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The Analyst Mar 2024Carrier-based polymeric membrane potentiometric sensors are an ideal tool for detecting ionic species. However, in the fabrication of these sensors, the screening of...
Carrier-based polymeric membrane potentiometric sensors are an ideal tool for detecting ionic species. However, in the fabrication of these sensors, the screening of carriers still relies on empirical trial- and error-based optimization, which requires tedious and time-consuming experimental verification. In this work, computer-aided screening of carriers is applied in the preparation of polymeric membrane potentiometric sensors. Molecular docking is used to study the host-guest interactions between receptors and targets. Binding energies are employed as the standard to screen the appropriate carrier. As a proof-of-concept experiment, the antibiotic ciprofloxacin is selected as the target model. A series of supramolecular macrocyclic receptors including cyclodextrins, cucurbiturils and calixarenes are chosen as potential receptors. The proposed sensor based on the receptor calix[4]arene screened by molecular docking shows a lower detection limit of 0.5 μmol L for ciprofloxacin. It can be expected that the proposed computer-aided screening technique of carriers can provide a simple but highly efficient method for the fabrication of carrier-based electrochemical and optical sensors.
Topics: Anti-Bacterial Agents; Molecular Docking Simulation; Potentiometry; Macrocyclic Compounds; Polymers; Calixarenes; Ciprofloxacin
PubMed: 38324339
DOI: 10.1039/d3an02154h -
Ecotoxicology and Environmental Safety Mar 2024Deferiprone, generally, is considered an important chelating agent for Fe overload. From a literature data analysis, a lack of information on the interaction of this...
Deferiprone, generally, is considered an important chelating agent for Fe overload. From a literature data analysis, a lack of information on the interaction of this molecule toward a series of metal cations emerged, inducing to fill out the topic. The complexing ability of deferiprone toward Ca, Mg, Cd and Pb was studied by potentiometry and H NMR spectroscopy, in KCl aqueous solutions at different ionic strength values (0.1 ≤ I/mol dm ≤ 1.0) and T = 298.15 K. The same speciation model featured by the ML, ML, ML and ML(OH) (M = metal and L = deferiprone or DFP) species was obtained for Cd and Pb; the formation constants calculated at infinite dilution are: logβ = 7.23±0.02, 12.47±0.03, 16.70±0.04, and -2.53±0.04, respectively for Cd and 9.91±0.01, 15.99±0.02, 19.93±0.05 and 0.99±0.02 for Pb. Only two species, namely ML and ML, were determined for Ca and Mg, whose formation constants at infinite dilution are respectively: 3.72±0.01 and 6.50±0.02, for the first one, 5.31±0.01 and 9.58±0.01, for the second. The ligand sequestering ability and affinity toward M were evaluated by determining the pL and pM parameters at different pHs and ionic strengths. The results suggest that deferiprone has the best complexing and sequestering ability toward Pb, followed by Cd, Mg and Ca, respectively. H NMR studies confirmed the DFP affinity for Cd and Pb, and in combination with DFT calculations showed that metal cations are bound to the hydroxo-oxo moiety of the pyridinone ring. The data reported in this study provide information on the possible employment of a small molecule like deferiprone, as a chelating and sequestering agent for Pb accumulation or overload from environmental and biological matrices.
Topics: Deferiprone; Cadmium; Lead; Cations; Models, Theoretical; Chelating Agents
PubMed: 38295733
DOI: 10.1016/j.ecoenv.2024.116027 -
RSC Advances Jan 2024A highly promising flower-shaped WS-WO/poly-2-aminobenzene-1-thiol (P2ABT) nanocomposite was successfully synthesized a reaction involving 2-aminobenzene-1-thiol, NaWO,...
Simple potentiometry and cyclic voltammetry techniques for sensing Hg ions in water using a promising flower-shaped WS-WO/poly-2-aminobenzene-1-thiol nanocomposite thin film electrode.
A highly promising flower-shaped WS-WO/poly-2-aminobenzene-1-thiol (P2ABT) nanocomposite was successfully synthesized a reaction involving 2-aminobenzene-1-thiol, NaWO, and KSO as oxidants. The WS-WO/P2ABT nanocomposite demonstrated remarkable potential as a sensor for detecting harmful Hg ions in aqueous solutions. The sensing behavior was evaluated over a wide concentration range, from 10 to 10 M, using a simple potentiometric study on a two-electrode cell. The calibration curve yielded an excellent Nernstian slope of 33.0 mV decade. To further validate the sensing capabilities, cyclic voltammetry was employed, and the results showed an increasing trend in the cyclic voltammetry curve as the Hg concentration increased from 10 to 10 M with an evaluated sensitivity of 2.4 μA M. The WS-WO/P2ABT nanocomposite sensor exhibited exceptional selectivity for detecting Hg ions, as no significant effects were observed from other interfering ions such as Zn, Ni, Ca, Mg, Al, and K ions in the cyclic voltammetry tests. Furthermore, the sensor was tested on a natural sample that was free of Hg ions, and the cyclic voltammetry curves did not produce any characteristic peaks, confirming the sensor's specificity for Hg detection. The sensor's cost-effectiveness and ease of fabrication present the potential for developing a simple and practical sensor for detecting highly poisonous ions in aqueous solutions.
PubMed: 38283592
DOI: 10.1039/d3ra07932e -
Angewandte Chemie (International Ed. in... Mar 2024Spreading depolarization (SD) is one of the most common neuropathologic phenomena in the nervous system, relating to numerous diseases. However, real-time monitoring the...
Spreading depolarization (SD) is one of the most common neuropathologic phenomena in the nervous system, relating to numerous diseases. However, real-time monitoring the rapid chemical changes during SD to probe the molecular mechanism remains a great challenge. We develop a potentiometric dual-channel microsensor for simultaneous monitoring of H S and pH featuring excellent selectivity and spatiotemporal resolution. Using this microsensor we first observe real time changes of H S and pH in the rat brain induced by SD. This changes of H S are completely suppressed when the rat pre-treats with aminooxyacetic acid (AOAA), a blocker to inhibit the H S-producing enzyme, indicating H S fluctuation might be related to enzyme-dependent pathway during SD and less pH-dependent. This study provides a new perspective for studying the function of H S and the molecular basis of SD-associated diseases.
Topics: Rats; Animals; Potentiometry; Brain; Hydrogen-Ion Concentration
PubMed: 38272831
DOI: 10.1002/anie.202318973 -
Nanoscale Feb 2024Li intercalation is commonly used to enhance the carrier density in epitaxial graphene and mitigate coupling to the substrate. So far, the understanding of the...
Li intercalation is commonly used to enhance the carrier density in epitaxial graphene and mitigate coupling to the substrate. So far, the understanding of the intercalation process, particularly how Li penetrates different layers above the substrate, and its impact on electron transport remains incomplete. Here, we report different phases of Li intercalation and their kinetic processes in epitaxial mono- and bilayer graphene grown on SiC. The distinct doping effects of each intercalation phase are characterized using scanning tunneling spectroscopy. Furthermore, changes in the local conduction regimes are directly mapped by scanning tunneling potentiometry and attributed to different charge transfer states of the intercalated Li. The stable intercalation marked by the formation of Li-Si bonds leads to a significant 56% reduction in sheet resistance of the resulting quasi-free bilayer graphene, as compared to the pristine monolayer graphene.
PubMed: 38259148
DOI: 10.1039/d3nr03070a -
Biomolecules Jan 2024Because of their capacity to bind metals, metal chelators are primarily employed for therapeutic purposes, but they can also find applications as colorimetric reagents...
Because of their capacity to bind metals, metal chelators are primarily employed for therapeutic purposes, but they can also find applications as colorimetric reagents and cleaning solutions as well as in soil remediation, electroplating, waste treatment, and so on. For instance, iron-chelation therapy, which is used to treat iron-overload disorders, involves removing excess iron from the blood through the use of particular molecules, like deferoxamine, that have the ability to chelate the metal. The creation of bioinspired and biodegradable chelating agents is a crucial objective that draws inspiration from natural products. In this context, starting from bioavailable molecules such as maltol and pyrogallol, new molecules have been synthetized and characterized by potentiometry, infrared spectroscopy and cyclic voltammetry. Finally, the ability of these to bind iron has been investigated, and the stability constants of ferric complexes are measured using spectrophotometry. These compounds offer intriguing scaffolds for an innovative class of versatile, multipurpose chelating agents.
Topics: Iron Chelating Agents; Iron; Chelation Therapy; Biological Products; Colorimetry; Ligands
PubMed: 38254692
DOI: 10.3390/biom14010092 -
Chemphyschem : a European Journal of... Apr 2024Ionic liquids (ILs) are organic chemical compounds that are composed only of ions, a large organic cation and a smaller inorganic or organic anion. These are salts whose... (Review)
Review
Ionic liquids (ILs) are organic chemical compounds that are composed only of ions, a large organic cation and a smaller inorganic or organic anion. These are salts whose melting point is lower than the boiling point of water. ILs have many interesting properties, thanks to which they find great practical applications in analytics, electrochemistry, separation techniques, catalysis and others. One of the many areas of application of ionic liquids is sensors especially electrochemical sensors including ion-selective electrodes. In this case, the properties of ILs that are particularly useful include very good electrical conductivity, high electrochemical stability, good extraction properties, hydrophobic character and compatibility with other materials, e. g. polyvinyl chloride plasticizers or carbon nanomaterials. ILs were used as components of ion-selective membranes, both polymeric ones based on PVC and membranes in carbon paste electrodes. ILs performed various functions in these membranes, including lipophilic ionic additive, ionophore/ion exchanger, plasticizer, transducer media and matrix. They were also used as a component of the intermediate layer in solid contact ISEs. The last chapter presents examples of the use of ILs in reference electrodes. This review discusses the use of ionic liquids in ion-selective electrodes (ISEs) and reference electrodes over the last ten years.
PubMed: 38252078
DOI: 10.1002/cphc.202300818 -
Magnetic Resonance in Chemistry : MRC Feb 2024Potentiometry is the primary pH measurement method, but alternatives are sought beyond glass electrodes operative limitations. In nuclear magnetic resonance (NMR)...
Potentiometry is the primary pH measurement method, but alternatives are sought beyond glass electrodes operative limitations. In nuclear magnetic resonance (NMR) experiments, electrodeless pH sensing is important to track changes along titrations, during chemical reactions or inside compartmentalized environments inaccessible to electrodes, for instance. Although several interesting NMR pH indicators have been already presented, the potential of inorganic phosphate is overlooked, despite its common presence in NMR samples as the buffer main component. Its use for electrodeless pH determination can be expanded by exploiting all its three proton dissociations. This study was aimed at verifying the use of inorganic phosphate P chemical shift to sense pH variations, and at exploring the complementary use of pyrophosphate ions to cover a wide pH range. A simple set of equations is presented to utilize both phosphate and pyrophosphate P chemical shift in combination for accurate pH determination without a glass electrode over the 5-12 pH range, and without affecting the spectrum of other nuclei. The present study demonstrated an average deviation of 0.09 (maximum <0.2) pH unit from glass electrode measurements. The trimethylphosphate can be used as a suitable chemical shift reference for both P and H (also C), with its hydrolysis being significant only at pH > 12. The method was also demonstrated by determining the pKa of three distinct molecules in a mixture and by comparing the results to those obtained when the glass electrode was used to measure the pH. The approach shown here can be easily tuned to different experimental conditions.
PubMed: 38243872
DOI: 10.1002/mrc.5429 -
Inorganic Chemistry Jan 2024A series of macrocyclic ligands were considered for the chelation of Pb: 1,4,7,10-tetrakis[2-(methylsulfanyl)ethyl]-1,4,7,10-tetraazacyclododecane (DO4S),...
A series of macrocyclic ligands were considered for the chelation of Pb: 1,4,7,10-tetrakis[2-(methylsulfanyl)ethyl]-1,4,7,10-tetraazacyclododecane (DO4S), 1,4,7-tris[2-(methylsulfanyl)ethyl]-1,4,7,10-tetraazacyclododecane (DO3S), 1,4,7-tris[2-(methylsulfanyl)ethyl]-10-acetamido-1,4,7,10-tetraazacyclododecane (DO3SAm), 1,7-bis[2-(methylsulfanyl)ethyl]-1,4,7,10-tetraazacyclododecane-4,10-diacetic acid (DO2A2S), 1,5,9-tris[2-(methylsulfanyl)ethyl]-1,5,9-triazacyclododecane (TACD3S), 1,4,7,10-tetrakis[2-(methylsulfanyl)ethyl]-1,4,7,10-tetrazacyclotridecane (TRI4S), and 1,4,8,11-tetrakis[2-(methylsulfanyl)ethyl]-1,4,8,11-tetrazacyclotetradecane (TE4S). The equilibrium, the acid-mediated dissociation kinetics, and the structural properties of the Pb complexes formed by these chelators were examined by UV-Visible and nuclear magnetic resonance (NMR) spectroscopies, combined with potentiometry and density functional theory (DFT) calculations. The obtained results indicated that DO4S, DO3S, DO3SAm, and DO2A2S were able to efficiently chelate Pb and that the most suitable macrocyclic scaffold for Pb is 1,4,7,10-tetrazacyclododecane. NMR spectroscopy gave insights into the solution structures of the Pb complexes, and H-Pb interactions confirmed the involvement of S and/or O donors in the metal coordination sphere. Highly fluxional solution behavior was discovered when Pb was coordinated to symmetric ligands (i.e., DO4S and DO2A2S) while the introduction of structural asymmetry in DO3S and DO3SAm slowed down the intramolecular dynamics. The ligand ability to chelate [Pb]Pb under highly dilute reaction conditions was explored through radiolabeling experiments. While DO4S and DO3S possessed modest performance, DO3SAm and DO2A2S demonstrated high complexation efficiency under mild reaction conditions (pH = 7, 5 min reaction time). The [Pb]Pb complexes' integrity in human serum over 24 h was appreciably good for [Pb][Pb(DO4S)] (80 ± 5%) and excellent for [Pb][Pb(DO3SAm)] (93 ± 1%) and [Pb][Pb(DO2A2S)] (94 ± 1%). These results reveal the promise of DO2A2S and DO3SAm as chelators in cutting-edge theranostic [Pb]Pb radiopharmaceuticals.
Topics: Humans; Lead; Precision Medicine; Cyclams; Chelating Agents; Ligands
PubMed: 38230993
DOI: 10.1021/acs.inorgchem.3c02610 -
Molecules (Basel, Switzerland) Dec 2023The present work describes the complexation of the anti-inflammatory sialorphin derivative Pal-Lys-Lys-Gln-His-Asn-Pro-Arg (palmitic...
Complex-Forming Properties of the Anti-Inflammatory Sialorphin Derivative Palmitic Acid-Lysine-Lysine-Glutamine-Histidine-Asparagine-Proline-Arginine with Cu(II) Ions in an Aqueous Solution.
The present work describes the complexation of the anti-inflammatory sialorphin derivative Pal-Lys-Lys-Gln-His-Asn-Pro-Arg (palmitic acid-lysine-lysine-glutamine-histidine-asparagine-proline-arginine) with Cu(II) ions in an aqueous solution, at a temperature of 25.0 ± 0.1 °C, over the whole pH range. The complexing properties were characterized by potentiometric and UV-Vis spectrophotometric methods. The potentiometric method was used to calculate the logarithms of the overall stability constants (log ) and the values of the stepwise dissociation constants (p) of the studied complexes. The percentage of each species formed in an aqueous solution was estimated from the species distribution curve as a function of pH. The absorbance () and molar absorption coefficient () values for the Cu(II)-sialorphin derivative system were determined with UV-Vis spectroscopy. Our studies indicate that the sialorphin derivative forms stable complexes with Cu(II) ions, which may lead to future biological and therapeutic applications.
Topics: Proline; Asparagine; Arginine; Glutamine; Histidine; Lysine; Palmitic Acid; Amino Acids; Ions; Anti-Inflammatory Agents; Peptides
PubMed: 38202673
DOI: 10.3390/molecules29010090