Acid Molecules Research Articles

Decomposition and Growth Pathways for Ammonium Nitrate Clusters and Nanoparticles.

Understanding the formation and decomposition mechanisms of aerosolized ammonium nitrate species will lead to improvements in modeling the thermodynamics and kinetics of aerosol haze formation. Studying the sputtered mass spectra of cation and anion ammonium nitrate clusters can provide insights as to which growth and evaporation pathways are favored in the earliest stages of nucleation and thereby guide the development and use of accurate models for intermolecular forces for these systems. Simulated annealing Monte Carlo optimization followed by density functional theory optimizations can be used reliably to predict minimum-energy structures and interaction energies for the cation and anion clusters observed in mass spectra as well as for neutral nanoparticles. A combination of translational and rotational mag-walking and sawtooth simulated annealing methods was used to find optimum structures of the various heterogeneous clusters identifiable in the mass spectra. Following these optimizations with ωB97X-D3 density functional theory calculations made it possible to rationalize the pattern of peaks in the mass spectra through computation of the binding energies of clusters involved in various growth and dissociation pathways. Testing these calculations against CCSD(T) and MP2 predictions of the structures and binding energies for small clusters demonstrates the accuracy of the chosen model chemistry. For the first time, the peaks corresponding with all detectable species in both the positive and negative ion mass spectra of ammonium nitrate are identified with their corresponding structures. Thermodynamic control of particle growth and decomposition of ions due to loss of ammonia or nitric acid molecules is indicated. Structures and interaction energies for larger (NH4NO3)n nanoparticles are also presented, including the prediction of new particle morphologies with trigonal pyramidal character.

An Accurate and Fast 31P qNMR Assay Method for Oligonucleotide Therapeutics.

Chemically modified nucleic acid molecules have been developed as oligonucleotide therapeutics, and its assay is critical in quality assurance. The common DNA/RNA quantification method using UV-260 nm can lack accuracy because of structure modifications and the possible formation of higher-order structure (HOS). Additionally, process-associated water and counterions affect the accuracy in gravimetric analysis. Thus, to improve accuracy, efficiency, and flexibility, in this work a fast (<1 h) externally referenced 31P quantitative-NMR (qNMR) method was developed. The qNMR assay results agreed within 1-5% of the UV-260 nm results for the single-stranded DNA standards, confirming the method accuracy. Next, an NMR and UV comparison study was performed on intact oligonucleotide drug products. The 31P qNMR method showed 7 ± 2%, 8 ± 1%, and 12 ± 1% lower concentration values compared with drug product labels for eteplirsen, inotersen, and inclisiran, respectively. Meanwhile the UV-260 nm results showed 28 ± 3%, 10 ± 3%, and 10 ± 1% lower concentrations than the label for the same three drugs. The agreement between NMR and UV for phosphorothioate (PS)-based inotersen and mostly phosphodiester (PO)-based inclisiran suggest that the labeled concentration may have been obtained using different extinction coefficients. The underestimate of UV results for eteplirsen, which has a phosphorodiamidate morpholino oligomer (PMO) structure, suggests that the UV-260 nm extinction coefficient may need to be re-established for the PMO based oligonucleotide. Therefore, the 31P qNMR method could be a primary assay method for the oligonucleotide drug and reference standard.

Synthesis and structural characterization of acrylonitrile/vinyl imidazole copolymers and their amidoximated derivatives

Recently, environmental applications of copolymers such as CO2 capture and separation have become of significant interest. The development of copolymers with basic functional groups, such as amidoxime (AO) groups, represents a successful approach for enhancing absorption and separation of acidic molecules, such as CO2. In this research, acrylonitrile/N-vinyl imidazole (AN/VIM) copolymers were first synthesized through a free radical copolymerization method using 2,2′-azobisisobutyronitrile (AIBN) as the initiator and dimethylformamide as the solvent. The synthesized copolymers were then functionalized using hydroxylamine hydrochloride (NH2OH · HCl), the result being amidoximated (AO) copolymers. The synthesized copolymers were characterized by nuclear magnetic resonance (NMR) spectroscopy, thermogravimetric analysis and Fourier transform infrared spectroscopy. The analytical results simply confirmed that the copolymers and their amidoximated derivatives had successfully been synthesized. A microstructural study of amidoximated polymers using NMR spectroscopy clearly showed the tautomerization of AO groups.

Computational Study of the Formation of Atmospheric Aerosol Precursors Under Ambient Conditions: A Case Study of the Interaction Between Sea Salt, Water, and Sulfuric Acid Molecules

ABSTRACTCluster formation has significant implications in atmospheric science and environmental chemistry. These clusters are characterized by complex interactions between their constituents, which influence their structure, stability, and growth. Experimental investigations are difficult for the initial stages of prenucleation cluster formation, which leads to larger aerosols. To understand the formation of clusters, the interactions between sea salts (NaCl, KCl, and MgCl2), water, and sulfuric acid molecules have been investigated. Each step has been comprehensively examined and thermodynamic parameters have been computed using DLPNO‐CCSD(T)/CBS//M06‐2X/6‐311++G(3df,3pd) to find the stabilities of the molecular complexes. Among all complexes, the binding energies of cluster (SS)1(W)1(SA)3 are found to be the lowest due to the formation of HCl, hydrogen bonding, and weak van der Waal forces. Sea salts have shown a more favorable interaction with H2SO4 compared to H2O molecules. The addition of H2SO4 increases the reactivity of the cluster (SS)1(W)n, while the addition of H2O molecules reduces the reactivity of the cluster (SS)1(SA)n. However, further addition of H2SO4 or H2O to the existing cluster (SS)1(W)n(SA)n increases the free energy of formation. Furthermore, the influence of temperature was also investigated, suggesting that complex formation is slightly more favorable at lower temperatures than at higher temperatures. The negative values of thermodynamic parameters indicate, that these complexes are spontaneous and exothermic over the colder regions.

C-H Functionalization of Poly(ethylene oxide) - Embracing Functionality, Degradability, and Molecular Delivery.

This study presents an organocatalytic C-H functionalization approach for postpolymerization modification (PPM) of poly(ethylene oxide) (PEO). Most of PEO PPM is previously processed at the end hydroxy group, but recent advances in C-H functionalization open a way to modify the backbone position. Structurally diverse carboxylic acids are attached to PEO through a cascade process of radical generation by peroxide and oxidation to oxocarbenium by tertiary butylammonium iodide. Attaching carboxylic acids yields a series of functionalize PEO with acetal units (2-5 mol%) in a backbone, which is not accessible via conventional copolymerization of epoxides. The optimized conditions minimizes the uncontrolled degradation or crosslinking from the highly reactive radical and oxocarbenium intermediate. The newly introduced acetal units bring degradability of PEO as well as delivery of carboxylic acid molecules. Hydrolysis studies with high molecular weight functionalization PEO (Mn = 13.0kgmol-1) confirm the steady release of fragmented PEO (Mn ∼ 2.0kgmol-1) and carboxylic acid over days and the process rate is not sensitive to pH variation between pH 5 and 9. The presented method offers a versatile and efficient way to modify PEO with potential energy and medical applications.

8808 Characterization and pre-clinical study on a novel hormonal compound with potent analgesic and anti-inflammatory properties

Abstract Disclosure: T. Antakly: Other; Self; Theriac Biomedical. A. Brox: Owner/Co-Owner; Self; Theriac Biomedical. J. Menezes: Advisory Board Member; Self; Theriac Biomedical. H.H. Zingg: None. Hormones and naturally occurring compounds with therapeutic benefits have provided the basis of some of the most celebrated drugs e.g. Taxol (extracted from the Pacific Hew tree) and Premarin, a hormone replacement therapy (extracted from horse urine). Our team has discovered and chemically identified a bioactive compound (called “HIP-2”) found in folk medicinal admixtures. It has unique analgesic and anti-inflammatory properties. The chemical structure of HIP-2 consists of small fatty acid molecules which bind and activate the PPAR-gamma transcription factor, and furthermore they have HDAC inhibitory properties. A synthetic replica of the bioactive compounds was obtained and administered orally or by injection in a single dosage form. Using animal models for pain and inflammation, HIP-2 has demonstrated an outstanding efficacy and safety profile in animals (rats, mice) rendered experimentally inflamed (e.g. carrageenan injection) or osteoarthritic (surgery or iodoacetate injection). Pain and inflammation have decreased (by up to 50%) after HIP-2 administration. Inflammatory cytokines biomarkers were also reduced by about 50% as compared to baseline or to the positive controls (classical NSAID’s). HIP-2, with an outstanding safety and efficacy profile, offers an advantage over currently available analgesic and anti-inflammatory drugs, which have significant draw-backs due to limited efficacy and significant side effects such as gastrointestinal bleeding/ulcers/perforation and cardiac toxicity (Advil, Celebrex), osteoporosis and immunosuppression (corticosteroids), or addiction (opioids). As a potential solution to these problems, HIP-2 is likely to be superior both at the safety and efficacy levels. The HIP-2 IMP was cleared by FDA and is entering Phase 2 clinical trials. Presentation: 6/3/2024

Computational Analyses of Amino Acid Molecules in PDE7A for Elucidating their Evolutionary Diversity and Protein Interactions in Multiple Mammalian Species

This study explores the protein interactions and evolutionary conservation of phosphodiesterase type 7A (PDE7A) across different species, to identify the species with the highest similarity to humans, which has important applications in many fields such as pharmacology, comparative biology, biochemistry, oncology, endocrinology, and reproductive sciences. Computational analyses of the amino acid sequence of this enzyme revealed a common evolutionary relationship between the selected species and humans, but camels show the most variable evolutionary lineage in their PDE7A protein over time. In searches for homologous proteins, identity analysis results for four returned amino acid sequences were as follows: 91.81 ± 4.25% (mean ± SD), while the similarity between the sequences was 94.66% ± 4.55, and analysis of BLOSUM62 (Blocks Substitution Matrix 62) yielded a minimum value of 0.901 ± 0.055. All species have closely related physicochemical properties. The computational analyses revealed conserved amino acid residues of the gene across the studied species, which likely contribute to the similar expression patterns of the PDE7A gene in various animals. The findings also suggest that rats are a suitable model for gaining deeper insights into human biology.

Corrosion resistance and forming mechanism of phytic acid conversion film on copper foil prepared by electrolysis

In this paper, the phytic acid conversion film was prepared on copper foil by electrolysis for the first time. Its morphology and chemical composition were characterized by SEM, EDS, FTIR and XPS, and its corrosion resistance was evaluated using electrochemistry. Finally, the formation mechanism of the phytic acid conversion film on the surface of copper foil and its corrosion resistance mechanism were revealed by quantum chemical calculations and molecular dynamics simulations. The results show that the phytic acid conversion film on the surface of copper foil prepared by electrolysis is uniform and dense. The electrochemical impedance value of copper foil in 3.5 wt% NaCl solution increased from 3956 Ω·cm2 to 24828 Ω·cm2 after the preparation of phytic acid conversion film, and the protection efficiency reached 91 %. During the electrolysis process, copper atoms are oxidized into copper ions, which can be coordinated with phytate ions to form negatively charged complexes. Under the action of electric field force, these complexes move toward the anode copper foil, and finally adsorbed on the surface of the anode copper foil to form phytic acid conversion film. The molecular dynamics show that the adsorption configuration of the phytic acid molecule on Cu(111) surface changed from perpendicular to parallel, and the binding energy increased from 234.87 kJ/mol to 354.23 kJ/mol after applying an electric field, Therefore, the phytic acid conversion film prepared on the surface of copper foil by electrolysis has good corrosion resistance. This study provides a new method for the rapid preparation of phytic acid conversion film with excellent performance on metal surface.

Online characterization of primary and secondary emissions of particulate matter and acidic molecules from a modern fleet of city buses

Abstract. The potential impact of transitioning from conventional fossil fuel to a non-fossil-fuel vehicle fleet was investigated by measuring primary emissions via extractive sampling of bus plumes and assessing secondary mass formation using the Gothenburg Potential Aerosol Mass (Go:PAM) reactor from 76 in-use transit buses. Online chemical characterization of gaseous and particulate emissions from these buses was conducted using chemical ionization mass spectrometry (CIMS) with acetate as the reagent ion, coupled with the Filter Inlet for Gases and AEROsols (FIGAERO). Acetate reagent ion chemistry selectively ionizes acidic compounds, including organic and inorganic acids, as well as nitrated and sulfated organics. A significant reduction (48 %–98 %) in fresh particle emissions was observed in buses utilizing compressed natural gas (CNG), biodiesels like rapeseed methyl ester (RME) and hydrotreated vegetable oil (HVO), and hybrid-electric HVO (HVOHEV) compared to diesel (DSL). However, secondary particle formation from photooxidation of emissions was substantial across all the fuel types. The median ratio of particle mass emission factors of aged to fresh emissions increased in the following order: DSL buses at 4.0, HVO buses at 6.7, HVOHEV buses at 10.5, RME buses at 10.8, and CNG buses at 84. Of the compounds that can be identified by CIMS, fresh gaseous emissions from all Euro V/EEV (Enhanced Environmentally friendly Vehicle) buses, regardless of fuel type, were dominated by nitrogen-containing compounds such as nitrous acid (HONO), nitric acid (HNO3), and isocyanic acid (HNCO), alongside small monoacids (C1−C3). Notably, the emission of nitrogen-containing compounds was lower in Euro VI buses equipped with more advanced emission control technologies. Secondary gaseous organic acids correlated strongly with gaseous HNO3 signals (R2=0.85–0.99) in Go:PAM, but their moderate to weak correlations with post-photooxidation secondary particle mass suggest that they are not reliable tracers of secondary organic aerosol formation from bus exhaust. Our study highlights that non-regulated compounds and secondary pollutant formation, not currently addressed in legislation, are crucial considerations in the evaluation of environmental impacts of future fuel and engine technology shifts.

Cocrystal screening in minutes by solution-mediated phase transformation (SMPT): Preparation and characterization of ketoconazole cocrystals with nine aliphatic dicarboxylic acids

The rapid and efficient cocrystal screening, based on solution-mediated phase transformation (SMPT), was applied to the screening of cocrystals between ketoconazole (KTZ) and nine aliphatic dicarboxylic acids. Cocrystals formed successfully, in minutes, with a change of suspension characteristics, either a cake formation or the formation of large particles. Bulk cocrystals were characterized by powder X-ray diffraction, thermal analysis, and Raman spectroscopy. Single crystals were grown, and molecular structures were determined. Three previously reported cocrystals were reproduced, and six new cocrystals were discovered, including one that was reported as a failure in literature by solution or grinding method. Two hydrogen-bonded motifs are observed in these nine cocrystals: Most cocrystals form hydrogen bonded discrete tetramer with two KTZ and two acids molecules; while two cocrystals form infinite chain. This study demonstrated the high efficacy of cocrystal generation using the slurry screening method. It should be fully utilized in future cocrystal screening.

Ionizable Drugs Enable Intracellular Delivery of Co-Formulated siRNA.

Targeting complementary pathways in diseases such as cancer can be achieved with co-delivery of small interfering ribonucleic acid (siRNA) and small molecule drugs; however, current formulation strategies are typically limited to one, but not both. Here, ionizable small molecule drugs and siRNA are co-formulatedin drug-rich nanoparticles. Ionizable analogs of the selective estrogen receptor degrader fulvestrant self-assemble into colloidal drug aggregates and cause endosomal disruption, allowing co-delivery of siRNA against a non-druggable target. siRNA is encapsulated in lipid-stabilized, drug-rich colloidal nanoparticles where the ionizable lipid used in conventional lipid nanoparticles is replaced with an ionizable fulvestrant analog. The selection of an appropriate phospholipid and formulation buffer enables endocytosis and potent reporter gene knockdown in cancer cells. Importantly, siRNA targeting cyclin E1 is effectively delivered to drug-resistant breast cancer cells, demonstrating the utility of this approach. This strategy opens the possibility of using ionizable drugs to co-deliver RNA and ultimately improve therapeutic outcomes.

Dynamic Chemistry of DNA-Based Nanoassemblies in Living Cells.

ConspectusIn recent years, the controlled assembly/disassembly of exogenous chemical components inside cells has become an emerging approach to regulating cell functions. However, the construction of dynamic material chemistry systems in living cells always remains highly challenging due to the complicated intracellular microenvironment. Nucleic acid is a category of biological components that can achieve efficient molecular assembly via specific base-pairing and perform biological functions in the intracellular microenvironment. Deoxyribonucleic acid (DNA) molecules exhibit the superior performance of intracellular assembly, including sequence programmability, molecule recognition ability, and nanostructure predictability, as well as the unique biological functions that traditional synthetic polymers do not carry, showing great superiority in the construction of dynamic material chemistry systems. Moreover, the technologies of DNA synthesis are relatively mature, and the conjugation of DNA with functional small molecules can be achieved through established chemical synthesis methods, facilitating the construction of DNA-based dynamic materials with more functions. In addition, a few specific DNA molecules have been proven to show responsiveness toward different stimuli, functioning as dynamic modules.In this Account, we summarize our recent work in dynamic chemistry of DNA-based nanoassemblies in living cells from the perspective of stimulus types including enzyme, H+, glutathione (GSH), adenosine triphosphate (ATP), and light. Upon the specific stimuli, DNA-based nanoassemblies undergo precise assembly in living cells, executing disassembly or aggregation, which consequently affects the functions and behaviors of living cells. In the first part, we describe the interactions between DNA-based nanoassemblies and intracellular enzymes, namely the enzymatic cleavage of intracellular enzymes on the DNA or RNA sequences. In the second part, we summarize the effects of H+ in lysosomes on DNA-based nanoassemblies, including the formation of a tetraplex i-motif structure and the decomposition of acid-degradable polymeric coating. In the third part, we discuss the mechanism of GSH responsiveness of DNA-based nanoassemblies, including the breaking of disulfide bonds and reduction-responsive nanoparticles. In the fourth part, we describe the ATP-mediated conformational transition for the specific release of functional RNA sequences. In the fifth part, we demonstrate the light-mediated spatiotemporally dynamic chemistry of DNA-based nanoassemblies. In summary, based on the achievements of our group in the study of dynamic chemistry of DNA-based nanoassemblies, the assembly, disassembly, and reassembly in living cells are well-controlled, the regulation of cellular functions are explored, and the new strategies for cancer therapeutics are demonstrated. We envision that our work on the dynamic chemistry of DNA-based nanoassembly is a new paradigm for constructing dynamic material chemistry systems inside living cells, and will facilitate the development of precision medicine.

Multifunctional poly(ether‐urethane) elastomer based on dynamic phenol-urethane and disulfide bonds: Simultaneously showing superior toughness, self-healing, shape memory, antibacterial, and antioxidative properties

Multifunctional polymers are highly desirable for developing smart materials in medical applications. This study proposed a facile strategy to fabricate a new multifunctional poly(ether‐urethane) incorporating disulfide bonds and phenol-urethane bonds (PEU−TS). The distinctive feature of the designed PEU−TS elastomers was the presence of abundant phenolic hydroxyl groups, dynamic aromatic disulfide bonds, phenol-urethane bonds, and multiple H-bonds between urethane groups and tannic acid (TA) molecules, which endowed the materials with superior antibacterial and antioxidative activities, self‐healing capabilities, and shape memory functions. Furthermore, the phenol-carbamate crosslinked networks enhanced the tensile properties and improved the biostability of the elastomers. Biocompatibility evaluation further demonstrated that networked PEU−TS composites possessed favorable cell viability and high cytocompatibility. The multifunctional PEU−TS elastomers with robust tensile properties hold great potential for application in durable implants and chronic wound dressings. This elaborate design could inspire the development of multifunctional PU materials over wide medical applications.

Investigating the synergistic effect of fish waste extract and KI on the corrosion inhibition of carbon steel in sulfuric acid solution

Biowaste has become a serious problem that can lead to serious environmental pollution and waste of resources if not handled properly. Waste materials are often high in proteins, which are easily extracted and hydrolyzed to provide an adequate quantity of amino acids. This indicates that biowastes can be used as green and efficient corrosion inhibitors (CIs). This work aimed to prepare fish waste extract (FWE) by acid hydrolysis with alkaline leaching using fish waste as the raw material. The results of the characterization analysis identified the presence of 17 amino acids, with Leucine, Phenylalanine, Methionine, and Alanine being the most abundant. FWE was then tested as a corrosion inhibitor (CI) for carbon steel in 0.5 mol/L H2SO4. Further, the effect of KI on the corrosion inhibition performance of FWE for carbon steel in 0.5 mol/L H2SO4 was systematically investigated by the weight loss method, electrochemical method, and surface analysis. The maximum corrosion inhibition efficiencies were 88.7 % and 63.9 % for the FWE and KI alone, and 97.10 % for the combination of FWE and KI. The synergistic coefficient study confirmed that the synergistic coefficients of the FWE and KI exceeded 1 across all concentration conditions, indicating a synergistic effect between them. The surface analysis results showed that the deterioration of carbon steel after adding the compounded CI was mild, and pitting and crevice corrosion was not observed. Theoretical calculations revealed the active reaction sites of four major amino acid molecules via quantum chemical and molecular dynamics simulations. The effect of different types of side chains and heteroatoms of amino acid molecules on their corrosion inhibition performance was elucidated to provide theoretical guidance for designing biowaste CIs.

High-performance of anti-bacterial composite membrane prepared from polyethersulfone-polyethylene glycol-silver nanoparticles

A bench-scale study of river water treatment using composite polyethersulfone (PES) membrane was carried out. Polyethylene glycol-silver nanoparticles (PEG-AgNPs) additive was designed to support the simultaneous filtration and disinfection performance of PES membranes via in situ incorporation. Significant improvements in the PES membranes after modification with PEG-AgNPs were observed. The experimental results showed that the PEG-AgNPs increased the PES membrane water flux from 2.87 to 172.84 L/m2·h. The anti-fouling test of the PES membrane toward humic acid molecules after the addition of PES/PEG-AgNPs increased the reversible fouling and decreased the irreversible fouling. In terms of filtration performance, the PES/PEG-AgNP membranes showed high filtration performance, with a water disinfection ability of 99.99 %. Moreover, the leach of silver particles from the PES membrane forced by ultrasonication was <50 ppb, indicating the security and stability of the PES/PEG-AgNP membrane.

Microscopic mechanistic study of the penetration distributions for plasma reactive oxygen and nitrogen species based on sialic acid targeting on the cell membrane surface

The ability of cold atmospheric plasmas (CAPs) to produce a wide range of active constituents while maintaining a low or even room temperature of the gas has made it a novel research area of great interest. During plasma action, cancer cell membrane surface components are susceptible to oxidative modification by reactive oxygen and nitrogen species (RONS). In this study, the process of oxidative modification of membrane surface components sialic acid by RONS was investigated based on molecular dynamics simulations, and the penetration mechanism of long-lived particles ONOOH and its homolytic products at the membrane-water interface and the effect of appropriate electric field action were studied. The results showed that cancer cells with high sialic acid expression were less stable than healthy cells. Plasma treatment may promote the ONOOH homolysis process, and its homolysis product OH free radical is more likely to adsorb near sialic acid molecules by hydrogen bonding, resulting in oxidative modification. The interaction force between OH free radical and sialic acid molecules is stronger than ONOOH, which helps to further understand the oxidative modification reaction in membrane environment. At the same time, appropriate electric field stimulation can enhance the depth of penetration of RONS to more effectively treat the pathological state of biological tissues. The study proposes the use of membrane surface sialic acid as a cancer therapeutic target and provides guidance for improving the depth of RONS penetration and maximizing the survival of healthy cells, which contributes to the further clinical translation of plasma biomedicine.

3D-printed copolymer semi-cavity sensor with inner optical filter-effecting quantum dots photoluminescence for multiple drugs and amino acids detection

Here, we demonstrate a prototype for a novel optical sensor based on 3D-printed copolymer semi-cavity embedded with colloidal ZnCuInS (ZCIS) quantum dots (QDs) and utilizing the optical filter-effect in the QDs photoluminescence excitation pathway by analytes in the solution. First, in situ copolymerization of styrene and n-butyl methacrylate (P(S-BMA)) with colloidal ZCIS QDs allowed formation of solid P(S-BMA) matrix homogeneously impregnated with QDs. Then QDs@P(S-BMA) mixed with polylactic acid (PLA) has been processed into QDs@P(S-BMA)@PLA hybrid filaments using extruder. Then, a semi-cavity optical cell was 3D-printed out of QDs@P(S-BMA)@PLA filaments. Such 3D-printed semi-cavity cell can be used as the optical sensor on various molecules utilizing the optical absorption by analyte molecules through inner filter effect (IFE) of a properly selected QDs excitation beam. The multiple drug and amino acid molecules have been utilized having selective UV absorption to examine our proof of concept.

Switching Photoluminescence “On‐Off‐On” for Detection of Chromium (VI) Ion and Ascorbic Acid with N,S‐Codoped Carbon Dots

AbstractA photoluminescent‐based “Turn On → Off → On” technique was adopted for a toxic, heavy metal ion detection, that is, specifically chromium (VI) and a pharmaceutically relevant ascorbic acid molecule. Metal‐free, environmentally benign, and fluorescent carbon dots, a potential vehicle for spectrofluorometric detection, were successfully deployed as sensors. Carbon dots synthesized from citric acid and sulfanilamide conserve the fragments of the precursor molecule on the surface. Zeta potential measurement evidenced the positively charged carbon nanoparticles physically interact with the Cr(VI)/Cr2O72− in acidic pH, resulting in a remarkable quenching in net fluorescence. Thorough studies revealed that the static quenching and inner filter effect were responsible for the reduction in fluorescence intensity. We have demonstrated a new rapid (in seconds) detection platform for Cr(VI) and ascorbic acid.

Utilization of azamacrocyclic ionophores as recognition elements for the potentiometric determination of gallic acid in various matrices

Gallic acid is a naturally occurring low molecular weight triphenolic molecule identified as a potent antioxidant, protecting against various types of reactive species and non-radicals. Three novel carbon paste electrodes were developed for the potentiometric determination of gallic acid. Azamacrocyclic ionophors; cyclen, hexacyclen, and kryptofix-22 were utilized as recognition ionophores separately. A multi-walled carbon nanotubes/titanium oxide nanocomposite was employed as the ion-to-electron transducer in the designed sensors. The prepared transducer was characterized by FT-IR and TEM. Molecular docking was implemented to study the recognition mechanism between these ionophores and the gallic acid molecule. It revealed promising binding interactions between gallic acid and the three recognition ionophores, especially hexacyclen and Kryptofix-22. In studying the potentiometric response of the proposed sensors, they exhibited high stability, sensitivity, accuracy, and precision in the quantitation of gallic acid. Gallic acid can be accurately quantified over the linearity range of 1 × 10−1–1 × 10−3 M, 1 × 10−2–1 × 10−6 M, and 1 × 10−2–1 × 10−6 M with a Limit of detection (LOD) 4 × 10−4 M, 3 × 10−7 M, and 7 × 10−7 M, for CPE1, CPE 2 and CPE 3, respectively. The electrodes showed high efficiency in determining gallic acid in Krameria lappacea root alcoholic extract, black tea, green tea, and human plasma without sophisticated pretreatment steps.

Clinical markers of Charcot-Marie-Tooth disease (own experience)

Charcot-Marie-Tooth disease is also called hereditary motor and sensory neuropathy. It is a genetically determined disease that has different variants of inheritance whose substratum is neuromuscular disorders. It may begin during childhood or later in life. Scientists have identified and described more than thirty genetic mutations that form an individual unique passport of violations of the sequence of a group of organic compounds or nucleotides in nucleic acid molecules. There are autosomal dominant, autosomal recessive and X-linked types of genetic inheritance of Charcot-Marie-Tooth disease. This pathology was first described in 1886 and affects about 10 to 40 per 100,000 population. More than 15,000 cases of Charcot-Marie-Tooth disease have been registered in Ukraine. It should be noted that peripheral myelin protein 22 became the first described gene causing Charcot-Marie-Tooth disease. Autosomal dominant Charcot-Marie-Tooth type 1 is the most common form of the disease. When observing patients, a neurologist pays attention to gait disturbances (steppage gait), foot distortion (pes cavus), distal hypotrophy, decrease or absence of tendon and periosteal reflexes, weakness and loss of sensitivity in the distal parts of the limbs. Hypotrophic changes in the limbs are continuously progressive. As a result of muscle atrophy and foot deformity, high-arched feet and extension of the big toe (Friedreich’s foot) are formed. To date, no pathogenetically substantiated treatment exists for Charcot-Marie-Tooth disease, but a multi-vector approach to comprehensive rehabilitation measures creates the necessary conditions to effectively control the manifestations of the inevitable progression of this pathology.