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The detection of glucose plays an important role in monitoring and controlling diabetes as well as its complications caused by high blood glucose levels. There have been a lot of research on glucose sensors and integrated flexible sensing platforms; however, the detection in oxygen-restrictive environments is few reported. Herein, we described the use of a novel system made up of TiO2 and ceria-cerium phosphate (CeO2-CePO4) composite nanostructures synthesized by a simple procedure to address the oxygen dependence problem confronted in the first-generation amperometric glucose biosensors. The enzymatic activity of sensors was tested in both oxygen-rich and restrictive environments. Our results showed that the resulting composites present good electro-catalytic activity towards glucose oxidation. The electrodes decorated by TiO2/CeO2-CePO4 showed a wide linear range from 0.1 to 1.7 mM with a low detection limit of 17.1 μM while the CeO2-CePO4 showed the linear range of 0.1–2.5 mM with limit of detection of 58.0 μM in oxygen-rich environment. Two types of decorated electrodes both responded to glucose well under the oxygen-restrictive environment but former showed better response performance. The as-fabricated electrodes also owned the good anti-interference, stability, and reproducibility. This strategy promises for increasing the sensitivity of glucose biosensors and provides more opportunities for operation in oxygen-restrictive conditions.

Rhombohedral nickel sulfide thin films were deposited on c-sapphire substrate via the atomic layer deposition (ALD) method using nickel acetylacetonate [Ni(acac)2] as nickel and H2S gas as sulfur p...

Uniform nanoneedles of binary oxide (Ni and Co) were synthesized on appropriate conducting substrates [fluorine-doped tin oxide (FTO) coated glass and carbon cloth (CC)] and investigated for dual a...

The increasing demand for monitoring the glucose concentration in the blood of diabetic patients has aroused the attention of researchers to prepare high-performance glucose biosensors. After decades of development, enzyme-based biosensors have gradually matured and commercialized, but they still suffer from insufficient stability due to the inherent defects of the enzyme. Non-enzymatic glucose sensor was proposed to address this issue. The introduction of nanotechnology has provided more possibilities for the preparation of highly efficient catalytic materials. Among the synthesized electrocatalysts, metal oxides are one of the most important components owing to their outstanding properties. Recent studies have integrated metal oxides with other materials to further improve sensor performance. This review focuses on the application of metal oxide-based hybrid structure in the glucose sensor, mainly including metal oxide/metal oxide, metal/metal oxide, and carbon material/metal oxide. The preparation method, electrochemical properties, and catalytic mechanism of the sensors are discussed in detail. Finally, we present some of the existing challenges and make personal predictions for the future development of non-enzymatic glucose sensors.

The saturation of nonenzymatic blood glucose sensors at lower than normal blood glucose levels has blocked their practical applications. The mechanistic understanding of the saturation, however, has long been under debate. Employing cyclic voltammetry, amperometry, and FTIR with various electrolytes of varying concentrations, we were able to uproot the saturation cause. It was found to be related to the hydroxide ion concentration, which must be 11 times greater than that of the glucose concentration, contrary to the prior understanding. Together with the satisfactory sensitivity at high pH, nonenzymatic blood glucose sensing has finally been achieved, eliminating the usual problem of electrochemical current saturation as well as the need for enzyme found in the present technology.

Metal organic frameworks derived hybrid microspheres consisted of Ni3N and nitrogen-doped carbon were prepared by a facile in situ nitridation process. The as prepared Ni3N@C electrocatalysts displ...

Glucose sensors have transformed diabetes control. Most glucose sensors are enzymatic, but a non-enzymatic metal oxide-based glucose sensor on a nanostructured substrate is of considerable interest for future always-on wearable closed-loop sensing for hypoglycemia management. Recently, various research groups have demonstrated that different nanostructured substrates (fabricated by a variety of innovative techniques) boost the sensitivity of non-enzymatic glucose sensor. In this work, we develop a physics-based model to correlate the geometrical and chemical design parameters to the non-linear amperometric response of non-enzymatic glucose sensor on geometrically complex substrates. Using this model, we can interpret the scattered results in the literature within a common conceptual framework. Our results show that while non-enzymatic glucose sensor still does not have sufficient dynamic range to replace the classical blood glucose sensors, these sensors could be useful for low concentration glucose sensing applications involving sweat, saliva, and ocular fluid. Our model will predictably improve the design of non-enzymatic glucose sensors for the integration into a continuous glucose monitoring system embedded in wearable and implantable platforms.

Analytical performance and tissue interactions of nitric oxide (NO)-releasing continuous glucose sensors were evaluated over a 28 d study in a diabetic swine model. Interstitial glucose was detected using an implanted needle-type amperometric glucose sensor. Two NO-release durations from the sensor surface were achieved by doping the membranes with nonporous (14 d release) or porous (30 d release) S-nitrosothiol-functionalized silica nanoparticles. Numerical and clinical accuracy of the sensors were assessed at time points (1, 7, 14, 21, and 28 d) following implantation. Nitric oxide-releasing sensors demonstrated accurate glucose detection over a time period directly correlated with the active release of NO. Silica particle-doped sensors that released NO for 30 d showed standard-compliant accuracy (i.e., mean absolute relative difference ≤ 15%) for >3 weeks post-implantation. Histological staining for inflammatory biomarkers suggested that the observed performance improvement was the result of decreased inflammatory cell count and a lower density collagen capsule.

More than five decades have been invested in understanding glucose biosensors. Yet, this immensely versatile field has continued to gain attention from the scientific world to better understand and diagnose diabetes. However, such extensive work done to improve glucose sensing devices has still not yielded desirable results. Drawbacks like the necessity of the invasive finger‐pricking step and the lack of optimization of diagnostic interventions still need to be considered to improve the testing process of diabetic patients. To upgrade the glucose‐sensing devices and reduce the number of intermediary steps during glucose measurement, fourth‐generation glucose sensors (FGGS) have been introduced. These sensors, made using robust electrocatalytic copper nanostructures, improve diagnostic efficiency and cost‐effectiveness. This review aims to present the essential scientific progress in copper nanostructure‐based FGGS in the past 10 years (2010 to present). After a short introduction, we presented the working principles of these sensors. We then highlighted the importance of copper nanostructures as advanced electrode materials to develop reliable real‐time FGGS. Finally, we cover the advantages, shortcomings, and prospects for developing highly sensitive, stable, and specific FGGS.

Rapid glucose testing is very important in the care of diabetes. Monitoring of blood glucose is the most critical indicator of disease control in diabetic patients. The invention and popularity of electrochemical sensors have made glucose detection fast and inexpensive. The first generation of glucose sensors had limitations in terms of sensitivity and selectivity. In order to overcome these problems, scientists have used a range of new materials to produce new glucose electrochemical sensors with higher sensitivity, selectivity and lower cost. A variety of different electrochemical sensors including enzymatic electrochemical sensors and enzyme-free electrochemical sensors have been extensively investigated. We discussed the development process of electrochemical glucose sensors in this review. We focused on describing the benefits of carbon materials in nanomaterials, specially graphene for sensors. In addition, we discussed the limitations of the sensors and challenges in future research.

A comprehensive review of the electroactive materials for non-enzymatic glucose sensing and sensing devices has been performed in this work. A general introduction for glucose sensing, a facile electrochemical technique for glucose detection, and explanations of fundamental mechanisms for the electro-oxidation of glucose via the electrochemical technique are conducted. The glucose sensing materials are classified into five major systems: (1) mono-metallic materials, (2) bi-metallic materials, (3) metallic-oxide compounds, (4) metallic-hydroxide materials, and (5) metal-metal derivatives. The performances of various systems within this decade have been compared and explained in terms of sensitivity, linear regime, the limit of detection (LOD), and detection potentials. Some promising materials and practicable methodologies for the further developments of glucose sensors have been proposed. Firstly, the atomic deposition of alloys is expected to enhance the selectivity, which is considered to be lacking in non-enzymatic glucose sensing. Secondly, by using the modification of the hydrophilicity of the metallic-oxides, a promoted current response from the electro-oxidation of glucose is expected. Lastly, by taking the advantage of the redistribution phenomenon of the oxide particles, the usage of the noble metals is foreseen to be reduced.

A patterned photonic array chip based on an intertwined polymer network (IPN) is proposed for the visual detection of glucose. The IPN networks are composed of photonic and poly(acrylic acid) (PAA) networks. Aminophenylboronic acid, as a nonenzymatic glucose-responsive moiety that can covalently bond to glucose at alkaline pH, forming tetragonal complexes, is immobilized in the PAA network; in hydrogels, this bonding generates Donnan osmotic pressure, resulting in a volumetric increase of the photonic IPN and reflected color change. The photonic band gap wavelength linearly increases with the glucose concentration (in the 1-12 mM range), with a limit of detection of 0.35 mM. The dots of the photonic IPN array respond independently, with high sensitivity and stability, to glucose via color changes; different glucose levels, from hypo- to hyperglycemia, can be visually detected in this way. Serum samples spiked with different glucose concentrations were tested for practical evaluation of the chip. The proposed chip could be utilized as a new biosensor platform for cost-effective and easy visual detection in remote areas, without the need of advanced instruments or technology.

The X-ray structure of the catalytic subunit of Burkholderia cepacia FAD glucose dehydrogenase complexed with a hitchhiker protein was determined as a representative molecule of direct electron transfer-type FAD-dependent dehydrogenase complexes. The 3Fe–4S cluster is present at the surface of the catalytic subunit and serves in the intramolecular and intermolecular electron transfer from FAD to the electron-transfer subunit., The bacterial flavin adenine dinucleotide (FAD)-dependent glucose dehydrogenase complex derived from Burkholderia cepacia (BcGDH) is a representative molecule of direct electron transfer-type FAD-dependent dehydrogenase complexes. In this study, the X-ray structure of BcGDHγα, the catalytic subunit (α-subunit) of BcGDH complexed with a hitchhiker protein (γ-subunit), was determined. The most prominent feature of this enzyme is the presence of the 3Fe–4S cluster, which is located at the surface of the catalytic subunit and functions in intramolecular and intermolecular electron transfer from FAD to the electron-transfer subunit. The structure of the complex revealed that these two molecules are connected through disulfide bonds and hydrophobic interactions, and that the formation of disulfide bonds is required to stabilize the catalytic subunit. The structure of the complex revealed the putative position of the electron-transfer subunit. A comparison of the structures of BcGDHγα and membrane-bound fumarate reductases suggested that the whole BcGDH complex, which also includes the membrane-bound β-subunit containing three heme c moieties, may form a similar overall structure to fumarate reductases, thus accomplishing effective electron transfer.

At the point of care (POC), on-side clinical testing allows fast biomarkers determination even in resource-limited environments. Current POC systems rely on tests selective to a single analyte or complex multiplexed systems with important portability and performance limitations. Hence, there is a need for handheld POC devices enabling the detection of multiple analytes with accuracy and simplicity. Here we present a reconfigurable smartphone-interfaced electrochemical Lab-on-a-Chip (LoC)with two working electrodes for dual analyte determination enabling biomarkers' selection in situ and on-demand. Biomarkers selection was achieved by the use of electrodepositable alginate hydrogels. Alginate membranes containing either glucose oxidase (GOx)or lactate oxidase (LOx)were selectively electrodeposited on the surface of each working electrode in around 4 min, completing sample measurement in less than 1 min. Glucose and lactate determination was performed simultaneously and without cross-talk in buffer, fetal bovine serum (FBS)and whole blood samples, the latter being possible by the size-exclusion filtration capacity of the hydrogels. At optimal conditions, glucose and lactate were determined in a wide linear range (0–12 mM and 0–5 mM, respectively)and with high sensitivities (0.24 and 0.54 μA cm −2 mM −1 , respectively), which allowed monitoring of Type-1 diabetic patients with a simple dual analysis system. After the measurement, membranes were removed by disaggregation with the calcium-chelator phosphate buffer. At this point, new membranes could be electrodeposited, this time being selective to the same or another analyte. This conferred the system with on-demand biomarkers’ selection capacity. The versatility and flexibility of the current architecture is expected to impact in POC analysis in applications ranging from homecare to sanitary emergencies.

Background: Isobornyl acrylate (IBOA) has recently been identified as one sensitizer in the FreeStyle Libre glucose sensor. Analyses with gas chromatography-mass spectrometry (GC-MS) have indicated the presence of N,N-dimethylacrylamide (DMAA) in the sensor. Material and methods: Seven patients were referred for patch testing after developing skin reactions when using FreeStyle Libre. All patients were patch tested with IBOA and DMAA. Two patients were tested with adhesive patches that had been removed from the sensors “as is,” and two patients were tested with acetone extracts of materials from the sensor. The extracts were analysed with GC-MS. Results: Six patients reacted to both IBOA and DMAA, and one patient reacted only to DMAA. Positive reactions were also observed in both patients tested with the adhesive patch "as is". One patient reacted to both an extract of the adhesive patch and an extract of the sensor itself. When analysed with GC-MS, IBOA was found in both extracts and DMAA was found in the extract of the sensor. Conclusion: Both IBOA and DMAA may be present in adhesives used in medical devices such as glucose sensors or insulin pumps, and should be patch tested when suspected contact allergic reactions to these products are investigated. (Less)

Ultrathin two-dimensional NiS/Ni(OH)2 nanosheets (NiS/Ni(OH)2 NSs) were successfully filled within the hollow interiors of ammonium polyacrylate-functionalized polypyrrole nanotubes (NH4PA/PPyNTs) by a simple solvothermal method. This kind of novel hierarchical nanostructures with typical structural features of a nanoconfined system, denoted by NiS/Ni(OH)2/NH4PA/PPyNTs, were prepared by two main sections: polyacrylic acid (PAA) was first polymerized on PPyNTs containing vinyl groups, and the obtained PAA/PPyNTs exhibited a typical Janus structure, whose external surface was covered with carboxyl groups and the internal surface was still covered with PPy chains; second, Ni2+ ions as a precursor were facilely combined with -NH- segments in PPy chains by the coordination interaction under the solvothermal environment; therefore, NiS/Ni(OH)2 NSs (

BODIPY dyes are strongly fluorescent small molecules widely used in fluorescence sensing various analytes. In this study, 8-chloromethyl-2,6-diethyl-4,4-difluoro-1,3,5,7-tetramethyl-4-bora-3a,4a-diaza-s-indacene (BODIPY-CH2Cl) was successfully synthesized and used as a sensing platform in a 96-well microplate. After synthesis, commercial 96-well microplate surfaces covered with Poly-D-Lysine layer were modified with BODIPY. Glucose oxidase (GOx) was selected as a model enzyme to test the applicability of the BODIPY-coated surface as a fluorescence sensing platform. Since oxygen acts as a quencher for BODIPY, the addition of substrate to modified surfaces caused oxygen depletion and resulted in a quick increase fluorescence intensity. The increments were in proportion to the glucose concentration. Using these data, a linear graph was obtained between 0.0025 and 0.1 mM glucose with a LOD of 2.19 µM. There was no interference effect of some compounds, such as uric acid, ascorbic acid, phenols, and ethanol on sensing. Glucose detection in various complex matrices was carried out. © 2018 Elsevier Ltd

Diabetes mellitus is a chronic disease and leading cause of death worldwide, affecting more than 420 million people. High blood glucose levels are a common effect of uncontrolled diabetes, which can cause serious health damage. Diabetic individuals must measure their blood glucose levels regularly in order to control glycemic levels and minimize the effects of the disease. Glucose sensors have been used in the management of diabetes for more than 50 years, when Clark and Ann Lyons developed the first glucose enzyme electrode in 1962. Electrochemical sensors have become the leading technology for glucose concentration measuring with most of the commercially available devices being based on amperometric detection. However, the detection of glucose in the blood is still an object of intense research. The development of new fluorescent nanomaterials begins to constitute an alternative for glucose blood quantification. These sensors include carbon dots, quantum dots, graphene quantum dots, gold, silver and upconversion nanoparticles. This paper reviews the last 10 year fluorescent nanoparticles based technologies proposed for glucose monitoring and provide an insight into emerging optical fluorescence glucose biosensors.

Chemosensory signaling in organs such as the mouth and gut contributes to the mechanisms that control metabolism. We investigated the chemosensory pathways that regulate secretion of the hunger hormone ghrelin in response to neurotransmitters, bitter and sweet tastants at the cellular level in the human gut mucosa, and the disturbances in this regulatory pathway induced by obesity. Obesity impaired ghrelin protein production and adrenalin-induced ghrelin secretion in fundic cells, which was counterbalanced by somatostatin. Bitter agonists selective for taste receptor type 2 (TAS2Rs), TAS2R5 and TAS2R10 stimulated ghrelin secretion in fundic cells. The stimulatory effect of the broadly tuned bitter agonist, denatonium benzoate, was selectively blunted by obesity in the small intestine but not in the fundus. Luminal glucose concentrations inhibited ghrelin secretion via sodium-dependent glucose cotransporter and taste receptor type 1 member 3. Obesity altered the sensitivity of the ghrelin cell to glucose in the small intestine but not in the fundus. Sweet taste receptor activation inhibited bitter taste signaling of the ghrelin cell. In conclusion, obesity impairs the sympathetic drive that controls ghrelin release in the fundus and affects the sensitivity of the ghrelin cell to bitter and sweet stimuli in the small intestine but not in the fundus. Region-selective targeting of gut taste receptors in obesity is indicated.-Wang, Q., Liszt, K. I., Deloose, E., Canovai, E., Thijs, T., Farré, R., Ceulemans, L. J., Lannoo, M., Tack, J., Depoortere, I. Obesity alters adrenergic and chemosensory signaling pathways that regulate ghrelin secretion in the human gut. ispartof: FASEB JOURNAL vol:33 issue:4 pages:4907-4920 ispartof: location:United States status: published

Fertility hormone levels are constantly changing, but it is crucial for a woman to be able to monitor her fertility levels if she is interested in conceiving. Women and physicians often have a difficult time determining ovulation windows due to fluctuating menstrual cycles and inaccurate interpretations of hormone levels. Current methods of fertility monitoring include physical or vaginal exams, laparoscopy, ultrasound scans, as well as evaluation of hormone levels. A rapid, at-home fertility monitoring tool can help alleviate the apprehensiveness associated with routine screenings and give women the privacy desired when trying to conceive. Herein, we discuss the development of an electrochemical biosensor for quantification of three fertility hormones: beta-estradiol, progesterone, and FSH. Each biomarker's MRE was immobilized onto a gold disk electrode through the use of self-assembled monolayer linking chemistry. Using electrochemical impedance spectroscopy (EIS), the biomarker concentration was correlated to impedance magnitude. An optimal binding frequency was identified for each biomarker, permitting simplistic hardware requirements and investigation into multimarker detection. Analytes were tested in both purified solutions and 1%-90% whole blood. Each biomarker exhibited a unique imaginary impedance peak and optimal binding frequency. The determination was made by assessing the response parameters including the linear fit correlation across the physiological hormone ranges. The existence of unique optimal frequencies permits for simultaneous detection of multiple hormones in a single test. Additionally, the identified frequency was robust across purified and complex solutions. Response characteristics were negatively impacted by the introduction of blood-based contaminants. However, the introduction of Nafion membranes, similar to ones used in commercial glucose sensors, is both feasible and beneficial.

In this work, a non-enzymatic electrochemical sensor platform was developed for catalyze of glucose using graphite electrode modifiedwithKeggin typeK7[CoIIICoII(H2O)W11O39].15H2O(Co-POM) and multi-walled carbon nanotube (MWCNT) composite. The Keggin type Co-POM composing of a unique mixed-valence Co(III) and Co(II) structures was confined in a matrix of MWCNT on graphite electrodes to improve the electron transfers. Cyclic voltammetry (CV) and amperometric measurements were performed to investigate the electroanalytical performance of the Co-POM/MWCNT composite for direct electrochemical oxidation of glucose. The proposed this non-enzymatic sensor platform showed a wide linear range from 0.1 mM to 10.0 mM (R = 0.9937) for detection of glucose. Besides it exhibited low detection limit of 1.21 ìM and fast response time of 6s and high sensitivity of 256.4 μAmM-1 cm-2. The results demonstrated that the proposed Co-POM/MWCNT based sensor platform has a high sensitivity, good stability, excellent selectivity, an enhanced electrocatalytic property and acceptable recovery. Therefore, Co-POM/MWCNT based sensor platform is promising potential application for the development of non-enzymatic sensor and catalyst applications. © 2019 The Electrochemical Society.

Glucose detection is of vital importance to diabetes diagnosis and treatment. Optical approaches in glucose sensing have received much attention in recent years due to the relatively low cost, portable, and mini-invasive or non-invasive potentials. Surface enhanced Raman spectroscopy (SERS) endows the benefits of extremely high sensitivity because of enhanced signals and specificity due to the fingerprint of molecules of interest. However, the direct detection of glucose through SERS was challenging because of poor adsorption of glucose on bare metals and low cross section of glucose. In order to address these challenges, several approaches were proposed and utilized for glucose detection through SERS. This review article mainly focuses on the development of surface enhanced Raman scattering based glucose sensors in recent 10 years. The sensing mechanisms, rational design and sensing properties to glucose are reviewed. Two strategies are summarized as intrinsic sensing and extrinsic sensing. Four general categories for glucose sensing through SERS are discussed including SERS active platform, partition layer functionalized surface, boronic acid based sensors, and enzymatic reaction based biosensors. Finally, the challenges and outlook for SERS based glucose sensors are also presented.

This review encompasses the mechanisms of electrochemical glucose detection and recent advances in non-enzymatic glucose sensors based on a variety of materials ranging from platinum, gold, metal alloys/adatom, non-precious transition metal/metal oxides to glucose-specific organic materials. It shows that the discovery of new materials based on unique nanostructures have not only provided the detailed insight into non-enzymatic glucose oxidation, but also demonstrated the possibility of direct detection in whole blood or interstitial fluids. We critically evaluate various aspects of non-enzymatic electrochemical glucose sensors in terms of significance as well as performance. Beyond laboratory tests, the prospect of commercialization of non-enzymatic glucose sensors is discussed.

We propose a new, simple and effective strategy to enhance the electro-catalytic activity by regulating the valence states of the electro-catalyst. The proportion of Ni3+/Ni2+ on the ammonium nickel phosphate/nickel foam electrode surface was increased after H2O2 solution treatment. The kinetic analysis results showed catalytic rate constants (Kcat) of Ni3+-rich surface electrode (4.028 × 106 cm3·mol−1·s−1) is bigger than the original electrode (4.928 × 105 cm3·mol−1·s−1), suggesting higher electro-catalytic activity of Ni3+-rich surface electrode. Ni3+-rich surface electrode shows an ultra high sensitivity (11,361 µA·mM−1·cm−2) in the range of 0.001–1 mM, which is much higher than the original electrode in the same linear range. And the sensitivity of 3579.9 µA·mM−1·cm−2 of Ni3+-rich surface electrode in the range of 2–4 mM is also enhanced compared with the original electrode.

The constant progress in novel nanomaterials synthesis has contributed to the rapid development of nonenzymatic glucose sensors. For working electrodes preparation, drop casting proved to be the most convenient and thus most widely applied method. However, appropriate interpretation of obtained electrochemical signal requires in-depth knowledge of limitations related to this technique. In this study, we prepared solutions based on commonly reported polymers for nanostructures immobilization and investigated their influence on copper sulfides distribution on the electrode. Characterization of suspensions properties and behavior of particles during droplet drying revealed that nonionic polyvinylpyrrolidone (PVP) was favorable for electrodes modification with copper sulfides in comparison with Nafion and chitosan. It ensured homogeneity of the suspension as well as the uniform coverage of the electrode surface with particles, what resulted in increased active surface area and, therefore, higher signal from glucose addition. On the other hand, when cationic chitosan was used as a binder, suspensions were agglomerated and, within dry deposits, a coffee-ring effect was observed. Appropriate adjustment of material and polymer interactions led to enhanced electrode electrochemical performance.

In recent years, glucose biosensors play an important role in diabetes detection. This paper describes a potentiometric non-enzymatic glucose biosensor. The sensor is modified by silver nanowires (Ag NWs) which are fabricated by the polyol method. Using the voltage-time (V-T) system and electrochemical impedance spectroscopy (EIS), the sensing characteristics of the sensor are analyzed and the impact of silver nanowires (Ag NWs) on the performance of the sensor are investigated.

Wound monitoring is essential to tackle chronic complications at their infancy and thus objectively scrutinize any delay in the epithelization process. Since glucose in wound exudates is recognized as key bio-marker in wound monitoring, the development of a cost-efficient detection method for glucose would aid at tackling early-stage infections in wounds. For the first time, we present a novel platform for one-step synthesis of non-enzymatic, cost-efficient optical glucose sensors. These are based on complexes formed by the interactions between polyborates and ethanolamines. The complexes, synthesized by just heating a solution of boric acid and ethanolamines at 150 °C, were characterized using 13C-NMR, 1H-NMR, 11B-NMR, analytical ultracentrifugation and DFT. The results show that the complexes in solution are extremely small (hydrodynamic diameter of around 0.5 nm) and that the polyborates species interact with the ethanolamines via both moderate and weak hydrogen bondings. These complexes were then tested on glucose concentrations ranging from 0 to 10 mM, showing significant changes in the fluorescent emission between the glucose level expressed in an healable wound (5.0–7.6 mM) and a chronic one (0.3–1.0 mM). published

In this study, novel Pd nanowire networks (PdNW) grown on three-dimensional polyaniline hydrogel (3D-PANI) were prepared via a facile one-step electrodeposition approach at a constant potential of − 0.2 V and further utilized as an electrochemical sensing material for sensitive determination of glucose in alkaline medium. Compared with the sensor based on Pd nanofilm (PdNF)/3D-PANI prepared by electrodeposition at − 0.9 V, the sensor based on PdNW/3D-PANI presented substantially enhanced electrocatalytic activity towards glucose oxidation, with an excellent sensitivity of 146.6 μA mM−1 cm−2, a linear range from 5.0 to 9800 μM, and a low detection limit of 0.7 μM and was, therefore, demonstrated to be available for the determination of glucose in human serum. These findings are likely attributed to the combination of advantages of both PdNW and 3D-PANI, which outperformed most other Pd-based non-enzymatic glucose sensors reported earlier. Moreover, this non-enzymatic electrochemical sensor based on PdNW/3D-PANI may serve as an alternative tool for the assay of glucose and possibly other biomolecules.

BACKGROUND: Concomitant positive patch test reactions in patients sensitized to isobornyl acrylate (IBOA) have rarely been documented. OBJECTIVES: To report concomitant sensitizations in patients with allergic contact dermatitis (ACD) from the glucose sensor FreeStyle Libre and sensitized to IBOA. METHODS: In 2019, 26 patients with suspected ACD from FreeStyle Libre were patch tested to a baseline series and to a (meth) acrylate series containing IBOA and 2-phenoxyethyl acrylate (PEA) 0.1% pet. Diabetes devices and patch test preparations were analyzed with gas chromatography - mass spectrometry (GC-MS) for the presence of IBOA and PEA. RESULTS: Of the 26 patients, 18 (69%) were sensitized to IBOA, and eight (44%) and 11 (61%) of these were co-sensitized to sesquiterpene lactones and fragrances, respectively. Ten patients (56%) were co-sensitized to PEA, which, contrary to IBOA, could not be detected in any device. The PEA test material was shown to be contaminated with IBOA. CONCLUSIONS: Contact allergy to IBOA appears to be declining and IBOA-sensitized patients are most often co-sensitized to sesquiterpene lactones and fragrances. Vigilance is required when patch testing (acrylate) materials obtained from industry, as these might be contaminated and, hence, alter the results and their interpretation. ispartof: CONTACT DERMATITIS vol:84 issue:3 pages:166-174 ispartof: location:England status: published

Using density functional theory (DFT) method, hexa-peri-hexabenzocoronene (HBC) and its central ring doped analogues (BN-HBC and AlN-HBC) were studied as non-enzymatic glucose sensors. The HOMO-LUMO energy gap (Eg) of pristine HBC and BN-HBC remain almost constant upon adsorption of GLU molecule, and therefore these nanographenes do not show electronic sensitivity toward GLU molecule. The Eg value of AlN-HBC decreases by about −18.48% after GLU adsorption and the electrical conductance of AlN-HBC turns out to be 1.2 × 105 times higher after adsorption of GLU molecule. AlN-HBC can behave as a selective sensor of GLU in the presence of FRU molecule.

This article deals with assessment of accuracy of the widely used glucose sensors MMT-7002 (Medtronic, USA), for continuous monitoring of glucose levels. The samples were gained from a 35-year-old sportswoman with diagnosed DM type 1. The sampling was carried out by her common daily as well as extreme physical and sport activities. The evaluated data were collected during 45 months, 56 sensors were used and 603 calibrations were carried out. The tested glucose sensor operates on the principle of a needle sensor, which electrochemically evaluates the reaction products catalyzed by glucose oxidase. Accuracy was evaluated by Clarke error grid analysis and the results were compared with the accuracy given by the sensor manufacturer. The measurements carried out by the tested sensor in the range of the normal glucose levels, realized under usual life conditions and by sport activities were even more accurate than those given by the manufacturer. However, in the regions of hypoglycemia or hyperglycemia, the number of errors was higher than specified by the manufacturer. The continuous glucose monitoring proved to be sufficiently accurate for prevention of acute complications in patients with DM type 1 during their common as well as extreme sport and physical activities.

The growing recent interest in wearable and mobile technologies has led to increased research efforts toward development of non-invasive glucose monitoring platforms. Continuous glucose monitoring addresses the limitations of finger-stick blood testing and provides the opportunity for optimal therapeutic interventions. This article reviews recent advances and challenges toward the development of non-invasive epidermal electrochemical glucose sensing systems. Recent reports claim success in glucose monitoring in human subjects using skin-worn electrochemical sensors. Such epidermal electrochemical biosensors obviate the disadvantages of minimally-invasive subcutaneous glucose biosensors and offer promise for improved glycemic control. The ability of such systems to monitor glucose non-invasively offers an attractive route toward advancing the management of diabetes and achieving improved glycemic control. However, realizing the potential diagnostic impact of these new epidermal sensing strategies would require extensive efforts toward addressing key technological challenges and establishing a reliable correlation to gold standard blood glucose meters.

The diversity of materials proposed for non-enzymatic glucose detection and the lack of standardized protocols for assessing sensor performance have caused considerable confusion in the field. Therefore, methods for pre-evaluation of working electrodes, which will enable their conscious design, are currently intensively sought. Our approach involved comprehensive morphologic and structural characterization of copper sulfides as well as drop-casted suspensions based on three different polymers—cationic chitosan, anionic Nafion, and nonionic polyvinylpyrrolidone (PVP). For this purpose, scanning electron microscopy (SEM), X-ray diffraction (XRD), and Raman spectroscopy were applied. Subsequently, comparative studies of electrochemical properties of bare glassy carbon electrode (GCE), polymer- and copper sulfides/polymer-modified GCEs were performed using electrochemical impedance spectroscopy (EIS) and voltammetry. The results from EIS provided an explanation for the enhanced analytical performance of Cu-PVP/GCE over chitosan- and Nafion-based electrodes. Moreover, it was found that the pH of the electrolyte significantly affects the electrocatalytic behavior of copper sulfides, indicating the importance of OHads in the detection mechanism. Additionally, diffusion was denoted as a limiting step in the irreversible electrooxidation process that occurs in the proposed system.

CuO nanorods supported Pd nanoparticles (CuO-Pd) are fabricated as highly active electrocatalysts. The current density for CuO-Pd is ca. 3.7 times than that of CuO and ca. 129.3 times of Cu(OH)2-Pd precursor towards glucose detection. Moreover, the CuO-Pd nanorods also display low detection limit, high sensitivity, wide linear range, fast response, high stability and anti-interference performance for glucose detection. The excellent electrocatalytic performance of CuO-Pd nanorods might be ascribed to the synergistic effect of CuO and noble metal Pd, which is promising for applications as nonenzymatic glucose sensors.

As populations expand worldwide, medical care will need to diversify its data collection techniques to be able to provide adequate healthcare to global populations, this could be achieved through point-of-care analysis by wearable analytical devices. Holographic sensors are reusable optical biosensors with the capability to continuously monitor variations, generating the prospect of in vivo monitoring of patient homeostasis. Holographic optical sensors have emerged as an opportunity for low cost and real-time point-of-care analysis of biomarkers to be realised. This review aims to summarise the fundamentals and fabrications of holographic sensors; a key focus will be directed to examining the biotechnology applications in a variety of analytical settings. Techniques covered include surface relief gratings, inverse opals, metal nanoparticle and nanoparticle free holographic sensors. This article provides an overview of holographic biosensing in applications such as pH, alcohol, ion, glucose, and drug detection, alongside antibiotic monitoring. Details of developments in fabrication and sensitising techniques will be examined and how they have improved the applicability of holographic sensors to point-of-care analytics. Although holographic sensors have made significant progress in recent years, the current challenges, and requirements for advanced holographic technology to fulfil their future potential applications in biomedical devices will be discussed.

It is of great significance to prepare electrochemical glucose sensors with high selectivity and stability via effective and rapid methods. In this work, the self-support electrode with copper and nickel-based oxide is prepared by chemical-etching reaction which occurred under the property of electrochemical potential difference. In this processing, nickel foam is etched selectively by Cu[Formula: see text] ions and they not only act as self-supporting electrode substrate, but also as nickel ions precursor of NiO. Moreover, the reaction can be completely satisfied on 30 min at room temperature. As a self-supporting electrode nonenzymic glucose electrochemical sensor, the electrode exhibited a wide linear range (0.04–3.00[Formula: see text]mM), low detection limit (0.02[Formula: see text]mM) with high sensitivity of 1096[Formula: see text][Formula: see text] and good selectivity, repeatability and stability. Furthermore, the application of the prepared sensor provides an avenue for the application of the transition metal materials in the field of electrochemical sensing.

Chemiluminescence (CL) has been widely applied in many fields, but it is rarely used in a very simple, economical but effective way. In this work, for the first time, the CL cloth-based glucose test sensors (CCGTSs) are developed as a new class of CL glucose sensors, with no need for complicated, expensive device fabrication and peripheral equipment. When integrated with desirable hydrophobic barrier in the flow channel and gravity/capillary flow induced by a difference in height between the loading zone and the detection zone, a single cloth-based device can perform the whole CL process involving two steps of enzyme reactions. The wax screen-printing approach is used to fabricate ultra-cheap CCGTSs, the glucose detection involves the enzymatic oxidation of glucose to gluconic acid and H 2 O 2 followed by the horseradish peroxidase (HRP)-catalyzed oxidation of luminol by H 2 O 2 , and the emitted CL signals are heightened with p-iodophenol (PIP) and imaged using an inexpensive, portable CCD camera. Under optimized conditions, glucose can be determined over the range of 0.1–100 mM, with a detection limit of 0.0948 mM and an analysis time of less than 5.5 min. Finally, the applicability and validity of the CCGTSs are demonstrated for the measurement of glucose in clinical urine and serum samples. Thus, the proposed sensors could provide great promise in applications in many areas, and may facilitate the achievement of point-of-care testing.

A new unsymmetrical zinc(ii) phthalocyanine (ZnPc2) bearing one EDOT group was efficiently synthesized as a monomer through the statistical condensation reaction. The other products of mixed cyclotetramerization ZnPc1, ZnPc3 and ZnPc4 were also isolated. Obtained ZnPc2 is a good precursor for the synthesis of new functional linear electropolymers. This was approved by the successful electrochemical copolymerization reaction between ZnPc2 and SNS type monomer HKCN in which the amino group was desired for the enzyme immobilization. The electrochromic and glucose sensing properties of copolymer P(ZnPc2-co-HKCN) obtained by electrochemical oxidative polymerization were investigated. Based on spectroelectrochemical studies, the P(ZnPc2-co-HKCN) copolymer showed a greenish yellow colour in the reduced state and a dark blue colour in the oxidized state as a film. An optical contrast ratio of 44% at 471 nm was achieved with a fast switching time (2.5 s). Meanwhile, the novel biosensor constructed from P(ZnPc2-co-HKCN) showed a linear amperometric response to glucose within a concentration range of 0.1 mM to 1.5 mM (LOD: 0.049 mM). These data illustrate the possible use of the P(ZnPc2-co-HKCN) modified electrode as an amperometric glucose sensor. © 2017 The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.

With the growing demand of miniaturization of cell cultivation a new approach towards measuring and sensing bio-analytes needs to be made due to the problem of small volumes (less than 150μl) containing small amounts of analytes. Most of the available glucose sensors monitor the glucose concentration with the help of enzymes, which become very inaccurate in terms of long time measurement and uses (i.e. consumes) glucose during the measurement becoming not available anymore for the cells. Therefore, we focused on applying an enzyme-free glucose sensor based on a microelectromechanical system (MEMS).

Continuous glucose monitoring from sweat and tears can improve the quality of life of diabetic patients and provide data for more accurate diagnosis and treatment. Current continuous glucose sensors use enzymes with a one-to-two week lifespan, which forces periodic replacement. Metal oxide sensors are an alternative to enzymatic sensors with a longer lifetime. However, metal oxide sensors do not operate in sweat and tears because they function at high pH (pH > 10), and sweat and tears are neutral (pH = 7). Here, we introduce a non-enzymatic metal oxide glucose sensor that functions in neutral fluids by electronically inducing a reversible and localized pH change. We demonstrate glucose monitoring at physiologically relevant levels in neutral fluids mimicking sweat, and wireless communication with a personal computer via an integrated circuit board.

International audience; There is still a growing interest in developing glucose sensors using glucose oxidase. Since 2012, over 1000 papers are published every year, while efficient commercial sensors exist on the market. Among those glucose sensors, few have been thought and well-engineered and do not solve the problems associated with glucose oxidase; among which the O 2 sensitivity of the enzyme or the competition between O 2 and redox mediators for GOx's electrons. Enzyme engineering has been employed to solve those issues but screening GOx in homogeneous solution with O 2 as an electron acceptor is not suitable. Very few reports describe the specific reengineering of GOx for electrochemical applications and are the subject of this review. It starts with a brief presentation of glucose oxidase and presents the recent progress in glucose oxidase reengineering by highlighting the kind of engineering/mutations performed to increase its electron transfer rate to electrode surfaces and, to decrease its O 2 sensitivity. In addition, the review highlights the need to develop new screening methods involving electrochemical probing, essential to develop the next generation of glucose sensors; specific to glucose, O 2 independent, biocompatible and stable over 2 weeks.

Diabetes is a chronic disease, which can give serious damages to the human organs that affect life expectancy. Such a life-threatening diabetes is diagnosed by systematic monitoring of blood glucose levels; thus, accurate detection of glucose within a specified target range becomes more important for glucose sensor to provide detailed information relating with diabetes, which can result in reliable decision for diabetes treatment. Thanks to many efforts developing the reliable glucose sensors, electrochemical performance of the sensor including sensitivity and selectivity in response to glucose is gradually improved. Herein, we developed spinel type NiCo2O4 (NCO) nanostructure with excellent sensitivity, selectivity and chemical robustness for glucose detection. NCO was prepared by conversion of NiCo-layered double hydroxide (NCH) at comparatively low temperature, which is synthesized by simple and facile chemical bath method and following post-heat treatment of the NCH. Electrochemical sensitivity, selectivity and detection time of the NCO in response to glucose was investigated, compared to those of the NCH. Also, long-term stability of the NCO on repetitive glucose detection was evaluated. Based on the systematic analysis on materials properties and electrochemical performance of the NCO, possible mechanism of the glucose oxidation, which significantly improves electrochemical performance of the NCO, is discussed.