Application of a New Functionalized MWCNTs for the Construction of Surfactant Potentiometric Sensors

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

Preparation and in vitro diffusion study of essential oil Pickering emulsions stabilized by silica nanoparticles for Streptococcus mutans biofilm inhibition

A long-standing problem in patient care is the ability of bacteria to form biofilms, including Streptococcus mutans biofilm on teeth or dental implants [1]. The essential oils have a proven ability for biofilm inhibition [2], but their direct use is limited due to their physical-chemical properties, such as the hydrophobicity and low water solubility. EOs are used as active ingredients in mouth care products, but the solvent components, e.g. DMSO or ethanol and surfactant as SDS or polysorbates in the case of emulsions, may influence the role and effect of EOs. To avoid the use of solvents and surfactants, we could use Pickering emulsions (PE), which are solid particle stabilized emulsions [3]. For this purpose, biologically inert solid particles are used, and this emulsion can be used for EO formulations. Besides emulsion stabilization, the solid particles may interact with biofilm [4] and targeted EO transportation can be also achieved. The aim of our work was to prepare silica nanoparticle stabilized PEs with thyme, clove, peppermint, and cinnamon EO, in order to enhance their bioavailability for potential biofilm inhibition. The droplet size and stability of PEs were determined by dynamic light scattering measurements. In vitro diffusion experiments have been performed on a model agar gel membrane with the PEs, conventional emulsions, and ethanolic EO solutions. EOs were used in the MIC/2 concentration against S. mutans. The results from diffusion experiments clearly show that EOs in PE form are more effective regarding the cumulative amount of EOs passed through the model membrane. Biofilm inhibition test has been also performed, where we have determined, that the EOs in PE form have a better biofilm inhibition effect then the solutions or conventional emulsions

Sol-Gel Synthesis of Ceria-Zirconia-Based High-Entropy Oxides as High-Promotion Catalysts for the Synthesis of 1,2-Diketones from Aldehyde

Efficient Lewis-acid-catalyzed direct conversion of aldehydes to 1,2-diketones in the liquid phase was enabled by using newly designed and developed ceria–zirconia-based high-entropy oxides (HEOs) as the actual catalysts. The synergistic effect of various cations incorporated in the same oxide structure (framework) was partially responsible for the efficiency of multicationic materials compared to the corresponding single-cation oxide forms. Furthermore, a clear, linear relationship between the Lewis acidity and the catalytic activity of the HEOs was observed. Due to the developed strategy, exclusively diketone-selective, recyclable, versatile heterogeneous catalytic transformation of aldehydes can be realized under mild reaction conditions

A new sensor for direct potentiometric determination of thiabendazole in fruit peels using the Gran method

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 ionselective 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

Influence of Aliphatic Chain Length on Structural, Thermal and Electrochemical Properties of n-alkylene Benzyl Alcohols: A Study of the Odd–Even Effect

The century-old, well-known odd–even effect phenomenon is still a very attractive and intriguing topic in supramolecular and nano-scale organic chemistry. As a part of our continuous efforts in the study of supramolecular chemistry, we have prepared three novel aromatic alcohols (1,2- bis[2-(hydroxymethyl)phenoxy]butylene (Do4OH), 1,2-bis[2-(hydroxymethyl)phenoxy]pentylene (Do5OH) and 1,2-bis[2-(hydroxymethyl)phenoxy]hexylene (Do6OH)) and determined their crystal and molecular structures by single-crystal X-ray diffraction. In all compounds, two benzyl alcohol groups are linked by an aliphatic chain of different lengths (CH2)n; n = 4, 5 and 6. The major differences in the molecular structures were found in the overall planarity of the molecules and the conformation of the aliphatic chain. Molecules with an even number of CH2 groups tend to be planar with an all-trans conformation of the aliphatic chain, while the odd-numbered molecule is non-planar, with partial gauche conformation. A direct consequence of these structural differences is visible in the melting points—odd-numbered compounds of a particular series display systematically lower melting points. Crystal and molecular structures were additionally studied by the theoretical calculations and the melting points were correlated with packing density and the number of CH2 groups. The results have shown that the generally accepted rule, higher density = higher stability = higher melting point, could not be applied to these compounds. It was found that the denser packaging causes an increase in the percentage of repulsive H· · · H interactions, thereby reducing the stability of the crystal, and consequently, the melting points. Another interesting consequence of different molecular structures is their electrochemical and antioxidative properties—a non-planar structure displays the highest oxidation peak of hydroxyl groups and moderate antioxidant activit

Szénhidrogének és alkoholok reakciójának katalitikus és felületkémiai vizsgálata = Catalytic and surface science studies related to the reactions of hydrocarbons and alcohols

Tanulmányoztuk a benzol, metanol, dimetil és dietil éter aromatizációját és a metilezését a ZSM-5 zeolitra rávitt Mo2C, Ga2O3 és ZnO-on. Mindhárom anyag hatásosan katalizálta a metanol aromatizációját, és a Mo2C/ZSM-5 elősegítette a benzol metilezését is. Spektroszkópiai módszerekkel feltártuk a zeolit és a Mo2C szerepét. Kísérleteink másik részében a hidrogén előállítására koncentráltunk. Elsődleges célunk a drága platina fémeket helyettesítő olcsó és stabilis katalizátor szintézise volt. Erre a célra legmegfelelőbbnek ismét a Mo2C bizonyult. Amennyiben a Mo2C-t nagy felületű többfalú szén nanocsőre vagy Norit szénre vittük rá, az alkoholok átalakításának iránya megváltozott: az etanol és metanol aromatizációja helyett a hidrogén képződése került előtérbe. A hidrogén előállításával kapcsolatos kutatási programunk talán egyik legfontosabb eredménye, hogy a Mo2C/carbon katalizátoron a HCOOH bomlásának katalízisével sikerült tiszta, CO mentes hidrogént előállítanunk alacsony hőmérsékleten. Párhuzamosan folyó elektron-spektroszkópiai módszerekkel feltártuk a reakciók primér lépéseit és a felületen képződő gyökök átalakulásának irányát. Elektron- foton- és ion spektroszkópiával (AES, XPS, LEIS, RAIRS), valamint STM-el tanulmányoztuk a kétfémes nanoszerkezetek képződését és fizikai-kémiai sajátságait egykristály titán-dioxid felületen. Eredményeinket 20 nemzetközi folyóiratban megjelent dolgozatban közöltük és azokról különböző nemzetközi konferenciákon 35 előadást tartottunk. | The adsorption and reaction pathways of methanol, dimethyl and diethyl ethers have been investigated on pure and Mo2C containing ZSM-5. ZSM-5 effectively catalyzed the reaction of all the three compounds above 473 K to yield various olefins and aromatics. Adding Mo2C to the zeolites greatly promoted the formation of aromatics very likely by catalyzing the aromatization of olefins formed in the reaction. Addition of benzene to dimethyl ether markedly increased the formation of toluene, xylene and C9 aromatics on ZSM-5. The enhancement was further increased by ZnO and Mo2C promoters. Extensive research has been carried out recently to develop a procedure for the production of clean hydrogen for fuel cells. Efforts were also made to replace the expensive Pt metals with more effective, stable, and less expensive catalysts. We found that Mo2C when it is prepared on different carbon supports is an effective catalyst for the decomposition of alcohols and ether to give hydrogen. In the case of reforming of HCOOH we achieved to produce H2 free of CO. The adsorption and reaction pathways of above compounds on Mo2C/Mo(100) have been studied by several electron spectroscopic methods. The results helped to establish the mechanism of the catalytic reactions. Detailed spectroscopic experiments were performed concerning the interaction of Au with Rh on TiO2(100). We gave account on our results in 20 papers published in international journals, and presented 35 lectures at various Conferences

Applicability of cinnamon bark essential oil in respiratory tract diseases – from in vitro to in vivo experiments

Introduction: Because respiratory tract diseases affect every age group and antibiotic resistance is an increasing problem in healthcare, there is a need for additional therapies. Essential oils (EOs) are used via inhalation for the treatment of respiratory tract diseases for a long time. Similarly to other plant extracts, their efficacy should also be proved in several test systems. Therefore, our aim was to study the antibacterial and antiinflammatory effects of cinnamon bark oil in in vitro and in vivo models.                Methods: The chemical composition of cinnamon EO was determined by GC-FID/MS and SPME-GC-MS methods. The antibacterial effect of the EO was tested by macrodilution and vapor-phase methods against respiratory tract pathogens. The emulsion of the EO prepared by nanotechnology was also used for the examination of the biofilm inhibitory effect. The antiinflammatory effect was studied in an LPS-induced acute airway inflammation mouse model.                Results and conclusion: The main component of the EO was trans-cinnamaldehyde (74.0%, 46.0%) in both analytical systems. In the liquid medium, cinnamon EO exhibited antibacterial activity against Streptococcus pyogenes, S. pneumoniae, S. mutans, Haemophilus influenzae and H. parainfluenzae (MIC: 0.06 mg/mL). In the vapor-phase test, the EO was the most effective against Haemophilus strains (MIC: 15.6 μL/L). The biofilm formation of S. mutans was more effectively reduced by the emulsion of cinnamon oil prepared by nanotechnology compared to the emulsions prepared with Tween80 or alcohol. In the animal model, cinnamon oil inhalation reduced airway hyperreactivity, macrophage accumulation in histological images, but did not affect MPO activity. Therefore, cinnamon oil may be a potential antibacterial and antiinflammatory agent for the treatment of respiratory tract diseases

Preparation of multifunctional N-doped carbon quantum dots from citrus clementina peel: investigating targeted pharmacological activities and the potential application for Fe3+ sensing

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