles (AgNPs) are novel compounds used as antimicrobial and antiviral agents. In addition, AgNPs have been used to improve the growth of different plants, as well as the in vitro multiplication of plant material. In this work the effect of AgNPs on in vitro growth of 'Canino' and 'Mirlo Rojo' cultivars, as well as the leaf ion composition, are studied. Different concentrations of AgNPs (0, 25, 50, 75 and 100 mg L-1) were added to two culture systems: semisolid medium with agar (SSM) in jars and liquid medium in temporary immersion system (TIS). Proliferation (number of shoots), shoot length, productivity (number of shoot × average length), leaf surface, fresh and dry weight were measured. Additionally, the silver and other ion accumulation in the leaves were evaluated by inductively coupled plasma optical emission spectroscopy (ICP-OES) analysis. The productivity of 'Canino' and 'Mirlo Rojo' decreased when increasing the concentration of AgNPs in the semisolid medium. However, the use of AgNPs in the TIS improved the proliferation and productivity of 'Canino' and Mirlo Rojo', increasing biomass production, and the concentration of nutrients in the plants, although these effects are genotype-dependent. TISs are the best system for introducing silver into shoots, the optimum concentration being 50 mg L-1 for 'Canino' and 75 mg L-1 for 'Mirlo Rojo'. Principal component analysis, considering all the analyzed ions along the treatments, separates samples in two clear groups related to the culture system used. The use of bioreactors with a liquid medium has improved the productivity of 'Canino' and 'Mirlo Rojo' in the proliferation stage, avoiding hyperhydration and other disorders. The amount of metallic silver that penetrates apricot plant tissues depends on the culture system, cultivar and concentration of AgNPs added to the culture medium. Silver ion accumulation measured in the shoots grown in the TIS was higher than in shoots micropropagated in a semisolid medium, where it is barely detectable. Furthermore, AgNPs had a beneficial effect on plants grown in TIS. However, AgNPs had a detrimental effect when added to a semisolid medium.

A Comparative Study of Cancer Cells Susceptibility to Silver Nanoparticles Produced by Electron Beam.

INTRODUCTION: Silver nanoparticles (AgNPs) have a wide range of bioactivity, which is highly dependent on particle size, shape, stabilizer, and production method. Here, we present the results of studies of AgNPs cytotoxic properties obtained by irradiation treatment of silver nitrate solution and various stabilizers by accelerating electron beam in a liquid medium. METHODS: The results of studies of morphological characteristics of silver nanoparticles were obtained by transmission electron microscopy, UV-vis spectroscopy, and dynamic light scattering measurements. MTT test, alamar blue test, flow cytometry, and fluorescence microscopy were used to study the anti-cancer properties. As biological objects for standard tests, adhesive and suspension cell cultures of normal and tumor origin, including prostate cancer, ovarian cancer, breast cancer, colon cancer, neuroblastoma, and leukemia, were studied. RESULTS: The results showed that the silver nanoparticles obtained by irradiation with polyvinylpyrrolidone and collagen hydrolysate are stable in solutions. Samples with different stabilizers were characterized by a wide average size distribution from 2 to 50 nm and low zeta potential from -7.3 to +12.4 mV. All AgNPs formulations showed a dose-dependent cytotoxic effect on tumor cells. It has been established that the particles obtained with the combination of polyvinylpyrrolidone/collagen hydrolysate have a relatively more pronounced cytotoxic effect in comparison to samples stabilized with only collagen or only polyvinylpyrrolidone. The minimum inhibitory concentrations for nanoparticles were less than 1 µg/mL for various types of tumor cells. It was found that neuroblastoma (SH-SY5Y) is the most susceptible, and ovarian cancer (SKOV-3) is the most resistant to the action of silver nanoparticles. The activity of the AgNPs formulation prepared with a mixture of PVP and PH studied in this work was higher that activity of other AgNPs formulations reported in the literature by about 50 times. CONCLUSIONS: The results indicate that the AgNPs formulations synthesized with an electron beam and stabilized with polyvinylpyrrolidone and protein hydrolysate deserve deep study for their further use in selective cancer treatment without harming healthy cells in the patient organism.

Silver nanoparticles induce a non-immunogenic tumor cell death.

Immunogenic cell death (ICD) is a form of cell death characterized by the release of danger signals required to trigger an adaptive immune response against tumor-associated antigens. Silver nanoparticles (AgNP) display anti-proliferative and cytotoxic effects in tumor cells, but it has not been previously studied whether AgNP act as an ICD inductor. The present study evaluated the in vitro release of calreticulin as a damage-associated molecular pattern (DAMP) associated with the cytotoxicity of AgNP and their in vivo anti-cancer effects. In vitro, mouse CT26 colon carcinoma and MCA205 fibrosarcoma cells were exposed to AgNP and then cell proliferation, adhesion, and release of calreticulin were determined. The results indicated there were time- and concentration-related anti-proliferative effects of AgNP in both the CT26 and MCA205 lines. Concurrently, changes in cell adhesion were detected mainly in the CT26 cells. Regarding DAMP detection, a significant increase in calreticulin was observed only in CT26 cells treated with doxorubicin and AgNP; however, no differences were found in the MCA205 cells. In vivo, the survival and growth of subcutaneous tumors were monitored after vaccination of mice with cell debris from tumor cells treated with AgNP or after intra-tumoral administration of AgNP to established tumors. Consequently, anti-tumoral prophylactic immunization with AgNP-dead cells failed to protect mice from tumor re-challenge; intra-tumor injection of AgNP did not induce a significant effect. In conclusion, there was a noticeable anti-tumoral effect of AgNP in vitro in both CT26 and MCA205 cell lines, accompanied by the release of calreticulin in CT26 cells. In vivo, immunization with cell debris derived from AgNP-treated tumor cells failed to induce a protective immune response in the cancer model mice. Clearly, further research is needed to determine if one could combine AgNP with other ICD inducers to improve the anti-tumor effect of these nanoparticles in vivo.

Ash and Slag Waste Processing in Self-Shielded Atmospheric DC Arc Discharge Plasma.

In this paper, we report the experimental results obtained in slag waste processing by direct current arc discharge initiated in ambient air. The method does not employ vacuum and gas equipment, therefore increasing the energy efficiency of processing. Plasma processing of coal slag was performed at different arc exposure times: 5, 10, 15, 20, and 25 s. The obtained materials contained a significant amount of graphite, which was removed through combustion. The micropowder based on silicon carbide and aluminum nitride was obtained and then sintered by spark plasma. The bulk ceramic samples based on silicon carbide with the hardness of ~10.4 GPa were finally fabricated.