Glucose Solutions Of Different Concentrations Research Articles

Cavity-Length Spectrum Sensing (CLSS) based on multi fiber Fabry-Pérot(F-P) cavities for refractive index monitoring

A Cavity-Length Spectrum Sensing (CLSS) based on multi fiber Fabry-Pérot(F-P) cavities is proposed for detecting refractive index. Traditional wavelength spectrum sensing (WSS) achieves refractive index monitoring by demodulating the wavelength shifting with changing of refractive index under fixed F-P cavity with a certain length. Fixing the wavelength as a reference, changing the refractive index and observing the intensity of wavelength, the curve shifting with length of the cavity, Length as the independent variable is called CLSS. Eight F-P cavities were fabricated and used to reconstruct the cavity-length spectrum. CLSS only need a single-frequency laser and photodetector, and avoid some expensive equipments, such as spectrometers and broadband lasers. On the other hand, compared to optical intensity sensing, CLSS remains immune to laser power fluctuations and allows for software-adjustable sensitivity, utilizing the sampling vernier effect. By demodulating the shifting of the interference dips, the refractive index of glucose solutions of different concentrations can be monitored. Experimental results show that when λ= 1550.00nm, the sensitivity can reach −75.9778μm/RIU near a glucose solution with a refractive index of 1.341. In addition, the sampling vernier effect was utilized, and the sensitivity can be increased −2089.9705μm/RIU by changing the sampling interval. CLSS has low system cost, excellent stability and adjustable sensitivity, which has great potential applications in biomedical analysis, drug discovery, chemical production, etc.

Biosensors Fabricated by Laser-Induced Metallization on DLP Composite Resin

With the growing emphasis on medical testing, people are seeking more technologies to detect indexes of the human body quickly and at a low cost. The electrochemical biosensors became a research hotspot due to their excellent properties. In this study, dicopper hydroxide phosphate (Cu2(OH)PO4) was incorporated in resin, and the resin sheets were prepared by digital light processing (DLP). The copper base points were activated on the resin sheet surface by Nd: YAG laser and then covered by the electroless copper plating and the electroless silver plating. The laser could effectively activate copper base points on the resin surface. Furthermore, silver electrodes on the detection chips could distinguish glucose solutions of different concentrations well. Finally, a novel detection kit with a three-electrode chip was designed for rapid health testing at home or in medical institutions in the future.

RFID-Based Microwave Biosensor for Non-Contact Detection of Glucose Solution.

Due to the increasing number of diabetic patients, early monitoring of glucose levels is particularly important; therefore, glucose biosensors have attracted enormous attention from researchers. In this paper, we propose a glucose microwave biosensor based on RFID and achieve a non-contact measurement of the concentration of glucose solutions. The Reader is a complementary split-ring resonator (CSRR), and the Tag is comprised of a squared spiral capacitor (SSC). A polydimethylsiloxane microfluidic quantitative cavity with a volume of 1.56 μL is integrated on the Tag to ensure that the glucose solution can be accurately set to the sensitive area and fully contacted with the electromagnetic flux. Because the SSC exhibits different capacitances when it contacts glucose solutions of different concentrations, changing the resonant frequency of the CSRR, we can use the relationship to characterize the biosensing response. Measurement results show that bare CSRR and RFID-based biosensors have achieved sensitivities of 0.31 MHz/mg·dL−1 and 10.27 kHz/mg·dL−1, and detection limits of 13.79 mg/dL and 1.19 mg/dL, respectively, and both realize a response time of less than 1 s. Linear regression analysis of the abovementioned biosensors showed an excellent linear relationship. The proposed design provides a feasible solution for microwave biosensors aiming for the non-contact measurement of glucose concentration.

Copper Oxide Decorated Zinc Oxide Nanostructures for the Production of a Non-Enzymatic Glucose Sensor

The glucose concentration in human blood can have a worrisome impact on human health, so the distribution of blood glucose contaminants in the human body is an important indicator that can be used to monitor diabetes. Diabetes affects many parts of the human body, such as neurological impairment, erectile dysfunction, and hardening of the arteries resulting in organ loss. In this study, cyclic voltammetry (CV) was used to process the electrical properties of a solution by preparing electrodes with CuO nanoparticles modified ZnO tetrapod nanostructures deposited on fluorine-doped tin oxide glass (CuO/ZnO/FTO). The measurements were processed in glucose solutions of different concentrations purposing for developing the sensitivity of the sensor. Different immersion times in the precursor copper sulfate solution were also used for preparing the electrode and carried out for electrochemical studies to adjust the electrode capability. The modified electrode, which was immersed in copper sulfate for 30 s, was efficient in detecting glucose molecules in different concentrations at the potential of +0.6 V. The rising slope is strongly and positively correlated with the concentration of glucose. One of the significant results is the indication that glucose concentration is linearly proportional to the current value of CV. After the measurement test with the addition of interference, the sensor can still identify the glucose concentration in the solution without being affected. This result proves that the sensor has considerable potential for developing into a high-performance non-enzymatic glucose sensor.

Knowledge-based genetic algorithm for resolving the near-infrared spectrum and understanding the water structures in aqueous solution

The structure of water has been an interesting subject in various research fields due to its complexity and flexibility. Near-infrared (NIR) spectroscopy has been proven to be a powerful tool for analyzing the structure of water in aqueous solutions. However, low resolution of the spectrum and overlapping of the peaks make it difficult to obtain the spectral components for understanding the structure of water. In this work, a knowledge-based genetic algorithm was developed for Gaussian fitting of the NIR spectra of water measured at different temperatures. The number of the water structures was determined from the result of molecular dynamics simulation, and the spectral peak of the structures was simulated by a Gaussian function. Continuous wavelet transform was adopted to enhance the resolution and remove the background variation of the spectra. Through the variation of the water structures with temperature, the dissociation of the larger clusters into smaller ones was observed. Furthermore, an enhancement of the ordered (tetrahedral) water structures is indicated by the relative content in the glucose solutions of different concentrations, providing a proof for glucose making the water structure more ordered to explain the protective effect of glucose on the bio-molecules in bio-aqueous solution.

Highly Sensitive Closed Loop Enclosed Split Ring Biosensor With High Field Confinement for Aqueous and Blood-Glucose Measurements

This paper presents a highly sensitive closed loop enclosed split ring biosensor operating in microwave frequencies for measuring blood glucose levels in the human body. The proposed microwave glucose biosensor, working on the principle of high field confinement and concentrated energy, has been tested using both in-vitro and in-vivo methods. This principle allows the sensor to concentrate energy at the surface which results in improved accuracy of measurements. For in-vitro measurements, the biosensor has been tested using de-ionized water glucose solutions of different concentrations. The miniaturized micrometer scale biosensor is fabricated over a thin Si-substrate using photolithographic technique. The biosensor has been designed in a way to operate at desired microwave frequencies. Highly confined fields and concentrated energy inside the closed loop line containing the split ring resonators are responsible for the sensitivity enhancement. This new biosensor has obtained a high sensitivity of 82 MHz/mgmL−1 within the clinical diabetic range during in-vivo testing over the human body. In addition, the subjects (undergoing experiments) steady state has been continuously monitored throughout the experiment which helps in improving the accuracy of the results. The proposed biosensor has further obtained a low detection limit of <0.05 wt.% and can be useful for continuous non-invasive blood glucose monitoring.

Soil respiration and microbial biomass in multiple drying and rewetting cycles – Effect of glucose addition

Previous studies showed that the respiration flush upon rapid rewetting of dry soil decreases with increasing number of drying and rewetting (DRW) cycles which is thought to be due to various factors, for example, lower substrate availability or microbial biomass or changes in microbial community structure. To investigate if the reduction of respiration flush with increasing cycle number is due to lack of available substrate upon rewetting, incubation experiments with four DRW cycles were conducted where glucose solutions of different concentrations, low (50μgCg−1 soil), medium (250μgCg−1 soil) and high (500μgCg−1 soil) were added either in all four cycles or only in cycle 1, 2, 3 or 4 (the other cycles rewetted with water). Additional treatments included a constantly moist control (CM, 70% of maximum water-holding capacity) and DRW treatments with only RO water. When dry soil was rewetted only with RO water, the respiration flush upon rewetting was about twice as high in the first two cycles than in cycles 3 and 4. Soil microbial biomass C (MBC) one day after rewetting remained stable until cycle 3 after which it decreased by about 20%. In all glucose treatments, the glucose-induced increase in respiration rate was greater in earlier than later cycles, irrespective of whether glucose was added to one cycle only or in all cycles. But when expressed relative to CM, the respiration rate was greater in the last two cycles. Single glucose addition increased MBC only in the cycle in which it was added whereas repeated glucose addition increased MBC over time. Glucose addition and DRW increased the metabolic quotient, thus reduced C use efficiency. In treatments with glucose added in all four cycles, the metabolic quotient increased with DRW cycle number which indicates lower efficiency in later cycles. It is concluded that lower substrate availability can be one of the reasons for the decrease in respiration flush upon rewetting with cycle number.

Rapid determination of the chemical oxygen demand of water using a thermal biosensor.

In this paper we describe a thermal biosensor with a flow injection analysis system for the determination of the chemical oxygen demand (COD) of water samples. Glucose solutions of different concentrations and actual water samples were tested, and their COD values were determined by measuring the heat generated when the samples passed through a column containing periodic acid. The biosensor exhibited a large linear range (5 to 3000 mg/L) and a low detection limit (1.84 mg/L). It could tolerate the presence of chloride ions in concentrations of 0.015 M without requiring a masking agent. The sensor was successfully used for detecting the COD values of actual samples. The COD values of water samples from various sources were correlated with those obtained by the standard dichromate method; the linear regression coefficient was found to be 0.996. The sensor is environmentally friendly, economical, and highly stable, and exhibits good reproducibility and accuracy. In addition, its response time is short, and there is no danger of hazardous emissions or external contamination. Finally, the samples to be tested do not have to be pretreated. These results suggest that the biosensor is suitable for the continuous monitoring of the COD values of actual wastewater samples.

Viability of the use of thin‐film a‐SiC:H photodiodes for protein identification

AbstractIn this paper, we present a multilayer device based on a‐Si:H/a‐SiC:H that operates as photodetector and optical filter. The use of such device in protein detection applications is relevant in Fluorescence Resonance Energy Transfer (FRET) measurements. This method demands the detection of fluorescent signals located at specific wavelengths bands in the visible part of the electromagnetic spectrum. The device operates in the visible range with a selective sensitivity dependent on electrical and optical bias. Several nanosensors were tested with a commercial spectrophotometer to assess the performance of FRET signals using glucose solutions of different concentrations. The proposed device was used to demonstrate the possibility of FRET signals detection, using visible signals of similar wavelength and intensity. The device sensitivity was tuned to enhance the wavelength band of interest using steady state optical bias at 400 nm. Results show the ability of the device to detect signals in this range. (© 2014 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

Integrated Visible optical filter and photodetector for detection of FRET signals

ABSTRACTIn this paper we present a multilayer device based on a-Si:H/a-SiC:H that operates as photodetector and optical filter. The use of such device in protein detection applications is pertinent in Fluorescence Resonance Energy Transfer (FRET) measurements that demand the detection of visible fluorescent signals located at specific wavelengths bands. This device was designed to operate in the visible range with a selective sensitivity dependent on the applied electrical bias. Several nanosensors were tested with a commercial spectrophotometer to judge the performance of the FRET signals using glucose solutions of different concentrations. Two nanosensors (FLIPglu-90μM and FLIPglu-600μM) were tested with a commercial spectrofluorimeter to judge the performance of the FRET signals by using glucose solutions of different concentrations. These measurements were carried out by using these nanosensors both in the free form and immobilized form on inner epidermis of onion bulb scale. The proposed device was used to demonstrate the possibility of FRET signals detection, using visible signals of similar wavelength and intensity. The device sensitivity was tuned to enhance the wavelength band of interest using adequate electrical biasing.

Dynamics of Sedimentation and Deformation of GUVs Under Different Tonicity Conditions

POPC Giant unilamellar vesicles (GUVs) with 1 mol% DiIC18(3) as a fluorescent marker were prepared by electroformation in sucrose solutions with varying osmolarities. These vesicles were resuspended in glucose solutions of different concentrations generating isotonic and hypertonic conditions. Vesicles sediment due to the density difference between the solutions. The movement of the vesicles as they approach the glass surface is studied using SPIM microscopy. We find that the velocity of the GUVs remains constant, given by Stokes law as expected when the distance from the surface is several radii in length. Velocity decreases exponentially as vesicles reach the surface. Vesicle deformation due to interactions with the surface was measured for different osmotic conditions using confocal and SPIM microscopy. Boundary element simulations were performed to model vesicle deformation during sedimentation within a viscous fluid. For isotonic conditions, vesicles are assumed to begin with zero tension and tension is generated through contact with the surface. For the hypertonic case, the same is true but with an initial excess area available. Computationally, the mechanical behavior of the lipid bilayer is simulated using a model that considers two modes of deformation responsible for increases in area strain. The first is the smoothing of suboptical thermal undulations and the second is the direct stretching of the area per lipid molecule. Properties of the lipid bilayer are controlled by adjusting bending and area compressibility moduli. A force field is implemented that takes into account local tension, local curvature force, and gravitational pull. Vesicle sedimentation, deformation, and membrane tension were evaluated as a function of g0, a dimensionless factor relating gravitational and curvature energies. Simulations are in agreement with the experimental results and provide additional information of the deformation of vesicles and sedimentation dynamics.

Interplay between Solvent Effects of Different Nature in Interfacial Bond Breaking Electron Transfer

Solvent dynamics effects on electroreduction of peroxodisulphate anion on mercury electrode (a typical bond breaking electron transfer reaction) are explored in the framework of the Sumi-Marcus model. The reaction three-dimensional free energy surface is constructed using the Anderson model Hamiltonian. A new interpretation of short- and long-time survival times is presented as well. Since the reduction is assumed to proceed from aqueous sucrose and glucose solutions of different concentrations (which are used to vary the solution viscosity), unavoidable changes in the Pekar factor (static effect) are also taken into account. The results of model calculations are employed to interpret challenging experimental data on nonmonotonous constant rate vs solution viscosity dependence reported earlier (in part, appearance of an ascent plot). The influence of mixed solvent composition on the reaction rate and transfer coefficient is explained in terms of the saddle point avoidance in the vicinity of activationless discharge. Splitting of the reaction coordinates into slow (solvent) and fast (intramolecular) ones is argued to be crucial, as the most important reaction features cannot be described by means of more simplified models, even if both static and dynamic effects are addressed.

A dynamic and stationary rheological study of erythrocytes incubated in a glucose medium

A higher than normal glucose concentration in a suspending medium may produce non-enzymatic glycosylation of erythrocyte proteins. This process can modify the viscoelastic properties of erythrocytes. In this paper, we studied the possible relationship between glucose concentration in a suspending medium and erythrocyte rheological parameters. Human venous blood was obtained from the antecubital veins of 10 healthy volunteers. Blood samples were anticoagulated with EDTA and centrifuged. Red blood cells (RBCs) were washed and subsequently divided in aliquots, which were incubated in vitro with glucose solutions of different concentrations. Dynamic and stationary viscoelastic parameters of RBCs were determined by laser diffractometry in an Erythrodeformeter. Aggregate shape parameter (ASP) of the RBCs was determined by digital image processing. Significant changes were observed both in ASP and in rheological parameters when the glucose concentration in the medium was increased, demonstrating that a glucose concentration as low as 1% induces alterations in the mechanical properties of RBCs.

Biochemical sensors based on polymer microrings with sharp asymmetrical resonance

Photonic microresonators have great potential in the application of highly sensitive sensors due to high Q-factor resonances and steep slopes between zero and unity transmission. A microring resonator with increased resonance slopes is proposed by introducing two partially reflecting elements implemented by waveguide offsets. This configuration produces a Fano-resonant line shape and can greatly enhance the sensitivity of the sensor. Polystyrene microring resonators were fabricated by the nanoimprinting technique, and the optical spectra were measured in glucose solutions of different concentrations. The shift in resonant wavelength and variation of the normalized transmitted intensity are linearly related to the concentration of the glucose solution.

Macrokinetics of processes in glucose oxidase—peroxidase bienzyme systems when assaying glucose by the H2O2 reduction current: Effect of the enzyme ratio on the steady-state potential and H2O2 reduction current in glucose solutions of different concentrations

The effect of the enzyme ratio on the steady-state potential and H2O2 reduction current at a bienzyme glucose oxidase-peroxidase electrode in glucose solutions of different concentrations is studied. The derived equations adequately describe the experimental data and allow one to estimate characteristics of bienzyme electrodes in the linear domain of the current variation with the glucose concentration and the system’s sensitivity

IgG glycation and function during continuous ambulatory peritoneal dialysis.

IgG in dialysate may have an important role in anti-infection mechanisms during continuous ambulatory peritoneal dialysis (CAPD). As Fc fragment oligosaccharidic chains are crucial for IgG effector functions, we have tested the hypothesis that IgG glycation might occur during CAPD and modify IgG properties. Purified normal IgG was incubated with glucose solutions of different concentrations and pH. Separation of glycated IgG was performed by affinity chromatography. Complement activation (C3c deposition) and phagocytosis by polymorphonuclear leucocytes (PMN) were studied in vitro using Staphylococcus aureus Wood (STAW) as antigen. In addition, we compared the percentages of glycated IgG in IgG purified from sera and dialysates of 12 CAPD patients. The percentage of glycated IgG after in vitro incubation of normal IgG with glucose solutions was directly proportional to glucose concentrations, incubation time and pH. Glycated IgG anti-STAW induced a higher C3c deposition than non-glycated IgG anti-STAW (C3c/IgG (mean +/- SD) 0.96 +/- 0.06 vs 0.79 +/- 0.08; P = 0.027). PMN phagocytosis was not affected by IgG glycation. The percentages of glycated IgG in dialysates of CAPD patients were greater than those in corresponding sera (5.38 +/- 2.36% vs 4.56 +/- 2.47%; P = 0.006). It is concluded that IgG glycation may take place in the peritoneal cavity during CAPD and lead to enhanced complement activation. This could explain the high degree of complement activation previously described in dialysate of CAPD patients and might theoretically result in a reduction of complement factors available in dialysate for adequate anti-infection mechanisms.

Integrated optical chemical and direct biochemical sensors

Abstract An overview is given on work by the author's group on integrated optical (IO) sensors. The sensors make use of guided waves or modes in optical waveguides, in particular of the orthogonally polarized TE 0 and TM 0 modes in very thin planar waveguides of high refractive index. The principle of all direct (bio)chemical waveguide or IO sensors is as follows. A chemically selective coating on the waveguide surface binds the analyte molecules contained in the gaseous or liquid sample. Thus, the refractive index of the medium near the waveguide surface (more precisely, within the penetration depth Δz of the evanescent field of the guided wave) is changed. This effect in turn induces changes ΔN TE 0 and ΔN TM 0 of the effective refractive indices N TE 0 and N TM 0 of the guided modes. for example, in biochemical affinity sensors the chemically selective coating contains receptor molecules that specifically or selectively bind certain ligands as analyte molecules; in particular, in immunosensors or immunoassays the receptors are antibodies (or antigens, respectively) and the analyte molecules are the corresponding antigens (or antibodies). These ‘direct’ affinity of immunosensors eliminate the use of (e.g., fluorescently) labelled reagents. Effective refractive-index changes ΔN can also be induced by two other effects; namely by unspecific adsorption of molecules on the (uncoated) waveguide surface (or in pores of a waveguiding film F itself if it is microporous) and by refractive-index changes Δn C of the liquid sample. In the latter case the IO sensors work as refractometers. The effective refractive indices N give the phase velocity ν ph = c / N of the guided modes, where c is the velocity of light in vacuum. This means that the effective refractive-index changes ΔN can be measured by various optical means. Consequently, a number of different types of IO sensors can be used, in particular, grating couplers and interferometers. In the paper, I report on our own work on IO sensors including: the discovery of the basic sensor effect with grating couplers as sensors for relative-humidity changes, the theory of the sensor sensitivities, and experimental results obtained with three different types of IO sensors developed in our laboratory, namely input grating couplers, output grating couplers and the difference or polarimetric interferometer. The experiments have been performed with dip-coated SiO 2 TiO 2 waveguiding films of refractive index n F ≈ 1.75–1.88, on glass, silica and silicon wafers with oxidized buffer layers as substrates. The sensors working as refractometers are tested, for example, with glucose solutions of different concentrations. The adsorption of proteins (h-IgG, BSA, protein A, avidin) is monitored in real time. Not only the surface concentration Γ, with a resolution of a few pg mm −2 , but also the thickness d F′ and the refractive index n F′ of the adsorbing (mono)layers are determined as functions of time. Also immunoreactions (e.g., between h-IgG and anti-h-IgG, and between IgGs and protein A) and affinity reactions (between avidin and biotinylated proteins, such as biotin BSA) are observed in real time. The feasibility of IO immunosensors or affinity sensors or immunoassays with sub-nanomolar detection limits is demonstrated.

Glucose preferences in wild and domestic guinea pigs

Male wild (Cavia aperea) and domestic (C. porcellus) guinea pigs were tested in two-bottle choice tests for preferences between glucose solutions of different concentrations and de-ionized water. Wild males showed significant preferences for concentrations between 0.025 and 0.4 M glucose while domestic males preferred only the 0.2 M glucose solution to de-ionized water. C. aperea males also consumed significantly greater volumes of liquid per kg body wt. 3 4 during the glucose tests than did the C. porcellus males. These comparative results contrast sharply with those obtained by other authors with wild and domestic Norway rats.

Effect of gonadectomy on taste preference for glucose solutions in rats

Mature male and female rats maintained on an ad lib diet were given a choice between tap water and glucose solutions of different concentrations (1, 5 and 12 percent). Both sexes exhibited a definite preference for the 12 percent glucose solution, but the females drank significantly more than males. Gonadectomy produced neither quantitative nor qualitative changes in the choice made by male rats. On the contrary, gonadectomized females showed a depression of the 12 percent glucose solution intake and an increase in the 5 percent glucose solution intake, resulting in a decrease of the total fluid intake. A comparison of ovariectomized and intact female rats in regard to the self-selection of tap water and a 5 percent glucose solution confirmed the stimulatory effect of ovariectomy on the 5 percent glucose solution intake. When a choice between tap water and a 12 percent glucose solution was permitted the ovariectomized rats showed a weaker positive response to the sweet solution than the intact female rats.

The effect of glucose, galactose and sorbitol on gastric emptying in the young pig.

The emptying times of glucose solutions of different concentrations by the stomach of the young pig have been compared. The emptying of glucose solutions has also been compared with that of galactose, sorbitol and sodium chloride of similar osmolarity.The more concentrated the glucose solution, the more slowly it is emptied, as is reported in other species. The emptying rate of galactose is similar to that of glucose and slower than sorbitol which is emptied at a similar rate to sodium chloride.