Glucose Concentration In Solution Research Articles

Glucose controlled surface coating with polydopamine

Polydopamine (PDA) has garnered increasing popularity over recent years due to its abundance of applications as both a coating and a nanoparticle. The primary challenge with PDA is finding ways to control its polymerization in a manner that does not diminish its applications. In this study, glucose solutions of various concentrations were used as part of the reaction solvent to alter the polymerization process and polymer product solutions. The reaction rate was decreased significantly which allowed for controlled polymerization. The solution aggregation was reduced to the point that the thickness and roughness of the PDA coated surfaces was tunable. This tunable surface has consistent high biocompatibility regardless of glucose concentration. In addition, the resulting PDA also demonstrated unique characteristics, including coating which were super-hydrophilic and fluorescent dopamine oligomers with excitation wavelength at 330 nm. This controlled polymerization can be used to augment the different applications of PDA and increase the functionality of these applications.

RF-LqRNN:RFID-Based Concentration Detection of Alcohol Solutions and Glucose Solutions

Solution concentration detection plays an important role in many real-life applications. For example, alcohol concentration detection can prevent cases where low-concentration liquor red is used to replace high-concentration liquor, while glucose concentration detection can be used to prevent diabetes. In this paper, the RF-LqRNN system is proposed, which can classify solution concentrations using an inexpensive commercial off-the-shelf radio frequency identification device. The proposed system uses the feature that the phase and RSSI of radio frequency signals across solutions of different concentrations are different. Measurements of the two features were obtained at different concentrations and input into a GRU-RNN to train a solution concentration classification model. The experimental results show that 98.5% classification accuracy can be achieved for 10 alcohol solution concentrations, and 97.3% classification accuracy can be achieved for 10 glucose solution concentrations. The effects of ceramic, glass, paper and plastic containers on solution concentration classification are also investigated, and it is determined that the solution concentration classification accuracy is the lowest in ceramic containers and the highest in plastic containers. Even at the lowest accuracies achieved in ceramic containers, the proposed method achieves more than 94% in the classification of the concentration of alcohol and glucose solutions.

Rapid and non-invasive detection of high-thickness glucose solution concentrations using quantum cascade laser-based transmission infrared spectroscopy

Most existing spectroscopic methods measure the concentration of blood glucose using attenuated total reflection. However, the short penetration depth (in the range of 2–15 μm) is a severe limitation. In practice, this approach is difficult to use because the depth of blood vessels in the skin exceeds 0.2 mm. As a solution, this work introduces a transmission spectroscopic method to measure the concentration of glucose. A fast infrared spectroscopic glucose concentration measurement method using a mid-infrared wavelength-swept pulsed quantum cascade laser (QCL) is adopted. This method employs a transmission optics system that does not require complicated adjustments or maintenance, together with an asynchronous signal method developed to shorten the measurement time. The combination of the high power of the QCL with the proposed algorithm enables measurements of glucose solution samples with an optical path length of 0.2 mm, which is sufficient for obtaining absorbance spectra and calculating the concentration of glucose in these samples. A linear regression of the average absorbance of the different glucose concentrations yields R2 values as high as 0.999. Moreover, using the asynchronous signal–based method reduces the single measurement time to 20 ms, and a 30 × integration required only 0.6 s. The proposed transmission method not only enables detection on the skin but also exhibits potential for measuring tear film on the eyeball in the tangential direction. This has potential applications in the diagnosis and management of diabetes.

Development and stability analysis of an S-tapered optical fiber-based sensor structure.

In this paper, three S-tapered fiber (STF) structures with different diameters (40, 60, and 80µm) are fabricated using conventional single-mode fiber. First, the reproducibility of the proposed S-tapered structure is confirmed through an analysis of the diameter distribution. Considering the transmitted intensities of the three various diameter, S-tapered structures reveal that the STF with a 40µm diameter produces more evanescent waves and is more sensitive to external refractive index variations. Therefore, the STF structure with a 40µm diameter was evaluated for the detection of different concentration of glucose solutions, demonstrating that the structure has the potential to be utilized to develop a highly sensitive fiber sensor.

Microfluidic Chip with Fiber-Tip Sensors for Synchronously Monitoring Concentration and Temperature of Glucose Solutions

Monitoring the properties of fluids in microfluidic chips often requires complex open-space optics technology and expensive equipment. In this work, we introduce dual-parameter optical sensors with fiber tips into the microfluidic chip. Multiple sensors were distributed in each channel of the chip, which enabled the real-time monitoring of the concentration and temperature of the microfluidics. The temperature sensitivity and glucose concentration sensitivity could reach 314 pm/°C and -0.678 dB/(g/L), respectively. The hemispherical probe hardly affected the microfluidic flow field. The integrated technology combined the optical fiber sensor with the microfluidic chip and was low cost with high performance. Therefore, we believe that the proposed microfluidic chip integrated with the optical sensor is beneficial for drug discovery, pathological research and material science investigation. The integrated technology has great application potential for micro total analysis systems (μ-TAS).

Efficient use of discarded vegetal residues as cost-effective feedstocks for microbial oil production

BackgroundHorticultural intensive type systems dedicated in producing greenhouse vegetables are one of the primary industries generating organic waste. Towards the implementation of a zero-waste strategy, this work aims to use discarded vegetables (tomato, pepper and watermelon) as feedstock for producing microbial oil using the oleaginous yeast Cryptococcus curvatus.ResultsThe soluble fraction, resulting after crushing and centrifuging these residues, showed C/N ratios of about 15, with a total carbohydrate content (mainly glucose, fructose and sucrose) ranging from 30 g/L to 65 g/L. Using these liquid fractions as substrate under a pulse-feeding strategy with a concentrated glucose solution resulted in an intracellular total lipid accumulation of about 30% (w/w) of the total dry cell weight (DCW). To increase this intracellular lipid content, the initial C/N content was increased from 15 to 30 and 50. Under these conditions, the process performance of the pulse-feeding strategy increased by 20–36%, resulting in a total intracellular lipid concentration of 35–40% DCW (w/w).ConclusionThese results demonstrate the potential of discarded vegetables as a substrate for producing bio-based products such as microbial oil when proper cultivation strategies are available.

Sulodexide Prevents Hyperglycemia-Induced Endothelial Dysfunction and Oxidative Stress in Porcine Retinal Arterioles

Diabetes mellitus may cause severe damage to retinal blood vessels. The central aim of this study was to test the hypothesis that sulodexide, a mixture of glycosaminoglycans, has a protective effect against hyperglycemia-induced endothelial dysfunction in the retina. Functional studies were performed in isolated porcine retinal arterioles. Vessels were cannulated and incubated with highly concentrated glucose solution (HG, 25 mM D-glucose) +/- sulodexide (50/5/0.5 μg/mL) or normally concentrated glucose solution (NG, 5.5 mM D-glucose) +/- sulodexide for two hours. Endothelium-dependent and endothelium-independent vasodilatation were measured by videomicroscopy. Reactive oxygen species (ROS) were quantified by dihydroethidium (DHE) fluorescence. Using high-pressure liquid chromatography (HPLC), the intrinsic antioxidant properties of sulodexide were investigated. Quantitative PCR was used to determine mRNA expression of regulatory, inflammatory, and redox genes in retinal arterioles, some of which were subsequently quantified at the protein level by immunofluorescence microscopy. Incubation of retinal arterioles with HG caused significant impairment of endothelium-dependent vasodilation, whereas endothelium-independent responses were not affected. In the HG group, ROS formation was markedly increased in the vascular wall. Strikingly, sulodexide had a protective effect against hyperglycemia-induced ROS formation in the vascular wall and had a concentration-dependent protective effect against endothelial dysfunction. Although sulodexide itself had only negligible antioxidant properties, it prevented hyperglycemia-induced overexpression of the pro-oxidant redox enzymes, NOX4 and NOX5. The data of the present study provide evidence that sulodexide has a protective effect against hyperglycemia-induced oxidative stress and endothelial dysfunction in porcine retinal arterioles, possibly by modulation of redox enzyme expression.

Growth of well-arrayed ZnO nanorods over no-core fiber for the measurement of glucose solution concentration

Growth of well-arrayed ZnO nanorods over no-core fiber for the measurement of glucose solution concentration

Compact surface plasmon resonance sensor using the digital versatile disc grating as a coupler and a disperser

Compact surface plasmon resonance (SPR) sensors are highly demanded due to their small size, low cost, and wide application scenarios compared with benchtop sensors. To realize high-precision spectral or angular analysis, most compact SPR sensors need spectrometers or rotation stages, which increase the cost of the device. We demonstrate a low-cost and compact SPR sensor by utilizing a single grating as a coupler and a disperser. The polychromatic light emitted from a light-emitting diode was coupled to surface plasmon modes by a grating made from a digital versatile disc-recordable disc. The light was dispersed by the same grating and collected by a linear charge-coupled device. The real-time detection of the SPR spectra and the resonant wavelengths was realized by homemade software based on the laboratory virtual instrument engineering workbench. By measuring different concentrations of glucose solution and sodium chloride solution, we obtain a high refractive index (RI) resolution of 5.52 × 10 − 5 RI unit. This compact SPR sensor can be applied in the areas of food safety, environmental monitoring, medical diagnosis, and so on.

Embedded racetrack microring resonator sensor based on GeSbSe glasses.

In this article, a compact racetrack double microring resonator (MRR) sensor based on Ge28Sb12Se60 (GeSbSe) is investigated. The sensor device consists of a racetrack microring, an embedded small microring, and a strip waveguide. Electron beam lithography (EBL) and dry etching are used to fabricate the device. The compact racetrack double MRR device are obtained with Q-factor equal to 7.17 × 104 and FSR of 24 nm by measuring the transmission spectrum. By measuring different concentrations of glucose solutions, a sensitivity of 297 nm/RIU by linear fitting and an intrinsic limit of detection (iLOD) of 7.40 × 10-5 are obtained. It paves the way for the application of chalcogenide glasses in the field of biosensing.

A Total Transmitted Light Intensity Method for Detecting Concentration of Glucose Aqueous Solution Directly Irradiated by Near Infrared LED

Glucose plays an important role in biological fermentation and biosensing. Therefore, it is very important to detect the concentration of glucose aqueous solution quickly and accurately. A novel method for detecting the concentration of glucose solution is introduced in this article. Based on the spectral characteristics of the near-infrared light-emitting diode (NIR LED), the total transmitted light intensity (TTLI)-concentration model of glucose solution directly irradiated by NIR LED was established to detect the concentration of glucose solution. In this model, firstly, the TTLI of glucose solution and TTLI of deionized water were defined. Secondly, the definition formula of the change ratio of TTLI was provided. Finally, the linear relationship between the change ratio of TTLI and the concentration of glucose solution was derived. In order to verify the effectiveness of the TTLI method, NIR LED Glucose Solution Concentration Detection System (NIR LED-GSCDS) was designed. In this system, an alternating measurement method is designed to reduce the influence of the radiation fluctuation of the NIR LED light source on the accuracy of detection results, and the thermostatic circulation subsystem is designed to reduce the influence of the change of solution temperature on the infrared light absorption rate of glucose solution. The experimental results show that the linear correlation coefficient between the change rate of TTLI and glucose solution concentration is 0.998 and the relative uncertainty is 8.2% in the concentration range of 1000–5000 mg/dL. Therefore, the TTLI method can determine the concentration of glucose solution under the direct irradiation of the NIR LED light source without a complex spectroscopic system.

Large-area silicon photonic crystal supporting bound states in the continuum and optical sensing formed by nanoimprint lithography.

Optical bound states in the continuum (BIC) are found in various dielectric, plasmonic and hybrid photonic systems. The localized BIC modes and quasi-BIC resonances can result in a large near-field enhancement and a high-quality factor with low optical loss. They represent a very promising class of ultrasensitive nanophotonic sensors. Usually, such quasi-BIC resonances can be carefully designed and realized in the photonic crystal that is precisely sculptured by electron beam lithography or interference lithography. Here, we report quasi-BIC resonances in large-area silicon photonic crystal slabs formed by soft nanoimprinting lithography and reactive ion etching. Such quasi-BIC resonances are extremely tolerant to fabrication imperfections while the optical characterization can be performed over macroscopic area by simple transmission measurements. By introducing lateral and vertical dimension changes during the etching process, the quasi-BIC resonance can be tuned over a wide range with the highest experimental quality factor of 136. We observe an ultra-high sensitivity of 1703 nm per RIU and a figure-of-merit of 65.5 for refractive index sensing. A good spectral shift is observed for detecting glucose solution concentration changes and adsorption of monolayer silane molecules. Our approach involves low-cost fabrication and easy characterization process for large-area quasi-BIC devices, which might enable future realistic optical sensing applications.

Sensing performance optimization by refining the temperature and humidity of clad engraved optical fiber sensor in glucose solution concentration

The experiments and performance of an evanescence wave-based plastic multimode fiber optic sensor to delineate their spectral and output power response in a glucose solution at room temperature and also at varying temperatures and humidity are described in this paper. In this study, the spectral transmission and the amount of transmitted intensity of the fiber when its morphology was varied both linearly and U-bent were examined. Furthermore, the effect of temperature was investigated by monitoring response both spectrally and electrically for linearly aligned clad removed fiber as a function of time at varying temperatures (20 °C, 25 °C, 30 °C, 40 °C). The sensors’ response towards various glucose concentrations (10–100 mM) was also determined under different relative humidity conditions (30 %, 40 %, 50 % 60 %), maintaining the temperature constant. Changes in the refractive index, surface morphology, temperature, and humidity of the sensing region had an impact on the light-transmission modes and sensitivity of the sensor. In summary, our study on the influence of temperature and humidity on glucose sensitivity can broaden the scope of optical sensing, thereby advancing the development of plastic fiber-optic-based evanescent wave sensors.

A Noninvasive Sweat Glucose Biosensor Based on Glucose Oxidase/Multiwalled Carbon Nanotubes/Ferrocene-Polyaniline Film/Cu Electrodes.

Diabetes remains a great threat to human beings' health and its world prevalence is projected to reach 9.9% by 2045. At present, the detection methods used are often invasive, cumbersome and time-consuming, thus increasing the burden on patients. In this paper, we propose a novel noninvasive and low-cost biosensor capable of detecting glucose in human sweat using enzyme-based electrodes for point-of-care uses. Specifically, an electrochemical method is applied for detection and the electrodes are covered with multilayered films including ferrocene-polyaniline (F-P), multi-walled carbon nanotubes (MWCNTs) and glucose oxidase (GOx) on Cu substrates (GOx/MWCNTs/F-P/Cu). The coated layers enhance the immobilization of GOx, increase the conductivity of the anode and improve the electrochemical properties of the electrode. Compared with the Cu electrode and the F-P/Cu electrode, a maximum peak current is obtained when the MWCNTs/F-P/Cu electrode is applied. We also study its current response by cyclic voltammetry (CV) at different concentrations (0-2.0 mM) of glucose solution. The best current response is obtained at 0.25 V using chronoamperometry. The effective working lifetime of an electrode is up to 8 days. Finally, to demonstrate the capability of the electrode, a portable, miniaturized and integrated detection device based on the GOx/MWCNTs/F-P/Cu electrode is developed. The results exhibit a short response time of 5 s and a correlation coefficient R2 of 0.9847 between the response current of sweat with blood glucose concentration. The LOD is of 0.081 mM and the reproducibility achieved in terms of RSD is 3.55%. The sweat glucose sensor is noninvasive and point-of-care, which shows great development potential in the health examination and monitoring field.

Prolotherapy with Very Fine Needle and Low Concentration of Glucose in a Patient with Chronic Lateral Elbow Pain

Prolotherapy is a non-surgical injection treatment method that repeatedly injects small amounts of proliferators into damaged ligaments, tendon, joints and surrounding tissues. The most common proliferator is a high concentration of glucose solution. Glucose solutions with a concentration of 10-25% are commonly used. Prolotherapy using glucose solution has few serious adverse events, but common side effects include post injection pain, stiffness, edema, and mild bleeding. There are many cases of complaining of pain caused by injection during or after prolotherapy. Some patients give up treatment if the pain is severe. A 43-year-old male patient visited the hospital with both elbow pain and left wrist pain, and prolotherapy was performed. In order to minimize pain during procedure and post injection pain of the patient, 10% glucose solution with 0.5% lidocaine was injected using a very fine needle of 30 G. The total number of treatments was eight. The patient did not complain of pain caused by needle insertion during procedure and post-injection pain. Chronic pain that lasted for two years after treatment almost disappeared. The patient was very satisfied with this treatment method and result.

Real-Time Measurement of Refractive Index Using 3D-Printed Optofluidic Fiber Sensor

This work describes a 3D-printed optofluidic fiber sensor to measure refractive index in real time, combining a microfluidic system with an optical fiber extrinsic Fabry-Perot interferometer. The microfluidic chip platform was developed for this purpose through 3D printing. The Fabry-Perot cavity was incorporated in the microfluidic chip perpendicularly to the sample flow, which was of approximately 3.7 µL/s. The optofluidic fiber sensor platform coupled with a low-cost optical power meter detector was characterized using different concentrations of glucose solutions. In the linear regression analysis, the optical power shift was correlated with the refractive index and a sensitivity of -86.6 dB/RIU (r2 = 0.996) was obtained. Good results were obtained in terms of stability with a maximum standard deviation of 0.03 dB and a sensor resolution of 5.2 × 10-4 RIU. The feasibility of the optofluidic fiber sensor for dynamic analyses of refractive index with low sample usage was confirmed through real-time measurements.

Optofluidic Fabry-Perot interferometric sensor for the real-time measurement of refractive index

In this work, a microfluidic system combined with a fibre-optic extrinsic Fabry-Perot interferometer is proposed to measure refractive index continuously and in real time. A microfluidic platform was designed and created for this purpose through 3D printing. The Fabry-Perot cavity is an integral part of the microfluidic chip and is perpendicular to the sample flow. The light is conducted through a single mode optical fibre and the refractive index measurements were based on the optical power and wavelength shift of the reflected spectra. The developed optofluidic setup was characterised using different concentrations of glucose solutions. A sensitivity of 1102 nm/RIU was obtained when using the wavelength shift, however, when the same solution was analysed over time, the signal for wavelength shift measurements was found to be unstable. The optical power shift was correlated with the refractive index and a sensitivity of -79.6 dB/RIU was obtained, with a good linearity (r2 = 0.996). Good results were verified in terms of stability with a maximum standard deviation of 0.028 dB and a sensor resolution of 4.3×10−4 RIU. This sensor has a great potential for applications in which refractive index real-time measurements are required, such as food and beverages industry process control.

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.

Microfluidic microwave biosensor based on biomimetic materials for the quantitative detection of glucose

This paper presents a microwave microfluidic biosensor for monitoring blood glucose levels. The glucose sensor is a triple ring microstrip patch antenna integrated with a biomimetic microfluidic device capable of measuring a fixed volume of glucose solution. The sensor was utilized to detect 50–500 mg/dL glucose solutions. The interaction of the glucose solution with the electromagnetic field on the patch's surface influences both the resonance frequency and the magnitude of reflection coefficient. The results indicate that the microfluidic device can reduce experimental error and enhance the correlation between glucose concentration, resonant frequency, and reflection coefficient. Finally, the microfluidic sensor had a sensitivity of 0.25 MHz/(mg/dL), a detection limit as low as 7.7 mg/dL, and correlation coefficients of resonance frequency and reflection coefficient with a glucose concentration of 0.996 and 0.984, respectively. The experiment on the sensor's stability verifies the sensor's excellent stability and rapid response (~ 150 ms). Consequently, the device can be used to differentiate the concentration of glucose solutions, as well as to detect blood glucose levels at an early stage.

MIM waveguide system with independently tunable double resonances and its application for two-parameter detection.

A metal-insulator-metal (MIM) waveguide system consisting of a MIM waveguide, a ring cavity, and a semi-ring cavity is proposed. Using the finite element method, the transmission characteristics of the MIM waveguide system are discussed under the different geometry parameters. By detecting the resonance wavelength and varying the refractive index, the sensing performance of the MIM waveguide system is analyzed. The proposed structure can be used as a refractive index sensor with the maximum sensitivity of 2412 nm/RIU. Due to isolating the ring cavity and semi-ring cavity, the independent tuning of double resonances can be realized by changing the refractive index of the insulator in the ring cavity or the semi-ring cavity. Benefiting from two independent refractive index sensing modes, the structure with two isolated resonators can realize the simultaneous measurement of glucose solution concentration and blood plasma concentration. The sensitivity of glucose solution sensing in the ring cavity is 0.13133 nm/(g/L). Meanwhile, the blood plasma concentration detection in the semi-ring cavity is realized with the sensitivity of 0.358 nm/(g/L). The system with two isolated cavities has the potential to be used as an efficient nano sensor, which can achieve simultaneous measurement of two parameters.