Aqueous Solutions Of D-glucose Research Articles

Dehydration effect of ionic liquid, 1-pentyl-3-methylimidazolium bromide, on the aqueous d-glucose solutions: Thermodynamic study

Effect of an ionic liquid, 1-pentyl-3-methylimidazolium bromide ([PnMIm]Br), on the solution behavior of aqueous D-glucose solutions has been investigated. For this purpose, various thermophysical properties such as density, viscosity, electrical conductivity, and refractive index have been measured at T=298.15K. Thermophysical parameters including standard partial molar volume (Vφ0) and corresponding transfer volume (ΔtrVφ0), hydration number (nH), viscosity B-coefficient, free energy of activation per mole of the solvent (Δμ10≠) and the solute (Δμ20≠), ion association constant (Ka), and molar refraction at infinite dilution (RD0) have been calculated using the measured experimental data. The obtained parameters have been used to understand various mixing effects of components due to the solute–cosolute interactions. It was observed that the values of transfer volume and viscosity B-coefficient increase with increasing the concentration of [PnMIm]Br. The results suggest that ionic liquid has a dehydration effect on D-glucose in water. This opinion is confirmed by the observed depletion in the values of hydration number and ion association constant.

Simple enzyme immobilization inside glass tubes for enzymatic cascade reactions

The two enzymes Aspergillus nigerglucose oxidase (GOD) and horseradish peroxidase (HRP) were immobilized with a simple and quick procedure inside micropipette glass tubes with the help of the avidin–biotin system and of a biotinylated second generation polycationic dendronized polymer (de-PG2). De-PG2 strongly adheres to SiO2 surfaces and served as soft organic layer for non-covalently gluing the biotinylated enzyme–avidin complexes to the solid glass surface. The immobilized enzymes remained highly active for a period of several weeks. Furthermore, after connecting a glass tube containing immobilized GOD (first tube) with a glass tube containing immobilized HRP (second tube), this system was applied as a simple flow reactor for the spectrophotometric quantification of D-glucose in aqueous solution via a cascade reaction catalysed by the two immobilized enzymes. Moreover, preliminary measurements showed that the general procedure developed for the immobilization of HRP and GOD inside the glass tubes can also be applied to E. coli β-galactosidase, allowing the spectrophotometric determination of lactosevia a three-enzyme cascade reaction in a system composed of three sequentially connected tubes. The success of the work is based on two factors: (i) on the use of the dendronized polymerde-PG2 which combines properties of polycationic dendrimers as well as polycationic polymers in one and the same molecule, leading to efficient and reproducible binding to SiO2 surfaces; and (ii) on the monitoring of the immobilization on SiO2 with the transmission interferometric adsorption sensor (TInAS) for elaborating the optimal experimental conditions for the immobilization of the enzymes inside the tubes.

Structure-making tendency of ionic liquids in the aqueous d-glucose solutions

Densities (d) of d-glucose+ionic liquid {1-pentyl-3-methylimidazolium bromide ([PnMIm]Br) and 1-hexyl-3-methylimidazolium bromide ([HMIm]Br)}+water ternary solutions were measured at T=288.15, 298.15, 308.15 and 318.15K as a function of d-glucose molality in 0.2, 0.3, 0.4 and 0.5molkg−1 of ionic liquids. The measured density values were used to calculate the standard partial molar volume (Vϕ0), partial molar expansivity (Eϕ0), hydration number (nH) and volumetric interaction coefficients (VSIL and VSILIL) at different temperatures. These parameters have been discussed in terms of solute–solvent interactions and structure making/breaking abilities of d-glucose and ionic liquids. It is also attempted to understand the effects of cation size of ionic liquid and temperature on the volumetric properties. The results show that the longer alkyl chain of ionic liquid has the stronger interactions with d-glucose and this type of interactions is further increased at high temperatures.

Solution Properties of Ternary D-Glucose + 1-Ethyl-3-methylimidazolium Ethyl Sulfate + Water Solutions at 298.15 K

The effect of an ionic liquid, 1-ethyl-3-methylimidazolium ethyl sulfate ([EMIm]ESO4), on the thermophysical properties of aqueous D-glucose solutions including density, viscosity, and electrical conductivity have been investigated at 298.15 K. Using these properties, the apparent molar volumes, Vφ, the viscosity B-coefficients and the molar conductivities, Λm, have been computed for the ternary D-glucose + [EMIm]ESO4+water solutions. The Vφ values were used to calculate the standard partial molar volumes, \(V_{\phi}^{0}\), and transfer volumes, \(\Delta_{\mathrm{tr}}V_{\phi}^{0}\), of D-glucose from water to aqueous ionic liquid solutions. These volumetric parameters, for all the solutions studied, are positive and increase monotonically with increasing the concentration of [EMIm]ESO4. These observations have been interpreted in terms of the interactions between D-glucose and ionic liquid in the aqueous solution. The viscosity data were analyzed in terms of the Jones-Dole equation to determine the values of the viscosity B-coefficients. The calculated conductometric parameters, the limiting molar conductivities, Λ0, the association constants, Ka, and the Walden products, Λ0η, for [EMIm]ESO4, decrease with increasing concentration of D-glucose. This trend suggests that the ions of an ionic liquid do not have the same hydrodynamic size in the presence of D-glucose molecules (ILs) and consequently provides evidence for the dehydration effect of the ionic liquid in aqueous D-glucose solutions.

Non-invasive in vitro sensing of d-glucose in pig blood

We have developed an electromagnetic resonant spiral sensor and have measured the glycemia in pig blood and the concentration of d-glucose in aqueous solution by using a real-time electromagnetic interaction phenomenon between the microwave sensor and the liquid. We could determine the concentration of glucose with a minimal resolution of 5mg/dl in the 100–600mg/dl concentration range at operating frequencies of about 7.65GHz (for the glucose aqueous solution) and 7.77GHz (for the pig blood sample). The change in the glucose concentration brings the changes of the microwave reflection coefficient due to the electromagnetic interaction between the resonator and the glucose solution. The in vitro results show the measured signal-to-noise ratio of about 34dB, and the minimum detectible signal level of about 0.022dB/(mg/dl). Our proposed system provides a unique approach for non-invasive and non-contact glucose monitoring, and it may serve as a bloodless glucometer.

Effect of ionic liquid, 1-octyl-3-methylimidazolium bromide on the thermophysical properties of aqueous d-glucose solutions at 298.15 K

Thermophysical properties including densities, viscosities, refractive indices, and molar conductivities for ternary systems containing d-glucose, ionic liquid {1-octyl-3-methylimidazolium bromide ([OMIm]Br)} and water have been measured at 298.15 K. The density and viscosity data have been used to calculate apparent molar volumes, V ϕ , standard partial molar volumes (which equal in value with infinite dilution apparent molar volume), V ϕ 0 , transfer volumes, Δ tr V ϕ 0 , of d-glucose from water to aqueous [OMIm]Br solutions and viscosity B-coefficients. An increase in the values of V ϕ 0 , Δ tr V ϕ 0 and viscosity B-coefficient was observed with increase of ionic liquid concentration. Limiting molar conductivities, Λ 0, and ion association constants, K a, of [OMIm]Br in aqueous d-glucose solutions were estimated from low concentration chemical model (lcCM). Molar refractions, R D, were calculated from refractive index, n D, measurements using Lorentz–Lorenz equation. All of these parameters were discussed in terms of the different solute-solvent interactions occurring between d-glucose and ionic liquid.

Boiling point of aqueous d-glucose and d-fructose solutions: Experimental determination and modeling with group-contribution method

Boiling points of aqueous solutions affect the design and operation of evaporators. Hence, boiling points of aqueous solutions of d-glucose and d-fructose were experimentally determined at soluble solute concentration from 10 to 60% sugar by mass and pressure from 20 to 93.6 kPa. The experimental data were correlated with data predicted by the calculation of the activity coefficients with the UNIFAC-Lyngby model using different approaches for decomposition of the molecular structure: the aliphatic groups and the cyclic groups. Moreover, the rise in experimental boiling point of the aqueous sugar solutions was evaluated by the Dühring's rule. It was observed that the cyclic approach resulted in better accuracy for liquid–vapor equilibrium prediction and the non-ideality of these solutions are relevant in the boiling point rise, confirming that the rise in boiling point of aqueous d-glucose and d-fructose concentrated solutions is significant to the design of heat and mass transport operations.

Green Chemicals from d-glucose: Systematic Studies on Catalytic Effects of Inorganic Salts on the Chemo-Selectivity and Yield in Aqueous Solutions

The use of inorganic salts as catalysts for the reactions of d-glucose in aqueous solutions in a batch reactor is reported. The type of salt and effect of reaction time were examined in detail at a fixed salt (5 mM) and d-glucose concentration (0.1 M) and at a temperature of 140 °C. Al(III) and Cr(II) salts gave the highest conversion of d-glucose. Typical reaction products were organic acids like lactic acid, levulinic acid, furanics like hydroxymethylfurfural and insoluble products (humins). The chemo-selectivity is a clear function of the type of inorganic salt. For Al(III), the major water soluble product was lactic acid, for Zn(II) HMF was formed in the highest yields. A reaction scheme is proposed to explain the observed product compositions.

A Simple Laboratory Experiment To Determine the Kinetics of Mutarotation of D-Glucose Using a Blood Glucose Meter

A simple commercial blood glucose meter is used to follow the kinetics of mutarotation of D-glucose in aqueous solution. The results may be compared with those obtained using an automatic polarimeter, if this is available This experiment is proposed for use by students in a general chemistry, biology, organic chemistry, and physical chemistry laboratory at the college level. It can also be used as an alternative technique to the classical methods that use relatively expensive equipment, which are not always accessible to students. The technique of indirect measurement of the kinetics of mutarotation of D-glucose through an enzymatic redox reaction also provides an example of the chemical and kinetic approaches to the mutarotation phenomenon and the principle of enzymatic stereospecificity. The test strips of the blood glucose meter contain glucose dehydrogenase, an enzyme specific for the anomer of D-glucose in solution.

Influence of Side Chain of L-α-amino Acids on Their Interaction with D-glucose in Dilute Aqueous Solutions

Titration calorimetric and UV absorption spectroscopy measurements have been performed to study the interactions of some L-α-amino acids with D-glucose in dilute aqueous solutions. The obtained results showed that the ability of L-α-amino acids to form intermolecular complexes with D-glucose in aqueous solution is affected by the size and nature of their side chains.

Reference interaction site model study on the anomeric equilibrium of D-glucose in aqueous solution

The anomeric equilibrium of D-glucose in aqueous solution was studied by the extended reference interaction site model (XRISM) theory. In this study, all of the rotational degrees of freedom were considered upon the exocyclic hydroxyl and hydroxymethyl groups, namely 729 stereoisomers for each anomer. The free energy

Acoustical and Thermodynamical Studies of L-serine, L-glutamine and L-asparagine in Aqueous D-glucose Solutions at 298.15 K

Acoustical and Thermodynamical Studies of L-serine, L-glutamine and L-asparagine in Aqueous D-glucose Solutions at 298.15 K

Structure of Aqueous Glucose Solutions as Determined by Neutron Diffraction with Isotopic Substitution Experiments and Molecular Dynamics Calculations

Neutron diffraction with isotopic substitution (NDIS) experiments and molecular dynamics (MD) simulations have been used to examine the structuring of solvent around d-glucose in aqueous solution. As expected, no significant tendency for glucose molecules to aggregate was found in either the experiments or the simulation. To the extent that solute pairing does occur as the result of the high concentration, it was found to take place through hydroxyl-hydroxyl hydrogen bonds, in competition with water molecules for the same hydrogen-bonding sites. A detailed analysis of the hydrogen-bonding patterns occurring in the simulations found that the sugar hydroxyl groups are more efficient hydrogen bond donors than acceptors. From the comparison of the MD and NDIS data, it was found that while the modeling generally does a satisfactory job in reproducing the experimental data the force fields may produce sugar rings that are too rigid and thus may require future revisions.

Electrophoresis of Progesterone Particles Dispersed in Carbohydrate and Nonelectrolyte Solutions

Electrophoretic mobilities of progesterone particles dispersed in aqueous solutions of D-glucose and urea (concentration range 0.1 to 1 mM) have been measured in order to investigate the electrical properties of the interface. Zeta potentials have been determined for this purpose. The dependence of Zeta potentials on concentration has also been examined. Theory of the electrical double layer has been used to explain the results.

N-(1-Deoxy-d-fructos-1-yl) Fumonisin B1, the Initial Reaction Product of Fumonisin B1 and d-Glucose

Incubation of fumonisin B(1) and D-glucose in aqueous solutions resulted in the formation of N-(1-deoxy-D-fructos-1-yl) fumonisin B(1) in addition to the previously reported N-(carboxymethyl) fumonisin B(1). N-(1-Deoxy-D-fructos-1-yl) fumonisin B(1) is the first stable product formed after the Amadori rearrangement of the Schiff base formed by the reaction of the primary amine of fumonisin B(1) and the aldehyde group of D-glucose. N-(1-Deoxy-D-fructos-1-yl) fumonisin B(1) was synthesized by reacting fumonisin B(1) with an excess of D-glucose in methanol and heating for 6 h at 64 degrees C. It was purified using C(18) and strong cation exchange solid-phase extraction cartridges and characterized by nuclear magnetic resonance and liquid chromatography-mass spectrometry. Subsequently, N,N-dimethylformamide was found to be a better reaction solvent, requiring reaction for only 2-3 h at 64 degrees C and eliminating the formation of methyl esters. Alkaline hydrolysis of N-(1-deoxy-D-fructos-1-yl) fumonisin B(1) gave a mixture of hydrolyzed fumonisin B(1) and hydrolyzed N-(carboxymethyl) fumonisin B(1).

Molecular Dynamics of Carbohydrate Aqueous Solutions. Dielectric Relaxation as a Function of Glucose and Fructose Concentration

At some solute concentrations c between 1 and 5.4 mol/L, the complex (electric) permittivity of aqueous solutions of d-glucose and d-fructose has been determined as a function of frequency υ between 300 kHz and 40 GHz. The permittivity spectrum of the 5.4 mol/L d-fructose solution has been measured at six temperatures between 10 and 35 °C, and the other spectra have been taken at 25 °C. All dielectric spectra revealed one dispersion/dielectric loss region, which indicated a rather homogeneous relaxation of the solute and solvent dipole moments. Analytically, the measured spectra were represented by the Cole−Cole relaxation spectral function, which corresponds with a continuous, symmetrically bell shaped relaxation time distribution. The parameters of the spectral function are discussed to show that the monosaccharides exhibit unusual hydration properties. Particularly, when treated in terms of a wait-and-switch model of dipole reorientation, the principal dielectric relaxation time is indicative of the ex...

Apparent molar volumes and apparent molar heat capacities of aqueous d-glucose and d-galactose at temperatures from 278.15 K to 393.15 K and at the pressure 0.35 MPa

Apparent molar heat capacities Cp, φand apparent molar volumesVφ were determined for aqueous solutions of d-glucose and d-galactose at temperatures from 278.15 K to 393.15 K and at the pressure 0.35 MPa. The molalities m investigated ranged from 0.05 mol · kg−1to 0.5 mol · kg−1. A vibrating tube densimeter (DMA 512P, Anton PAAR, Austria) was used to investigate the densities and volumetric properties. Heat capacities were obtained using a twin fixed-cell, power-compensation, differential-output, temperature-scanning calorimeter (NanoDSC 6100, Calorimetry Sciences Corporation, Provo, UT, U.S.A.). The calculatedVφ and Cp, φof the solutions were fit to equations that describe the surfaces (Vφ, T, m) and (Cp,φ, T, m). These surfaces showed no dependence of VφorCp, φ on M. Infinite dilution partial molar volumesV2o and heat capacities Cp,2owere obtained over the range of temperature. The Cp,2oandV2o values were found to be large, positive, and to increase with increasing temperature.

Fluorescence Polarization of Inclusion Complexes of β-Cyclodextrin with 6-Anilino-2-naphthalenesulfonate and 8-Anilino-1-naphthalenesulfonate in Aqueous d-Glucose Solutions

Abstract In aqueous and aqueous d-glucose solutions, 6-anilino-2-naphthalenesulfonate (2,6-ANS) and 8-anilino-1-naphthalenesulfonate (1,8-ANS) form 1:1 inclusion complexes with β-CD. The molecular volume of 2,6-ANS bound to the β-CD cavity has been evaluated to be 4.7 nm3 from the viscosity dependence (Perrin plot) of the 2,6-ANS fluorescence polarization. This value indicates that 2,6-ANS incorporated into the β-CD cavity rotates as the inclusion complex on a fluorescence lifetime scale. The molecular volume of 2,6-ANS in solution without β-CD has been evaluated to be 0.88 nm3, which provides additional evidence for the whole rotation of the β-CD–2,6-ANS inclusion complex. The molecular volume of 1,8-ANS bound to the β-CD has been evaluated to be 2.7 nm3, which is comparable to the calculated molecular volume (1.9 nm3) of β-CD, indicating that 1,8-ANS most likely rotates as the inclusion complex. The fact that the molecular volume of the 1,8-ANS inclusion complex is smaller than that of the 2,6-ANS inclusion complex may be attributed to the differences in the binding site of β-CD and the substitution positions of anilino and sulfonato groups.

Fluorescence Polarization Studies of Inclusion Complexes between β-Cyclodextrin and 1-Chloronaphthalene in Aqueous and Aqueous d-Glucose Solutions

In aqueous and aqueous d-glucose solutions, 1-chloronaphthalene (1CN) has been found to form a 2:2 inclusion complex with β-cyclodextrin (β-CD), which is generated by the self-association of 1:1 β-CD−1CN inclusion complexes. The 2:2 inclusion complex is responsible for the excimer fluorescence of 1CN. Equilibrium constants for the formation of the 1:1 and 2:2 inclusion complexes in aqueous solutions have been evaluated from a simulation of the 1CN excimer fluorescence intensity which is a function of β-CD concentration. When a wavelength of 315 nm has been selected as an excitation light, the degree of polarization has been maximized at the wavelengths of the 1CN monomer fluorescence band, and is decreased at the 1CN excimer fluorescence band. The decrease in the degree of polarization is due to the long lifetime of the excimer fluorescence. The results of the fluorescence polarization are consistent with the theory that the transition moment of the 1CN excimer fluorescence is parallel to that of the monomer fluorescence. On the basis of a Perrin plot, the molecular volume of the 1CN excimer has been estimated to be 0.20 nm3, which corresponds to the molecular volume of the sandwich-type excimer of 1CN; the 1CN excimer does not rotate as the 2:2 inclusion complex but rotates as the guest within the β-CD cavities.

Inclusion of 2-Chloronaphthalene by α-Cyclodextrin and Room-Temperature Phosphorescence of 2-Chloronaphthalene in Aqueous d-Glucose Solutions Containing α-Cyclodextrin

In aqueous solutions, α-cyclodextrin (α-CD) forms a 1:1 inclusion complex with 2-chloronaphthalene (2-CN), and further associates with the 1:1 inclusion complex to form a 2:1 α-CD−2-CN inclusion complex. In aqueous d-glucose solutions, α-CD also forms the 1:1 and 2:1 inclusion complexes with 2-CN. Equilibrium constants for the formation of the 1:1 and 2:1 inclusion complexes have been evaluated from simulations of the observed fluorescence intensities of 2-CN in aqueous solutions with and without d-glucose. For 2-CN solutions containing both d-glucose and α-CD, the room-temperature phosphorescence of 2-CN has been observed. The 2:1 α-CD−2-CN inclusion complex is responsible for the room-temperature phosphorescence. The quantum yield (φp) of the room-temperature phosphorescence from the 2:1 inclusion complex has been determined to be at least 0.029, which is 19% of a φp value of 2-CN in ethanol at 77 K. When KI is added to d-glucose solutions containing α-CD, the room-temperature phosphorescence intensity ...