Non-enzymatic Electrochemical Sensor Research Articles

Laser-induced graphene decorated with Ni[sbnd]Pt alloy nanoparticles for non-enzymatic electrochemical quantification of glucose

Enzyme-free electrochemical glucose (Glu) sensors, adopting electrochemically active catalysts, are of vital significance to effectively monitoring and analyzing the blood Glu level in diabetes diagnosis. Meanwhile, developing novel electrode substrates have been the hot research pot to meet the demand for constructing flexible sensors. In this work, porous laser-induced graphene (LIG) was prepared through a facile one-step laser-engraving technique on a polyimide thin film, and then used directly as the electrode. Furthermore, NiPt alloyed nanoparticles (NPs) were electrodeposited on the LIG electrode surface to gain the NiPt/LIG composite electrode, which was applied to construct the nonenzymatic electrochemical Glu sensor. The morphology, element and electrochemical performance of NiPt/LIG composite was characterized through various techniques. NiPt alloyed NPs were homogeneously distributed on the LIG scaffolds, which possess plenty of porous structure, high surface area and many active sites. The cooperative effect between the outstanding electrocatalytic capacity of NiPt alloyed NPs, the extraordinary electroconductibility of LIG and the numerous exposed active sites endow the NiPt/LIG sensor outstanding electrocatalytic performance for electrochemical oxidation of Glu. Under the most appropriate conditions, the obtained NiPt/LIG sensor was adopted to detect Glu, showing a broad detection concentration range of 0.5 μM to 2.1 mM and 2.1 mM to 5.6 mM, good sensitivities of 1.824 and 0.467 μA μM−1 cm−2, a low detection limit of 0.03 μM. The as-fabricated nonenzymatic Glu sensor also displays high selectivity, stability considering ageing effects under different environment conditions and prominent reproducibility. Additionally, this novel NiPt/LIG nonenzymatic Glu sensor was applied to quantify Glu successfully in blood serum and food samples and the results were in good agreement with that by UV–vis spectrophotometer, demonstrating high precision and accuracy as well as excellent recovery, showing good application prospects in Glu monitoring. This research confirmed the potential of exploiting NiPt/LIG as a highly sensitive Glu nonenzymatic electrochemical sensor and provided a practicable and suitable approach for construction of novel electrochemical sensors.

A novel bifunctional electrochemical nanosensor for simultaneous detection of glucose and insulin based on NiO/Co3O4@CuAl LDH-MWCNT nanocomposite-modified carbon paste electrode

The appropriate development of electrocatalytic nanomaterials is a significant step for constructing high-quality non-enzymatic electrochemical sensors. In this work, we presented effective copper aluminum layered double hydroxide (CuAl LDH)-based nanoparticles with two consecutive optimization steps through nickel oxide/cobalt oxide (NiO/Co3O4) merging and subsequent assembly with multi-walled carbon nanotubes (MWCNT). The obtained nanostructures were characterized by using Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction pattern (XRD), and field emission scanning electron microscope images (FE-SEM). The synthesized nanomaterials were used as a carbon paste electrode (CPE) material for simultaneous dual-signal evaluation of glucose and insulin. The response of the modified electrode was investigated by some electrochemical approaches, including cyclic voltammetry (CV), electrical impedance (EI), differential pulse voltammetry (DPV), and amperometric titration. The NiO/Co3O4 CuAl LDH@MWCNT electrode displayed multi-functional properties through two well-defined separated peaks toward glucose and insulin detection with a linear range of 0.01–26.5 mM and 0.02–70.0 nM, respectively. The detection limit values were obtained as 2.8 µM for glucose and 17.3 pM for insulin. The sensor showed good tolerance to common interfering agents, excellent sensitivity, and appropriate stability during 30 days of dry storage at room temperature. This sensor was also used for the quantification of glucose and insulin in human serum samples, obtaining the recovery rate of 101.0 %-103.7 % and 98.0 %-106.0 %, respectively, with all the RSD values below 3.0 %. This study represented an efficient simultaneous sensing platform for glucose and insulin detection, which warrants its operational application in clinical samples.

Recent Advances in Non-Enzymatic Electrochemical Sensors for Glyphosate Detection: A Review

Glyphosate (GLY) is the most widely used organophosphorus pesticides globally with application in shielding crops against perennial and annual the weeds, domestic garden and agriculture. It is recognized for its toxicological harm and is implicated in potential connections with human carcinogenesis. Generally, glyphosate is considered to be less toxic but excessive use leads to pollute soil, food and water. Furthermore, it strongly effects the unicellular and multicellular organism. Therefore, there is urgent need to develop specific, accurate, online, and sensitive methods for detection of glyphosate. The present review is focused on recent advances in developing non-enzymatic sensors for glyphosate detection. Non-enzymatic electrochemical sensors have emerged as promising alternatives for glyphosate detection, offering advantages such as high sensitivity, selectivity, and rapid response. The electrodes were modified with metals, carbon materials, metal organic framework and molecular imprinted polymers using various electrochemical techniques. Execution, benefits, linear range, detection limit and limitations of the modified sensors for determination of glyphosate are reviewed thoroughly.

Non-enzymatic Glucose Sensor Based on Ni(OH)2/NF Materials Using Different Pulse Voltammetry Technique

Non-enzymatic glucose sensors have gained significant attention owing to their potential for accurate and cost-effective glucose detection. Nanomaterials play a pivotal role in enhancing performance of non-enzymatic glucose sensor. In this study, a novel non-enzymatic glucose sensor based on Ni(OH)2/NF (nickel hydroxide/nickel foam) materials was developed using different pulse voltammetry technique. Chemical precipitation methods have been used to grow Ni(OH)2 nanostructures directly on a nickel foam electrode. The characterization of the synthesized materials was performed through field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDX), and X-ray diffraction (XRD). The performance of the Ni(OH)2/NF-based glucose sensor was evaluated through electrochemical measurements. Nanoscale hive-like structures of Ni(OH)2 with a diameter ranging from 450 to 530 μm and a thickness of 20 nm were formed on the NF surface. The sensor exhibited good performance, displaying a high sensitivity of 8.42mA.mM-1.cm-2 with a low detection limit of 0.84 μM. These results position the synthesized electrode as a promising contender for non-enzymatic electrochemical glucose sensors.

Tailoring the d-band center on Ru1Cu single-atom alloy nanotubes for boosting electrochemical non-enzymatic glucose sensing.

The development of cost-effective and highly efficient electrocatalysts is critical to help electrochemical non-enzymatic sensors achieve high performance. Here, a new class of catalyst, Ru single atoms confined on Cu nanotubes as asingle-atom alloy (Ru1Cu NTs), with aunique electronic structure and property, was developed to construct a novel electrochemical non-enzymatic glucose sensor for the first time. The Ru1Cu NTs with a diameter of about 24.0nm showed amuch lower oxidation potential (0.38V) and 9.0-fold higher response (66.5 μA) current than Cu nanowires (Cu NWs, oxidation potential 0.47V and current 7.4 μA) for glucose electrocatalysis. Moreover, as an electrochemical non-enzymatic glucose sensor, Ru1Cu NTs not only exhibited twofold higher sensitivity (54.9 μA mM-1cm-2) and wider linear range (0.5-8mM) than Cu NWs, but also showed alow detection limit (5.0μM), excellent selectivity, and great stability. According to theoretical calculation results, the outstanding catalytic and sensing performance of Ru1Cu NTs could be ascribed to the upshift of the d-band center that helped promote glucose adsorption. This work presents a new avenue for developing highly active catalysts for electrochemical non-enzymatic sensors.

Synthesis of citral-tryptamine fused selenium nanospheres (CT@SeNP's) and exploration of their anticancer, antibacterial, and electrochemical sensor applications

A broad spectrum of antibiotics with multiple mechanisms of action is urgently required to combat the growing public health threat posed by drug-resistant pathogenic microorganisms. Biomedical researchers have concentrated on creating novel antibacterial and anticancer therapies due to the limited availability of conventional antibacterial and anticancer medications. In this study citral-tryptamine molecule was synthesized and characterized using 1HNMR , 13CNMR , LCMS and FT-IR spectral techniques and various biological properties of synthesized molecules were investigated using several in silico approaches such as molecular docking, ADME, PASS analysis and bioactive score. Using citral-tryptamine molecule, selenium nanoparticles (CT@SeNP's) were synthesized and characterized using different spectral and imaging techniques such as UV–Visible spectra, SEM, FTIR, EDX, XRD and DLS. EDX and mapping were used to investigate the relevant atoms and their distribution. Three significant signals from the EDX corresponding to C atom (15.4 %), along with signals from the Se atom (80.9 %) and the N atom (3.7 %). CT@SeNP's showed excellent antibacterial property against MRSA. The minimum inhibitory concentration of CT@SeNP's was found to be 20±0.36 mm with a good zone of inhibition in a dose dependent manner. CT@SeNP's was treated with both normal and cervical cancer cell lines such as SiHa to investigate the dose optimization and cytotoxicity by MTT assay. The nanoparticle showed an IC50 value is 0.68 µM and the data strongly suggested that CT@SeNP's could have a high potential in future medication development against MRSA and cervical cancer cells. The proper development and manufacturing of electrocatalytic nanomaterials are essential for enhancing the performance of non-enzymatic electrochemical sensors. The electrochemical sensing of H2O2 was enhanced by nanocomposite CT@SeNPs, which have a low detection limit of 60.96 nM and can detect H2O2 in a wide range of concentrations, from 25 µM to 250 µM. Thus, an efficient sensing platform for non-enzymatic H2O2 detection was discovered by this investigation.

CuCo2O4 nanoneedle arrays growth on carbon cloth as a non-enzymatic electrochemical sensor with low detection limit ketoprofen recognition.

An electrochemical sensor for detecting ketoprofen was constructed by in-situ grown copper cobaltate (CuCo2O4) nanoneedle arrays on a carbon cloth (CC) substrate. The resulting porous nanoneedle arrays not only expose numerous electrochemically active sites but also significantly enhance the electrochemical apparent active area and current transmission efficiency. By leveraging its electrochemical properties, the sensor achieves an impressive detection limit for ketoprofen of0.7 pM, with a linear range spanning from 2 pM ~ 2 µM. Furthermore, the sensor exhibits remarkable reproducibility, anti-interference capabilities, and stability. Notably, the developed sensor also performed ketoprofen detection on real samples (including drug formulations and wastewater) and demonstrated excellent recognition ability. These exceptional performances can be attributed to the direct growth of CuCo2O4 nanoneedle arrays on the CC substrate, which facilitates a robust electrical connection, provides abundant electrocatalytic active sites, and expands the apparent active area. Consequently, these improvements contribute to the efficient trace detection capabilities of the ketoprofen sensor.

Non-enzymatic electrochemical impedance sensor for selective detection of electro-inactive organophosphate pesticides using Zr-MOF/ZrO2/MWCNT ternary composite

The existence of multiple pesticide residues in fruits and vegetables constitutes a direct peril to living organisms. Therefore, it is crucial to develop a low-cost screening method for determining organophosphate pesticides (OPPs) in food samples. This study describes the solvothermal synthesis of a ternary composite comprising multi-walled carbon nanotubes (MWCNT), zirconium oxide, and a zirconium-metal-organic framework (Zr-MOF). The ternary composite was characterised using XRD, FESEM, FTIR, and BET. The ternary composite provides a large surface area (1158 m2/g) compared with the pristine Zr-MOF (868 m2/g). The composite-modified glassy carbon electrode was used to determine nine pesticides, including organophosphate (malathion, dimethoate, chlorpyrifos, monocrotophos, and glyphosate) and non-organophosphate (thiophanate methyl, carbendazim, atrazine, and 2,4, D). In particular, various chemical combinations of OPPs were selected, such as S–P=S, P=S, P=O, and non-OPPs such as C=S (with sulphur), and without sulphur. The sensor results show that the sensor selectivity is high for OPPs containing both phosphorus and sulphur molecules. The low detection limit of the sensor was 2.02, 2.8, 2.5, 1.11, and 2.01 nM for malathion, chlorpyrifos, dimethoate, monocrotophos, and glyphosate, respectively. The electrode exhibited significant chemical stability (93%) after 100 cycles, good repeatability, and a long shelf life. The sensor is reliable for qualitative real-time applications.

Electrochemical Characterization of a Novel Organoelectrocatalyst, 7-Azabicyclo[2.2.1]heptan-7-ol (ABHOL), and Its Application to Electrochemical Sensors.

Electrochemical enzyme sensors are suitable for simple monitoring methods, for example, as glucose sensors for diabetic patients; however, they have several disadvantages arising from the properties of the enzyme. Therefore, non-enzymatic electrochemical sensors using functional molecules are being developed. In this paper, we report the electrochemical characterization of a new hydroxylamine compound, 7-azabicyclo[2.2.1]heptan-7-ol (ABHOL), and its application to glucose sensing. Although the cyclic voltammogram for the first cycle was unstable, it was reproducible after the second cycle, enabling electrochemical analysis of ethanol and glucose. In the first cycle, ABHOL caused complex reactions, including electrochemical oxidation and comproportionation with the generated oxoammonium ions. The electrochemical probe performance of ABHOL was more efficient than the typical nitroxyl radical compound, 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO), and had similar efficiency to 9-azabicyclo[3.3.1]nonane N-oxyl (ABNO), which is activated by the bicyclic structure. The results demonstrated the advantages of ABHOL, which can be synthesized from inexpensive materials via simple methods.

Non-enzymatic electrochemical voltammetric sensors based on thulium:zinc oxide for dopamine detection

In this study, zinc oxide (ZnO) powders with dopant rates of 1 mol% thulium (Tm) (1Tm:ZnO), 2 mol% Tm (2Tm:ZnO), and 3 mol% Tm (3Tm:ZnO) nanoparticles were synthesized by co-precipitation method. Subsequently, Polyaniline (PANI)/1Tm:ZnO, PANI/2Tm:ZnO, and PANI/3Tm:ZnO nanocomposite sensors were prepared using a low-cost and simple sonication method. The results showed that the prepared PANI/1Tm:ZnO-based biosensor detected dopamine in the concentration range of (0.8–6.5) µM with a sensitivity of 0.2568 µAµM−1cm−2. Using these sensitivity values of the sensor, the LOD and LOQ values of the PANI/1Tm:ZnO-based sensor were calculated as 1.92 µM and 5.8 µM, respectively. The incorporation of 1% Tm into ZnO host (PANI/1Tm:ZnO) significantly enhanced the sensitivity of the biosensors.

A Wearable Electrochemical Biosensor Utilizing Functionalized Ti3C2Tx MXene for the Real-Time Monitoring of Uric Acid Metabolite.

Wearable, noninvasive sensors enable the continuous monitoring of metabolites in sweat and provide clinical information related to an individual's health and disease states. Uric acid (UA) is a key indicator highly associated with gout, hyperuricaemia, hypertension, kidney disease, and Lesch-Nyhan syndrome. However, the detection of UA levels typically relies on invasive blood tests. Therefore, developing a wearable device for noninvasive monitoring of UA concentrations in sweat could facilitate real-time personalized disease prevention. Here, we introduce 1,3,6,8-pyrene tetrasulfonic acid sodium salt (PyTS) as a bifunctional molecule functionalized with Ti3C2Tx via π-π conjugation to design nonenzymatic wearable sensors for sensitive and selective detection of UA concentration in human sweat. PyTS@Ti3C2Tx provides many oxidation-reduction active groups to enhance the electrocatalytic ability of the UA oxidation reaction. The PyTS@Ti3C2Tx-based electrochemical sensor demonstrates highly sensitive detection of UA in the concentration range of 5 μM-100 μM, exhibiting a lower detection limit of 0.48 μM compared to the uricase-based sensor (0.84 μM). In volunteers, the PyTS@Ti3C2Tx-based wearable sensor is integrated with flexible microfluidic sweat sampling and wireless electronics to enable real-time monitoring of UA levels during aerobic exercise. Simultaneously, it allows for comparison of blood UA levels via a commercial UA analyzer. Herein, this study provides a promising electrocatalyst strategy for nonenzymatic electrochemical UA sensor, enabling noninvasive real-time monitoring of UA levels in human sweat and personalized disease prevention.

Synthesis of biowaste-derived nanostructured material for the nanomolar detection of glucose: Biological sample analysis

Glucose electro-oxidation in an alkaline media was investigated using an electrode composed of carbon paste and sugarcane bagasse activated carbon (SBAC). The SBAC was prepared using an easy, affordable, and environmental friendly process. The porous activated carbon was produced using sugarcane bagasse through a pre-treatment process that involved carbonization at 650 °C and K2CO3. X-ray diffraction (XRD) was used to observe the formation of carbon crystallites during activation at higher temperatures. The Fourier-transform infrared (FTIR) spectrum shows functional groups that are present in the carbon material. The carbon sample's morphology was evaluated using scanning electron microscope (SEM). The surface roughness was studied using atomic force microscopy (AFM). Porous activated carbon derived from sugarcane bagasse was carefully mixed into electrode components such as graphite powder and mineral oil for glucose (GLS) detection. For precise GLS detection, the SBACs were employed as non-enzymatic electrochemical sensor probes in their as-prepared condition. According to the electrochemical experiments, the constructed sensor shows exceptional electrochemical performance towards glucose oxidation, including excellent selectivity, a low detection limit, good sensitivity, and a wide linear range. Investigation has been conducted on the oxidation of GLS in alkaline solutions with varying concentrations of halide ions such as iodide and chloride. The GLS oxidation peak current increased the performance of a SBAC modified electrode was compared to that of a bare carbon paste electrode (CPE). The role of sensitivity in minimizing halide poisoning is significant. The risk of poisoning is increased if iodide > chloride. As the modified electrode's voltage changes in a chloride solution containing glucose, the peak current gradually reduces. The redesigned electrode that is currently in use as a consequence not only promotes glucose oxidation but also shows strong resistance to electrode poisoning caused by halides. The sensitive and targeted SBAC/CPE has also improved its reliability while evaluating samples of human serum, urine, and breast milk.

Low-cost electrochemical biosensor based on a multi-walled carbon nanotube-doped molecularly imprinted polymer for uric acid detection

Uric acid is a naturally occurring antioxidant that must be maintained in the human body at 1.49–4.46 mM to prevent hyperuricemia, which may lead in the formation of monosodium urate (MSU) and Lesch–Nyhan syndrome. The objective of this research is to examine molecularly imprinted polymers (MIP)-based non-enzymatic electrochemical sensors that simulate the biological mechanism of uricase oxidase. As an affordable working electrode, commercial pencil graphite electrode (PGE) was modified with multi-walled carbon nanotubes (MWCNTs) and polypyrrole. With a 1:10 uric acid to monomer ratio, 20 cycles of polymerization, 100 mV s−1 of polymerization rate, and 30 cycles of template removal, the optimum MIP was obtained. By employing differential pulse voltammetry (DPV) to detect the presence of uric acid over the range of 0.22–3.5 mM, the limit of detection (LOD) was determined to be 0.76 mM, with a sensitivity of 97.459 µA µM−1 cm−2. This sensor demonstrated good repeatability and reproducibility, with relative standard deviation percentage (%RSD) of 3.43 % (n = 10) and 5.37 % (n = 3), respectively, which maintains a performance stability of 71 % after 19 days of use. This sensor also detected uric acid with good selectivity, even in the presence of interfering molecules including K+, Na+, sarcosine, citric acid, ascorbic acid, glucose, and dopamine.

Construction of hierarchical NiCo2 S4 /2D-Carbyne nanohybrid onto nickel foam for high performance supercapacitor and non-enzymatic electrochemical glucose sensor applications.

Synthesising and designing pseudocapacitive material with good electrochemical and electrocatalytic behaviour is essential to use as supercapacitor as well as non-enzymatic glucose sensor electrode. In this work, NiCo2 S4 nanoparticles decorated onto the 2D-Carbyne nanosheets are achieved by the solvothermal process. The as-prepared NiCo2 S4 @2D-Carbyne provides rich reaction sites and better diffusion pathways. On usage as an electrode for supercapacitor application, the NiCo2 S4 @2D-Carbyne exhibits the specific capacitance of about 2507 F g-1 at 1 A g-1 . In addition, the fabricated hybrid device generates an energy density of 52.2 Wh kg-1 at a power density of 1.01 kW kg-1 . Besides, the glucose oxidation behaviour of NiCo2 S4 @2D-Carbyne modified GCE has also been performed. The diffusion of glucose from the electrolyte to the electrode obeys the kinetic control process. Furthermore, the fabricated NiCo2 S4 @2D-Carbyne non-enzymatic glucose sensor exhibits a limit of detection of about 34.5 μM with a sensitivity of about 135 μA mM-1 cm-2 . These findings highlight the need to design and synthesis electrode materials with adequate electrolyte-electrode contact, strong structural integrity, and rapid ion/electron transport.

A novel NiO/C@rGO nanocomposite derived from Ni(gallate): A non-enzymatic electrochemical glucose sensor

The development of suitable substrate materials in electrochemical sensors is essential for rapid and reliable quantification in the diagnostic and clinical fields. In this paper, NiO/C@rGO nanocomposite was synthesized through nickel (gallate) pyrolysis with graphene oxide and employed as a substrate to construct a glucose sensor with high selectivity and sensitivity. The structural characterizations of NiO/C@rGO were assessed by Fourier transform infrared spectroscopy, X-ray diffraction, field emission scanning electron microscopy, energy disperse spectroscopy, and elemental mapping. The newly fabricated biosensor (NiO/C@rGO/GCE) exhibited a high sensing performance with an extensive dynamic linear range (from 1 μM to 1115 μM) and a low limit of detection (LOD) 0.658 μM (S/N = 3) toward glucose. In addition, the NiO/C@rGO-based sensor displayed good stability, favorable repeatability, and anti-interference ability for determining glucose. It was also used to measure glucose in serum samples, and satisfactory results were attained. These results illustrated that the NiO/C@rGO nanocomposite could be applied as an excellent electrochemical sensing material with high sensitivity to diagnose glucose-related illnesses.

Non-enzymatic electrochemical sensor based on ZnO nanoparticles/porous graphene for the detection of hypoxanthine in pork meat

In this study, we developed a pioneering non-enzymatic electrochemical sensor utilizing a flexible porous graphene electrode modified with ZnO nanoparticles (ZnO/fPGE sensor) to assess hypoxanthine (HXA) content in pork at post-mortem time. The ZnO/fPGE sensor was synthesized via hydrothermal method and direct laser writing with a CO2 laser on a polyimide film at ambient conditions. Its characterization was analyzed by Raman, Fourier-transform infrared spectroscopy, field-emission scanning microscopy, energy-dispersive x-ray spectroscopy, and cyclic voltammetric techniques. Linear response, the limit of detection, and sensitivity to the HXA were enhanced with the values of the range from 1.5 to 150, 0.14 µM, and 6.6 µA μM−1 cm−2, respectively. Effective resistance to common physiological interferences (such as uric acid, ascorbic acid, dopamine, glucose, and xanthine) was indicated, and additionally, the determination of HXA concentration in real samples with good selectivity is attributed to the synergistic effects between ZnO nanoparticles and fPGE. Therefore, the ZnO/fPGE has provided a favorable electrical environment for developing high-performance electrochemical biosensors to determine hypoxanthine in pork meat.

Hydrothermally synthesized CuNiS@CNTs composite electrode material for hybrid supercapacitors and non-enzymatic electrochemical glucose sensor

Hydrothermally synthesized CuNiS@CNTs composite electrode material for hybrid supercapacitors and non-enzymatic electrochemical glucose sensor

Co1.22xNixO4/fMWCNTs-hybrid nanocomposite-based self-adhesive wearable non-enzymatic electrochemical sensor for continuous glucose monitoring in sweat

The development of polymer-based wearable, eco-friendly, and non-invasive sensors has been boosted by the rapid emergence and evolution of soft electronics. However, challenges in the catalysis of glucose and sweat sampling have hampered these advances in the development of efficient wearable glucose sensors. Herein, the porous Co1.22xNixO4 hybrid composite material with interconnecting fMWCNTs, referred to as Co1.22xNixO4/fMWCNTs, was hydrothermally synthesized, and covalently crosslinked into well-patterned, flexible PDMS polymer networks. The hydrophilic fMWCNTs enhanced the anchoring spots for the in situ growth of NiCo–Oxides, which significantly improved the conductive networks and introduced many interface zones with high sensitivity of (1190.9 and 1312.1) µA·mM−1·cm−2, wide linear range of (0.001 − 8.0) mM, low detection limit (20 μM), good long-term stability, and excellent selectivity in alkaline solution. A prototype sensor was fabricated by assembling transparent PDMS film with a hydrophilic membrane of supramolecular double network hydrogel (SP−DN) as adhesive, and breathable substrate for sweat collection. The sensitivity of the calibrated prototype was found to be 1326.83 µA·mM−1·cm−2 with a linear range of ≤ 800 µM, tested in artificial sweat samples. The feasibility of a non-invasive glucose sensor was validated by assembling and testing prototype sensors on multiple volunteers. The SP−DN hydrogel acts as a continuous OH− ion supplier, and makes it possible to oxidize the glucose by metal-oxide-based nano-enzyme. The facile fabrication method and reliability of the results with real blood samples show the potential of the metal-oxide-based sensor prototype as a flexible, and environment-adaptable sensing device.

A novel non-enzymatic electrochemical glucose sensors based on graphene oxide nanoribbons: Tracking energy expenditure and nutritional intake in sports

This work revealed the development of a novel non-enzymatic electrochemical sensor for glucose detection based on a modified glassy carbon electrode made of graphene oxide nanoribbons (GONRs). The TEM, XRD), XPS, FTIR, and Raman spectroscopy were used to characterize the shape and structure of the modified electrode made of GONRs. Using amperometry and cyclic voltammetry (CV), the nanocomposite's electrochemical performance was assessed (AMP). The TEM results support the XPS, Raman, and XRD observations, demonstrating the capability of the suggested approach to generate single-layered GONRs with good edge linearity. The suggested non-enzymatic glucose sensing method was found to be selective, stable, repeatable, and reproducible through electrochemical analyses. The response behavior of GONRs/GCE was found to be linear within the 0.1–105 mM range, and the sensitivity and detection limit were found to be roughly 20.815 µA/mM and 3 µM, respectively. To verify the GONRs/GCE sensor's practicality and viability, tests were conducted on human serum and orange juice samples. The recovery rate ranged from 94.00% to 99.20%, according to the results, and the relative-standard deviation (RSD) values were 3.21% to 4.41%. These encouraging RSD and recovery rates showed that GONRs/GCE would work well as electrodes for measuring glucose in actual samples.

Printing surface cuprous oxides featured liquid metal for non-enzymatic electrochemical glucose sensor

Electrochemical glucose sensors that rely on two-dimensional (2D) oxides have attracted significant attention owing to the strong sensing activity of 2D oxides, but their practical application is hindered by the complexity and high cost of fabrication of electrodes and integrated devices. Herein, a convenient and effective fabrication route that includes printing a Ga-based liquid metal (LM) as a current collection electrode, followed by growing electrochemically active 2D oxides directly on the surface of Ga-based LMs under mild conditions, is developed for non-enzyme-based electrochemical sensors. Specifically, 2D annealed Cu-Oxide (ACO) is successfully grown on a printed Ga electrode through a galvanic replacement reaction, resulting in the formation of a mechanically and electrically well-matched interface between the active sensing materials and the current collection substrate. Benefitting from the high quantity of 2D ACO and good charge transfer at the interface, the as-prepared ACO electrode exhibits attractive glucose sensing performance, with a wide linear range (1 μM-10 mM) of effective detection, low detection limit down to 1 μM, and high sensitivity of 0.87 μA·mM-1·cm-2. Our study highlights the potential of using LMs in bio-sensing applications and provides a non-enzyme-based electrochemical biosensor platform for effective glucose detection in diets and clinical diagnostic settings.