AuNi bimetallic aerogel with ultra-high stability applied in smart and portable biosensing.

Glucose detection is of significant importance in providing information to the human health management. However, conventional enzymatic glucose sensors suffer from a limited long-term stability due to the losing activity of the enzymes. In this work, the AuNi bimetallic aerogel with a well-defined nanowire network is synthesized and applied as the sensing nanomaterial in the non-enzymatic glucose detection. The three-dimensional (3D) hierarchical porous structure of the AuNi bimetallic aerogel ensures the high sensitivity of the sensor (40.34 µA mM-1 cm-2). Theoretical investigation unveiled the mechanism of the boosting electrocatalytic activity of the AuNi bimetallic aerogel toward glucose. A better adhesion between the sensing nanomaterial and the screen-printing electrodes (SPEs) is obtained after the introduction of Ni. On the basis of a wide linearity in the range of 0.1-5 mM, an excellent selectivity, an outstanding long-term stability (90 days) as well as the help of the signal processing circuit and an M5stack development board, the as-prepared glucose sensor successfully realizes remote monitoring of the glucose concentration. We speculate that this work is favorable to motivating the technological innovations of the non-enzymatic glucose sensors and intelligent sensing devices.

Unravelling caramelization and Maillard reactions in glucose and glucose + leucine model cakes: Formation and degradation kinetics of volatile markers extracted during baking.

A large number of volatile compounds are formed during the baking of foods by reactions such as caramelization and Maillard reactions. Elucidating the reaction mechanisms may be useful to predict and control food quality. Ten reaction volatile markers were extracted during baking of solid model cakes implemented with known amounts of precursors (glucose with or without leucine) and then quantified by Thermal desorption-Gas chromatography-Mass spectrometry. The kinetic data showed that the level of air convection in the oven had no significant influence on the reaction rates. In contrast, increasing baking temperatures had a nonlinear accelerating impact on the generation of newly formed volatile compounds with a bell-shaped kinetic curve found for most of the markers at 200 °C. The presence of leucine triggered the activation of the Maillard and Strecker routes with a specific and very rapid formation of 3-Methylbutanal and pyrazines. A dynamic model was developed, combining evaporation flow rate and kinetic formation and consumption of reaction markers. It can be used to describe, for two furanic compounds of different volatilities, the vapor concentrations in the oven from the concentrations measured in the model cakes.

Optimized Fabrication of Carbon-Fiber Microbiosensors for Codetection of Glucose and Dopamine in Brain Tissue.

Dopamine (DA) signaling is critically important in striatal function, and this metabolically demanding process is fueled largely by glucose. However, DA and glucose are typically studied independently and, as such, the precise relationship between DA release and glucose availability remains unclear. Fast-scan cyclic voltammetry (FSCV) is commonly coupled with carbon-fiber microelectrodes to study DA transients. These microelectrodes can be modified with glucose oxidase (GOx) to generate microbiosensors capable of simultaneously quantifying real-time and physiologically relevant fluctuations of glucose, a nonelectrochemically active substrate, and DA, which is readily oxidized and reduced at the electrode surface. A chitosan hydrogel can be electrodeposited to entrap the oxidase enzyme on the sensor surface for stable, sensitive, and selective codetection of glucose and DA using FSCV. This strategy can also be used to entrap lactate oxidase on the carbon-fiber surface for codetection of lactate and DA. However, these custom probes are individually fabricated by hand, and performance is variable. This study characterizes the physical nature of the hydrogel and its effects on the acquired electrochemical data in the detection of glucose (2.6 mM) and DA (1 µM). The results demonstrate that the electrodeposition of the hydrogel membrane is improved using a linear potential sweep rather than a direct step to the target potential. Electrochemical impedance spectroscopy data relate information on the physical nature of the electrode/solution interface to the electrochemical performance of bare and enzyme-modified carbon-fiber microelectrodes. The electrodeposition waveform and scan rate were characterized for optimal membrane formation and performance. Finally, codetection of both DA/glucose and DA/lactate was demonstrated in intact rat striatum using probes fabricated according to the optimized protocol. Overall, this work improves the reliable fabrication of carbon-fiber microbiosensors for codetection of DA and important energetic substrates that are locally delivered to the recording site to meet metabolic demand.

Homochiral light-sensitive metal-organic framework photoelectrochemical gated transistor for enantioselective discrimination of monosaccharides.

As pure antipodes may differ in biological interactions, pharmacology, and toxicity, discrimination of enantiomers is important in the pharmaceutical and agrochemical industries. Two major challenges in enantiomer determination are transducing and amplifying the distinct chiral-recognition signals. In this study, a light-sensitive organic photoelectrochemical transistor (OPECT) with homochiral character is developed for enantiomer discrimination. Demonstrated with the discrimination of glucose enantiomers, the photoelectrochemically active gate electrode is prepared by integrating Au nanoparticles (AuNPs) and a chiral Cu(II)-metal-organic framework (c-CuMOF) onto TiO2 nanotube arrays (TNT). The captured glucose enantiomers are oxidized to hydrogen peroxide (H2O2) by the oxidase-mimicking AuNPs-loaded c-CuMOF. Based on the confinement effect of the mesopocket structure of the c-CuMOF and the remarkable charge transfer ability of the 1D nanotubular architecture, variations in H2O2 yield are translated into significant changes in OPECT drain currents (ID) by inducing a catalytic precipitation reaction. Variations in ID confer a sensitive discrimination of glucose enantiomers with a limit of detection (LOD) of 0.07 µM for L-Glu and 0.05 µM for D-Glu. This enantiomer-driven gate electrode response strategy not only provides a new route for enantiomer identification, but also helps to understand the origin of the high stereoselectivity in living systems.

Early feasibility study with an implantable near-infrared spectroscopy sensor for glucose, ketones, lactate and ethanol.

OBJECTIVE: To evaluate the safety and performance of an implantable near-infrared (NIR) spectroscopy sensor for multi-metabolite monitoring of glucose, ketones, lactate, and ethanol. RESEARCH DESIGN AND METHODS: This is an early feasibility study (GLOW, NCT04782934) including 7 participants (4 with type 1 diabetes (T1D), 3 healthy volunteers) in whom the YANG NIR spectroscopy sensor (Indigo) was implanted for 28 days. Metabolic challenges were used to vary glucose levels (40-400 mg/dL, 2.2-22.2 mmol/L) and/or induce increases in ketones (ketone drink, up to 3.5 mM), lactate (exercise bike, up to 13 mM) and ethanol (4-8 alcoholic beverages, 40-80g). NIR spectra for glucose, ketones, lactate, and ethanol levels analyzed with partial least squares regression were compared with blood values for glucose (Biosen EKF), ketones and lactate (GlucoMen LX Plus), and breath ethanol levels (ACE II Breathalyzer). The effect of potential confounders on glucose measurements (paracetamol, aspartame, acetylsalicylic acid, ibuprofen, sorbitol, caffeine, fructose, vitamin C) was investigated in T1D participants. RESULTS: The implanted YANG sensor was safe and well tolerated and did not cause any infectious or wound healing complications. Six out 7 sensors remained fully operational over the entire study period. Glucose measurements were sufficiently accurate (overall mean absolute (relative) difference MARD of 7.4%, MAD 8.8 mg/dl) without significant impact of confounders. MAD values were 0.12 mM for ketones, 0.16 mM for lactate, and 0.18 mM for ethanol. CONCLUSIONS: The first implantable multi-biomarker sensor was shown to be well tolerated and produce accurate measurements of glucose, ketones, lactate, and ethanol. TRIAL REGISTRATION: Clinical trial identifier: NCT04782934.

All-printed wearable biosensor based on MWCNT-iron oxide nanocomposite ink for physiological level detection of glucose in human sweat.

Wearable sensors for sweat glucose monitoring are gaining massive interest as a patient-friendly and non-invasive way to manage diabetes. The present work offers an alternative on-body method employing an all-printed flexible electrochemical sensor to quantify the amount of glucose in human sweat. The working electrode of the glucose sensor was printed using a custom-formulated ink containing multi-walled carbon nanotube (MWCNT), poly (3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOPT: PSS), and iron (II, III) oxide (Fe3O4) nanoparticles. This novel ink composition has good conductivity, enhanced catalytic activity, and excellent selectivity. The working electrode was modified using Prussian blue (PB) nanoparticles and glucose oxidase enzyme (GOx). The sensor displayed a linear chronoamperometric response to glucose from 1 µM to 400 µM, with a precise detection limit of ∼0.38 µM and an impressive sensitivity of ∼4.495 µAµM-1cm-2. The sensor stored at 4 °C exhibited excellent stability over 60 days, high selectivity, and greater reproducibility. The glucose detection via the standard addition method in human sweat samples acquired a high recovery rate of 96.0-98.6%. Examining human sweat during physical activity also attested to the biosensor's real-time viability. The results also show an impressive correlation between glucose levels obtained from a commercial blood glucose meter and sweat glucose concentrations. Remarkably, the present results outperform previously published printed glucose sensors in terms of detection range, low cost, ease of manufacturing, stability, selectivity, and wearability.

Synergistic enhancement of wearable biosensor through Pt single-atom catalyst for sweat analysis.

Real-time monitoring of biological markers in sweat is a valuable tool for health assessment. In this study, we have developed an innovative wearable biosensor for precise analysis of glucose in sweat during physical activities. The sensor is based on a single-atom catalyst of platinum (Pt) uniformly dispersed on tricobalt tetroxide (Co3O4) nanorods and reduced graphene oxide (rGO), featuring a unique three-dimensional nanostructure and excellent glucose electrocatalytic performance with a wide detection range of 1-800 µM. Additionally, density functional theory calculations have revealed the synergetic role of Pt active sites in the Pt single-atom catalyst (Co3O4/rGO/Pt) in glucose adsorption and electron transfer, thereby enhancing sensor performance. To enable application in wearable devices, we designed an S-shaped microfluidic chip and a point-of-care testing (POCT) device, both of which were validated for effectiveness through actual use by volunteers. This research provides valuable insights and innovative approaches for analyzing sweat glucose using wearable devices, contributing to the advancement of personalized healthcare.

Self-powered biosensing sutures for real-time wound monitoring.

Effective wound management has the potential to reduce both the duration and cost of wound healing. However, traditional methods often rely on direct observation or complex and expensive biological testing to monitor and evaluate the invasive damage caused by wound healing, which can be time-consuming. Biosensors offer the advantage of precise and real-time monitoring, but existing devices are not suitable for integration with sensitive wound tissue due to their external dimensions. Here, we have designed a self-powered biosensing suture (SPBS) based on biofuel cells to accurately monitor glucose concentration at the wound site and promote wound healing. The anode of the SPBS consists of carbon nanotubes-modified carbon fibers, tetrathiafulvalene (TTF), and glucose oxidase (GOx), while the cathode is composed of Ag2O and carbon nanotubes modified nanotubes modified carbon fibers. It was observed that SPBS exhibited excellent physical and chemical stability in vitro. Regardless of different bending degrees or pH values, the maximum power density of SPBS remained above 92%, which is conducive to long-term dynamic evaluation. Furthermore, the voltage generated by SPBS reflects blood glucose concentration, and measurements at wound sites are consistent with those obtained using a commercially available blood glucose meter. SPBS achieves the healing effect of traditional medical sutures after complete healing within 14 days. It offers valuable insights for intelligent devices dedicated to real-time wound monitoring.

Controllable radical polymerization of TEMPO redox for stable and sensitive enzyme electrode interface.

Assembling functional molecules on the surface of an enzyme electrode is the most basic technique for constructing a biosensor. However, precise control of electron transfer interface or electron mediator on the electrode surface remains a challenge, which is a key step that affects the stability and sensitivity of enzyme-based biosensors. In this study, we propose the use of controllable free radical polymerization to grow stable 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) polymer as electron mediator on enzyme surface for the first time. Through scanning electron microscopy (SEM), Raman spectroscopy, electrode surface coverage measurement, static contact angle (SCA), and a series of electrochemical methods, it has been demonstrated that the TEMPO-based enzyme electrode exhibits a uniform hydrophilic morphology and stable electrochemical performance. Furthermore, the results show that the sensor demonstrates high sensitivity for detecting glucose biomolecules in artificial sweat and serum. Attributing to the quantitative and controllable radical polymerization of TEMPO redox assembled enzyme electrode surface, the as-proposed biosensor providing a use, storage, and inter-batch sensing stability, providing a vital platform for wearable/implantable biochemical sensors.

A cost-effective and facile technique for realizing fabric based microfluidic channels using beeswax and PVC stencils.

Microfluidic channels fabricated over fabrics or papers have the potential to find substantial application in the next generation of wearable healthcare monitoring systems. The present work focuses on the fabrication procedures that can be used to obtain practically realizable fabric-based microfluidic channels (µFADs) utilizing patterning masks and wax, unlike conventional printing techniques. In this study, comparative analysis was used to differentiate channels obtained using different masking tools for channel patterning as well as different wax materials as hydrophobic barriers. Drawbacks of the conventional tape and candle wax technique were noted and a novel approach was used to create microfluidic channels through a facile and simple masking technique using PVC clear sheets as channel stencils and beeswax as the channel barriers. The resulting fabric based microfluidic channels with varying widths as well as complex microchannel, microwell, and micromixer designs were investigated and a minimum channel width resolution of 500 µm was successfully obtained over cotton based fabrics. Thereafter, the PVC clear sheet-beeswax based microwells were successfully tested to confine various organic and inorganic samples indicating vivid applicability of the technique. Finally, the microwells were used to make a simple and facile colorimetric assay for glucose detection and demonstrated effective detection of glucose levels from 10 mM to 50 mM with significant color variation using potassium iodide as the coloring agent. The above findings clearly suggest the potential of this alternative technique for making low-cost and practically realizable fabric based diagnostic devices (µFADs) in contrast to the other approaches that are currently in use.

[Non-invasive glucose measurements : where do we stand?] / Mesures du glucose non invasives : où en est-on ?

The technologies used to measure blood glucose have significantly evolved the past few years, especially with the introduction of continuous interstitial glucose measurements, simplifying the management of the disease. More recently, there has been a lot of interest regarding some potential revolutionary methods, such as smartwatches, and glucose measurements in sweat, saliva, and even tears. In this article, we review the different technologies that are under development, and notice that although promising, they rest imprecise. False measurements can have fatal consequences for our patients. Nevertheless, these innovations are promising and have the potential to change the daily life of people with diabetes in the future.

Les technologies utilisées pour mesurer les glycémies des personnes présentant un diabète ont beaucoup évolué ces dernières années, avec notamment l'introduction des mesures interstitielles en continu, rendant le contrôle glycémique plus aisé. Depuis peu, il y a un intérêt croissant, notamment dans les médias, autour de potentielles méthodes révolutionnaires via des montres intelligentes, la sueur, la salive et même les larmes. Dans cet article, nous répertorions les différentes technologies en cours d'investigation et notons que plusieurs d'entre elles restent imprécises, empêchant leur utilisation pour nos patients diabétiques, chez qui des mesures incorrectes peuvent avoir de graves conséquences. Néanmoins, ces nouveautés sont prometteuses et ont le potentiel de changer le quotidien des personnes présentant un diabète dans le futur.

A Wearable Thin-Film Hydrogel Laser for Functional Sensing on Skin.

Flexible photonics offers the possibility of realizing wearable sensors by bridging the advantages of flexible materials and photonic sensing elements. Recently, optical resonators have emerged as a tool to improve their oversensitivity by integrating with flexible photonic sensors. However, direct monitoring of multiple psychological information on human skin remains challenging due to the subtle biological signals and complex tissue interface. To tackle the current challenges, here, we developed a functional thin film laser formed by encapsulating liquid crystal droplet lasers in a flexible hydrogel for monitoring metabolites in human sweat (lactate, glucose, and urea). The three-dimensional cross-linked hydrophilic polymer serves as the adhesive layer to allow small molecules to penetrate from human tissue to generate strong light--matter interactions on the interface of whispering gallery modes resonators. Both the hydrogel and cholesteric liquid crystal microdroplets were modified specifically to achieve high sensitivity and selectivity. As a proof of concept, wavelength-multiplexed sensing and a prototype were demonstrated on human skin to detect human metabolites from perspiration. These results present a significant advance in the fabrication and potential guidance for wearable and functional microlasers in healthcare.

No effect of tattoos on local sweat concentrations of select cytokines, cortisol, glucose, blood urea nitrogen, or lactate during exercise.

Due to growing interest in the investigation of exercise induced sweat biomarkers to assess an individual's health and the increasing prevalence of tattoos in the world's population, investigators sought to determine whether local sweat concentrations and excretion rates of epidermal growth factor (EGF), interleukin (IL) -1α, IL-6, IL-8, cortisol, glucose, blood urea nitrogen (BUN), and lactate differ between tattooed and contralateral non-tattooed skin during exercise. Sixteen recreational exercisers [female (50%)] (age = 25-48 years) with ≥ 1 unilateral permanent tattoo [median tattoo age = 6 years, IQR = 5] on the arm/torso completed an outdoor group fitness session. There were no significant differences between tattooed and non-tattooed skin for sweat EGF, IL-1α, IL-8, cortisol, glucose, BUN, or lactate concentrations. There were no significant differences between tattooed and non-tattooed skin for sweat EGF, IL-1α, IL-8, cortisol, glucose, BUN, or lactate excretion rate. Findings suggest that permanent tattoos older than 1 year may not impact local sweat EGF, IL-1α, IL-8, cortisol, glucose, BUN, and lactate concentrations or excretion rates during exercise.Clinical trial identifier NCT04920266 was registered on June 9, 2021.

Pyrene Derivative Incorporated Ni MOF as an Enzyme Mimic for Noninvasive Salivary Glucose Detection Toward Diagnosis of Diabetes Mellitus.

Herein, we demonstrate the detection of glucose in a noninvasive and nonenzymatic manner by utilizing an extended gate field-effect transistor (EGFET) based on the organic molecule pyrene phosphonic acid (PyP4OH8) incorporated nickel metal-organic framework (NiOM-MOF). The prepared electrode responds selectively to glucose instead of sucrose, fructose, maltose, ascorbic acid, and uric acid in a 1× phosphate buffer saline solution. Also, utilizing the scanning Kelvin probe system, the sensing electrode's work function (Φ) is measured to validate the glucose-sensing mechanism. The sensitivity, detection range, response time, limit of detection, and limit of quantification of the electrode are determined to be 24.5 µA mM-1 cm-2, 20 µM to 10 mM, less than 5 s, 2.73 µM, and 8.27 µM, respectively. Most interestingly, the developed electrode follows the Michaelis-Menten kinetics, and the calculated rate constant (km) 0.07 mM indicates a higher affinity of NiOM-MOF toward glucose. The real-time analysis has revealed that the prepared electrode is sensitive to detect glucose in real human saliva, and it can be an alternative device for the noninvasive detection of glucose. Overall, the outcomes of the EGFET studies demonstrate that the prepared electrodes are well-suited for expeditious detection of glucose levels in saliva.

Microfluidic Sensing Textile for Continuous Monitoring of Sweat Glucose at Rest.

Wearable sweat sensors have received considerable attention due to their great potential for noninvasive continuous monitoring of an individual's health status applications. However, the low secretion rate and fast evaporation of sweat pose challenges in collecting sweat from sedentary individuals for noninvasive analysis of body physiology. Here, we demonstrate wearable textiles for continuous monitoring of sweat at rest using the combination of a heating element and a microfluidic channel to increase localized skin sweat secretion rates and combat sweat evaporation, enabling accurate and stable monitoring of trace amounts of sweat. The Janus sensing yarns with a glucose sensing sensitivity of 36.57 mA cm-2 mM-1 are embroidered into the superhydrophobic heated textile to collect sweat directionally, resulting in improved sweat collection efficiency of up to 96 and 75% retention. The device also maintains a highly durable sensing performance, even in dynamic deformation, recycling, and washing. The microfluidic sensing textile can be further designed into a wireless sensing system that enables sedentary-compatible sweat analysis for the continuous, real-time monitoring of body glucose levels at rest.

In-depth correlation analysis between tear glucose and blood glucose using a wireless smart contact lens.

Tears have emerged as a promising alternative to blood for diagnosing diabetes. Despite increasing attempts to measure tear glucose using smart contact lenses, the controversy surrounding the correlation between tear glucose and blood glucose still limits the clinical usage of tears. Herein, we present an in-depth investigation of the correlation between tear glucose and blood glucose using a wireless and soft smart contact lens for continuous monitoring of tear glucose. This smart contact lens is capable of quantitatively monitoring the tear glucose levels in basal tears excluding the effect of reflex tears which might weaken the relationship with blood glucose. Furthermore, this smart contact lens can provide an unprecedented level of continuous tear glucose data acquisition at sub-minute intervals. These advantages allow the precise estimation of lag time, enabling the establishment of the concept called 'personalized lag time'. This demonstration considers individual differences and is successfully applied to both non-diabetic and diabetic humans, as well as in animal models, resulting in a high correlation.

Fingerprinting of hydroxy propyl methyl cellulose by comprehensive two-dimensional liquid chromatography-mass spectrometry of monomers resulting from acid hydrolysis.

Hydroxypropyl methyl cellulose (HPMC) is a type of cellulose derivative with properties that render it useful in e.g. food, cosmetics, and pharmaceutical industry. The substitution degree and composition of the ß-glucose subunits of HPMC affect its physical and functional properties, but HPMC characterization is challenging due to its high structural heterogeneity, including many isomers. In this study, comprehensive two-dimensional liquid chromatography-mass spectrometry was used to examine substituted glucose monomers originating from complete acid hydrolysis of HPMC. Resolution between the different monomers was achieved using a C18 and cyano column in the first and second LC dimension, respectively. The data analysis process was structured to obtain fingerprints of the monomers of interest. The results revealed that isomers of the respective monomers could be selectively separated based on the position of substituents. The examination of two industrial HPMC products revealed differences in overall monomer composition. While both products contained monomers with a similar degree of substitution, they exhibited distinct regioselectivity.

A paper-based dual functional biosensor for safe and user-friendly point-of-care urine analysis.

Safe, accurate, and reliable analysis of urinary biomarkers is clinically important for early detection and monitoring of the progression of chronic kidney disease (CKD), as it has become one of the world's most prevalent non-communicable diseases. However, current technologies for measuring urinary biomarkers are either time-consuming and limited to well-equipped hospitals or lack the necessary sensitivity for quantitative analysis and post a health risk to frontline practitioners. Here we report a robust paper-based dual functional biosensor, which is integrated with the clinical urine sampling vial, for the simultaneous and quantitative analysis of pH and glucose in urine. The pH sensor was fabricated by electrochemically depositing IrOx onto a paper substrate using optimised parameters, which enabled an ultrahigh sensitivity of 71.58 mV pH-1. Glucose oxidase (GOx) was used in combination with an electrochemically deposited Prussian blue layer for the detection of glucose, and its performance was enhanced by gold nanoparticles (AuNPs), chitosan, and graphite composites, achieving a sensitivity of 1.5 µA mM-1. This dual function biosensor was validated using clinical urine samples, where a correlation coefficient of 0.96 for pH and 0.98 for glucose detection was achieved with commercial methods as references. More importantly, the urine sampling vial was kept sealed throughout the sample-to-result process, which minimised the health risk to frontline practitioners and simplified the diagnostic procedures. This diagnostic platform, therefore, holds high promise as a rapid, accurate, safe, and user-friendly point-of-care (POC) technology for the analysis of urinary biomarkers in frontline clinical settings.