Determination Of Glucose In Serum Research Articles

Polyoxometalate-induced hydrogel with in situ nano/bioenzyme cascade reaction generating intensive and long-lasting glow-type chemiluminescence

In this study, we introduce a straightforward one-step, in-situ strategy for the generation of long-lasting and intensive glow-type chemiluminescence (CL) for glucose sensing in biological samples. The approach involves the utilization of polyoxometalate (POM)-induced alginate hydrogel, which effectively encapsulates both the catalysts (POM and glucose oxidase (GOx)) and the CL reagent (luminol) in solution. Leveraging the peroxidase-like nanozyme properties of POM and the bioenzyme GOx, embedded within the nano-sized pores of the hydrogel, we achieve intensive and persistent CL emission lasting over 16 h. The POM-hydrogel-based CL system demonstrates remarkable storage stability and reproducibility, and it can be applied to quantitatively determine serum glucose with high accuracy. Our study indicates that the POM-hydrogel platform, supporting and confining nano/bioenzyme cascade reactions, holds great promise for the establishment of glow-type CL systems, which could be of great value in various fields of CL biosensing and imaging.

Incorporation of laser-induced graphene with hierarchical NiCo layered double hydroxide nanosheets for electrochemical determination of glucose in food and serum

Dependable and sensitive glucose (Glu) testing in foodstuff and blood serum is highly desirable to prevent and treat diabetes. Electrochemical quantification of Glu has attracted great interests due to the advantages, including simple operation, higher sensitivity, easy miniaturization, ease of on-site and wearable detection as well as fast response. High costs and environmental dependence of enzymes pose a challenge to the electrochemical enzymatic biosensors. Nonenzymatic electrochemical Glu sensors are urgently needed to aid the Glu detection in human serum and food samples. To fabricate flexible Glu electrochemical sensors, designing suitable electrode substrate and efficient electrocatalyst is of paramount significance. Herein, the porous patterned laser-induced graphene (LIG) was fabricated on polyimide substrates through an efficient laser-inducing technology, and then used directly as the electrode substrate. Electrochemical deposition of NiCo layered double hydroxide (LDH) nanoflakes on the LIG surface was then conducted to achieve NiCo-LDH/LIG electrode as a Glu sensor. Under optimal conditions, this sensor displays a low detection limit of 0.05 μM. Two sets of broad detection linear ranges were found to be from 0.5 to 270 μM and from 0.27 to 3.6 mM, with high sensitivities of 9.750 μA μM−1 cm−2 and 3.760 μA μM−1 cm−2, respectively. The enhanced performance was ascribed to the cooperative action of NiCo-LDH and LIG, in which porous LIG provides extraordinary electroconductibility and a high surface area, while NiCo-LDH offers numerous exposed active sites and outstanding electrocatalytic performance. Practical application was further verified during the Glu detection in human serum and food samples. This research confirms that the NiCo-LDH/LIG composite is a prospective electrode for high-performance Glu sensor and provides a way of developing nonenzymatic electrochemical sensors to analyze the Glu in human serum and food samples, opening new avenues in electrochemical sensing.

Facilely prepared Co-based MOF functionalized N, S-doped reduced graphene oxide for electrochemical non-enzymatic glucose sensing

Rational design of modified electrode materials is critical for electrochemical sensors. Metal-organic frameworks (MOFs), a novel sort of substance with porosity, has received widespread attention owing to various superior characteristics such as adjustable pore sizes, great surface area and controllable structures. Nevertheless, the poor charge transfer capability of MOFs leads to a general suppression of their electrochemical sensing performance. To solve this issue, compositing conductive substance with MOFs have been demonstrated to be an effective strategy. Herein, Co-based MOF (ZIF-67) functionalized N, S-doped reduced graphene oxide (N, S-RGO) heterostructure (ZIF-67/N, S-RGO) was fabricated through an in-situ synthesis method. The composite material was used in the modification of an electrode to construct a sensing platform for non-enzymatic glucose testing. The synergistic interaction of ZIF-67 and N, S-RGO not only provided more efficient active sites and larger surface areas, but also improved the electron transport efficiency and electrocatalytic performance. Under optimized conditions, the ZIF-67/N, S-RGO/GCE had a dynamic linear range of 1–3200 μM, with a detection limit of 0.33 μM (S/N = 3) for glucose detection. The sensing platform also provided excellent reproducibility, selectivity, and stability (70 % activity retained after 12 days). Furthermore, the sensor had the potential to apply for glucose determination in human serum. This work presented a novel strategy to the field of non-enzymatic glucose sensing and may provide effective coaching for optimizing the electrochemical sensing performance of other series of MOFs.

Determination of low concentrations of glucose through colorimetric analysis using CoFe2O4 magnetic catalyst and SAT-3.

Natural enzyme mimics have attracted attention as alternatives to natural peroxidases. Among these, magnetic nanoparticles, especially ferrites, have attracted attention because of their unique electronic and physical structures, which are expected to be applied in various fields, including high-frequency magnetic materials, biomaterials, gas sensors, and semiconductor photocatalysts. The structural properties of the synthesized catalysts were investigated using X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy. The prepared CoFe2O4 exhibited a spinel ferrite structure and formed a wood-flake-like bulk structure. In this study, magnetic CoFe2O4 was prepared using a precipitation method as a natural enzyme mimetic. CoFe2O4 showed excellent peroxidase-like activity, as demonstrated by the Michaelis-Menten constant (Km) and the maximum velocity (Vmax). The linear ranges of the calibration curves for H2O2 and glucose were in the range of 0-500µM, and the detection limits were 1.83 and 5.91µM, respectively. This analytical method was applied for the determination of glucose in human serum, and the results were satisfactory and consistent with certified values. The performance of this sensor was comparable to or superior to those of several other sensors commonly used for glucose analysis, indicating that its practical application is feasible.

High-sensitive detection of H2O2 in biological systems by persistent luminescent nanoprobes

Autofluorescence interference in the conventional fluorescence detection of hydrogen peroxide (H2O2) in biological systems represents a long-lasting problem in the field of biosensing. Here, we report a Cr3+, Y3+ co-doped ZnGaSnO4 (ZGSCY) nanoprobes which show long persistent luminescence (PL) that can be specifically enhanced by H2O2 without background fluorescence interference. The mesoporous organosilica are coated on the surface of ZGSCY to enhance the biocompatibility of the nanoprobes. Importantly, PL intensity of the nanoprobes can be further improved, because of the specific response of tetrasulfide bond in organosilica to H2O2. ZGSCY@MON show high-sensitive detection of H2O2 in living cells and human serum with the advantages of high specificity, low detection limit (91 nM), and wide linear range (0.5–60 μM, 60–400 μM). Furthermore, the extraordinary detection capability of H2O2 enables that the successful differentiate normal breast cells from breast cancer cells and the highly sensitive determination of serum glucose and cholesterol. We also clarified that the endogenous response originates from the UV-induced the interfacial electron transfer on ZGSCY regulated by H2O2 and exogenous response stems from the elimination of the adsorption of PL from the organosilica by H2O2. These findings open up a new effective way for autofluorescence-free detection of H2O2 in biological systems.

Administration of Akebia Saponin D Improved Blood Lipid Levels and Pregnancy Outcomes in Mice with Gestational Diabetes Mellitus

Gestational diabetes mellitus (GDM) is a prevalent and severe metabolic disease in pregnant women that is characterized by a high incidence. Placental oxidative stress and inflammation are recognized as the primary contributors to GDM pathogenesis. The repressive effect of akebia saponin D (ASD) on oxidative stress and inflammation has been demonstrated in various diseases. To investigate the impact of ASD on GDM. Animal experimental study. GDM mice were intraperitoneally treated with ASD. The effect of ASD on GDM symptoms, blood lipid levels, pancreatic tissue damage, gestational outcomes, oxidative stress, and inflammation was assessed via intraperitoneal glucose and insulin tolerance tests, serum glucose and insulin level determination, lipid biochemistry analysis, pathological staining, oxidative stress evaluation, western blot analysis, and enzyme-linked immunosorbent assay. ASD reduced the GDM-induced increase in body weight and blood glucose levels while restoring the decreased insulin levels associated with GDM. In addition, ASD improved the serum lipid parameters, pancreatic tissue damage, and gestational outcomes in GDM mice. Furthermore, ASD reversed the decreased levels of superoxide dismutase and glutathione while reducing the elevated concentrations of malondialdehyde and myeloperoxidase in GDM mice. In addition, ASD rescued the relative protein expression of nuclear factor-E2-related factor 2 and heme oxygenase-1 in the placenta of GDM mice. Additionally, ASD counteracted the increase in tumor necrosis factor-α, interleukin (IL)-6, and IL-1β levels in the sera and placenta of GDM mice. ASD suppressed oxidative stress and inflammation to effectively relieve symptoms and gestational outcomes of the GDM mice.

Synthesis of unique three-dimensional CoMn2O4@Ni(OH)2 nanocages via Kirkendall effect for non-enzymatic glucose sensing

Transition metal oxides / hydroxides, which have the advantages of wide distribution, low price, low toxicity, and stable chemical properties, have attracted much attention from researchers. Therefore, this work reports the construction of the unique CoMn2O4 nanocages assisted by the Kirkendall effect, and worm-like Ni(OH)2 nanoparticles were grown on the surface via hydrothermal method, the final product CoMn2O4@Ni(OH)2 nanocages were applied to construct efficient and sensitive non-enzymatic glucose electrochemical sensing. The stable three-dimensional hollow CoMn2O4 nanocages structure, not only can provide a wider specific surface area and more abundant active sites, its porous structure also can effectively inhibit the aggregation of nanoparticles, increase the ion diffusion path, shorten the electron transport distance, and improve the electrical conductivity. Loading Ni(OH)2 nanoparticles on the CoMn2O4 nanocages can increase catalytic sites, and further strengthen the electrocatalytic performance. Due to the good synergistic effect between CoMn2O4 and Ni(OH)2, CoMn2O4@Ni(OH)2 nanocages electrochemical sensor can achieve sensitive and rapid detection of trace glucose, with excellent linear range (8.5–1830.5 μM), low limit of detection (0.264 μM), high sensitivity of 0.00646 μA mM−1 cm−2, and outstanding repeatability. More importantly, the sensor has been successfully applied to the determination of blood glucose in human serum with good recoveries (95.64–104.3 %). This work provides a novel scheme for blood glucose detection and expands the application of transition metal oxides / hydroxides in the field of electrochemical sensing.

Flexible Specific Determination of Glucose in Solution, Blood Serum, and Sweat Using a Terahertz Hydrogel‐Functionalized Metamaterial

Terahertz metamaterials have shown promises in biomolecules detection, however, aqueous solvents such as blood serum strongly absorb the terahertz waves, interfering with the detection. To avoid such interference, an ultrathin, flexible, biogel‐based metamaterial that can specifically detect the transmission of terahertz waves through biomolecules in aqueous solution is proposed and demonstrated. The glucose in water can be detected with a sensitivity of 0.0446 dL mg−1 and a detection limit of 1.64 mg dL−1, as well as glucose in human serum. The metamaterial that detects glucose in human sweat is part of a wearable device. The biosensor functions well for more than 100 detection cycles. The results suggest a strategy for real‐time detection of glucose and potentially other biomolecules.

Tunable Non-Enzymatic Glucose Electrochemical Sensing Based on the Ni/Co Bimetallic MOFs.

Constructing high-performance glucose sensors is of great significance for the prevention and diagnosis of diabetes, and the key is to develop new sensitive materials. In this paper, a series of Ni2Co1-L MOFs (L = H2BPDC: 4,4'-biphenyldicarboxylic acid; H2NDC: 2,6-naphthalenedicarboxylic acid; H2BDC: 1,4-benzenedicarboxylic acid) were synthesized by a room temperature stirring method. The effects of metal centers and ligands on the structure, compositions, electrochemical properties of the obtained Ni2Co1-L MOFs were characterized, indicating the successful preparation of layered MOFs with different sizes, stacking degrees, electrochemical active areas, numbers of exposed active sites, and glucose catalytic activity. Among them, Ni2Co1-BDC exhibits a relatively thin and homogeneous plate-like morphology, and the Ni2Co1-BDC modified glassy carbon electrode (Ni2Co1-BDC/GCE) has the highest electrochemical performance. Furthermore, the mechanism of the enhanced glucose oxidation signal was investigated. It was shown that glucose has a higher electron transfer capacity and a larger apparent catalytic rate constant on the Ni2Co1-BDC/GCE surface. Therefore, tunable non-enzymatic glucose electrochemical sensing was carried out by regulating the metal centers and ligands. As a result, a high-sensitivity enzyme-free glucose sensing platform was successfully constructed based on the Ni2Co1-BDC/GCE, which has a wide linear range of 0.5-2899.5 μM, a low detection limit of 0.29 μM (S/N = 3), and a high sensitivity of 3925.3 μA mM-1 cm-2. Much more importantly, it was also successfully applied to the determination of glucose in human serum with satisfactory results, demonstrating its potential for glucose detection in real samples.

Lambda-cyhalothrin-induced pancreatic toxicity in adult albino rats

Lambda-cyhalothrin (LCT) is one of the most frequently utilized pyrethroids. This study aimed to explore the toxic effects of subacute exposure to LCT on the pancreas and the hepatic glucose metabolism in adult male albino rats. 20 rats were equally grouped into; Control group and LCT group. The latter received LCT (61.2 mg/kg b.wt.), orally on a daily basis for 28 days. At the end of experiment, blood samples were collected for the determination of serum glucose and insulin levels. Pancreases were harvested and levels of malondialdehyde (MDA); catalase (CAT); superoxide dismutase (SOD); reduced glutathione (GSH); tumor necrosis factor-α (TNF-α); interleukin-6 (IL-6); nuclear factor erythroid 2–related factor 2 (Nrf2); heme oxygenase 1 (HO-1); and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) were assessed. Also, liver samples were analyzed for the activity of glucose metabolism enzymes, glycogen content, and pyruvate and lactate concentrations. Histopathological and immunohistochemical examinations of pancreatic tissues were undertaken as well. Results revealed hyperglycemia, hypoinsulinemia, increased MDA, TNF-α, IL-6, and NF-κB levels, in association with reduced CAT, SOD, GSH, Nrf2, and HO-1 levels in LCT group. Liver analyses demonstrated a clear disturbance in the hepatic enzymes of glucose metabolism, diminished glycogen content, decreased pyruvate, and increased lactate concentrations. Besides, pancreatic islets displayed degenerative changes and β-cells loss. Immunohistochemistry revealed diminished area percentage (%) of insulin and Nrf2 and increased TNF-α immunoreaction. In conclusion, subacute exposure to LCT induces pancreatic toxicity, mostly via oxidative and inflammatory mechanisms, and dysregulates hepatic glucose metabolism in albino rats.

Electrochemical sensors based on modified track–etched membrane for non-enzymatic glucose determination

In this research, a non-enzymatic sensor for electrochemical glucose detection based on modified poly(ethyleneterephthalate) track-etched membrane (PET TeMs) was firstly reported in the field of sensing of organic substances. The electrochemical sensors were obtained by photograft polymerization with 2-hydroxyethyl methacrylate (HEMA) and further formation of a polyelectrolyte complex with poly(allylamine) (PAlAm). 4-mercaptophenylboronic acid was functionalized on the surface of PET TeMs via Au-S bond and –OH group of polymerized HEMA to recognize glucose by formation of cyclic boronic ester. The modified PET TeMs were characterized by infrared spectroscopy, gas permeability test, scanning electron microscopy and energy dispersive analysis. Optimal parameters for graft polymerization, such as monomer concentration, polymerization time and distance from the UV-lamp were found. Electrochemical determination of glucose was done by square wave voltammetry. The non-enzymatic sensors for glucose detection showed a good linear relationship between the area under the oxidation peak and glucose concentration in the range from 0.1 mM to 8 mM with a low detection limit of 0.1 mM (R2 = 0.999). In addition, the sensors showed excellent reproducibility, repeatability and good selectivity for metal ions and ascorbic acid. The determination of glucose in apple juice and human blood serum demonstrated that the obtained sensors can be used in real samples with sufficient reproducibility of results.

Glucose determination in human serum by applying inner filter effect quenching mechanism of upconversion nanoparticles.

Accurate blood glucose determination is essential to the clinical diagnosis and management of diabetes. This work establishes an inner filter effect (IFE) strategy between upconversion nanoparticles (UCNPs) and quinone-imine complex for glucose monitoring in human serum simply and efficiently. In this system, the enzyme glucose oxidase (GOx) catalyzes the reaction of glucose into hydrogen peroxide (H2O2) and gluconic acid when compulsion by oxygen. In the presence of horseradish peroxidase (HRP), the produced H2O2 can catalytically oxidize phenol and 4-amino antipyrine (4-AAP) to generate quinone-imine products. The purple-colored quinone-imine complex effectively absorbed the fluorescence of NaYF4:Yb3+, Er3+ UCNPs, leading to the strong fluorescence quenching of UCNPs through IFE. Thus, a new approach was established for glucose monitoring by determining the fluorescence intensity. Under the optimal condition, this approach shows better linearity to glucose from 2-240μmol/L with a low detection limit at 1.0μmol/L. Owing to the excellent fluorescence property and background-free interference of the UCNPs, the biosensor was applied for glucose measurements in human serum and got a satisfactory result. Furthermore, this sensitive and selective biosensor revealed great potential for the quantitative analysis of blood glucose or different kinds of H2O2-involved biomolecules for the application of clinical diagnosis.

Assessment of effectiveness of oral supplementation of isolated fiber of carrot on metabolic parameters in mature rats

The present study was conducted to evaluate the metabolic effects of isolated fiber of carrot supplementation in rats. Physicochemical properties of fiber were determined. The groups were as follows: animals fed a standard diet, control group; high fiber supplementation (70 mg); low fiber supplementation (35 mg); for 12 weeks. Blood samples were collected at the time of sacrifice. The weights of heart, liver, kidneys and spleen of the experimental rats with respect to body weight were recorded. Commercial kits were used to determine serum glucose concentration, lipid profile (cholesterol, HDL-cholesterol, triglycerides), and the two main aminotransferases glutamic-oxalacetic transaminase (GOT)/glutamate-pyruvate transaminase (GPT). A histopathological assay was performed on the heart, liver, and spleen tissues of animals. Supplementation with fiber favors weight loss in female ((242.03 ± 23.73)−(197.81 ± 10.45) g); and male rats ((262.50 ± 32.21)−(213.96 ± 12.56) g) and induces a decrease in glucose levels in the supplemented animals. With the exception of total high-density lipoprotein cholesterol, the other lipid fractions decrease significantly in rats supplemented. Fiber supplementation did not induce changes in the dissected organs of the supplemented animals. In conclusion supplementation of fiber, improves glucose control, lower plasma lipid concentrations and reduced body weight in normal rats.

Microplasma and quenching-induced Co doped NiMoO4 nanorods with oxygen vacancies for electrochemical determination of glucose in food and serum

In this paper, Co-doped NiMoO4 nanorods with oxygen vacancies are synthesized on carbon cloth (Co-NiMoO4 NRs/CC) via microplasma and quenching-induced method.Owing to the surface defects and metal ion doping, the electronic structure and surface properties of the catalyst are tuned.Cyclic voltammetry (CV) and amperometry are used to investigate the electrocatalytic behavior of the glucose sensor in an alkaline medium with sensitivities of 7411 and 3125 μA L mmol−1 cm−2 in the linear range 1.0 μmol L–1 to 1.0 mmol L–1 and 1.0 mmol L–1 to 7.0 mmol L–1, respectively. The detection limit is 0.079 μmol L–1 at S/N = 3. Moreover, the as-prepared catalyst electrode is also successfully used in real food and serum samples, with a recovery rate of 97.1%-107.4%.The DFT calculations show that the Co site of the catalyst significantly influenced glucose sensing performance. This idea expands the application of quenching chemistry in electrochemical sensing.

Construction of Covalent Organic Framework Capsule-Based Nanoreactor for Sensitive Glucose Detection.

Enzyme immobilization is critical to boosting its application in various areas. Covalent organic frameworks (COFs) are ideal hosts for enzyme immobilization due to their porous and predesignable structures. Nevertheless, the construction of COFs-based enzyme immobilization systems with high activity via existing immobilization methods (including covalent linkages and channel entrapment) remains a considerable challenge. Herein, a versatile approach was introduced to encapsulate enzymes within hollow COF capsule (named enzyme@COF) using metal-organic frameworks (including ZPF-1(C8H11N4O4.5Zn), ZIF-8(C8H10N4Zn), and ZIF-90(C8H6N4O2Zn)) as sacrificial templates. The obtained porous COF capsule could not only facilitate the efficient mass transfer of enzymatic reactions but also protect enzymes against the incompatible conditions, resulting in enhanced activity and stability of the encapsulated enzymes. Moreover, this approach offered an opportunity to spatially organize multienzymes in COF capsule to construct enzyme cascade system. For instance, glucose oxidase (GOx) and cytochrome c (Cyt c) were coencapsulated within COF capsule to construct GOx-Cyt c cascade. The integration of GOx and Cyt c within COF capsule achieved ∼1.6-fold improvement in catalytic activity than that of free enzymes and the resultant GOx-Cyt c@COF was successfully adopted as a nanoreactor for the sensitive determination of glucose in serum. This work provided a new insight into the design of COFs-based enzyme immobilization systems.

Synthesis of uniformly dispersed Fe2TiO5 nanodisks: a sensitive photoelectrochemical sensor for glucose monitoring in human blood serum.

A novel photoelectrochemical (PEC) sensor was constructed, using Fe2TiO5 nanodisks under visible-light irradiation, for the determination of glucose in human blood serum. The uniformly dispersed Fe2TiO5 nanodisks were synthesized for the first time by an ion exchange method and subsequent heat treatment. As excellent catalysts, the Fe2TiO5 nanodisks can directly catalyze the oxidation of glucose to produce current in the absence of glucose oxidase. Compared with commercial TiO2, the Fe2TiO5 nanodisks exhibit better activity in the electrocatalytic oxidation of glucose and can generate a photocurrent as a signal for glucose detection. The PEC sensor shows a wide linear range (4 μM-10 mM), a low limit of detection (0.588 μM) and a super sensitivity of 2653 μA mM-1 cm-2, which are much better than similar configurations reported previously. This PEC sensor has been successfully used to monitor glucose in human blood serum. Moreover, this PEC glucose sensor based on Fe2TiO5 nanodisks possesses great potential for application in point-of-care clinical diagnosis.

Gold Nanoparticle (Au NP)-Decorated Ionic Liquid (IL) Based Liposome: A Stable, Biocompatible, and Conductive Biomimetic Platform for the Fabrication of an Enzymatic Electrochemical Glucose Biosensor

A novel liposomal nanocomposite with biocompatibility and conductivity, Au@ILs-polysome, was fabricated and first utilized as the electrode material to immobilize the redox enzyme glucose oxidase (GOD) for the sensitive determination of glucose. Ionic liquids (ILs)-based polysome (ILs-polysome) was prepared via the radical polymerization of ILs based liposome (ILs-liposome) and improved by ion exchange with chloroauric acid to prepare Au nanoparticles (Au NPs) modified ILs based polysome (Au@ILs-polysome). The morphology, surface properties, and structure of Au@ILs-polysome were characterized; the results suggest that the nanocomposite exhibited excellent stability on the surface of solid electrodes without fusion. Electrochemical impedance spectroscopy (EIS) demonstrated that the nanocomposite had enhanced conductivity. Cyclic voltammetry (CV) shows that the direct electron transfer of GOD was achieved on the GOD/Au@ILs-polysome/GCE electrode since the Au@ILs-polysome provided a biocompatible microenvironment that made the immobilized enzyme stay natural and active. Differential pulse voltammetry (DPV) demonstrates that the GOD/Au@ILs-polysome/GCE electrode exhibited improved electrocatalytic activity compared with the GOD/ILs-polysome/GCE electrode. The electrochemical sensor exhibited a low detection limit of 0.02 mM, high sensitivity of 32.52 µA mM−1 cm−2, high selectivity toward glucose, and good stability. The practical application of the sensor was verified by the determination of glucose in human serum. The multi-component liposomal nanocomposites possess universal significance in protein-based direct electrochemical devices while offering a facile route to fabricating a highly sensitive glucose sensor for practical clinical diagnosis.

The protective role of iodine and MS-222 against stress response and bacterial infections during Nile tilapia (Oreochromis niloticus) transportation

Fish transportation is a regular farming and experimental practice that mainly results in stress conditions that may extend to induce a high mortality rate. In the present experimental simulation, Oreochromis niloticus were transported for 2 h and maintained for another 6 h in transportation containers to assess the effect of tranquilization with tricaine methanesulfonate (MS-222) and/or the addition of iodine on mortality rate and restoring the normal physiological functions. Experimental fish were divided into four groups: group 1 (control) was transported in farm water without MS-222 or iodine, group (2) was transported in farm water supplemented with 40 mg/L of MS-222, fish in group (3) were transported in farm water supplemented with 40 mg/L of MS-222 + 10 ppm iodine, and fish in group (4) were transported in farm water containing 10 ppm iodine. Blood samples were collected for the determination of serum cortisol and glucose, while skin mucus was collected for assaying lysozyme, peroxidase and antibacterial activity; cumulative mortality rate; and food reflexes which were assessed at 0 h, 1 h, 6 h, 48 h, 7 days and 14 days post 2 h transportation. The results indicated that fish tranquilization with MS-222 and/or treatment with iodine mitigated the stress condition associated with transportation and accelerate restoration of the normal physiological and immunological status. So, it was recommended to use the MS-222 as a tranquillizer together with iodine as an antiseptic during transportation of O. niloticus.

Non-Enzymatic Phenylboronic Acid-Based Optode Membrane for Glucose Monitoring in Serums of Diabetic Patients and in the Culture Medium of Human Embryos.

Monitoring glucose levels is important not only for diabetics, but also for tracking embryonic development in human embryo culture media. In this study, an optochemical sensor (glucose-selective polymer membrane) was fabricated for the determination of glucose in serum from diabetic patients and the culture media of human embryos. The optode membranes were formulated using polyvinyl chloride (PVC) as the polymer matrix and 4′,5′-dibromofluorescein octadecyl ester (ETH 7075) as the chromoionophore. The sensitivity of the optode membranes was optimized using two different plasticizers (tricresyl phosphate-TCP and nitrophenyloctyl ether-NOPE) and three ionophores (nitrophenylboronic acid-NPBA, trifluorophenyboronic acid-TFPBA, 4′-nitrobenzo-15-crown-5) and tested for glucose detection. The best optode membrane was formulated from 49.5% PVC, 49.5% TCP, 1% NPBA, and 1% ETH 7075. It showed a linear dynamic range of 10−3 M to 10−1 M, with a detection limit of 9 × 10−4 M and a response time of 2 min. The detection mechanism involves H-bonding between NPBA and glucose, which was confirmed by Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR). The reaction also involves the formation of boronate esters in basic media with deprotonation of the chromoionophore (ETH 7075), leading to a decrease in UV–Vis absorbance at λmax = 530 nm. The membrane optode was used for glucose determination in synthetic culture medium, commercial embryo culture medium (GLOBAL® TOTAL® W/HEPES), and serum from normal and diabetic patients, showing good accuracy and precision of the optode.

A wearable enzyme-free glucose sensor based on nickel nanoparticles decorated laser-induced graphene

• A flexible glucose sensor is fabricated based on multilayer laser-induced graphene. • The sensor exhibits wide linear range and high sensitivity towards glucose. • No signal attenuation is observed after drastic folding for 100 times. • The sensor has been applied to the determination of glucose in human serum. Wearable biosensors that can detect glucose molecules is a promising monitoring device for clinic and health-care analysis. A flexible enzyme-free glucose sensor based on multilayer porous laser-induced graphene (LIG) produced from polyimide (PI) film was developed in this work. Ni/LIG electrode was prepared by electrochemical deposition of Ni nanoparticles on LIG for enzyme-free glucose detection. Ag/AgCl/LIG was prepared as the reference by coating with silver conductive gel and electrochemical anodization methods on LIG. The Ni/LIG glucose sensor possesses excellent flexibility and can function properly after being folded for a hundred times. The sensor exhibits desirable analytical performance towards glucose with wide linear range (0.50 μM to 1666 μM), ultra-high sensitivity (2040 μA/mM·cm 2 ), and low detection limit (0.29 μM). Ni/LIG glucose sensor also shows high stability and minimal responses to the interference substances and has been successfully applied to the determination of glucose in human blood serum with a relative standard deviation (RSD, n = 10) of 0.85%, and recoveries ranging from 99.36% to 100.45%.