Diffusion Coefficient Of Glucose Research Articles

Glucose stockpile in the intestinal apical brush border in C. elegans

Revealing the mechanisms of glucose transport is crucial for studying pathological diseases caused by glucose toxicities. Numerous studies have revealed molecular functions involved in glucose transport in the nematode Caenorhabditis elegans, a commonly used model organism. However, the behavior of glucose in the intestinal lumen-to-cell remains elusive. To address that, we evaluated the diffusion coefficient of glucose in the intestinal apical brush border of C. elegans by using fluorescent glucose and fluorescence recovery after photobleaching. Fluorescent glucose taken in the intestine of worms accumulates in the apical brush border, and its diffusion coefficient of ∼10−8 cm2/s is two orders of magnitude slower than that in bulk. This result indicates that the intestinal brush border is a viscous layer. ERM-1 point mutations at the phosphorylation site, which shorten the microvilli length, did not significantly affect the diffusion coefficient of fluorescent glucose in the brush border. Our findings imply that glucose enrichment is dominantly maintained by the viscous layer composed of the glycocalyx and molecular complexes on the apical surface.

Synthesis of Ag and Mn/ZnO nanoparticles using a hydrothermal method - A brief study and their role in the electrocatalytic oxidation of glucose in alkaline media

Ag and Mn/ZnO were synthesized via a low-temperature hydrothermal process and applied as glucose oxidation reaction (GOR) catalysts. The sample characterization was performed by scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX), which revealed homogenous clustered nanoparticles for synthesized materials. The various amounts of Ag and Mn were loaded in ZnO nanostructure and their electrocatalytic effect on GOR was investigated by electrochemical techniques such as cyclic voltammetry (CV) and electrochemical impedance spectroscopy in an alkaline solution containing 3 mM glucose and 0.1 M NaOH. The Ag/ZnO and Mn/ZnO with 50% and 60% loading, respectively, were identified as the best electrocatalysts. The experimental data showed that the larger effective surface area of Ag/ZnO-50 (6.9 cm2) and Mn/ZnO-60 (9.25 cm2) accompanied by faster glucose diffusion coefficient due to the effective impact of Ag and Mn loading on the ZnO nanostructure improved the GOR for Ag/ZnO-50 and Mn/ZnO-60 compared to the ZnO.

Evaluation of the amount of glucose adsorbed on water-soluble dietary fibres by the analysis of its diffusion rate through a dialysis membrane

A model for describing the rate of glucose diffusion through a dialysis membrane was developed. The diffusion coefficient of glucose in the dialysis membrane, D, was constant, regardless of the glucose concentration. The data on the diffusion rate of glucose both in the presence and absence of water-soluble dietary fibres were well described by the model, and the amounts of glucose adsorbed on different fibres were evaluated. The amount of adsorbed glucose increased linearly with an increase in the glucose concentration. A decrease in diffusion rate was caused by adsorption of glucose on water-soluble dietary fibre but not by viscosity. Since the rate of desorption of glucose from dietary fibres is slow enough, the amount of glucose adsorbed is considered to be kept almost constant during the dialysis experiment.

Solid-liquid Extraction of Soluble Carbohydrates from Soybean Meal: an Experimental Study, Kinetics, and Modeling

HIGHLIGHTS SPC is obtained by solid-liquid extraction process with hydroalcoholic solvent. Box-Behnken was applied to evaluate the effect of operational parameters. Soluble carbohydrate extraction from DSM is limited by intraparticle diffusion. Diffusion coefficient of stachyose, raffinose, sucrose, and glucose was estimated.

Grain boundary enriched CuO nanobundle for efficient non-invasive glucose sensors/fuel cells

Glucose oxidation reaction (GOR) plays a significant role in glucose fuel cells anode and glucose sensors. Therefore, optimizing the GOR catalyst nanostructure is auxiliary to their efficient operation. In this study, we present a cascade-assembled strategy to prepare CuO nanobundles (CuO-NB) with high-density and homogenous grainboundaries (GBs). The essence of activity in GOR that depended on GBs are thoroughly investigated. The increased glucose diffusion coefficient of CuO-NB means that GBs has a faster glucose mass transfer, which is attributed to the terraces in GBs dislocation surface. Furthermore, the accumulation of electrons on GBs makes the glucose adsorption increased and the free energy of dehydrogenation step decreased, leading to a lower glucose oxidation barrier. Therefore, CuO-NB is appropriate for non-invasive glucose detection and glucose fuel cells. This study sheds new light on the GBs effect in GOR and paves the way for developing high-efficiency electrocatalysts.

Diffusion of glucose in water: A molecular dynamics study

A glucose molecule, simple structure of carbohydrate, has many functions in our body. It is transported to every cell and served as of energy source. The investigation of transport properties of glucose in aqueous medium would be useful to understand the body metabolism. In this research work, molecular dynamics (MD) simulations have been utilized to study the transport and structural properties of glucose in water at different temperature (298.15 K, 303.15 K, 308.15 K, and 312.15 K). The self diffusion coefficients of glucose and water have been estimated from mean square displacement plot (MSD) by using Einstein’s relation. Further, Darken’s relation has been used to find the binary diffusion coefficients of the mixture. The structural analysis of the system has been estimated with the help of radial distribution function (RDF) of its constituent atom/molecule pairs. The outcomes from the MD simualtions depicts that the temperature dependence of self diffusion coefficients of solute and solvent follow Arrhenius behavior, which further assist to calculate the activation energy of the system. The results from the present work agree well with the previously reported experimental values.

Tissue Spectroscopy and Optical Clearing of Colorectal Mucosa in the Pursuit of New Cancer Diagnostic Approaches

In this paper we present three studies that demonstrate the applicability of spectroscopy methods and optical clearing treatments in pathology identification and monitoring. In the first study, by obtaining the absorption spectra of human healthy and pathological (adenocarcinoma) colorectal mucosa tissues, it was possible to identify a higher content of a pigment in the diseased tissues. This study also shows that machine learning methods can be used to reach the same differentiated results in vivo through diffuse reflectance spectroscopy. In the second study, the combination of collimated transmittance spectroscopy with optical clearing treatments allowed to obtain the diffusion coefficients of glucose in healthy and pathological colorectal mucosa as: D glucose =5.8x 10 – 7 cm 2 /s and D glucose =4.4x 10 – 7 cm 2 /s, respectively. This study also demonstrated that the diseased tissues contains about 5% more mobile water than the healthy tissues. The third study was performed to evaluate the protein dissociation mechanism of optical clearing. By treating both healthy and pathological colorectal mucosa tissues with 93%-glycerol, a protein dissociation rate of about 3 times higher was obtained for the pathological mucosa. All the discriminating parameters that result from these studies can be obtained in the in vivo situation through diffuse reflectance spectroscopy and further studies to evaluate their values in different stages of cancer progression are of great importance to develop disease monitoring protocols.

Evaluation of ITO/TiO2/Co3O4 as a non-enzymatic heterojunction electrode to glucose electrooxidation

Electroactive Co3O4 films were deposited by reactive magnetron sputtering (RMS) onto an assembly composed of a thin TiO2 layer over a commercial indium-doped tin oxide (ITO) conductor electrode, forming an ITO/TiO2/Co3O4 electrocatalytic platform. The platform was tested as a non-enzymatic device for glucose electrooxidation. The characterization of the electroactive TiO2/Co3O4 heterojunction was carried out by x-ray diffraction (XRD), Raman spectroscopy, field-emission scanning electron microscope (FE-SEM), and energy dispersive spectroscopy (EDS) techniques. It was shown that the Co3O4 top layer is homogeneous and free from undesirable secondary phases. The electrochemical measurements, characterization and performance, were carried out by cyclic voltammetry (CV), chronoamperometry, and electrochemical impedance spectroscopy (EIS). The cyclic voltammogram shows the linear dependence between the anodic and cathodic current peak of the redox process at the electrode surface, showing the electrochemical activity of the Co3+/Co4+ redox pair, as well as good reversibility and efficiency of charge transfer. From the chronoamperometric curves, two electrochemical parameters were estimated, the diffusion coefficient (D) and catalytic rate constant (kobs) of glucose with the values of 1.2 × 10−6 cm2 s−1 and 2.8 × 106 cm3 mol−1 s−1, respectively. The ITO/TiO2/Co3O4 heterojunction electrode showed an acceptable linear range from 10 to 1000 μM glucose concentration with a molar sensitivity (S) of 30.0 μA cm−2 mM−1 and a detection limit (LOD) of 1.42 μM (S/N = 3). These electrochemical results show the higher electroactivity of TiO2/Co3O4 heterojunction electrode than that of bare Co3O4 electrode and other literature results.

Distribution and diffusion coefficients of glucose and sodium chloride onto konjac and egg white gel

Distribution and diffusion coefficients of glucose and sodium chloride onto konjac and egg white gel

Estimating glucose diffusion coefficient of membranes for tissue engineering applications using Fick’s First Law

The idea of growing artificial tissues in bioreactors such as hollow fibre membrane bioreactors (HFMBs) has started years ago and preparation of biocompatible porous membranes and scaffolds has been attempted extensively. There also have been several studies on modelling glucose transport processes in HFMBs. However, there is little information available that discusses specifically the glucose diffusivity across tissue engineering membranes or scaffolds and, importantly, its dependence on the properties of the materials (i.e., membrane and scaffold). Therefore, the objective of this study is to deduce the glucose diffusivity across different membranes. Using Fick’s law and a diffusion cell in this study, we have determined glucose diffusion coefficients for two different membranes namely cellulose nitrate (CN) and polyvinylidene fluoride (PVDF). These membranes possessed similar pore size with varying thickness and were saturated with water and cell culture medium (CCM). The diffusion experiments were conducted in a thermostated water bath at either 27 or 37 ± 1°C. It was observed that PVDF membrane with greater thickness has a lower diffusivity than CN membrane when both were saturated in CCM and water at 37°C. From the results, we derive the significance of the decrease of diffusion coefficient with increasing thickness of the membranes.

A novel and sensitive Cu2ZnSnS4 quantum dot–based non–enzymatic glucose sensor

Copper–chalcogenide quantum dots (QDs) featuring big surface–to–volume ratio, capably electrochemical activities, highly electrical conductivity, natural abundance, low cost and nontoxicity fitted quite well as electrocatalyst for non–enzymatic glucose oxidizing sensor. Presently, 1–octadecanamine–capped quaternary Cu2ZnSnS4 QDs (CZTS QDs) with size of 4–6 nm, fabricated by facile solvothermal approach with cost–effective and non–toxic precursors, were used as a novel materials modified onto fluorine doped tin oxide (FTO) glass to develop CZTS QD–based non–enzymatic glucose biosensor for first time. And, the route of partial removal of 1–octadecanamine ligand has been established to enhance the sensitivity from 1561 to 2503 μA mM–1 cm–2 for CZTS QD–based non–enzymatic glucose biosensor, ascribed fundamentally to enlarging active surface area, reducing the charge transfer resistance, improving glucose diffusion coefficient and advancing catalytic rate constant. The performance of CZTS QD–based non–enzymatic sensor in high sensitivity, broad linear range, short respond time, low detection limit, precise selectivity, long–time stability, good reproducibility and practical application in blood serum determination deserved the potential candidate for electrochemically non–enzymatic glucose biosensor in future.

Towards improved understanding of the viscoelastic properties of functionalized lemon peel fibers in suspension based on microstructure, hydration value and swelling volume

Lemon peel fibers were obtained using different processing conditions (pH, addition of salts, mechanical processing and storage), they showed distinctly different viscoelastic properties when dispersed in an aqueous solution. In order to gain insight in the mechanism underlying their texturizing properties, the volume occupation in dispersion was determined through small molecule diffusion experiments and the swelling volume was measured by a conventional method. Based on the diffusion coefficient of glucose as a function of fiber concentration, the hydration value and volume occupancy of differently functionalized fibers were calculated. The diffusion based volume occupancy and the swelling volume were related with the fiber suspension microstructure and its rheological properties. High pressure homogenization (HPH) improved the viscoelastic properties, mainly due to an increase of the swelling volume. Salt addition and pH influenced the hydration value, the swelling volume and viscoelastic properties. These results show that the texturizing properties of lemon peel fibers induced by HPH, are mainly determined by the extent of swelling and network formation rather than an increased fiber hydration value.

Long duration stabilization of porous silicon membranes in physiological media: Application for implantable reactors.

The natural biodegradabilty of porous silicon (pSi) in physiological media limits its wider usage for implantable systems. We report the stabilization of porous silicon (pSi) membranes by chemical surface oxidation using RCA1 and RCA2 protocols, which was followed by a PEGylation process using a silane-PEG. These surface modifications stabilized the pSi to allow a long period of immersion in PBS, while leaving the pSi surface sufficiently hydrophilic for good filtration and diffusion of several biomolecules of different sizes without any blockage of the pSi structure. The pore sizes of the pSi membranes were between 5 and 20 nm, with the membrane thickness around 70 μm. The diffusion coefficient for fluorescein through the membrane was 2 × 10-10 cm2 s-1, and for glucose was 2.2 × 10-9 cm2 s-1. The pSi membrane maintained that level of glucose diffusion for one month of immersion in PBS. After 2 months immersion in PBS the pSi membrane continued to operate, but with a reduced glucose diffusion coefficient. The chemical stabilization of pSi membranes provided almost 1 week stable and functional biomolecule transport in blood plasma and opens the possibility for its short-term implantation as a diffusion membrane in biocompatible systems.

Optical Clearing of the Gastric Mucosa Using 40%-glucose Solution

The kinetics of collimated transmittance of the gastric mucosa under the action of an aqueous 40%-glucose solution was experimentally investigated. Based on the analysis of the transmittance kinetics, the value of the effective diffusion coefficient of glucose in the gastric mucosa was estimated and amounted to (1.59±0.96)×10 -6 cm 2 /s. The permeability coefficient of the mucosa for glucose, calculated using the first Fick diffusion law, was estimated as (2.81±0.90)×10 -5 cm/s. It was shown that the introduction of the glucose solution into the mucosa reduced the light scattering coefficient by approximately 5–10%. The increase in the depth of light penetration was from 5% to 15%, depending on the selected spectral range. The results can be used to develop new methods of diagnosis and treatment of stomach diseases.

Kinetics of Rat Skin Optical Clearing at Topical Application of 40%Glucose: <italic>Ex Vivo </italic> and <italic>In Vivo</italic> Studies

Optical, molecule diffusion, and mechanical properties of skin and blood microcirculation in the underlying tissues at topical application of 40%-glucose solution in rats were investigated. Optical clearing of ex vivo and in vivo skin was measured within the wavelength range of 400–900 nm using standard spectrometer, and blood microcirculation alterations was measured with laser speckle contrast imaging. Increase of skin collimated transmittance, transverse, and along skin shrinkage and weight loss was observed for the first 20–60 min of immersion, for the longer time, tissue swelling was found. The glucose diffusion coefficients in ex vivo and in vivo rat skin were evaluated as (1.11 ± 0.78) × 10−6 and (1.54 ± 0.28) × 10−6 cm2/s, respectively. The decrease of average rate of microcirculation in 2.2 fold was observed. The results received allow one to evaluate glucose impact on skin tissue optical and mechanical properties and blood microcirculation.

The Effect of Immersion Agents on the Weight and Geometric Parameters of Myocardial Tissue in Vitro

Abstract—The effect of 40%-glucose solution and 60%-glycerol solution on the weight and geometric parameters of the myocardium was studied in vitro in order to improve the accuracy of estimating the glucose and glycerol diffusion coefficients in the myocardium by including changes in the geometry and water content of a tissue sample in a mathematical algorithm. The temporal kinetics of the weight, thickness, area, and volume were measured using porcine myocardium samples during their immersion in 60%-glycerol solution or 40%-glucose solution in vitro. All parameters started to decrease immediately after placing myocardium samples in immersion agents (tissue shrinkage). The weight and geometric parameters of the sample then increased gradually (tissue swelling), leading to tissue saturation in almost all cases. By approximating the temporal kinetics, the degree of dehydration and the characteristic times of transverse and longitudinal shrinkage and swelling of the myocardium were determined. More significant and rapid dehydration of myocardial tissue was observed case of using 60%-glycerol solution, while a stronger and faster swelling of the myocardium was observed when 40%-glucose solution was applied.

Diffusion Studies of Glucose and Sucrose in Chitosan Membranes and Beads for Enzymatic Production Processes

AbstractThe diffusion of glucose and sucrose was investigated in membrane and bead experiments. Concentration‐dependent diffusion coefficients of pure glucose and sucrose were determined in precipitated chitosan membranes of varying thickness using diffusion cell experiments. Contrary to fructose, the resulting diffusion coefficients of glucose and sucrose did not reach their free diffusion coefficients at infinite dilution suggesting additional interactions between chitosan and these two sugars. Counter‐diffusion in bead experiments showed a good agreement between predicted and measured data allowing the inclusion of the diffusion data in the simulation of the proposed production process for laminaribiose. In conclusion, the encapsulation in chitosan presented a good trade‐off between increased mass transfer resistance as evaluated by the Thiele modulus and improved thermal stability and antibacterial activity.

Determination of Diffusion Coefficient in Hydrogel

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Measurement of temperature-dependent diffusion coefficients of aqueous solutions by near-infrared simultaneous imaging of temperature and concentration

The diffusion coefficients of methanol, ethanol, ethylene glycol, and glucose in water, and their temperature dependence are measured by analysing the simultaneously acquired temperature and concentration images. Simultaneous imaging is achieved using two wavelengths, 1905 nm and 1935 nm, in the ν2 + ν3 absorption band of water. In the band, the absorbance at 1905 nm is the most sensitive to temperature, whereas that at 1935 nm is independent of the temperature but strongly dependent on the concentration. To measure the diffusion coefficients, the time evolutions of the diffusion lengths are obtained by fitting the analytical solutions of the two-dimensional steady-state diffusion equation to the transverse concentration profiles in a Y-shaped microfluidic channel. The measured diffusion coefficients and their temperature dependence are verified by comparison with literature values.

In-vitro model for assessing glucose diffusion through skin

Pig ear skin membrane-covered glucose biosensor based on oxygen electrode has been assessed as a tool to evaluate glucose penetration through skin in-vitro. For this, glucose oxidase (GOx) was immobilised on oxygen electrode and covered with the skin membrane. Exposing this electrode to the solution of glucose resulted in glucose penetration though skin membrane, its oxidation catalysed by GOx, consumption of O2 and decrease of the current of the oxygen electrode. By processing the biosensor responses to glucose, we found that glucose penetration through 250 µm thick skin membrane is slow; 90% of steady-state current response was reached in 32( ± 22) min. Apparent diffusion coefficient for glucose in skin was found to be equal to 0.15( ± 0.07)* 10−6 cm2 s−1. This value is 45 times lower than glucose diffusion coefficient in water. Tape-stripping of stratum corneum (SC) allows considerably faster glucose penetration. The electrodes covered with tape-stripped skin reached 90% of steady-state current response in 5.0(± 2.7) min. The theoretical estimate of glucose flux through SC was considered exploiting four-pathway theory of transdermal penetration. Theoretical flux values were more that three orders lower than measured experimentally. This high discrepancy might indicate that glucose penetration through healthy human skin could be even slower, allowing much lower flux, than it was found in our study for skin membranes from pig ears.