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The ability to manipulate droplets on a substrate using electric signals1-known as digital microfluidics-is used in optical2,3, biomedical4,5, thermal6 and electronic7 applications and has led to commercially available liquid lenses8 and diagnostics kits9,10. Such electrical actuation is mainly achieved by electrowetting, with droplets attracted towards and spreading on a conductive substrate in response to an applied voltage. To ensure strong and practical actuation, the substrate is covered with a dielectric layer and a hydrophobic topcoat for electrowetting-on-dielectric (EWOD)11-13; this increases the actuation voltage (to about 100 volts) and can compromise reliability owing to dielectric breakdown14, electric charging15 and biofouling16. Here we demonstrate droplet manipulation that uses electrical signals to induce the liquid to dewet, rather than wet, a hydrophilic conductive substrate without the need for added layers. In this electrodewetting mechanism, which is phenomenologically opposite to electrowetting, the liquid-substrate interaction is not controlled directly by electric field but instead by field-induced attachment and detachment of ionic surfactants to the substrate. We show that this actuation mechanism can perform all the basic fluidic operations of digital microfluidics using water on doped silicon wafers in air, with only ±2.5 volts of driving voltage, a few microamperes of current and about 0.015 times the critical micelle concentration of an ionic surfactant. The system can also handle common buffers and organic solvents, promising a simple and reliable microfluidic platform for a broad range of applications.
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Electrohumectación/métodos , Microfluídica/métodos , Tensoactivos/química , Acetonitrilos/química , Tampones (Química) , Dimetilsulfóxido/química , Glicol de Etileno/química , Interacciones Hidrofóbicas e Hidrofílicas , Iones/química , Microfluídica/instrumentación , Silicio/químicaRESUMEN
As cisplatin is one of the most broadly used chemotherapeutics, it is widely tested in vitro & in vivo assays, involving attempts to better understand its mechanism of action, develop strategies to mitigate its toxicity, or develop new drug combinations. Presently, for in vitro assays, dissolving cisplatin in dimethyl sulfoxide (DMSO) is discouraged due to its significant reduction in drug activity, Alternatively, inorganic solvents like normal saline (NS) are recommended. However, this approach is still problematic, including 1) instability of cisplatin in NS, 2) limited solubility, 3) the need to avoid long-term storage at -80 °C (or -20 °C) after dissolving, and 4) complications when combining with other DMSO-solubilized compounds. Here, we report a DMSO-HCl mixture as an alternative solvent to address these challenges. Cisplatin in DMSO-HCl not only retains comparable drug activity to cisplatin in NS but also exhibits increased stability over an extended period. Our brief report sheds light on cisplatin action, providing insights to aid in cancer research in vitro.
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Antineoplásicos , Cisplatino , Dimetilsulfóxido , Solventes , Cisplatino/farmacología , Cisplatino/química , Solventes/química , Dimetilsulfóxido/farmacología , Dimetilsulfóxido/química , Antineoplásicos/farmacología , Antineoplásicos/química , Humanos , Solubilidad , Estabilidad de Medicamentos , Línea Celular Tumoral , Concentración de Iones de HidrógenoRESUMEN
Plaque assays quantify the amount of active, replicating virus to study and detect infectious diseases by application of samples to monolayers of cultured cells. Due to the time taken in thawing, propagating, plating, counting, and then conducting the assay, the process can take over a week to gather data. Here, we introduce assay-ready cryopreserved Vero monolayers in multiwell plates, which can be used directly from the freezer with no cell culture to accelerate the process of plaque determination. Standard dimethyl sulfoxide cryopreservation resulted in just 25% recovery, but addition of polyampholytes (macromolecular cryoprotectants) increased post-thaw recovery and viability in 12- and 24-well plate formats. Variability between individual wells was reduced by chemically induced ice nucleation to prevent supercooling. Cryopreserved cells were used to determine influenza viral plaques in just 24 h, matching results from nonfrozen controls. This innovation may accelerate viral detection and quantification and facilitate automation by eliminating extensive cell culturing.
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Criopreservación , Crioprotectores , Animales , Criopreservación/métodos , Chlorocebus aethiops , Células Vero , Crioprotectores/farmacología , Crioprotectores/química , Dimetilsulfóxido/farmacología , Dimetilsulfóxido/químicaRESUMEN
On December 12th, 2023, the European Commission took regulatory action to amend Annex XVII of REACH, imposing restrictions on the use of N,N-dimethylformamide (DMF) within the EU market owing to its high toxicity. Historically, DMF has been widely considered the gold standard for solid-phase peptide synthesis (SPPS). Being urgent to propose alternative solvents, we tested the suitability of non-hazardous neat and mixed solvents. Notably, binary solvent mixtures containing dimethyl sulfoxide as one of the solvent partners demonstrated high efficacy in solubilizing reagents while maintaining the desired swelling characteristics of common resins. A series of binary solvent mixtures were tested in automated SPPS, both at room temperature and high temperature, employing the PurePep® Chorus synthesizer, which enabled controlled induction heating between 25 and 90°C with oscillation mixing. The performances were assessed in challenging peptide sequences, i.e., ACP (65-74), and in longer and aggregating sequences like SARS-CoV-2 RBM (436-507) and ß-amyloid (1-42). Furthermore, as part of the proposed sustainable approach to minimize the utilization of hazardous solvents, we coupled the novel PurePep EasyClean catch-and-release purification technology. This work, addressing regulatory compliance, emphasizes the crucial role of green chemistry in advancing safer and more environmentally friendly practices in SPPS.
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Péptidos , Técnicas de Síntesis en Fase Sólida , Solventes , Solventes/química , Péptidos/química , Péptidos/síntesis química , Técnicas de Síntesis en Fase Sólida/métodos , Péptidos beta-Amiloides/química , Tecnología Química Verde , Dimetilformamida/química , Dimetilsulfóxido/química , Fragmentos de Péptidos/química , Fragmentos de Péptidos/síntesis química , SARS-CoV-2 , Calefacción , Automatización , CalorRESUMEN
Pyrrole-containing natural products form a large group of structurally diverse compounds that occur in both terrestrial and marine organisms. In the present study the formation of trideuteromethylated artifacts of pyrrole-containing natural products was investigated, focusing on the discorhabdins. Three deuterated discorhabdins, 1, 3, and 5, were identified to be isolation procedure artifacts caused by the presence of DMSO-d6 during NMR sample preparation and handling. Three additional semisynthetic derivatives, 7-9, were made during the investigation of the mechanism of formation, which was shown to be driven by trideuteromethyl radicals in the presence of water, methanol, TFA, and traces of iron in the deuterated solvent. Generation of trideuteromethylated artifacts was also confirmed for other classes of pyrrole-containing metabolites, namely, makaluvamines, tambjamines, and dibromotryptamines, which had also been dissolved in DMSO-d6 during the structure elucidation process. Semisynthetic discorhabdins were assessed for antiproliferative activity against a panel of human tumor cell lines, and 14-trideuteromethyldiscorhabdin L (3) averaged low micromolar potency.
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Productos Biológicos , Dimetilsulfóxido , Humanos , Dimetilsulfóxido/química , Pirroles/química , Productos Biológicos/farmacología , Artefactos , Solventes/químicaRESUMEN
We study, through molecular dynamics simulations, three aqueous solutions with one lysozyme protein and three different concentrations of trehalose and dimethyl sulfoxide (DMSO). We analyze the structural and dynamical properties of the protein hydration water upon cooling. We find that trehalose plays a major role in modifying the structure of the network of HBs between water molecules in the hydration layer of the protein. The dynamics of hydration water presents, in addition to the α-relaxation, typical of glass formers, a slower long-time relaxation process, which greatly slows down the dynamics of water, particularly in the systems with trehalose, where it becomes dominant at low temperatures. In all the solutions, we observe, from the behavior of the α-relaxation times, a shift of the Mode Coupling Theory crossover temperature and the fragile-to-strong crossover temperature toward higher values with respect to bulk water. We also observe a strong-to-strong crossover from the temperature behavior of the long-relaxation times. In the aqueous solution with only DMSO, the transition shifts to a lower temperature than in the case with only lysozyme reported in the literature. We observe that the addition of trehalose to the mixture has the opposite effect of restoring the original location of the strong-to-strong crossover. In all the solutions analyzed in this work, the observed temperature of the protein dynamical transition is slightly shifted at lower temperatures than that of the strong-to-strong crossover, but their relative order is the same, showing a correlation between the motion of the protein and that of the hydration water.
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Dimetilsulfóxido , Simulación de Dinámica Molecular , Muramidasa , Trehalosa , Agua , Trehalosa/química , Dimetilsulfóxido/química , Muramidasa/química , Agua/química , Crioprotectores/química , Criopreservación/métodos , FríoRESUMEN
Solid surface freezing or vitrification (SSF/SSV) can be done by depositing droplets of a sample, e.g., cells in a preservation solution, onto a pre-cooled metal surface. It is used to achieve higher cooling rates and concomitant higher cryosurvival rates compared to immersion of samples into liquid nitrogen. In this study, numerical simulations of SSF/SSV were conducted by modeling the cooling dynamics of droplets of cryoprotective agent (CPA) solutions. It was assumed that deposited droplets attain a cylindrical bottom part and half-ellipsoidal shaped upper part. Material properties for heat transfer simulations including density, heat capacity and thermal conductivity were obtained from the literature and extrapolated using polynomial fitting. The impact of CPA type, i.e., glycerol (GLY) and dimethyl sulfoxide (DMSO), CPA concentration, and droplet size on the cooling dynamics was simulated at different CPA mass fractions at temperatures ranging from -196 to 25 °C. Simulations show that glycerol solutions cool faster compared to DMSO solutions, and cooling rates increase with decreasing CPA concentration. However, we note that material property data for GLY and DMSO solutions were obtained in different temperature and concentration ranges under different conditions, which complicated making an accurate comparison. Experimental studies show that samples that freeze have a delayed cooling response early on, whereas equilibration times are similar compared to samples that vitrify. Finally, as proof of concept, droplets of human red blood cells (RBCs) were cryopreserved using SSV/SSF comparing the effect of GLY and DMSO on cryopreservation outcome. At 20% (w/w), similar hemolysis rates were found for GLY and DMSO, whereas at 40%, GLY outperformed DMSO.
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Criopreservación , Crioprotectores , Dimetilsulfóxido , Congelación , Glicerol , Vitrificación , Crioprotectores/química , Crioprotectores/farmacología , Glicerol/química , Glicerol/farmacología , Dimetilsulfóxido/química , Criopreservación/métodos , Humanos , Conductividad Térmica , Eritrocitos , Simulación por ComputadorRESUMEN
The intermolecular aggregation between the solvent and organic molecules is covered in the current article. 4,4'-(Buta-1,3-diyne-1,4-diyl)dibenzoic acid (DADBA) was used as an organic molecule and dimethyl sulfoxide (DMSO) as a solvent to create the target compound DADBA-DMSO. The material's hydrogen bonding and intermolecular aggregation were determined by appropriate characterization methods, including single-crystal X-ray diffraction (XRD), Fourier-transform infrared (FTIR), photoluminescence (PL), and cyclic voltammetry (CV) analysis. Each hydrogen of the carboxylic group is coordinated by oxygen from the DMSO molecule in the stiff planar layer packing that makes up the DADBA-DMSO crystal structure.
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Dimetilsulfóxido , Solventes/química , Dimetilsulfóxido/química , Cristalografía por Rayos X , Enlace de HidrógenoRESUMEN
Ruthenium chloride (RuCl3) is widely utilized for synthesis and catalysis of numerous compounds in academia and industry and is utilized as a key molecule in a variety of compounds with medical applications. Interestingly, RuCl3 has been demonstrated to modulate human plasmatic coagulation and serves as a constituent of a compounded inorganic antivenom that neutralizes the coagulopathic effects of snake venom in vitro and in vivo. Using thrombelastography, this investigation sought to determine if RuCl3 inhibition of the fibrinogenolytic effects of Crotalus atrox venom could be modulated by vehicle composition in human plasma. Venom was exposed to RuCl3 in 0.9% NaCl, phosphate-buffered saline (PBS), or 0.9% NaCl containing 1% dimethyl sulfoxide (DMSO). RuCl3 inhibited venom-mediated delay in the onset of thrombus formation, decreased clot growth velocity, and decreased clot strength. PBS and DMSO enhanced the effects of RuCl3. It is concluded that while a Ru-based cation is responsible for significant inhibition of venom activity, a combination of Ru-based ions containing phosphate and DMSO enhances RuCl3-mediated venom inhibition. Additional investigation is indicated to determine what specific Ru-containing molecules cause venom inhibition and what other combinations of inorganic/organic compounds may enhance the antivenom effects of RuCl3.
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Antivenenos , Coagulación Sanguínea , Venenos de Crotálidos , Crotalus , Dimetilsulfóxido , Humanos , Dimetilsulfóxido/farmacología , Dimetilsulfóxido/química , Antivenenos/farmacología , Antivenenos/química , Venenos de Crotálidos/antagonistas & inhibidores , Venenos de Crotálidos/farmacología , Animales , Coagulación Sanguínea/efectos de los fármacos , Compuestos de Rutenio/farmacología , Compuestos de Rutenio/química , Cloruro de Sodio/farmacología , Cloruro de Sodio/química , Tromboelastografía , Serpientes VenenosasRESUMEN
BACKGROUND: Transformation of state diagrams of cryoprotectant solutions under the influence of weak intramolecular interactions was considered. MATERIALS AND METHODS: Phase states of aqueous glycerol and DMSO solutions within temperature range +25 to -150 degree С were studied using method of volumetric scanning tensodilatometry. Temperatures below which hydrogen bonds significantly affect crystallization-melting kinetics of such solutions were determined. RESULTS: Principles for plotting of state diagram for binary solutions with weak intermolecular interaction of the components were set up. The study demonstrates that in such solutions formation of clusters based on ice microcrystals and cryoprotectant occurs. Based on the obtained results, state diagrams for glycerol and DMSO aqueous solutions were plotted. These diagrams include area of cluster phase existence and differ fundamentally from those describing eutectic crystallization. CONCLUSION: Nanostructures occurring in cryoprotectant solutions during their cooling were analyzed. Difference between these structures and classical solid phase eutectics were demonstrated. Doi.org/10.54680/fr24410110712.
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Crioprotectores , Cristalización , Dimetilsulfóxido , Glicerol , Enlace de Hidrógeno , Crioprotectores/química , Glicerol/química , Dimetilsulfóxido/química , Soluciones , Agua/química , Transición de FaseRESUMEN
Hydrophilic drugs could be incorporated into the skin surface by manes of Lipogel. This study aimed to prepare miconazole lipogel with natural ingredients to enhance drug permeability using dimethyl Sulfoxide (DMSO). The miconazole lipogels, A1 (without DMSO) and A2 (with DMSO) were formulated and evaluated for organoleptic evaluation, pH, viscosity, stability studies, freeze-thawing, drug release profile and drug permeation enhancement. Results had stated that prepared lipogel's pH falls within the acceptable range required for topical delivery (4 to 6) while both formulations show good results in organoleptic evaluation. The A2 formulation containing DMSO shows better permeation of miconazole (84.76%) on the artificial skin membrane as compared to A1 lipogel formulation (50.64%). In in-vitro drug release studies, A2 for-mulation showed 87.48% drug release while A1 showed just 60.1% drug release from lipogel. Stability studies were performed on model formulations under environmental conditions and both showed good spreadibility, stable pH, free of grittiness and good consistency in formulation. The results concluded that A2 formulation containing DMSO shows better results as compared to DMSO-free drug lipogel.
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Dimetilsulfóxido , Liberación de Fármacos , Geles , Miconazol , Permeabilidad , Miconazol/administración & dosificación , Miconazol/química , Miconazol/farmacocinética , Dimetilsulfóxido/química , Viscosidad , Estabilidad de Medicamentos , Concentración de Iones de Hidrógeno , Absorción Cutánea/efectos de los fármacos , Química Farmacéutica , Composición de Medicamentos , Antifúngicos/administración & dosificación , Antifúngicos/química , Antifúngicos/farmacocinética , Administración CutáneaRESUMEN
Protein-ligand-exchange kinetics determines the duration of biochemical signals and consequently plays an important role in drug design. Binding studies commonly require solubilization of designed ligands in solvents such as dimethyl sulfoxide (DMSO), resulting in residual amounts of DMSO following titration of solubilized ligands into aqueous protein samples. Therefore, it is critical to establish whether DMSO influences protein-ligand binding. Here, we address the general and indirect effect of DMSO on protein-ligand binding caused by solvent viscosity, which is strongly dependent on the relative concentrations of DMSO and water. As a model system, we studied the binding of a drug-like ligand to the carbohydrate recognition domain of galectin-3 in the presence of variable amounts of DMSO. We used isothermal titration calorimetry to characterize binding thermodynamics and 15N NMR relaxation to monitor kinetics. The binding enthalpy is not affected, but we observe a subtle trend of increasingly unfavorable entropy of binding, and consequently decreased affinity, with increasing DMSO concentration. The increasing concentration of DMSO results in a reduced association rate of binding, while the dissociation rate is less affected. The observed association rate is inversely proportional to the viscosity of the DMSO-water mixture, as expected from theory, but significantly reduced from the diffusion-controlled limit. By comparing the viscosity dependence of the observed association rate with that of the theoretical diffusion-controlled association rate, we estimate the success rate of productive complex formation following an initial encounter of proteins and ligands, showing that only one out of several hundred binding "attempts" are successful.
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Dimetilsulfóxido , Proteínas , Solventes/química , Dimetilsulfóxido/química , Ligandos , Viscosidad , Proteínas/química , Agua/química , CinéticaRESUMEN
The ability to adjust conformations in response to the polarity of the environment, i.e. molecular chameleonicity, is considered to be important for conferring both high aqueous solubility and high cell permeability to drugs in chemical space beyond Lipinski's rule of 5. We determined the conformational ensembles populated by the antiviral drugs asunaprevir, simeprevir, atazanavir and daclatasvir in polar (DMSO-d6 ) and non-polar (chloroform) environments with NMR spectroscopy. Daclatasvir was fairly rigid, whereas the first three showed large flexibility in both environments, that translated into major differences in solvent accessible 3D polar surface area within each conformational ensemble. No significant differences in size and polar surface area were observed between the DMSO-d6 and chloroform ensembles of these three drugs. We propose that such flexible compounds are characterized as "partial molecular chameleons" and hypothesize that their ability to adopt conformations with low polar surface area contributes to their membrane permeability and oral absorption.
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Cloroformo , Dimetilsulfóxido , Dimetilsulfóxido/química , Antivirales/farmacología , Conformación MolecularRESUMEN
Increasing environmental pollution and petroleum resource depletion are important indicators for the necessary and inevitable replacement of fossil-based polymeric materials with more sustainable counterparts. Hence, the development of bio-based materials from renewable resources, such as cellulose, is of great importance. Herein, we introduce a rapid and homogeneous microwave assisted synthesis of high molecular weight (59 kDa ≤ Mn ≤ 116 kDa) short chain (mixed) cellulose esters (CEs) with variable acyl side chain length (2 ≤ C ≤ 8) by using a DMSO/TMG/CO2 switchable solvent system. Accordingly, (mixed) CEs were synthesized by implementing tetramethylguanidine (TMG) into a switchable solvent system (DMSO/TMG/CO2), followed by in-depth structural characterization via IR, 1H NMR, 13C NMR, and SEC. Examination of the structure-property relationships revealed a decrease in the glass transition temperature (177 °C ≤ Tg ≤ 204 °C), an increase in surface hydrophobicity, i.e., water contact angle (WCA) (65° ≤ WCA ≤ 98°), and a decrease of Young's modulus (7.51 MPa ≤ E ≤ 13.6 MPa), with longer alkyl side chains.
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Celulosa , Ésteres , Celulosa/química , Ésteres/química , Solventes , Dimetilsulfóxido/química , Dióxido de Carbono , AguaRESUMEN
Conformational analysis is central to the design of bioactive molecules. It is particularly challenging for macrocycles due to noncovalent transannular interactions, steric interactions, and ring strain that are often coupled. Herein, we simulated the conformations of five macrocycles designed to express a progression of increasing complexity in environment-dependent intramolecular interactions and verified the results against NMR measurements in chloroform and dimethyl sulfoxide. Molecular dynamics using an explicit solvent model, but not the Monte Carlo method with implicit solvation, handled both solvents correctly. Refinement of conformations at the ab initio level was fundamental to reproducing the experimental observationsâstandard state-of-the-art molecular mechanics force fields were insufficient. Our simulations correctly predicted the intramolecular interactions between side chains and the macrocycle and revealed an unprecedented solvent-induced conformational switch of the macrocyclic ring. Our results provide a platform for the rational, prospective design of molecular chameleons that adapt to the properties of the environment.
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Dimetilsulfóxido , Simulación de Dinámica Molecular , Solventes/química , Dimetilsulfóxido/química , Conformación Molecular , CloroformoRESUMEN
The peculiarities of the optical properties of 2-aryl-1,2,3-triazole acids and their sodium salts were investigated in different solvents (1,4-dioxane, dimethyl sulfoxide DMSO, methanol MeOH) and in mixtures with water. The results were discussed in terms of the molecular structure formed by inter- and intramolecular noncovalent interactions (NCIs) and their ability to ionize in anions. Theoretical calculations using the Time-Dependent Density Functional Theory (TDDFT) were carried out in different solvents to support the results. In polar and nonpolar solvents (DMSO, 1,4-dioxane), fluorescence was provided by strong neutral associates. Protic MeOH can weaken the acid molecules' association, forming other fluorescent species. The fluorescent species in water exhibited similar optical characteristics to those of triazole salts; therefore, their anionic character can be assumed. Experimental 1H and 13C-NMR spectra were compared to their corresponding calculated spectra using the Gauge-Independent Atomic Orbital (GIAO) method and several relationships were established. All these findings showed that the obtained photophysical properties of the 2-aryl-1,2,3-triazole acids noticeably depend on the environment and, therefore, are good candidates as sensors for the identification of analytes with labile protons.
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Ácidos Carboxílicos , Dimetilsulfóxido , Dimetilsulfóxido/química , Triazoles/química , Sales (Química) , Espectroscopía de Resonancia Magnética , Solventes , Agua , Espectroscopía Infrarroja por Transformada de Fourier , Teoría CuánticaRESUMEN
PAF and related antifungal proteins are promising antimicrobial agents. They have highly stable folds around room temperature due to the presence of 3-4 disulfide bonds. However, unfolded states persist and contribute to the thermal equilibrium in aqueous solution, and low-populated states might influence their biological impact. To explore such equilibria during dimethyl sulfoxide (DMSO)-induced chemical unfolding, we studied PAF and its inactive variant PAFD19S using nuclear magnetic resonance (NMR) and differential scanning calorimetry (DSC). According to the NMR monitoring at 310 K, the folded structures disappear above 80 v/v% DMSO concentration, while the unfolding is completely reversible. Evaluation of a few resolved peaks from viscosity-compensated 15N-1H HSQC spectra of PAF yielded ∆G = 23 ± 7 kJ/M as the average value for NMR unfolding enthalpy. The NMR-based structures of PAF and the mutant in 50 v/v% DMSO/H2O mixtures were more similar in the mixed solvents then they were in water. The 15N NMR relaxation dynamics in the same mixtures verified the rigid backbones of the NMR-visible fractions of the proteins; still, enhanced dynamics around the termini and some loops were observed. DSC monitoring of the Tm melting point showed parabolic dependence on the DMSO molar fraction and suggested that PAF is more stable than the inactive PAFD19S. The DSC experiments were irreversible due to the applied broad temperature range, but still suggestive of the endothermic unfolding of PAF.
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Antifúngicos , Dimetilsulfóxido , Dimetilsulfóxido/farmacología , Dimetilsulfóxido/química , Antifúngicos/farmacología , Antifúngicos/química , Rastreo Diferencial de Calorimetría , Disulfuros/química , Proteínas , Espectroscopía de Resonancia Magnética , Agua , Termodinámica , Desnaturalización Proteica , Desplegamiento ProteicoRESUMEN
BACKGROUND: This study aimed to evaluate the effect of dentin pretreatment by Dimethyl Sulfoxide (DMSO) on the bond strength and microleakage of a universal bonding agent to dentin. METHODS: Fifty-six dentinal discs (thickness = 2 mm) were obtained from the crowns of the human third molars. The disks were assigned into 4 groups and treated as follows; self-etch-control group: G-Premio universal adhesive was used in self-etch mode, total-etch-control: G-Premio universal adhesive was used in total-etch mode, self-etch-DMSO: Water-based DMSO (50% volume) was applied on the samples for 60 s followed by application of G-Premio universal adhesive in self-etch mode, and Total-etch-DMSO: The samples were etched, and then, water-based DMSO was applied on them for 60 s followed by the application of G-Premio universal adhesive in total-etch mode. Afterward, resin composite was placed on all samples and light-cured. The samples were kept in distilled water and subjected to 5000 thermal cycles. Microshear bond strength was measured using the universal testing machine and failure modes were analyzed using a stereomicroscope. Forty-eight human third molars were used for microleakage evaluation and a standardized class five cavity was prepared on the buccal surface of each tooth. The teeth were assigned into 4 groups and received aforementioned surface treatment and the cavities were filled with resin composite. After storing in water for 24 h, the samples were subjected to 5000 cycles of thermocycling and the microleakage level of the samples was evaluated using silver nitrate uptake at the bonded interface. Two-way ANOVA test was used to analyze the effect of bonding technique (self-etch/ total-etch) and DMSO pretreatment on the microshear bond strength and microleakage of G-Premio adhesive to dentin. RESULTS: Bonding technique had no effect on the bond strength values (p = 0.17) while DMSO pretreatment significantly decreased the microshear bond strength of the samples (p = 0.001). DMSO application increased microleakage significantly in total-etch (P-value = 0.02) while it had no effect in self-etch mode (P-value = 0.44). CONCLUSIONS: Pretreatment of dentin using 50% DMSO significantly reduced the bond strength of G-Premio Bond in both self-etch and total-etch modes. DMSO effect on microleakage depended on the etching technique; DMSO increased the microleakage level when the adhesive was used in total-etch mode while did not affect the microleakage in self-etch mode.
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Recubrimiento Dental Adhesivo , Cementos Dentales , Humanos , Dimetilsulfóxido/farmacología , Dimetilsulfóxido/química , Recubrimientos Dentinarios/química , Cementos de Resina/química , Recubrimiento Dental Adhesivo/métodos , Dentina , Resinas Compuestas/química , Agua/química , Ensayo de MaterialesRESUMEN
Protein unfolding and denaturation are main issues in biochemical and pharmaceutical research. Using a global parameter, the translational diffusion coefficient D, folded, unfolded, and intrinsically disordered proteins of a given molar mass M can be distinguished based on their distinct hydrodynamic properties. For broader applications, we provide generalized, PFG-NMR-based empirical D-M relations validated at different temperatures and ready to use with the corresponding corrections in different media. We demonstrate that these relations enable a more accurate molecular mass determination and show fewer potential errors than those of the common methods based on small-molecular diffusion standards. We monitor unfolding of three model proteins using 8 M urea and dimethyl sulfoxide (DMSO)-water mixtures as denaturing agents, highlighting the effect of disulfide bonds. Denaturation in 8 M urea is pH-dependent; in addition, for proteins with highly stable disulfide bonds, a reducing agent (TCEP) is required to achieve complete unfolding. Regarding the effect of local parameters, we show that at low DMSO concentrationsâcommon conditions in pharmaceutical binding studiesâthe PFG-NMR-derived global parameters are not significantly affected. Still, the atomic environments can change, and the bound solvent molecule can inhibit the binding of a partner molecule. Using proteins with natural isotopic abundance, this effect can be proven by fast 1H-15N 2D correlation spectra. Our results enable fast and easy estimation of protein molecular mass and the degree of folding in various media; moreover, the effect of the cosolvent on the atomic-level structure can be traced without the need of isotope labeling.
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Dimetilsulfóxido , Proteínas , Difusión , Dimetilsulfóxido/química , Disulfuros , Desnaturalización Proteica , Pliegue de Proteína , Proteínas/química , Termodinámica , UreaRESUMEN
We have identified cellulose solvents, comprised of binary mixtures of molecular solvents and ionic liquids that rapidly dissolve cellulose to high concentration and show upper-critical solution temperature (UCST)-like thermodynamic behaviour - upon cooling and micro phase-separation to roughly spherical microparticle particle-gel mixtures. This is a result of an entropy-dominant process, controllable by changing temperature, with an overall exothermic regeneration step. However, the initial dissolution of cellulose in this system, from the majority cellulose I allomorph upon increasing temperature, is also exothermic. The mixtures essentially act as 'thermo-switchable' gels. Upon initial dissolution and cooling, micro-scaled spherical particles are formed, the formation onset and size of which are dependent on the presence of traces of water. Wide-angle X-ray scattering (WAXS) and 13 C cross-polarisation magic-angle spinning (CP-MAS) NMR spectroscopy have identified that the cellulose micro phase-separates with no remaining cellulose I allomorph and eventually forms a proportion of the cellulose II allomorph after water washing and drying. The rheological properties of these solutions demonstrate the possibility of a new type of cellulose processing, whereby morphology can be influenced by changing temperature.