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Nonsteroidal anti-inflammatory drugs (NSAIDs) are the first choice of treatment for rheumatic disorders and other degenerative inflammatory diseases. One of them, indomethacin (INDO), is highlighted in this study. With its analgesic, antipyretic, and anti-inflammatory properties, it is one of the most powerful drugs used in various clinical trials and therapies related to the mechanism of blocking prostaglandin synthesis, thus reducing and eliminating many inflammatory conditions in patients. To ensure the efficacy and safety of this drug in pharmaceutical and clinical use, precise product quality control is required. Such control is performed with routine pharmaceutical analysis using various chemical methods by which INDO is identified as a separate active ingredient in the multicomponent system of a complete pharmaceutical form. In addition, the determination of INDO is important in clinical practice, where its concentration is determined in different biological samples, ensuring better monitoring of a particular therapy. The most commonly used methods for the determination of INDO are high-performance liquid chromatography (37% of developed methods), voltammetry (16% of developed methods), and UV spectroscopy (11% of developed methods). However, each of these methods must provide precise validation parameters. A combination of analytical methods can lead to more precise results and safer application in practice.

A new sensor for direct potentiometric determination of thiabendazole (TBZ) was prepared. The ionic pair of TBZ cation and the 5-sulfosalicylate anion was used as the new sensor material incorporated in liquid type of ion-selective electrode membrane for TBZ determination. For optimization of the membrane of the sensor for TBZ determination, six different plasticizers and the content of the sensor material in the membrane were varied. The chosen sensor with dibutyl sebacate (DS) as plasticizer and 1% of sensor material in the membrane was characterized with Nernstian response towards TBZ (62.2 mV/decade of activity), a wide working range (8.6∙10-7–1.0∙10-3 M), and a low limit of detection (3.2·10-7 M). Also, it proved to be an accurate and reliable sensor for TBZ determination in pure and real samples (peel of oranges, lemons and bananas) where it was determined using direct potentiometry and Gran method.

Cocrystals have been extensively used to improve the physicochemical properties and bioavailability of active pharmaceutical ingredients. Cocrystals of anti-tuberculosis medications are among those commonly reported. This review provides a summary of the tuberculosis antibiotic cocrystals reported in the literature, providing the main results on current tuberculosis medications utilized in cocrystals. Moreover, anti-tuberculosis cocrystals limitations and advantages are described, including evidence for enhanced solubility, stability and effect. Opportunities to enhance anti-tuberculosis medications and fixed dose combinations using cocrystals are given. Several cocrystal pairs are suggested to enhance the effectiveness of anti-tuberculosis drugs.

The COVID-19 virus is spread by pulmonary droplets. Its high infectivity is caused by the high-affinity binding of the viral spike protein to the ACE2 receptors on the surface of respiratory epithelial cell membranes. The proper hydration of nasal mucosa plays an essential role in defense of bacterial and viral infections. Therefore, a nasal formulation, which can moisture the nasal mucosa and contains the ACE2 receptor inhibitor, can reduce the risk of COVID-19 infection. This article presents a systematic study of the preparation of chitosan hydrogels with dicarboxylic acids (malic and glutaric acid) and their detailed characterization (Fourier transform infrared spectroscopy, determination of cross-linking efficiency, rheological studies, thermal analysis, and swelling kinetics). The results confirm that chemically cross-linked chitosan hydrogels can be synthesized using malic or glutaric acid without additives or catalysts. The adsorption capacity of hydrogels for three different ACE2 inhibitors, as APIs, has also been investigated. The API content of hydrogels and their mucoadhesive property can provide an excellent basis to use the hydrogels for the development of a nasal formulation in order to reduce the risk of SARS-CoV 2 infection.

Carbon quantum dots (CQDs) have recently emerged as innovative theranostic nanomaterials, enabling fast and effective diagnosis and treatment. In this study, a facile hydrothermal approach for N-doped biomass-derived CQDs preparation from Citrus clementina peel and amino acids glycine (Gly) and arginine (Arg) has been presented. The gradual increase in the N-dopant (amino acids) nitrogen content increased the quantum yield of synthesized CQDs. The prepared CQDs exhibited good biocompatibility, stability in aqueous, and high ionic strength media, similar optical properties, while differences were observed regarding the structural and chemical diversity, and biological and antioxidant activity. The antiproliferative effect of CQD@Gly against pancreatic cancer cell lines (CFPAC-1) was observed. At the same time, CQD@Arg has demonstrated the highest quantum yield and antioxidant activity by DPPH scavenging radical method of 81.39 ± 0.39% and has been further used for the ion sensing and cellular imaging of cancer cells. The obtained results have demonstrated selective response toward Fe3+ detection, with linear response ranging from 7.0 µmol dm−3 to 50.0 µmol dm−3 with R2 = 0.9931 and limit of detection (LOD) of 4.57 ± 0.27 µmol dm−3. This research could be a good example of sustainable biomass waste utilization with potential for biomedical analysis and ion sensing applications.

Essential oils (EOs) are commonly applied in mouth care products like mouthwashes, mostly as an ethanolic solution or by usage of surfactants as solubilising agents. In this study, we present a formulation for preparation of Pickering nano-emulsions (PnE) of EOs as a novel form for application of EOs in mouth care. For the preparation of PnE, we have synthesised surface-modified silica nanoparticles with a mean diameter of 20 nm, as well as we have examined the effect of EOs concentration on PnE droplet size and stability. In vitro study of their effect on the Streptococcus mutans biofilm as the main pathogen of dental health problems has been performed. We have found that EOs in the PnE form has the highest effectiveness against biofilm formation. Diffusion through the biofilm model membrane was studied to explain this observation. We have found that PnEs have a better performance in the transportation of EOs trough model membrane than the ethanolic solutions and conventional emulsions (CEs).

The oxygen plays an important role in the development and function of the human brain. In the central nervous system, a different neuron types can be very sensitive to varying concentrations of oxygen. Despite several cell biology researches, the time course of the effects of non-physiological oxygen concentrations, but especially high oxygen concentrations on the membrane of neurons, and the dynamics of damage are unknown. In the present study, with this in view, electrical impedance spectroscopy (EIS) measurements are carried out using a graphene-based self-developed four-electrode measurement and data collection process. Our goal was to produce a plate layout for our further experiments that could be used to examine cell cultures under hypoxic and hyperoxic conditions. The designs differ in the distance between the electrodes, we used three types of distances: 1 mm, 3 mm 5 mm, using one distance per plate. On the plate with 5 mm electrode spacing we found the ideal. From a measurement point of view, the plate with 5 mm electrode spacing was the most suitable. As we increased the distance, the size of the electrode surfaces decreased. It can be assumed that reducing the size of the electrodes did not negatively affect the measurement results. Our results can greatly contribute to better understand the process of cell membrane damage.

In Hungary, cancer causes a quarter of all deaths. Our goal is to develop a method of early diagnosis. Our research team is developing a new non-invasive bioimpedance spectrometry-based procedure that enables early detection of cancers. The measurement procedure as well as the instruments used for the measurement have been specially developed to measure tumor cells. The system, which is entirely self-developed, is an innovative solution for eliminating contact impedance due to the agility of the ions during the two electrode measurements known to this time. In our article, we present a cell culture plate that generates data that is free from the distractions of the aforementioned contact impedance. During the physical validation, we have demonstrated that the methodology we have developed can be used in a wide frequency range, so it is therefore fully suitable for further cellular testing.

Drug–drug cocrystals are formulated to produce combined medication, not just to modulate active pharmaceutical ingredient (API) properties. Nano-crystals adjust the pharmacokinetic properties and enhance the dissolution of APIs. Nano-cocrystals seem to enhance API properties by combining the benefits of both technologies. Despite the promising opportunities of nano-sized cocrystals, the research at the interface of nano-technology and cocrystals has, however, been described to be in its infancy. In this study, high-pressure homogenization (HPH) and high-power ultrasound were used to prepare nano-sized cocrystals of 4-aminosalysilic acid and sulfamethazine in order to establish differences between the two methods in terms of cocrystal size, morphology, polymorphic form, and dissolution rate enhancement. It was found that both methods resulted in the formation of form I cocrystals with a high degree of crystallinity. HPH yielded nano-sized cocrystals, while those prepared by high-power ultrasound were in the micro-size range. Furthermore, HPH produced smaller-size cocrystals with a narrow size distribution when a higher pressure was used. Cocrystals appeared to be needle-like when prepared by HPH compared to those prepared by high-power ultrasound, which had a different morphology. The highest dissolution enhancement was observed in cocrystals prepared by HPH, however, both micro- and nano-sized cocrystals enhanced the dissolution of sulfamethazine.

A series of nitrogen heterocycles containing long alkyl and polyalkyl chains were prepared in the form of quaternary ammonium salts using the one-step procedure in good to excellent yields. The method generally gives rise to exclusive N-alkylation. The newly synthesized quaternary alkylammonium compounds (QAC) characterized by standard analytical methods including IR, 1H- and 13C-NMR, MS and elemental analysis, were theoretically studied and tested as ionophores for surfactant selective sensors. A selective and highly sensitive potentiometric sensors for anionic surfactants (ASs) determination were prepared by using a new QAC-tetraphenylborate (TPB) ion pairs as sensing elements. For each QAC-TPB sensor the response time, selectivity and influence of pH were determined. The electrode with the best response characteristics showed Nernstian response towards dodecyl sulfate (DDS) in the concentration range from 1.5 ∙ 10−7 to 5.0 ∙ 10−3 M and limit of detection of 7.5 ∙ 10−8 M. Also, they were successfully used for ASs determination in pure and real systems.

Carnosine is a dipeptide synthesized in the body from β-alanine and L-histidine. It is found in high concentrations in the brain, muscle, and gastrointestinal tissues of humans and is present in all vertebrates. Carnosine has a number of beneficial antioxidant properties. For example, carnosine scavenges reactive oxygen species (ROS) as well as alpha-beta unsaturated aldehydes created by peroxidation of fatty acid cell membranes during oxidative stress. Carnosine can oppose glycation, and it can chelate divalent metal ions. Carnosine alleviates diabetic nephropathy by protecting podocyte and mesangial cells, and can slow down aging. Its component, the amino acid beta-alanine, is particularly interesting as a dietary supplement for athletes because it increases muscle carnosine, and improves effectiveness of exercise and stimulation and contraction in muscles. Carnosine is widely used among athletes in the form of supplements, but rarely in the population of cardiovascular or diabetic patients. Much less is known, if any, about its potential use in enriched food. In the present review, we aimed to provide recent knowledge on carnosine properties and distribution, its metabolism (synthesis and degradation), and analytical methods for carnosine determination, since one of the difficulties is the measurement of carnosine concentration in human samples. Furthermore, the potential mechanisms of carnosine’s biological effects in musculature, metabolism and on immunomodulation are discussed. Finally, this review provides a section on carnosine supplementation in the form of functional food and potential health benefits and up to the present, neglected clinical use of carnosine.

Despite polymorphism of crystalline active pharmaceutical ingredients (APIs) being a common phenomenon, reports on polymorphic co- crystals are limited. As polymorphism can vastly affect API properties, controlling polymorph generation is crucial. Control of the polymorph nucleation through the use of different solvents during solution crystallization has been used to obtain a desirable crystal polymorph. There have been two reported polymorphic forms of the 4- aminosalicylic acid-sulfamethazine co-crystals. These forms were found to have different thermodynamic stabilities. However, the control of co-crystal polymorph generation using preparation parameter manipulation has never been reported. The aim of this study was to establish the effect of different solvent parameters on the formation of different co- crystal polymorphic forms. Selection of the solvents was based on Hansen Solubility Parameters (HSPs) as solvents with different solubility parameters are likely to interact differently with APIs, ultimately affecting co- crystallization. Eight solvents with different HSPs were used to prepare co-crystals by solvent evaporation at two different temperatures. Through characterization of the co-crystals, a new polymorph has been obtained. The hydrogen bond acceptability seemed to affect the co-crystal form obtained more than the hydrogen bond donation ability. Furthermore, the use of HSPs can be utilized as an easy calculation method in screening and design of co-crystals.

In the field of essential oil research, the low water solubility of essential oils (EOs) causes several problems, not only in pharmaceutical applications, but also in microbiological experiments. The aim of our work was to prepare Pickering emulsions with tea tree, thyme, and anise EOs stabilized with silica nanoparticles, in order to enhance their availability for microbiological tests. We have examined the influence of surface properties and concentration of silica nanoparticles and dispergation energy on emulsion stability and droplet size. In vitro diffusion experiments have been performed on model agar gel membranes, with the stable Pickering emulsions and conventional emulsions of EOs stabilized with Tween80 surfactant. We have examined the influence of surface modifying group type, surface coverage of silica nanoparticles, and droplet size of the emulsions on the diffusion properties of the EOs. Our results show that highly stable Pickering emulsions can be prepared with silica nanoparticles of 20 nm diameter and 20% of surface covered with ethyl groups, in a wide EO concentration range. The cumulative amount of the EO was more effective in Pickering emulsions than in conventional emulsions for tea tree and thyme EOs, whereas the opposite case was true for anise EO. As the droplet size of the Pickering emulsion decreases, the cumulative concentration of the EO increases. In this work, we have shown that the Pickering emulsions of EOs are a suitable form for EO transport through complex membranes, and hopefully can be effectively applied in microbiological and pharmaceutical experiments.

Essential oils (EOs) are becoming increasingly popular in medical applications because of their antimicrobial effect. Direct bioautography (DB) combined with thin layer chromatography (TLC) is a screening method for the detection of antimicrobial compounds in plant extracts, for example, in EOs. Due to their lipophilic character, the common microbiological assays (etc. disk diffusion) could not provide reliable results. The aim of this study was the evaluation of antibacterial and anti-biofilm properties of the EO of cinnamon bark, clove, peppermint, thyme, and their main components against Haemophilus influenzae and H. parainfluenzae. Oil in water (O/W) type Pickering nano-emulsions stabilized with silica nanoparticles from each oil were prepared to increase their water-solubility. Samples with Tween80 surfactant and absolute ethanol were also used. Results showed that H. influenzae was more sensitive to the EOs than H. parainfluenzae (except for cinnamon bark oil). In thin layer chromatography-direct bioautography (TLC-DB) the ethanolic solutions of thyme oil presented the best activity against H. influenzae, while cinnamon oil was the most active against H. parainfluenzae. Pickering nano-emulsion of cinnamon oil inhibited the biofilm formation of H. parainfluenzae (76.35%) more efficiently than samples with Tween80 surfactant or absolute ethanol. In conclusion, Pickering nano-emulsion of EOs could inhibit the biofilm production effectively.

This work combines the laboratory quantitative analysis of colored solutions and common devices for digital imaging (digital or web camera or mobile phones, i.e., smartphones). ColorX software, specially designed for this study, was used for data collection and analysis in order to calculate concentration of colored solutions from measured RGB values. Three different custom methods for determination of concentration have been developed: (i) RGB value measurement by pixel ; (ii) RGB value measurement by pixel and Gaussian blur ; and (iii) calculation of average RGB value of the selected image area. The performance of the developed software ColorX is demonstrated using different colored solutions: KMnO4 (purple) ; CoSO4 (red) ; NiSO4 (green) ; and CuSO4 (blue) solutions, as well as the Lowry protein assay (blue) to determine the concentration of an unknown sample. The most suitable and effective method for study of the mentioned solutions was calculation of average RGB value of the selected image area. ColorX software is primarily designed for accessibility and simplicity with the aim of promoting and encouraging students to explore and discover potential applications of digital imaging technology in basic analytical chemistry concepts.

A new solid-state potentiometric sensor for anionic surfactants (AnS) determination was prepared. The sensor material in the liquid membrane was made of multi-walled carbon nanotubes (MWCNTs) chemically functionalized with a quaternary ammonium group and tetraphenylborate (TPB) anion (MWCNT-N+(CH3)3TPB−). The response of the MWCNT-N+(CH3)3TPB− sensor was Nernstian (59.3 mV/decade of activity) for both AnS investigated (sodium dodecyl sulfate (NaDDS) and sodium dodecylbenzenesulfonate (NaDBS)). The limits of detection were 2.0 ∙ 10−7 and 1.5 ∙ 10−7 for NaDDS and NaDBS, respectively, and the average response time was only 5 s. The new MWCNT-N+(CH3)3TPB− sensor was very selective for NaDDS compared to anions usually contained in commercial products and is not affected by nonionic surfactants that can also be present in these products. It was tested to determine AnS concertation by the potentiometric titration method in a pH range between 3 and 12 and successfully applied for its determination in three-component mixtures and real systems.

Two novel discrete cadmium(II) complexes, namely [CdBr2(pia)2] (1) and [CdI2(pia)2] (2) were prepared by reactions of aqueous solutions of CdX2 (X = Br, I) salts with picolinamide (pia) in the 2:1 ligand to metal stoichiometric ratio. Both compounds were characterized by elemental analysis, IR-spectroscopy, TG/DSC analyses and electrochemical methods. The electrochemical characteristics of both ligand (pia) and prepared complexes were studied by cyclic and (cyclic) square-wave voltammetry, on a static mercury drop electrode (SMDE), in aqueous media over a wide pH range. The molecular and crystal structure of the compounds was determined by the single crystal X- ray diffraction method. X-ray structure analysis of 1 and 2 have shown that the compounds are isostructural with minor differences in the bond angles of the coordination sphere. In both compounds the Cd(II) ion is coordinated by two halide atoms and two mutually orthogonal picolinamide ligands that act as N, O-chelators in a distorted octahedral arrangement. In the crystal structure, the molecules of 1 and 2 are primarily linked via strong head–to–head amide hydrogen bond interactions forming dimers. In 1 the adjacent dimers are connected via Nsingle bondH⋯Br hydrogen bonds and offset face to face π⋯π interactions that involve pyridine rings, while in the structure of 2, the dimers are connected via Csingle bondH⋯O, Csingle bondH⋯N and Nsingle bondH⋯I hydrogen bonds into the final 3D structure. The intermolecular interactions in both crystal structures were further studied by Hirshfeld surface analysis. Electrochemical analysis of 2-picolinamide indicates the irreversible nature of its electro-reduction reaction on SMDE at pH 2. To provide better insight into the redox mechanism and electrokinetic properties of 2-picolinamide, the study of the effect of signal frequency on CSWV response was carried out, too. The electrochemical reduction of complex 2 involves two electron transfer reactions at −0.55 V and −0.83 V, indicating two redox active centers in the molecule, while complex 1 appears to be apparently electro-inactive in the studied potential range.

Onychomycosis is a disease that affects many adults, whose treatment includes both oral and topical therapies with low cure rates. The topical therapy is less effective but causes fewer side effects. This is why the development of an effective, easy to apply formulation for topical treatment is of high importance. We have used a nanotechnological approach to formulate Pickering emulsions (PEs) with well-defined properties to achieve site-specific delivery for antifungal drug combination of tioconazole and Melaleuca alternifolia essential oil. Silica nanoparticles with tailored size and partially hydrophobic surface have been synthesized and used for the stabilization of PEs. In vitro diffusion studies have been performed to evaluate the drug delivery properties of PEs. Ethanolic solution (ES) and conventional emulsions (CE) have been used as reference drug formulations. The examination of the antifungal effect of PEs has been performed on Candida albicans and Trichophyton rubrum as main pathogens. In vitro microbiological experimental results suggest that PEs are better candidates for onychomycosis topical treatment than CE or ES of the examined drugs. The used drugs have shown a significant synergistic effect, and the combination with an effective drug delivery system can result in a promising drug form for the topical treatment of onychomycosis.

Pharmaceutical co-crystals present an opportunity to improve the solubility of conventional active pharmaceutical ingredients (APIs). Despite advances in co-crystal screening, the rational design of even the chemically simplest co-crystals remains challenging. Hansen solubility parameters (HSPs) have previously been used as a tool to predict co-crystal formation using only the chemical structure. The aim of this study was to validate the use of HSPs as a tool to predict co-crystal formation, analyse its limitations and examine the previously set Δδ inclusion cut-off value. A total of 109 co-formers of carbamazepine, caffeine and theophylline were used as a training set. Sixteen different descriptors were examined. An additional 72 co-formers of piroxicam and nicotinamide were used to test the methods and new cut-off values. The established cut-off value (8.18 MPa0.5) despite being similar to the previously reported value (7 MPa0.5), offered no real advantage over the previously reported value. Our results suggest the use of the modified radius (Ra) method of calculating the solubility difference, which had higher sensitivity of 90% compared to 86% for the previously reported method and cut-off value to indicate co-crystal formation as well as a lower miss and false omission rates.

The multi-walled carbon nanotubes (MWCNTs) were noncovalently functionalized with tetraoctadecylammonium tetraphenylborate (TODA-TPB) used as a sensing element and incorporated into a liquid PVC membrane of the new fast, low drift and sensitive potentiometric sensor (FCNSS) for anionic surfactants (ASs). The sensor exhibits a sub-Nernstian response for both dodecyl sulfate (DS) and dodecylbenzenesulfonate in H2O and in 10 mM Na2SO4. The lower limits of detection for DS and DBS in H2O were 1.5 · 10−7 and 2.0 · 10−7 M and in 10 mM Na2SO4, they were 2.0 · 10−7 M for both surfactants. The response time of the sensor varied between 8 and 12 s, depending on AS concentration and its signal drift was 2.1 mV/hour. The FCNSS exhibited excellent selectivity for DS against nearly all anions usually found in commercial products. It was successfully employed for end-point detection at potentiometric titrations of ASs in detergent products and effluents. This work is licensed under a Creative Commons Attribution 4.0 International License.

Essential oils (EOs) are highly lipophilic, which makes the measurement of their biological action difficult in an aqueous environment. We formulated a Pickering nanoemulsion of chamomile EO (CPe). Surface-modified St&ouml, ber silica nanoparticles (20 nm) were prepared and used as a stabilizing agent of CPe. The antimicrobial activity of CPe was compared with that of emulsion stabilized with Tween 80 (CT80) and ethanolic solution (CEt). The antimicrobial effects were assessed by their minimum inhibitory concentration (MIC90) and minimum effective (MEC10) concentrations. Besides growth inhibition (CFU/mL), the metabolic activity and viability of Gram-positive and Gram-negative bacteria as well as Candida species, in addition to the generation of oxygen free radical species (ROS), were studied. We followed the killing activity of CPe and analyzed the efficiency of the EO delivery for examined formulations by using unilamellar liposomes as a cellular model. CPe showed significantly higher antibacterial and antifungal activities than CT80 and CEt. Chamomile EOs generated superoxide anion and peroxide related oxidative stress which might be the major mode of action of Ch essential oil. We could also demonstrate that CPe was the most effective in donation of the active EO components when compared with CT80 and CEt. Our data suggest that CPe formulation is useful in the fight against microbial infections.

Mo2C deposited on silica is an effective catalyst for the decomposition of ethanol ; the extent of the reaction approached 100% even at 623–673 K. Beside H2 several C-containing compounds were produced, which caused the low yield of hydrogen. Preparation of Mo2C by the reaction of MoO3 with multiwall carbon nanotube, however, dramatically altered the product distribution. The formation of hydrogen came into prominence ; about 40% of hydrogen content of ethanol decomposed at 523–723 K has been converted into H2. Another feature of the Mo2C/C nanotube is the relatively slow deactivation. Adding water to ethanol further enhanced the hydrogen production.

The formation of Mo 2 C by the reaction of MoO 3 with carbon Norit in H 2 flow was followed by X-ray photoelectron spectroscopy. It was found that the conversion of MoO 3 into Mo 2 C in the surface layer of Norit was complete at 973 K. Mo 2 C prepared in this way on the surface of carbon Norit was found to be an effective catalyst for the decomposition of ethanol to generate H 2 ; the extent of the reaction approached 100% even at 623–673 K. Depending on the temperature and the Mo 2 C loading about 32–62% of hydrogen content of the decomposed ethanol has been converted into H 2 . Besides H 2 , acetaldehyde was the major product indicating that the dehydrogenation reaction of ethanol is the main process. The formation of CH 4 , CO, C 2 H 4 and C 2 H 6 also occurred in few percents. Another feature of the Mo 2 C/Norit catalysts is its high stability. The conversion of ethanol decreased only with few percent even after 75 h at 723 K. Adding potassium to Mo 2 C/Norit enhanced the catalytic efficiency of Mo 2 C and increased the formation of hydrogen. Mo 2 C prepared on multiwall carbon nanotube also proved to be active for the decomposition of ethanol. Adding water to ethanol enhanced the hydrogen production only to a small extent.

Mo2C prepared by the carburization of MoO3 with a C2H6/H2 mixture is an effective catalyst for the decomposition of both ethanol and methanol. The total decomposition of both compounds was attained at 573−623 K. The selectivity of H2 production in the decomposition of ethanol was 40−45% even at 723 K. With regard to the formation of H2, more attractive results were obtained in the case of methanol decomposition when H2, with a selectivity of 60%, was the major product. An important feature of this catalyst is the high thermal stability at 573−723 K. Adding water to methanol somewhat decreased the content of CO and increased that of H2 in the products. The highest yield of H2 production, ∼75%, was reached at 723 K.

The reaction of ethanol was investigated on Mo2C, Mo2C/SiO2 and Mo2C/ZSM-5 catalysts at temperature ranging 573–973 K under atmospheric pressure. Mo2C and Mo2C/SiO2 catalyzed only the decomposition of ethanol to H2, ethylene, acetaldehyde and different hydrocarbons. The main reaction pathway on pure ZSM-5 is the dehydration reaction yielding ethylene, small amounts of hydrocarbons and aromatics. Deposition of Mo2C on zeolite greatly enhanced the yield of benzene and toluene by catalyzing the aromatization of ethylene formed in dehydration process of ethanol.

Layer-by-layer self-assembly was used to prepare nanofilms of (2:1) MgAl-layered double hydroxide (LDH) nanoparticles and polyacrylic acid or sodium polystyrene sulfonate. The multilayers were attached to ~50-nm thick gold films on microscopy glass slides prepared by vacuum evaporation. The contact between the gold film and the multilayered films was mediated via surface modification with thiols, adsorption of poly(diallyl dimethyl ammonium) chloride (PDDA) or direct binding of the LDH particles. Surface plasmon resonance (SPR) spectra of the multilayered films were analyzed by fitting the Fresnel equations. The shifts in the SPR angle (ΔΘSPR) due to the adsorption/deposition on the gold surface were used to evaluate the process of building up the multilayers. Strong surface/multilayer contact formed when electrostatic attraction and hydrophobic interaction were combined as in the case of mercaptopropanoic acid or PDDA sticking layers. The LDH suspension concentration strongly influenced the number of deposited layers. The multilayer films were investigated by reflection FT-IR spectroscopy.

Similarly to the case of methane, ethane and propane, Mo2C deposited on ZSM-5 significantly enhanced the aromatization of n-butane observed on ZSM-5 (SiO2/Al2O3 ratio of 80) alone. The catalytic performance of Mo2C/ZSM-5 sensitively depended on its preparation and pretreatment. The selectivity of aromatics measured for pure ZSM-5 increased from 11-13% to 28-34% at the conversion level of 60-65%. The formation of aromatics was also observed over Mo2C/SiO2.

A platinum redox sensor for the direct potentiometric determination of α-amylase concentration has been described. The sensor measured the amount of triiodide released from a starch-triiodide complex, which was correlated with the α-amylase activity after biocatalytic starch degradation. The composition and stability of the potassium triiodide solution was optimized. The starch-triiodide complex was characterized potentiometrically at variable starch and triiodide concentrations. The response mechanism of the platinum redox sensor towards α-amylase was proposed and the appropriate theoretical model was elaborated. The results obtained using the redox sensor exhibited satisfactory accuracy and precision and good agreement with a standard spectrophotometric method and high-sensitive fully automated descret analyser method. The sensor was tested on pure α-amylase (EC 3.2.1.1, Fluka, Switzerland), industrial granulated α-amylase Duramyl 120 T and an industrial cogranulate of protease and α-amylase Everlase/Duramyl 8.0 T/60 T. The detection limit was found to be 1.944 mU for α-amylase in the range of 0-0.54 U (0-15 μg), 0.030 mKNU for Duramyl 120 T in the range of 0-9.6 mKNU (0-80 μg) and 0.032 mKNU for Everlase/Duramyl 8.0 T/60 T in the range of 0-9.24 mKNU (0-140 μg).

The reaction pathways of n-octane were studied on various Mo2C-containing catalysts. On unsupported Mo2C prepared by C2H6/H2 gas mixture the reaction of octane started at 573 K, and the conversion reached an initial value of ∼38% at 873 K. At lower temperature, 573–623 K, the main process is the dehydrogenation with some cracking. At 673–873 K, however, aromatics, xylene, toluene, benzene and ethylbenzene also formed with 58–30% selectivity. On Mo2C/Al2O3 the product distribution was different. At 773–823 K the main aromatics were ethylbenzene and o-xylene, they formed with ∼62–51% selectivity at 23–50% conversion. In contrast, on Mo2C/ZSM-5(80), which was found to be the most effective catalyst in the present work, toluene and benzene were the dominant aromatics. This suggests that the occurrence of the hydrogenolysis of C8 aromatics on the acidic sites of ZSM-5. This catalyst exhibited a very stable activity: the conversion decayed only with few percent even after 10 h, and the aromatizing capability also remained high. The results are interpreted by the monofunctional (pure Mo2C) and bifunctional mechanism (supported Mo2C) of the aromatization of n-octane.