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The presence of antibiotics in soils is increasing drastically in last decades due to the intensive farming industry and excessive human consumption. Clay minerals are one of the soil components with great adsorption capacity for organic pollutants. The study of interactions between antibiotics and mineral surfaces will give us scientific knowledge of these pollutants through soils. In this work, we study the adsorption of the antibiotic ciprofloxacin in the clay mineral fraction of soils from the Argentinian zone of Santa Rosa (Corrientes), in a collaborative research of experiments and atomistic modelling calculations of the intercalation of ciprofloxacin in the interlayer space of montmorillonite. Adsorption and desorption isotherms were performed and compared with different isotherm models. Additionally, enthalpy, entropy, and free energy were determined from equilibrium constants at a function of temperature. All these experiments and calculations lead to the conclusions that two adsorption types of ciprofloxacin are found on clay minerals: one weakly sorbed that is released during the desorption experiments, and other one strongly joined that remains in the soil. [ABSTRACT FROM AUTHOR]

Nowadays the use of hydrogels for biomedical purposes is increasing because of their interesting features that allow the development of targeted drug delivery systems. Herein, hydrogel based on Laponite® (Lap) clay mineral as gelator and cucurbit[6]uril (CB[6]) molecules were synthetized for the delivery of flufenamic acid (FFA) for potential topical application. Firstly, the interaction between CB[6] and FFA was assessed by UV‐vis spectroscopic measurements and molecular modeling calculations. Then, the obtained complex was used as filler for Lap hydrogel (Lap/CB[6]/FFA). The properties of the hydrogel in terms of viscosity and, self‐repair abilities were investigated; its morphology was imaged by scanning electron and polarized optical microscopies. Furthermore, the changes in the hydrodynamic radii and in the colloidal stability of CB[6]/Lap mixture were investigated in terms of translational diffusion from dynamic light scattering and ζ‐potential measurements. Finally, the kinetic in vitro release of FFA, from Lap/CB[6]/FFA hydrogel, was studied in a medium mimicking the pH of skin and the obtained results were discussed both by an experimental point of view and by molecular modeling calculations. [ABSTRACT FROM AUTHOR]

The article titled "Front Cover: Thixotropic Hydrogels Based on Laponite® and Cucurbituril for Delivery of Lipophilic Drug Molecules" in the journal ChemPlusChem discusses the potential use of laponite hydrogels filled with a supramolecular complex of cucurbit[6]uril and flufenamic acid for topical drug delivery. The cover picture showcases this application. The research article, authored by Viseras‐Iborra, Riela, and their colleagues, provides more detailed information on this topic. The authors of the article are Marina Massaro, Giuseppe Cinà, Ana Borrego‐Sánchez, C. Ignacio Sainz‐Díaz, César Viseras‐Iborra, Rita Sánchez‐Espejo, Raquel de Melo Barbosa, Federica Leone, Ivana Pibiri, Renato Noto, and Serena Riela. [Extracted from the article]

In previous papers, we investigated via Monte Carlo simulation the order-disorder behavior of an individual octahedral phyllosilicate sheet, with respect to two-species systems Al/Fe, Al/Mg, and Fe/Mg, and some three-species systems Al/Fe/Mg that were relevant to clay compositions found in nature. We have extended the work on Al/Fe/Mg systems to include a wide range of different octahedral compositions that can represent different natural and synthetic clay minerals, by means of Monte Carlo simulations based only on atomistic models. In many cases, phase transitions do not occur, in that long-range order is not attained, but most systems exhibit short-range order at low temperatures. The ordering of the octahedral cations is highly dependent on the cation composition. [ABSTRACT FROM AUTHOR]

Praziquantel is an antiparasitic drug indicated for the treatment of the schistosomiasis disease. This drug has very low aqueous solubility, requiring high oral doses for its administration which gives rise to side effects, therapeutic noncompliance and the appearance of resistant forms of the parasite. Clay minerals, like sepiolite and montmorillonite, are innocuous, non-toxic, biocompatible and low-cost excipients. Additionally, clays have high adsorbent properties that allow them to encapsulate drugs in nanometric spaces present in the channels in the case of the sepiolite or between the layers in the case of the montmorillonite. The interactions between the drug and clay minerals are studied experimentally with the strategy for preparing interactions products in organic solvents (ethanol, acetonitrile and dichloromethane) so that the interaction will be more effective and will be enhanced the aqueous solubility of praziquantel. The results showed that in the interaction products, the drug interacted with both clay minerals, which produced the loss of the crystallinity of the drug demonstrated by different techniques. This led to a significant increase in the dissolution rate of the praziquantel in all the interaction products in the simulated gastrointestinal tract media, except for the praziquantel–montmorillonite product prepared in dichloromethane that presented a controlled release in acid medium. Moreover, in vitro cytotoxicity and cell cycle studies were performed in the interaction products prepared with ethanol. The interaction product with sepiolite was biocompatible with the HTC116 line cells, and it did not produce alterations in the cell cycle. However, interaction products with montmorillonite did not produce cell death, but they showed affectation and damage of cells in the cell cycle study at the highest concentration tested (20–100 µM). Therefore, the different organic solvents used are adequate for the improvement of the biopharmaceutical profile of praziquantel. Drug–clay interaction products, specifically with sepiolite, showed very promising results in which new accelerated oral release systems of the praziquantel were obtained. [ABSTRACT FROM AUTHOR]

Clay dehydration at great depth generates fluids and overpressures in organic-rich sediments that can release isotopically light boron from mature organic matter, producing 10B-rich fluids. The B can be incorporated into the tetrahedral sites of authigenic illite during the illitization of smectite. Therefore, the crystal-chemical and geochemical characterization of illite, smectite or interlayered illite–smectite clay minerals can be an indicator of depth (temperature) and reactions with the basin fluids. The aim of this study was to determine the detailed clay mineralogy, B-content and isotopic composition in illite–smectite rich samples of mud volcanoes from the Gulf of Cádiz, in order to evaluate interactions of hydrocarbon-rich fluids with clays. Molecular modeling of the illite structure was performed, using electron density functional theory (DFT) methods to examine the phenomenon of B incorporation into illite at the atomic level. We found that it is energetically preferable for B to reside in the tetrahedral sites replacing Si atoms than in the interlayer of expandable clays. The B abundances in this study are high and consistent with previous results of B data on interstitial fluids, suggesting that hydrocarbon-related fluids approaching temperatures of methane generation (150 °C) are the likely source of B-rich illite in the studied samples. [ABSTRACT FROM AUTHOR]

Praziquantel drug is nowadays in continuo study to overcome adverse biopharmaceutical properties as drug of first choice for the treatment of the human schistosomiasis. Meanwhile, sepiolite and montmorillonite have been studied experimentally as low-cost nanocarrier to design new praziquantel delivery systems. In this work, the interactions between the drug and clay minerals surfaces are studied at molecular level by computational methods. The optimization of the adsorption of praziquantel in sepiolite nanochannels and in the montmorillonite interlayer space has been studied by using force fields based on empirical interatomic potentials and at quantum mechanical level. The results showed the main interactions between the drug and both clay minerals surfaces at the confined spaces of these minerals, and favorable adsorption energies of the praziquantel-clays complexes were obtained. Therefore, theoretical calculations allow knowing how the drug is adsorbed in the clays and in the case of the montmorillonite how many molecules of the drug are adsorbed in the interlayer space of the mineral according to the experimental data. Unlabelled Image • Clay-drug adsorption properties are determined by molecular modeling. • Sepiolite and montmorillonite can be praziquantel delivery nanocarriers. • Theoretical calculations allow knowing how the drug is adsorbed in clays. [ABSTRACT FROM AUTHOR]

· Sulfonamides can be intercalated likely into montmorillonite confirming experiments. · Hydration of sulfonamides has been calculated by molecular dynamics and DFT. · Molecular dynamics simulations confirm the stability of SMX in montmorillonite. · Frequency shifts in IR spectroscopy confirm intercalation of sulfamides in clays. The intensive use of antibiotics and especially sulfonamides in the livestock industry is getting an alarming level. The presence of these drugs in wastewaters, rivers and underground waters is increasing considerably in developing countries. The molecular interactions of these drugs with the surfaces of clay minerals can be interesting for evaluating their mobility in soils and for preparing composite complexes for optimal use. In this work, the intercalation of antibiotics derivatives of sulfonamides, such as sulfamethazine, sulfamethoxazole, sulfachloropyridazine and sulfacetamide, into the interlayer space of montmorillonite (MNT) is studied at molecular and 3-D periodical crystal structure level by using computational modeling, molecular dynamics and calculations based Density Functional Theory (DFT). Most of these intercalations are energetically favourable, where the role of water molecules is critical. In general, the bioavailability of these compounds by intercalation in MNT is bigger than from the crystalline powder. Spectroscopic properties of these systems showed interesting frequency shifts in the bands of the IR spectrum produced during the intercalation in the confined space of MNT. These results predict that the IR spectroscopy as an interesting analytical technique for monitoring the intercalation of drugs in clay minerals. [ABSTRACT FROM AUTHOR]

The application of clay minerals in therapeutics is becoming important due to their structural and surface physicochemical properties. 5-aminosalicylic acid (5-ASA) is a very common pharmaceutical drug and is used worldwide. The interactions between the 5-ASA molecule and both the aluminol and siloxane surfaces of kaolinite are studied by means of atomistic calculations using force fields based on empirical interatomic potentials and quantum mechanics calculations based on density functional theory. A conformational analysis of 5-ASA has been performed and the anion of 5-ASA was also studied. The calculated adsorption energy values indicate that 5- ASA is likely to be adsorbed on the kaolinite surfaces with greater affinity to the aluminol surface. Hence, kaolinite may be considered as a promising pharmaceutical carrier of 5-ASA. [ABSTRACT FROM AUTHOR]

Praziquantel is the drug of first choice for the treatment of the human schistosomiasis. It is administered orally, requiring high doses to overcome adverse biopharmaceutical properties, including high lipophilia and intense hepatic first pass metabolism. According to its biopharmaceutical profile, praziquantel has very low water solubility and high permeability. Therefore, dissolution is the limiting factor for absorption in the gastrointestinal tract. Improvement of the aqueous solubility of the drug would reduce the currently high oral doses. Meanwhile, montmorillonite and sepiolite are clay minerals, with a high adsorption and swelling properties, potentially useful as a low-cost nanocarrier to design praziquantel delivery systems. In this work, the interactions between the drug and clay minerals are studied experimentally, with the aim of improving the biopharmaceutical profile of the drug. The results showed the effective loading of the drug in the clay minerals as well as the significant increase of the dissolution rate and the dissolved amount of praziquantel, potentially improving the bioavailability of the drug. [ABSTRACT FROM AUTHOR]

The design of multifunctional nanomaterials which can help the healing processes of skin, preventing the bacterial infections, is crucial for the development of suitable therapy for the treatment of chronic lesions. The use of clay minerals in wound healing applications is well documented since the prehistoric period and offers several advantages due to their intrinsic properties. Herein, we report the development of ciprofloxacin carrier systems based on hectorite/halloysite (Ht/Hal) hybrid hydrogels for potential wound healing applications. To achieve this objective firstly the ciprofloxacin molecules were loaded onto Hal by a supramolecular and covalent approach. The so obtained fillers were thoroughly investigated by several techniques and at molecular level by means of quantum mechanics calculations along with empirical interatomic potentials. Afterwards the modified Hal were used as filler for Ht hydrogels. The introduction of modified Hal, in hectorite hydrogel, helps the gel formation with an improvement of the rheological properties. The in vitro kinetic release from both the fillers and from the hybrid hydrogels was studied both at skin's pH (5.4) and under neutral conditions (pH 7.4); in addition, the factors controlling the ciprofloxacin release process were determined and discussed. Finally, the in vitro biocompatibility of the Hal fillers was evaluated by means of cytotoxic assays and laser scanning confocal microscopy on normal human dermal fibroblasts. [Display omitted] • Ciprofloxacin carrier systems based on Ht/Hal hybrid hydrogels were developed. • Ciprofloxacin molecules were loaded onto Hal filler by a supramolecular and covalent approach. • The introduction of modified Hal in Ht hydrogel improved rheological properties. • Kinetic release of the drug was studied both at skin's pH and under neutral conditions. • Biocompatibility of the Hal fillers was evaluated on normal human dermal fibroblasts. [ABSTRACT FROM AUTHOR]