Guanidine Hydrochloride Solutions Research Articles

Encapsulation of cytochrome c in hollow mesoporous silica spheres by denaturation

Cytochrome c (Cyt-c) was encapsulated in hollow mesoporous silica spheres as a support for immobilization. Cyt-c was denatured by an aqueous solution of guanidine hydrochloride to increase the flexibility of Cyt-c structure by unfolding and subsequently passed through the mesopores into the hollow spaces by diffusion. After incorporation, the refolding of Cyt-c was carried out by removing the guanidine hydrochloride using dialysis. Considering that the mesopore size was slightly smaller than the native Cyt-c size, Cyt-c was immobilized inside the hollow spheres. Modification of encapsulated Cyt-c with 18-crown-6 showed catalytic activity for the asymmetric oxidation of methyl 4-tolyl sulfoxide. The encapsulated catalyst could be reused to achieve almost the same catalytic activity.

How to better select SARS-CoV-2 preservation solution of virus nucleic acid testing.

Sampling and testing for SARS-CoV-2 is a widely recognized method for identifying patients with COVID-19. However, there is limited research available on the stability of nucleic acids in viral storage solutions. This paper investigates the components that provide better protection for virus and nucleic acid detection. The study utilized real-time quantitative fluorescent PCR to detect SARS-CoV-2 and evaluate the preservation effect and stability of SARS-CoV-2 viral storage solution under various conditions, including different guanidinium salts, brands, and storage conditions. All brands of inactivated virus preservation solutions demonstrated effective preservation and stability. However, 0.5 mol/L guanidine hydrochloride and guanidine isothiocyanate solutions exhibited poor antiseptic effects. Additionally, refrigerated storage showed better preservation compared to room temperature storage. We recommend using inactivated virus collection solution to preserve and transport samples and testing preferably within 6 hours to reduce false negatives of NAT results.

Development of a method for fire-resistant finishing of non-woven material using a phosphorus-containing composition

The aim of the study is to obtain a non-woven material with flame retardant properties. The conditions of the process of fire-retardant finishing were as follows: an aqueous solution of preparations of various concentrations was applied by spraying onto the surface of the material, then drying was carried out and heat treatment on a thermal press. According to GOST R 50810-95, non-woven material made from flax and wool fibers, treated with a composition based on an aqueous solution of sodium phosphate and guanidine hydrochloride, is classified as a flame-retardant material. Also, tests for toxic and skin-irritating effects of non-woven material treated with the proposed composition showed its safety for human health.

Avaliação de soluções antifúngicas de guanidina para resina base de dentadura: um estudo in vitro

Background: The purposes of this study were: (1) to formulate polyhexamethylene guanidine hydrochloride (PHMGH) solutions at different concentrations; (2) to evaluate their antifungal activity against a mature biofilm of Candida albicans on acrylic resins; (3) to evaluate possible effects on acrylic resins flexural strength and surface roughness. Methods: PHMGH solutions were formulated with distilled water and 0.125, 0.250, or 0.5 wt.% of PHMGH. One group without PHMGH was used as control. For antifungal activity analysis, acrylic resin specimens were contaminated with C. albicans. Specimens were immersed in PHMGH solutions or distilled water for 5 or 10 min. Ultimate flexural strength and surface roughness of acrylic resins were evaluated. Results: All PHMGH solutions at 5 or 10 min showed antifungal activity compared to the control group (p

Дослідження гострої токсичності та впливу мийно-дезінфекційного засобу «Аргомол» на культуру інфузорій Tetrahymena pyriformis

Detergents and disinfectants for sanitation of milking equipment and dairy equipment must have a wide range of antimicrobial activity and provide a proper cleaning effect. At the same time, they must meet high standards of environmental safety and non-toxicity. The article presents data on the parameters of acute toxicity of the new detergent-disinfectant “Argomol”, based on lactic acid, “Katamine AB”, polyhexamethylene guanidine hydrochloride and colloidal silver solution, as well as the toxicity of the tool, which was determined using the express method of Tetrachymena pyriformis. The acute toxicity of the means and its working 0.5% solution in tentative and detailed experiments on white mice was determined and the median lethal dose (DL50) was determined by the method of G. Kerber. It was found that the DL50 of the means in white mice for intragastric administration when calculated by the method of G. Kerber is 4250 mg/kg body weight, and 0.5% of its solution — more than 11000 mg/kg body weight, i. e. according to SOU 85.2-37-736:2011 “Veterinary drugs. Determination of acute toxicity”, this indicates that the means belongs to the IV class of toxicity, which combines low-toxic substances. The results of research on the effect of the new detergent-disinfectant “Argomol” on the culture of ciliates Tetrahymena pyriformis are presented. It was found that the detergent-disinfectant “Argomol” in concentrations of 0.02–0.5% at exposures of 1–10 min did not show toxic effects on the ciliate Tetrahymena pyriformis. Toxicological studies on ciliates suggest that the detergent-disinfectant “Argomol”, when used in the recommended doses and exposures, can be used for sanitation of milking equipment and dairy equipment, as it is environmentally friendly and low-toxic.

Pushing beyond specifications: Evaluation of linearity and clinical performance of the cobas 6800/8800 SARS-CoV-2 RT-PCR assay for reliable quantification in blood and other materials outside recommendations.

The ongoing SARS-CoV-2 pandemic presents a unique challenge to diagnostic laboratories. There are preliminary studies correlating qRT-PCR results from different materials to clinical outcomes, yet, comparability is limited due to the plethora of different assays used for diagnostics. In this study we evaluate clinical performance and linear range for the SARS-CoV-2 IVD (cobas6800/8800 system, a fully automated sample-to-result platform) in different clinically relevant matrix materials outside official specifications. Assay performance was assessed in human plasma, BAL/BL and transport medium following chemical inactivation. For analytical evaluation, respective matrix materials were spiked with SARS-CoV-2 RNA in ten-fold dilution series. The efficacy of chemical inactivation by guanidine hydrochloride solution was confirmed in cell culture infectivity experiments. For correlation, a total of 289 predetermined clinical samples including respiratory swabs, plasma and lower respiratory tract specimens were subjected to the SARS-CoV-2 IVD test and results were compared. The SARS-CoV-2 IVD showed excellent linearity over four to six log steps depending on matrix material. Chemical inactivation resulted in a reduction in plaque forming units of at least 3.5 log steps, while having no significant impact on assay performance. Inter-run consistency from three different testing sites demonstrated excellent comparability of RT-PCR results (maximum deviation was 1.53 CT). Clinical evaluation for respiratory swabs showed very good agreement with the comparator assay (Positive agreement 95.7 %, negative agreement 98.9 %). The SARS-CoV-2 IVD test for the cobas6800/8800 systems offers excellent linear range and inter-run consistency for quantification of SARS-CoV-2 RNA in different matrices outside official specifications.

Elastic Properties of Guanidine Hydrochloride Solutions with Various Concentrations in the Gigahertz Frequency Range

The temperature dependences of the veloсity of hypersound (V(T)) in solutions with various concentrations of guanidine hydrochloride (GndHCl) are studied by Brillouin–Mandelstam light scattering spectroscopy in the temperature range from 263 to 353 K. It is shown that the temperature dependence of the sound velocity has a pronounced maximum at low concentrations of GndHCl. An increase in the concentration of GndHCl in a solution is accompanied by a shift of the maximum to the low-temperature region and an increase in the absolute values of the sound velocity, which means a decrease in the adiabatic compressibility over the entire range of studied temperatures. The temperature dependence of the adiabatic compressibility is constructed at low concentrations of GndHCl. The contribution of relaxation processes to the temperature behavior of the attenuation of hypersound in solutions of GndHCl is determined. It is shown that their behavior is activated thermally and described by the Arrhenius law. The values of the activation energy of relaxation processes are calculated. Possible mechanisms that underlie the observed phenomena are discussed.

Reactive cavitation erosion as a technique for production of functionalized copper hydroxychloride nanomaterials

The production of functionalized clinoatacamite (Cu2(OH)3Cl) nanoparticles from Reactive Cavitation Erosion (RCE) of copper in 1 M aqueous guanidine hydrochloride (GHCl) solution was investigated for applications as potential quantum magnet materials. As-synthesized nanomaterial was characterized by Diffuse-Reflectance Infrared Fourier-Transform Spectroscopy (DRIFTS), XRD, and TEM. These analyses were compared to nanoparticles produced from RCE of Cu in KCl and RCE of Cu in GHCl in oxygen-depleted (Ar) and oxygen-rich (compressed air, CA) solutions to identify possible reaction pathways.

Efficacy of Mass Spectrometry Versus 1H Nuclear Magnetic Resonance With Respect to Denaturant Dependent Hydrogen-Deuterium Exchange in Protein Studies

Understanding how proteins fold holds the key to many crucial advancements in the medical field, such as the treatment of chronic diseases. Measuring the rate of hydrogen-to-deuterium exchange for labile hydrogens within proteins exposed to deuterium oxide (D2O) can help elucidate the folding pathway of a protein. Mass spectrometry can be used to determine the extent of deuterium exchange by calculating ΔGHX (mass-to-charge ratio) values. These values were then compared the mass spectrometry results to previous exchange measurements taken by 1H NMR to investigate if mass spectrometry can be a viable method for measuring hydrogen-deuterium exchange in proteins. Once all of the reactions at different time points (10 seconds to 172,800 seconds) were conducted in the mass spectrometer in a 1.5M guanidine hydrochloride and D2O solution, the plotted data resulted in sigmoidal curves which showed dissimilar exchange rates to the previously archived 1H NMR data. After completion of the experiment, we concluded that further studies are necessary to draw a sound conclusion, as the field of study in which we tested solely 1.5M guanidine hydrochloride was too narrow. If reactions at other concentrations of guanidine hydrochloride yield the same exchange rates, denaturant-dependent hydrogen-deuterium exchange techniques can be applied in novel protein studies.

Influence of mixed aqueous solutions of polyhexamethylene guanidine hydrochloride and OP-10 on vegetable crop seeds

Influence of mixed aqueous solutions of polyhexamethylene guanidine hydrochloride and OP-10 on vegetable crop seeds

Switching worm-based viscoelastic fluid by pH and redox

HypothesisThe smart responsive behavior of wormlike micelles (WLMs) depends on a special group in the monomer. Surfactant bearing selenium atom and the carboxylic acid group is expected to be redox- and pH- responsive. Hence, the redox- or pH- induced transition in molecular structure should allow a tuning of the morphology of the aggregates, thereby affecting macroscopic viscoelasticity. ExperimentsA viscoelastic fluid based on WLMs was fabricated by mixing potassium benzylselanylundecyl carboxylate (BSeUK), and commercially available sulfobetaine surfactant (C16DSB) with a stoichiometric ratio of 1:1 in a guanidine hydrochloride solution. The fluid was systematically characterized with rheology measurements, cryo-TEM, dynamic light scattering, surface tension and NMR. FindingsThe addition of H2O2 induced the transition of BSeUK from its reduced form (selenide) to its oxidized form (selenoxide) transition, thereby resulting in a transition of the aggregates from an entangled WLM to a small spherical ones as verified by a dramatic decrease in viscosity. The decrease in pH induced a transition of BSeUK from its dissociated form (surfactant) to an oil-soluble fatty acid form (non-surfactant), with the consequent loss of viscoelasticity and the transformation from a gel-like fluid to an emulsion. Both the redox and pH-responsive processes are reversible and at least 0.4 equiv. of H2O2 with respect to selenium, or 13% oil-soluble fatty acid, were required to decrease the viscosity to its minimum value.

Temperature dependence of the hydrogen bond network in trimethylamine N-oxide and guanidine hydrochloride-water solutions.

We present an X-ray Compton scattering study on aqueous trimethylamine N-oxide (TMAO) and guanidine hydrochloride solutions (GdnHCl) as a function of temperature. Independent from the concentration of the solvent, Compton profiles almost resemble results for liquid water as a function of temperature. However, the number of hydrogen bonds per water molecule extracted from the Compton profiles suggests a decrease of hydrogen bonds with rising temperature for all studied samples, and the differences between water and the solutions are weak. Nevertheless, the data indicate a reduced bond weakening with rising TMAO concentration up to 5 M of 7.2% compared to 8% for pure water. In contrast, the addition of GdnHCl appears to behave differently for concentrations up to 3.1 M with a weaker impact on the temperature response of the hydrogen bond structure.

Solvation behavior of some nucleic acid bases and nucleosides in water and in aqueous guanidine hydrochloride solutions: Viscometric, calorimetric and spectroscopic approach

Viscosity, η and enthalpy of dilution, q of studied nucleic acid bases (uracil, cytosine, thymine) and nucleosides (uridine, cytidine and thymidine) in water and in aqueous solutions of (0.10, 0.25, 0.50, 0.75 and 1.00)mol·kg−1 guanidine hydrochloride (GnHCl) have been determined over a temperature range (288.15-318.15)K at (101.3±0.5)kPa. These data have been used to calculate viscosity B-coefficients and standard molar enthalpy of dilution, ΔdilHo which have further been used to evaluate corresponding transfer parameters ΔtrB and ΔtrΔdilHo, respectively. Positive ΔtrB values and negative ΔtrΔdilHo values indicate the predominance of hydrophilic–ionic interactions in these systems. Temperature dependence of B-coefficient and ΔdilHo has also been discussed. Spectroscopic studies have been carried out to further investigate the structural changes and the interactions involved in the mixed aqueous solutions.

Volumetric studies on nucleic acid bases and nucleosides in aqueous guanidine hydrochloride solutions at T = (288.15 to 318.15) K and at atmospheric pressure

Apparent molar volumes (V2,ϕ) have been determined from density measurements for some nucleic acid bases (uracil, cytosine, thymine), and nucleosides (uridine, cytidine and thymidine) in water and in aqueous solutions of (0.10, 0.25, 0.50, 0.75 and 1.00)mol⋅kg−1 guanidine hydrochloride (co-solute) over the temperature range (288.15 to 318.15)K, at atmospheric pressure using vibrating-tube digital densimeter. These data have further been used to calculate apparent molar volumes V2,ϕo at infinite dilution and the corresponding apparent molar volumes of transfer ΔtrV2,ϕo at infinite dilution from water to aqueous solutions of guanidine hydrochloride (GnHCl). Apparent molar expansibilities (E2,ϕo), second-order derivative ∂2V2,ϕo/∂T2p and volumetric interaction coefficients have also been calculated. Co-sphere overlap model has been used to rationalize the data in terms of molecular interactions (hydrophilic, hydrophobic and ionic interactions). The present data have been compared and discussed for the systems studied with those reported in the presence of other co-solutes. The contributions of –CH2 group to V2,ϕo have also been calculated at different temperatures and concentrations of GnHCl.

Hexafluorosilicates with antibacterial active guanidine containing cations

The present research has studied the spectral data, thermochemical transformations and hydrolysis of hexafluorosilicates with guanidine containing cations (C22H32Cl2N10)SіF6 (І) and (C21H45N9)(SiF6)1.5 (ІІ) for their potential use as caries-preventive and antibacterial agents. Hexafluorosilicates of the com position I and II were separated as crystalline products of interaction of hexafluorosilicic acid with the methanol solutions of chlorhexidine hydrochloride and polyhexamethylene guanidine hydrochloride. The compounds isolated have been characterized by IR, NMR 19 F, mass-spectrometry, thermogravimetric analysis, potentiometry. According to IR spectroscopy data, “onium” hexafluorosilicates I and II have ionic structures. The vibrations of the groups ν(NH), ν(N + H2) in salts I and II appear as strong absorption bands at 3360-3180 cm –1 ; δ(N + H2) vibrations appear at 1634 and 1637 cm –1 . The strong ν(SiF) and δ(SiF2) stretches of SiF6 2– anions are observed in their characteristic regions (at 744, 734 and 482 cm –1 , respectively). The singlet character of ν(SiF) and δ(SiF2) vibrations indicates the absence of noticeable distortion of symmetry of SiF6 2– anion with regard to Oh. The NMR 19 F spectra of compounds I and II (in DMSO-d6 solutions) have one resonance at –136,70, –135,09 ppm (SiF6 2– ); additional resonance at –123,14 ppm, in the case of II it can be related to the octahedral complex anion [SіF5(ДМСО)] – . The results of thermogravimetric analysis are consistent with a multi-stage thermolysis scheme for hexafluorosilicates I and II. The temperatures of thermolysis beginning of complexes I and II are 270 and 100°C, respectively. The compounds I and II studied are characterized by the predicted tendency to hydrolysis in dilute aqueous solutions with formation of orthosilicic acid and fluoride ions, and it allows considering these salts as potential anticaries agents. The study of the biological activity of these compounds is the subject of further investigations. In recent years, several research groups consisting of experts from Japan, the United States [10-13] and Armenia [1, 8] demonstrated the possible use of ammonium and amino acids hexafluorosilicates as caries-preventive and hyposensitive agents in dental practice. These results [1, 8, 10-13] allow to consider the “onium” hexafluoro silicates as a promising new class of drugs possessing a number of advantages compared to the conventional agents of fluoride caries therapy such as sodium and po tassium fluorides, silver diamine fluoride, tin fluoride and sodium monofluorophosphate. The active components of treatment and prevention of dental caries are also antibacterial agents, including high efficient guanidine de rivatives (chlorhexidine, polyhexamethylene guanidine hydrochloride, etc.) [9, 13]. In principle, introducing guanidine containing cations possessing the antibacterial action into the composition of hexafluorosilicate allows to obtain compounds for which the caries-preventive effect of the anion is intensified by the bactericidal action of the cation. The aim of this work is the synthesis, the study of the structure and properties of chlorhexidine (CH) and polyhexamethylene guanidine (PHMG) hexafluorosilicates – the first representatives of fluoride-containing salts com bined with cations exhibiting the antibacterial activity. Materials and Methods The synthesis of hexafluorosilicates was performed by the ion exchange reaction between methanol solu

Stokes–Einstein–Debye Failure in Molecular Orientational Diffusion: Exception or Rule?

The Stokes-Einstein-Debye (SED) expression is used routinely to relate orientational molecular diffusivity quantitatively to viscosity. However, it is well-known that Einstein's equations are derived from hydrodynamic theory for the diffusion of a Brownian particle in a homogeneous fluid and examples of SED breakdown and failure for molecular diffusion are not unusual. Here, using optical Kerr-effect spectroscopy to measure orientational diffusion for solutions of guanidine hydrochloride in water and mixtures of carbon disulfide with hexadecane, we show that these two contrasting systems each show pronounced exception to the SED relation and ask if it is reasonable to expect molecular diffusion to be a simple function of viscosity.

Comparison of the Thermal Denaturing of Human Serum Albumin in the Presence of Guanidine Hydrochloride and 1-Butyl-3-methylimidazolium Ionic Liquids

The interaction of proteins with aqueous solutions of ionic liquids (ILs) has attracted considerable recent attention owing to the challenges of finding biocompatible water-free ILs. These systems remain of great interest because of the potential for using ILs as designer solvents for biocatalytic processes. Increasing evidence demonstrates that aqueous solutions of water-miscible ILs, such as the well-studied 1-alkyl-3-methylimidazolium ILs, disrupt the native fold of proteins and can drive the formation of non-native aggregates that could negatively impact catalytic function. Here, we present a study comparing the thermal unfolding of human serum albumin (HSA) in a 1 M solution of the protein denaturant guanidine hydrochloride with two 1 M aqueous solutions of 1-butyl-3-methylimidazolium ILs, namely the chloride and the acetate. Small-angle neutron scattering (SANS) measurements found qualitative agreement between the thermally driven unfolding process for the three denaturants, as well as with a Tris buffer solution. HSA irreversibly aggregates and unfolds in the three denaturant solutions upon heating to temperatures below that required to drive the same process in a simple Tris buffer solution. The results reveal subtle differences in the interaction of the ILs and guanidine hydrochloride with the protein, although the final states of the protein were similar in all cases. The results indicate that the ions of water-miscible ILs and guanidine hydrochloride have specific roles in disrupting protein structure and driving aggregation. The experimental approach employed has the potential to provide new insights into protein interactions with ionic liquids that may aid in the search for more biocompatible ionic liquids.

Conformational Properties of Polyglutamine Sequences in Guanidine Hydrochloride Solutions

Two sets of iso-1-cytochrome c variants have been prepared with N-terminal insertions of pure polyglutamine, i.e., PolyQ variants, or polyglutamine interrupted with lysine every sixth residue, i.e., Gln-rich variants. The polymer properties of these pure polyGln or Gln-rich sequences have been evaluated using equilibrium and kinetic His-heme loop formation methods for loop sizes ranging from 22 to 46 in 1.5, 3.0, and 6.0 M guanidine hydrochloride (GdnHCl). In 6.0 M GdnHCl, the scaling exponent, ν3, for the pure polyGln sequences, is ∼1.7—significantly less than ν3 ≈ 2.15 for the Gln-rich sequences. The stability of the His-heme loops becomes progressively greater for the pure polyGln sequences relative to the Gln-rich sequences as GdnHCl concentration decreases from 6.0 to 1.5 M. Thus, the context of the sequence effects the polymer properties of Gln repeats even in denaturing concentrations of GdnHCl. Comparison of data for the Gln-rich variants with previous results for Gly-rich and Ala-rich variants shows that ν3 ∼ 2.2 for the Gln-rich, Gly-rich, and Ala-rich sequences in 6.0 M GdnHCl, whereas ν3 remains unchanged at 3.0 M GdnHCl concentration for the Gln-rich and Ala-rich sequences but decreases to ∼1.7 for the Gly-rich sequences. Thus, the polymer properties of Gln-rich and Ala-rich sequences are less sensitive to solvent quality in denaturing solutions of GdnHCl than Gly-rich sequences. Evaluation of Flory’s characteristic ratio, Cn, for the Gln-rich and Ala-rich sequences relative to the Gly-rich sequences shows that Gln-rich sequences are stiffer than Ala-rich sequences at both 3.0 and 6.0 M GdnHCl.

Multicomponent Rayleigh scattering from guanidine hydrochloride solutions

We present results of Brillouin light scattering studies of lysozyme and guanidine hydrochloride solutions in the temperature range 290–350 K. The Brillouin spectra of 6 M guanidine hydrochloride have been found to contain an additional component in Rayleigh scattering that manifests itself as a broad quasi‐elastic scattering line centered at the unshifted frequency and described by a Lorentz function (i.e. a Debye relaxor with relaxation time τ1 ~ 25 ps at room temperature). The temperature dependence of τ1 is described by the Arrhenius law with activation energy Ea = 0.11 ± 0.01 eV and prefactor τ0= 0.33 ± 0.03 ps. The Brillouin spectra of lysozyme denatured by 6 M guanidine hydrochloride exhibit a more complicated structure of the additional contribution into Rayleigh scattering, which is fitted best of all by a sum of two Lorentzians centered at the unshifted frequency (with relaxation times τ1 ~ 19 ps and τ2 ~ 180 ps at 339 K). Possible origins of the quasi‐elastic scattering are discussed. Copyright © 2012 John Wiley & Sons, Ltd.

Scaling Properties of Glycine-Rich Sequences in Guanidine Hydrochloride Solutions

The intrinsic polymer properties of glycine-rich sequences are evaluated with a set of iso-1-cytochrome c variants with N-terminal inserts of the sequence (GGGGGK)n for n = 1–5. The thermodynamics and kinetics of His-heme loop formation are measured as a function of guanidine hydrochloride (GdnHCl) concentration for loop sizes ranging from 22 to 46 residues. The scaling exponent for loop formation, ν3, evaluated using the Jacobson-Stockmayer equation is near 1.8, at 1.5 and 3.0 M GdnHCl, but it increases to 2.2 in 6.0 M GdnHCl. Previous work on a set of iso-1-cytochrome c variants with (AAAAAK)n inserts gave ν3 = 2.2 for alanine-rich sequences in both 3.0 and 6.0 M GdnHCl. Chain stiffness was evaluated from the relative magnitude of Flory's characteristic ratio, Cn, for alanine-rich versus glycine-rich sequences. In 3.0 M GdnHCl, Cn(Ala)/Cn(Gly) is 1.6, decreasing to 1.3 in 6.0 M GdnHCl. The data suggest that solvent-backbone interactions dominate polypeptide conformational properties under good solvent conditions whereas side-chain-dependent properties are more important under poor solvent conditions. The results provide a direct experimental assessment in terms of polymer properties of the distinct roles of Gly versus Ala in the folding code.