Aqueous Glucose Solutions Research Articles

Hydrogenolysis of glucose and fructose in glycol solutions over CuO-MgO-ZrO2 catalyst

Ethylene glycol and propylene glycol are important representatives of polyols. On an industrial scale, they are obtained from petrochemical raw materials. Within a decade, significant efforts were made for the producing of polyols from biologically renewable raw materials - carbohydrates. The general trend for carbohydrate hydrogenolysis includes application of liquid-phase process with the use of modified metal-oxide catalysts, at 120-120 ° C and pressure of 3MPa or above. So high pressure is used for the reason to increase hydrogen solubility, and also due to the high partial pressure of low boiling solvents. We supposed that usage of high boiling solvents could allow hydrogenolysis to be performed at the lower pressure. Ethylene glycol and propylene glycol are of particular interest as such kind of solvent since they are both the main products of glucose hydrogenolysis. In this work, the process of hydrogenolysis of glucose and fructose over Cu / MgO-ZrO2 catalyst have been studied at temperature range of 160-200 °C and a pressure of 0.1-0.3 MPa in a flow reactor. The solvents were simultaneously the target products of the reaction - ethylene glycol and / or propylene glycol. Gas chromatography and 13C NMR were used for the reaction products identification. It was found that the solubility of glucose in propylene glycol is 21 % by weight, and in ethylene glycol 62% by weight. It was pointed out that the process of hydrogenolysis can take place at a pressure close to atmospheric. Under these conditions, the conversion of hexoses reaches 96-100 %. The reaction products are preferably propylene glycol and ethylene glycol. The total selectivity for C3-2 polyols is 90-94 %, that is higher than in the hydrogenolysis of glucose in aqueous solution.

Polyaromatic hydrocarbon inner-structured carbon nanodots for interfacial enhancement of carbon fiber composite.

It is well known that carbon substances with a polyaromatic hydrocarbon (PAH) inner structure only form at high temperature. In this work, we introduce fabrication of massive and PAH inner-structured carbon nanodots (CNDs) via hydrothermal treatment of glucose aqueous solution in the monolithic methyl silicone hydrogel at 200 °C. During the carbonization process, all the precursor solution is confined in nano-vessels (2–20 nm) of the thermostable methyl silicone hydrogel, thus forming CNDs without aggregation. The resulting CNDs, with a yield of 65%, were separated facilely and characterized using various spectroscopy and microscopy techniques. The glucose-derived CNDs have diameters of 2–5 nm and contain 18.9 wt% carboxyl groups, and their aqueous solubility depends on the pH. The CNDs consist of large PAH clusters, confirmed by solid-state 13C NMR, which were different to other reported carbon substances prepared at similar low temperatures. The formation mechanism of the PAH structure in the CNDs probably relates to the high interfacial energy of the prewetted superhydrophobic methyl silicone nano-framework in the hydrogel. Moreover, the tunable fluorescence properties of the CNDs prepared using this method can be attributed to the arene carboxylic groups in the CNDs. Finally, the resultant PAH CNDs with abundant groups were applied as a sizing in carbon fiber (CF) composite fabrication, resulting in an obvious interface enhancement of the CF/epoxy composite.

Ultra-high resolution sensing of glucose concentration based on amplified half-integer localized surface plasmons mode

Since the half-integer order localized surface plasmons mode is more sensitive to the change of the surrounding materials, an active spoof plasmonic microfluidic sensor using the mode for detecting minute change of glucose aqueous solutions has been proposed at microwave frequencies. By introducing an active coupling circuit near the slit of the spoof plasmonic resonator, the measured quality factor of the half integer order mode (n = 1.5) for the active spoof plasmonic resonator is increased from 148 to 40 000 and the dephasing time is increased to about 16.5 µs when the optimal bias voltage is applied, compared to the passive spoof plasmonic resonator. The resonance frequency changes from 2.45 GHz to 1.74 GHz, with a frequency shift of 710 MHz, when the microfluidic channel is filled with distilled water (about 12 µl). The experiments show that the resonance frequency increases almost linearly with the concentration of the glucose solution. The limit of detection of the active sensor is 9 mg dl−1. The figure of merit reaches 2236 MHz/(mg/dl). The high-resolution active spoof plasmonic sensor could find more potential applications for biological and chemical sensing.

Metamaterial-Inspired Microwave Microfluidic Sensor for Glucose Monitoring in Aqueous Solutions

A high-sensitive microwave microfluidic sensor based on improved split ring resonator (SRR) for detecting glucose concentration in aqueous glucose solutions is proposed. The novel SRR design of the proposed sensor incorporates inter-digital capacitor (IDC) in the gap of the resonator for enhanced electric field concentration over a larger surface area, which provides higher sensitivity for testing of dielectric liquids. In order to facilitate the measurement of lossy fluids using the proposed sensor, a microfluidic channel is appropriately positioned over the IDC region of the SRR, through which the glucose solutions are made to pass. The microfluidic channel, made of polydimethylsiloxane (PDMS) is biocompatible, economical, which is customized to preserve the sample from external contamination. Aqueous solutions with glucose concentrations ranging from 0 to 5000 mg/dl are characterized based on the shift in the resonant frequency and the normalized peak attenuation of the SRR sensor. The measured sensitivity of the proposed PDMS integrated novel SRR sensor for glucose testing is found to be 2.60E-02 MHz/mgdl−1, which is a fair improvement compared to earlier proposed sensors employing similar sensing methodologies. The applicability of the proposed sensor for quantitative analysis of aqueous glucose solutions is verified using both simulation and experimental procedures.

One-step electrodeposition to fabricate superhydrophobic coating and its reversible wettability transformation

A one-step electrodeposition method was utilized to fabricate coatings with switchable wettability on stainless steel meshes to extend the application of materials in the intelligent material industry. This method did not involve low surface energy materials and had advantages of simple and good repeatable. Through changing pH value, deposition temperature and voltage, the relationship between morphology and wettability of the as-prepared coatings were studied. The SEM results show numbers of particles on the coatings under the optimum condition and some of them aggregated into micro-pine hierarchical structures. The coatings achieved superhydrophobicity with a contact angle of 155.5°. After being placed at 450 °C for 3 h, the superhydrophobic film turned into superhydrophilic. The film regained superhydrophobicity after hydrothermal treatment in glucose aqueous solution, which exhibited a reversible transition between superhydrophobicity and superhydrophilicity. In addition, the superhydrophilic coatings could be used to separate light oil, such as diesel, gasoline, toluene, benzene and lubricants, excellent oil-water separation ability of 95%.

The Oligomerization of Glucose Under Plausible Prebiotic Conditions.

The prebiotic origin of polysaccharides, the largest class of biopolymers by mass in extant biology, has seldom been investigated experimentally. Herein, we report on the acid-catalyzed condensation of aqueous solutions of glucose, a model monosaccharide, under plausible prebiotic conditions employing a wet-dry (night-day) protocol with 0.01M HCl at 50°C. This protocol leads to the formation of oligosaccharides containing up to eight monomeric units identified by high resolution mass spectrometry. The regio- and stereochemistry of the oligomeric acetal linkages, as well as the quantitative analysis of glucose conversion, are elucidated by combining 1H, 13C and 2D NMR spectroscopy. Ten out of eleven possible acetal linkages, including α- and β- anomers, have been identified with the α- and β- 1,6-acetals being the dominant linkages observed. In addition, the acid-catalyzed oligomerization of several glucose disaccharides such as cellobiose, maltose, and gentiobiose are presented along with an accompanying comparison with the corresponding oligomerization of glucose.

Diffusion Characteristics in Ethyl Alcohol and Glucose Solutions Using Kedem‐Katchalsky Equations

AbstractFormulas for calculating the viscosity and diffusion coefficients for two‐component aqueous non‐electrolyte solutions as a function of the solution concentration under isothermal conditions were derived. The dependence of diffusion coefficient, filtration coefficient, and dynamic viscosity coefficient for these solutions on the solution concentration was estimated and evaluated. Based on the obtained formulas, the results of diffusion coefficient, membrane filtration coefficient, and dynamic viscosity calculations for aqueous solutions of ethanol and glucose are presented and compared with literature data.

A dual-band metamaterial absorber for graphene surface plasmon resonance at terahertz frequency

Abstract In this paper, we present a dual-band metamaterial absorber for graphene surface plasmon resonance at terahertz frequency. We use the finite difference time domain (FDTD) method to study the absorption characteristics of the homocentric graphene ring and disk nanostructure. These simulation results show that the change of the geometrical parameters and the substrate thickness of the nanostructure can change the absorption characteristics and the emergence of dual-band absorption peaks. Moreover, we study the field distribution of nanodisks with different radius in detail. By changing the Fermi level of graphene, the wavelength of their absorption peaks can be adjusted flexibly. In addition, the proposed dual-band absorber also shows a good angle tolerance for both TE and TM polarizations. By calculation the surface-filled water (n = 1.332) and 25% aqueous glucose solution (n = 1.372) for the metamaterial absorber, the sensitivities of mode I and mode II are 5.0 μm/RIU and 15.0 μm/RIU. These research results will have broad application prospects for sensing and spatial light modulators.

Gain‐Assisted Active Spoof Plasmonic Fano Resonance for High‐Resolution Sensing of Glucose Aqueous Solutions

AbstractFano resonance has received much attention in recent years due to its promising applications in surface enhanced phenomena, sensing, and nonlinear optics. However, it is challenging to achieve both high quality (Q) factor and high intensity using the Fano resonance. Different from active switching/tuning of plasmonic Fano resonances, gain‐assisted active spoof plasmonic Fano resonance is for the first time proposed to enhance both the Q factor and resonance intensity significantly, in which a subwavelength amplifier chip is incorporated into a passive plasmonic structure composed of two stacked corrugated metal rings. Experimental results show that the Q factor of the Fano resonance is increased from 49 to 2802, and the resonance intensity is improved from 19.89 to 37.42 dB. The high performance of the active plasmonic structure makes the limit of detection reach to 10 mg dL−1, and thus the minute change of glucose aqueous solutions has been successfully detected.

Decoration of Porous Silicon with Gold Nanoparticles via Layer-by-Layer Nanoassembly for Interferometric and Hybrid Photonic/Plasmonic (Bio)sensing.

Gold nanoparticle layers (AuNPLs) enable the coupling of morphological, optical, and electrical properties of gold nanoparticles (AuNPs) with tailored and specific surface topography, making them exploitable in many bioapplications (e.g., biosensing, drug delivery, and photothermal therapy). Herein, we report the formation of AuNPLs on porous silicon (PSi) interferometers and distributed Bragg reflectors (DBRs) for (bio)sensing applications via layer-by-layer (LbL) nanoassembling of a positively charged polyelectrolyte, namely, poly(allylamine hydrochloride) (PAH), and negatively charged citrate-capped AuNPs. Decoration of PSi interferometers with AuNPLs enhances the Fabry-Pérot fringe contrast due to increased surface reflectivity, resulting in an augmented sensitivity for both bulk and surface refractive index sensing, namely, about 4.5-fold using NaCl aqueous solutions to infiltrate the pores and 2.6-fold for unspecific bovine serum albumin (BSA) adsorption on the pore surface, respectively. Sensitivity enhancing, about 2.5-fold, is also confirmed for affinity and selective biosensing of streptavidin using a biotinylated polymer, namely, negatively charged poly(methacrylic acid) (b-PMAA). Further, decoration of PSi DBR with AuNPLs envisages building up a hybrid photonic/plasmonic optical sensing platform. Both photonic (DBR stop-band) and plasmonic (localized surface plasmon resonance, LSPR) peaks of the hybrid structure are sensitive to changes of bulk (using glucose aqueous solutions) and surface (due to BSA unspecific adsorption) refractive index. To the best of our knowledge, this is the first report about the formation of AuNPLs via LbL nanoassembly on PSi for (i) the enhancing of the interferometric performance in (bio)sensing applications and (ii) the building up of hybrid photonic/plasmonic platforms for sensing and perspective biosensing applications.

Highly biocompatible graphene quantum dots: green synthesis, toxicity comparison and fluorescence imaging

Graphene quantum dots (GQDs) have tremendous potential in biological imaging due to their bright visible photoluminescence mission. However, the tedious preparation procedures and potential toxicity of GQDs greatly limit their application in biological field. Here, highly biocompatible GQDs (HGQDs) have been successfully prepared only by glucose in aqueous solution. Compared with GQDs prepared from conventional methods (CGQDs), the cytotoxicity of HGQDs reduced by more than 60%, and the flow cytometric analysis of the normal cells treated with HGQDs showed that the early and late apoptotic rate reduced by more than 72% and 40%, respectively. In vitro fluorescence imaging showed that both cells and bacteria could be imaged by HGQDs, and the morphology of cells and bacteria could be kept to a maximum extent. A long-term in vivo study revealed that no obvious organ (heart, liver, spleen, lung and kidney) damage or lesions were observed, and the blood–brain barrier (BBB) could be overcome, which provides the possibility for treatment and diagnosis of brain-related diseases. With adequate studies of biocompatibility, both in vitro and in vivo, HGQDs may be considered for further biological application.

Comparison of Multivariate Regression Models Based on Water- and Carbohydrate-Related Spectral Regions in the Near-Infrared for Aqueous Solutions of Glucose.

The predictive power of the two major water bands centered at 6900 cm and 5200 cm in the near-infrared (NIR) region was compared to carbohydrate-related spectral areas located in the first overtone (around 6000 cm) and combination (around 4500 cm) region using glucose in aqueous solutions as a model substance. For the purpose of optimal coverage of stronger as well as weaker absorbing NIR regions, cells with three different declared optical pathlengths were employed. The sample set consisted of multiple separately prepared batches in the range of 50–200 mmol/L. Moreover, the samples were divided into a calibration set for the construction of the partial least squares regression (PLS-R) models and a test set for the validation process with independent samples. The first overtone and combination region showed relative prediction errors between 0.4–1.6% with only one PLS-R factor required. On the other hand, the errors for the water bands were found between 1.6–8.3% and up to three PLS-R factors required. The best PLS-R models resulted from the cell with 1 mm optical pathlength. In general, the results suggested that the carbohydrate-related regions in the first overtone and combination region should be preferred over the regions of the two dominant water bands.

Bubble point of aqueous mixtures of sugar-based deep eutectic solvents and their individual components: Experimental study and modeling

The bubble pressure of aqueous solutions of two natural deep eutectic solvents (DESs) was measured at temperatures 303.15 K–343.15 K and different concentration of the DESs. DESs were formed with combining choline chloride and a sugar (glucose or fructose) in a choline chloride: sugar molar ratio of 2:1. In addition, the bubble pressure of aqueous solutions of fructose, glucose, and choline chloride, were measured to define the impact of the individual components of the DESs on the bubble pressure. According to the results, choline chloride had the greatest effect and sugars had the least effect on the bubble pressure. Experimental bubble point data was used to estimate the binary interaction parameters of the NRTL activity model. An overall AARD of 1.91% indicates the good accuracy of the model in estimating the bubble pressure of aqueous solutions studied in this work. To verify the calculated binary interaction parameters, the NRTL model was used to estimate the solubility of glucose and fructose in water and the results were compared with the experimental solubility available in the literature.

Synthesis of boron carbide powders from mono- and polysaccharides

Boron carbide powders are usually synthesized by carbothermal or magnesiothermic reduction of boron oxy-compounds, a carbon source is usually graphite or some organic phases. The aim of the work is using of mono- and polysaccharides for synthesis of boron carbide powders in which the final grains are separated from each other by an unreacted excess of carbon preventing both grain growth and formation of strong aggregates. Aqueous solutions of glucose, fructose, dextrin or hydroxyethyl starch and boric acid were dried, pyrolyzed at 850 °C for 1 h and then heat-treated at temperatures from 1300 to 1700 °C for 1 h. The amount of boron carbide in the powders depends both on the saccharide and on the temperature. The grains prepared from precursors containing monosaccharides had oval shapes whereas polysaccharides were applied they had rhombohedral shapes corresponding to the boron carbide structure. This effect can be attributed to presence of molten boron oxide.

Large fragmentation under drop suspension splashing

In our work, we first experimentally checked whether the existing splashing criteria would work for droplets of dilute suspensions with particles 10 μm in diameter. The suspensions were a mixture of aqueous glucose solution with isodense hydrophilic polystyrene particles. The drop splashing of the suspensions began at lower impact velocities than for pure water under the impact onto hydrophilic flat glass substrates. The splashing of such suspensions could not be described by any of the existing criteria — neither for a pure liquid with effective viscosity nor by using criteria that consider the energy balance of separately escaping particles. Analysis of the escaping fragments showed that their diameter was an order of magnitude larger than the particles’ diameter. Taking into account the size of the escaping fragments in the criterion based on energy balance allowed to predict the splashing of the considered suspensions.

Determination of glucose concentration in aqueous solution using FT NIR spectroscopy

NIR spectroscopy is widely used due to its capability to measure a large number of solid and liquid samples, including water-soluble constituents. The measurements of glucose concentrations in aqueous solutions are useful to examine how low concentrations of glucose in water can be measured using near-infrared spectroscopy and its potential applications for non-invasive measurements of glucose level in the blood. This paper describes an alternative approach to the determination of glucose content in aqueous solutions below 1000 mg/dL using Fourier transform near-infrared spectroscopy. This technique has the advantage of being less intensive sample preparation and non-destructive. Glucose in aqueous solutions were carefully prepared with concentrations of 0 - 100 mg/dL at intervals of 5 mg/dL, 110 - 500 mg/dL at intervals of 10 mg/dL and 525 - 1000 mg/dL at intervals of 25 mg/dL. Thus, the total produces 81 samples of standard solutions for both calibration and validation sample sets. PLSR analysis to near-infrared spectra show that glucose content in aqueous solutions can be predicted accurately with a maximum deviation of 6 mg/dL, indicating that the near-infrared prediction model is sufficient to determine glucose content in the aqueous solutions below 1000 mg/dL. The ability of the NIR to detect glucose content below 1000 mg/dL is particularly important when designing a non-destructive glucose level measuring device using a near-infrared light source.

Adaptive Method for Quantitative Estimation of Glucose and Fructose Concentrations in Aqueous Solutions Based on Infrared Nanoantenna Optics.

In life science and health research one observes a continuous need for new concepts and methods to detect and quantify the presence and concentration of certain biomolecules—preferably even in vivo or aqueous solutions. One prominent example, among many others, is the blood glucose level, which is highly important in the treatment of, e.g., diabetes mellitus. Detecting and, in particular, quantifying the amount of such molecular species in a complex sensing environment, such as human body fluids, constitutes a significant challenge. Surface-enhanced infrared absorption (SEIRA) spectroscopy has proven to be uniquely able to differentiate even very similar molecular species in very small concentrations. We are thus employing SEIRA to gather the vibrational response of aqueous glucose and fructose solutions in the mid-infrared spectral range with varying concentration levels down to 10 g/l. In contrast to previous work, we further demonstrate that it is possible to not only extract the presence of the analyte molecules but to determine the quantitative concentrations in a reliable and automated way. For this, a baseline correction method is applied to pre-process the measurement data in order to extract the characteristic vibrational information. Afterwards, a set of basis functions is fitted to capture the characteristic features of the two examined monosaccharides and a potential contribution of the solvent itself. The reconstruction of the actual concentration levels is then performed by superposition of the different basis functions to approximate the measured data. This software-based enhancement of the employed optical sensors leads to an accurate quantitative estimate of glucose and fructose concentrations in aqueous solutions.

A fiber optic sensor for measuring glucose in aqueous solutions

A fiber optic sensor for measuring glucose in aqueous solutions

Light Scattering in Water and Water Solutions under the Action of a Low Magnetic Field

Light scattering in water and aqueous solutions of NaCl and glucose under the action of a magnetic field with an induction of 0.43 mT is studied. It is established that the magnetic field does not affect the light scattering in water and aqueous solution of NaCl. For an aqueous glucose solution, the switching on of a field leads to the appearance of large fluctuations in the scattering intensity. It has been shown that these fluctuations are due to turbulization of the solution that is caused by the magnetic field.

Understanding solvation behavior of glucose in aqueous solutions of some deep eutectic solvents by thermodynamic approach

In this work, effect of different deep eutectic solvents (DES) based on choline chloride (ChCl) and dimethyl ammonium chloride (Dmac) as hydrogen bond acceptor and thiourea (Tio), glycerol (Gly), malonic acid (Mal) and urea as hydrogen bond donor on the thermodynamic and transport properties of glucose in aqueous solutions have been evaluated at T = 298.15 K. Viscosity, density and speed of sound data of the systems containing glucose in aqueous solutions of DES were measured in different mass percent of DES, wDES = (0.0010, 0.002, 0.0030, 0.0040). Apparent molar volume, apparent molar isentropic compressibility, transfer apparent molar volume and viscosity B-coefficient values of the systems studied were calculated using the experimental data. The results have been interpreted in terms of various solute–solvent interactions. The results indicate that the solute–solvent interactions in choline-based DESs should be stronger than that in the dimethyl ammonium-based DES and the most suitable DES to dehydrate of glucose is a choline chloride-glycerol eutectic mixture.