Flexible Electrochemical Sensor Research Articles

Utilization of in-situ self-supporting materials for the preparation of flexible and stretchable electrodes for the detection of nitric oxide released from cells

Real-time monitoring of nitric oxide from endogenously cells released is crucial for revealing their physiological activities or pathological processes. However, designing electrochemical sensors for real-time monitoring at the cellular level is challenging due to the simultaneous requirements of sensitivity, transient recording capability, and biocompatibility. Combining the universally self-supported grown highly active materials with stretchable conductive flexible substrates holds promise for achieving sensitive detection of cells and real-time monitoring of mechanically induced biomolecular release. However, existing manufacturing strategies for highly sensitive stretchable flexible electrochemical sensors still face significant challenges due to low material activity, high processing requirements, and the complexity of further designing membrane electrodes. Here, we designed a method of in-situ self-supported growth to grow Co-doped Ni(OH)2 structures on rigid Ti foil. Leveraging the synergistic effect of Co and Ni, sensitive detection of NO was achieved, enabling real-time monitoring of trace amounts of NO released by Raw 264.7 cells. Based on this material, using catalytic ink method, it was transferred to low-resistance flexible ITO film (LIF), enabling real-time monitoring of mechanically induced NO release from Human Umbilical Vein Endothelial Cells (HUVECs) cells.

Flexible electrochemical sensor with 2D-on-2D layered structure for real-time on-site intelligent detection of carbendazim residues on fresh tea leaves

Excessive use of carbendazim (CBZ) for controlling fungal disease may result in pesticide residues in growth environments. There is an urgent requirement for real-time detection of CBZ content to enable rapid assessment of pesticide residues. Herein, a novel electrochemical sensor was created, which utilizes a laser-induced graphene (LIG) electrode modified with two-dimensional (2D) tungsten disulfide (WS2) nanosheets and a poly(L-lysine) (PLL) film to construct a 2D-on-2D layered structure. The PLL/WS2/LIG electrode exhibits strong charge transfer, excellent electrocatalytic performance, and high CBZ adsorption capacity, thus leading to enhanced sensitivity. As a result, the sensor exhibits a low detection limit of 1.2 ng/mL (6.2 nM), high sensitivity up to 135.1 μA(μg/mL)−1cm−2, and a wide response range of 0.01 to 1.5 μg/mL. Moreover, an intelligent analysis system, consisting of a portable device that connects to an online cloud platform equipped with a machine learning model and visualization software, has been developed for the real-time detection of CBZ residues on tea leaves in tea plantations. This study demonstrates that the PLL/WS2/LIG sensor and the intelligent analysis system have great potential to monitor pesticide residues to guarantee food safety.

Hierarchical Graphene Oxide/Nano-pyramidal Stainless-steel on Nickel Foam Substrate: A Flexible Electrochemical Sensor for Arsenic Compound Detection

The organoarsenic compound roxarsone (ROX) is added to chicken feed to enhance nutritional value. Although organic arsenic is generally less harmful than inorganic arsenic, concerns have arisen about its potential to transform into inorganic forms when excreted in animal waste, raising environmental and human health concerns. The potential dangers of long-term ROX exposure require reliable methods for the detection of the target analyte. In the current study, fabricated nanoscale graphene oxide (GO)/stainless steel (SS) pyramidal structures film on nickel foam (NF) is used as an electrode in the electrochemical detection of ROX. The proposed sensor was shown to outperform existing devices in terms of electrochemical activity, resulting in a wider linear range of detection for ROX (0.05–83.15µM) and lower detection limit (LOD) (0.006µM). Further, real sample analysis on water and meat samples confirmed the feasibility of the proposed GO/SS/NF sensor for the real-time detection of ROX in real-world applications. This research provides evidence to support the development of heterojunctions to improve ion transport channels and surface-active sites to promote ion mobility to enhance electrochemical responses.

Electrocatalysis in MOF Films for Flexible Electrochemical Sensing: A Comprehensive Review

Flexible electrochemical sensors can adhere to any bendable surface with conformal contact, enabling continuous data monitoring without compromising the surface’s dynamics. Among various materials that have been explored for flexible electronics, metal–organic frameworks (MOFs) exhibit dynamic responses to physical and chemical signals, offering new opportunities for flexible electrochemical sensing technologies. This review aims to explore the role of electrocatalysis in MOF films specifically designed for flexible electrochemical sensing applications, with a focus on their design, fabrication techniques, and applications. We systematically categorize the design and fabrication techniques used in preparing MOF films, including in situ growth, layer-by-layer assembly, and polymer-assisted strategies. The implications of MOF-based flexible electrochemical sensors are examined in the context of wearable devices, environmental monitoring, and healthcare diagnostics. Future research is anticipated to shift from traditional microcrystalline powder synthesis to MOF thin-film deposition, which is expected to not only enhance the performance of MOFs in flexible electronics but also improve sensing efficiency and reliability, paving the way for more robust and versatile sensor technologies.

A flexible non-enzymatic hydrogel-assisted electrochemical sensor: Wireless, sensitive, and selective uric acid detection for home monitoring

A smartphone-enabled, wireless, and battery-free electrochemical sensor equipped with electroactive poly (3,4-ethylenedioxythiophene):poly(styrenesulfonate)/polyvinyl alcohol (PEDOT:PSS/PVA) hydrogel composites, was developed for the non-enzymatic assessment of uric acid (UA) concentrations in human serum and wound exudate. The sensor was constructed with the aid of simple and sustainable modification techniques, such as drop-casting and crosslinking via a green freezing–thawing protocol. Gold nanoparticles (AuNPs) and the PEDOT:PSS/PVA electroactive hydrogel were employed to increase the surface area of the sensor and sample interactions, which improved the sensitivity and specificity for UA detection in the clinical range of 10–1,000 µM, with a detection limit of 0.05 mg/dL in addition to biocompatibility (L-929 cell viability > 90 %). In human serum and wound exudate samples, the prepared sensor demonstrated a good correlation for UA detection when compared to ISO15189 accredited medical laboratory measurements (Pearson correlation coefficient (r) = 0.97 and r = 0.98, respectively). The UA sensor was integrated with the flexible near field communication (NFC) circuit, and demonstrated the feasibility of measuring UA in human serum and wound exudate with results that were consistent with uricase enzymatic determination (p-value > 0.05). The sensor’s wearability was demonstrated by a recovery rate of 101–109 % UA detection when bending on the IV training arm. This NFC UA sensing device can serve as a good alternative platform for self–UA monitoring, along with the potential for developing a smart wound dressing for wound management.

Smart wearable flexible sensor based on laser-induced graphene/gold nanoparticles/black phosphorus nanosheets for in situ quercetin detection

In situ detection of metabolic substances in plants is necessary for the development of smart agriculture. However, there is a mechanical mismatch between the traditional rigid sensing interfaces and the softness surface of plant leaves, which can reduce the reliability and accuracy of sensor. Stretchable and flexible sensors provide new solutions to this problem. Herein, using quercetin (Que) as a model, we developed a flexible electrochemical sensor for in situ monitoring of metabolite in plants. A light and thin laser-induced graphene (LIG) electrodes with good flexibility were obtained after polydimethylsiloxane (PDMS) transfer. Gold nanoparticles (AuNPs) and two-dimensional black phosphorus (BP) nanosheets were fabricated on the electrode to further improve the electrochemical performance. The sensor can detect Que concentrations in the range of 1–100 μM with a detection limit of 0.65 μM (S/N=3). The sensor can adapt well to the soft plant leaf surfaces, thus realizing the application of in situ and in vivo detection in the field. This innovative plant wearable biosensor is expected to be a next-generation electronic candidate for intelligent agriculture, paving the way for in-situ and in vivo detection, and facilitating the intelligentsias of modern agriculture.

All-Fiber Flexible Electrochemical Sensor for Wearable Glucose Monitoring.

Wearable sensors, specifically microneedle sensors based on electrochemical methods, have expanded extensively with recent technological advances. Today's wearable electrochemical sensors present specific challenges: they show significant modulus disparities with skin tissue, implying possible discomfort in vivo, especially over extended wear periods or on sensitive skin areas. The sensors, primarily based on polyethylene terephthalate (PET) or polyimide (PI) substrates, might also cause pressure or unease during insertion due to the skin's irregular deformation. To address these constraints, we developed an innovative, wearable, all-fiber-structured electrochemical sensor. Our composite sensor incorporates polyurethane (PU) fibers prepared via electrospinning as electrode substrates to achieve excellent adaptability. Electrospun PU nanofiber films with gold layers shaped via thermal evaporation are used as base electrodes with exemplary conductivity and electrochemical catalytic attributes. To achieve glucose monitoring, gold nanofibers functionalized by gold nanoflakes (AuNFs) and glucose oxidase (GOx) serve as the working electrode, while Pt nanofibers and Ag/AgCl nanofibers serve as the counter and reference electrode. The acrylamide-sodium alginate double-network hydrogel synthesized on electrospun PU fibers serves as the adhesive and substance-transferring layer between the electrodes. The all-fiber electrochemical sensor is assembled layer-by-layer to form a robust structure. Given the stretchability of PU nanofibers coupled with a high specific surface area, the manufactured porous microneedle glucose sensor exhibits enhanced stretchability, superior sensitivity at 31.94 μA (lg(mM))-1 cm-2, a broad detection range (1-30 mM), and a significantly low detection limit (1 mM, S/N = 3), as well as satisfactory biocompatibility. Therefore, the novel electrochemical microneedle design is well-suited for wearable or even implantable continuous monitoring applications, thereby showing promising significant potential within the global arena of wearable medical technology.

Enhanced sensing performance of flexible non-enzymatic electrochemical glucose sensors using hollow Fe3O4 nanospheres of controllable morphologies

Rapid and accurate monitoring of glucose concentration is of great significance in clinical diagnosis and treatment of diabetes and hence, it is necessary to develop glucose sensors of superior electro-catalytic capacity. Most literature utilize synergistic effect of nanocomposites to enhance glucose sensing performance, whereas it suffers from crucial restriction in physical and chemical characteristics of each constituents. Morphology of nanostructures significantly affects the electro-catalytic capacity, thus it is a novel route to improve glucose sensing performance to adjust morphology of nanostructures. Herein, we presented highly sensitive non-enzymatic electrochemical sensors for rapid and accurate glucose analysis with hollow Fe3O4 nanospheres (Fe3O4NSs) of controllable morphologies decorated on flexible fibers. The morphologies of the Fe3O4NSs were evaluated with quantitative parameters like diameter, roundness, roughness, skewness, and kurtosis acquired from SEM images and image processing algorithms, and their effect on the interfacial characteristics and the electro-catalytic capacity of the glucose sensors was investigated. Owing to the unique spherical nanostructures and superior catalysis, the Fe3O4NSs exhibit desirable solid/liquid interface for mass diffusion and abundant active sites for sufficient oxidation of glucose. Moreover, much rounder and rougher Fe3O4NSs of near Gaussian surface are readily produced at a higher Fe3+ concentration and result in favorable sensing performance. Accordingly, the optimal glucose sensor shows sensitivities of 96.1 ± 5.4 μA mM−1 cm−2 and 38.2 ± 2.2 μA mM−1 cm−2 over a preferable range of 0–18.0 mM, and a lower detection limit of 19.2 μM. Besides, the glucose sensors remain acceptable response after continuous testing for 20 times and repetitive bending for 50 times, and display superior selectivity to glucose and accurate analysis to practical samples. It is a facile and effective methodology to regulate the morphologies of the Fe3O4NSs for enhanced electro-catalytic capacity of glucose sensors.

Simultaneous electrochemical detection of hydroquinone and catechol using flexible laser-induced metal-polymer composite electrodes

The conversion of waste polymers into functional materials presents a promising approach for PET upcycling. In this study, we exploit PET transformed into a Laser-Induced Graphene/Al NPs/PET nanocomposite (LIMPc − Laser-Induced Metal-Polymer composite) modified with electrodeposited gold nanoparticles (AuNPs). The morphology and structure of the material were investigated by scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), and X-ray photoelectron spectroscopy (XPS). The nanocomposite was employed as a flexible electrochemical sensor for the simultaneous electrochemical detection of hydroquinone (HQ) and catechol (CT). The LIMPc-plasma-NaOH-Au composite displayed well-defined oxidation peaks for HQ and CT during electrochemical analysis, with limits of detection (LOD) as low as 47 nM for CT and 56 nM for HQ, within a linear range of 0.1–300 μM for both compounds. The long-term stability of LIMPc-plasma-NaOH-Au and its performance in real sample analysis demonstrate its potential for environmental monitoring applications.

Flexible electrochemical fiber sensor for intracranial nitric oxide monitoring

Flexible electrochemical fiber sensor for intracranial nitric oxide monitoring

Nanofiber enhanced carbon cloth based flexible Miniaturized electrodes for Real-Time and specific insulin detection in blood serum

The development of sensitive and specific biosensors for real-time insulin monitoring is crucial for advancing diabetes management and improving patient outcomes. This study reports the fabrication of flexible electrodes based on titanium dioxide (TiO2) nanofiber-enhanced carbon cloth (CC) for the real-time, selective picomolar range of detection of insulin in blood serum. TiO2 nanofibers significantly increase the electrodes surface area and electron transfer capabilities, enhancing sensitivity and enabling rapid response times essential for real-time monitoring. The flexibility and mechanical stability of the carbon cloth substrate make it ideal for wearable and implantable biosensors, addressing limitations of conventional sensors, such as inadequate sensitivity, delayed response times, rigidity, and non-specific binding. The enhanced properties of the TiO2 nanofiber-modified carbon cloth composite facilitate the detection of low insulin concentrations, essential for early diagnosis and continuous monitoring in diabetes care. The robust TiO2 nanofibers and durable carbon cloth ensure sustained performance in complex biological environments. Chronoamperometry (CA) and cyclic voltammetry (CV) techniques are used to examine the electrocatalytic activity of the fabricated sensor, assessing parameters like pH, electrode resistance, concentration, and scan rate. While fasting, the normal range of insulin ranges from 12 to 150 pM. This sensor detects insulin in the 7 pM to 1000 pM range, with a detection limit of 2.7 pM and a quantification limit of 8.7 pM. Portability is validated using a handheld smartphone-based potentiostat. This developed miniaturized sensor provides a selective, interference-mitigated response for insulin detection in human serum, demonstrating significant advancements in flexible electrochemical sensor technology with crucial implications for diabetes care.

Progress in The Application of Flexible and Wearable Electrochemical Sensors in Monitoring Biomarkers of Athletes

AbstractAthletes continuously seek out creative methods and technologies to improve their physical fitness and overall performance. Wearable technology's progress offers a swift and eco‐conscious way to consistently observe physiological changes evidenced by biomarkers, stemming from an athlete's internal exertion or external workload. However, there is still a long distance to further understand the internal physiology of athletes which may bring hope to tailor training and recovery programs individually. The ongoing challenges faced by sports healthcare personnel are in finding biomarkers safely and continuously to control athletes' physical condition and tailor their recovery and eating patterns. The summary of this review encompasses the development of flexible and wearable electrochemical sensors. This article provides an overview of biofluids, commonly detected by wearable biochemical sensors and their mutual anatomical formations, with a focus on sweat and its associated biomarkers. Following this, its real‐world application in sports medicine becomes apparent, both theoretically and potentially. The paper ends by highlighting challenges and imagining the possible development of this exciting emerging field.

Flexible Wearable Electrochemical Sensors Based on AuNR/PEDOT:PSS for Simultaneous Monitoring of Levodopa and Uric Acid in Sweat.

As a facile substitute for the invasive technique of blood testing, wearable electrochemical sensors exhibit high potential for the noninvasive and real-time monitoring of biomarkers in human sweat. However, owing to enzyme specificity, the simultaneous detection of multiple biomarkers by enzymatic analysis is challenging. Moreover, sweat accumulation under sensors causes sweat contamination, which hinders real-time biomarker detection from sweat. This study reports the design and fabrication of flexible wearable electrochemical sensors containing a composite comprising Au nanorods (AuNRs) and poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) for the nonenzymatic detection of levodopa (LD) and uric acid (UA) in sweat. Each sensor was integrated with a flexible three-electrode system and a microfluidic patch for sweat sampling. AuNRs immobilized by PEG-doped PEDOT:PSS showed excellent analytical performance for LD and UA at different potentials. Thus, the newly fabricated sensors could detect LD and UA over a broad detection range with high sensitivity and showed a low limit of detection for both species. On-body assessments confirmed the ability of these sensors to simultaneously detect LD and UA in real time. Therefore, this study could open new frontiers in the fabrication of wearable electrochemical sensors for the pharmacokinetic profile tracking of LD and gout management.

Flexible electrochemical sensor based on a ZnO-doped SnO2 heterojunction for simultaneous electrochemical determination of p-aminophenol and acetaminophen

In this work, a novel flexible electrochemical sensor was successfully developed for the simultaneous determination of p-aminophenol and acetaminophen. The sensor is composed of a methanesulfonic acid-treated poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonic acid) film on a poly(ethylene terephthalate) substrate, which has been modified using a zinc oxide-doped tin oxide heterojunction applied through drop-coating (C-ZnO/SnO2-PEDOT/PET). The oxygen vacancies resulting from zinc oxide-doped tin oxide heterojunctions within highly conductive metal oxide nanomaterials enhance mass transfer and synergize seamlessly with methanesulfonic acid-treated electrically conductive dielectric PEDOT/PET films, leading to a substantial improvement in electrochemical activity. Under the optimal conditions, a wider linear range and lower detection limits were shown for p-aminophenol (2–511 μM, LOD=0.437 μM) and acetaminophen (2–591 μM, LOD=0.562 μM). In addition, the sensors demonstrated high accuracy in detecting p-aminophenol and acetaminophen in real samples, with recoveries of 99.36 %-99.60 % and 97.56 %-99.80 %, respectively. Furthermore, the flexible sensors maintained a superior electrochemical response when detecting p-aminophenol and acetaminophen at different bending angles, with relative standard deviations of 0.62 % and 1.68 %, respectively. These findings suggest potential applications for the development of wearable sensors in the future.

Flexible Dual‐Channel Molecularly Imprinted Electrochemical Sensor for Simultaneously Monitoring Sweat Cortisol and Lactate Levels

AbstractWhile exercise offers significant potential to enhance overall well‐being, unscientific exercise practices often cause exercise fatigue, posing a threat to human health. Flexible sweat sensors have garnered considerable attention owing to their ability to continuously, non‐invasively, and dynamically monitor human health during exercise at the molecular level. Therefore, in this study, we constructed a flexible molecularly imprinted polymer (MIP) sensor for the real‐time monitoring of cortisol and lactate levels in sweat using cortisol or lactate as template molecules and pyrrole (Py) as functional monomer. Prussian blue (PB) was embedded into the MIP as a built‐in redox probe, eliminating the need for an additional probe and facilitating the simultaneous quantification of cortisol and lactate concentrations. Moreover, the MIP‐doped platinum nanoparticles (PtNPs) ehanced the electron transfer capability, further improving the sensitivity of the sensors. The fabricated flexibile cortisol and lactate MIP sensors demonstrated low limits of detection (LOD; 1.07 nM and 1.09 mM, respectively), high sensitivity (0.09 μA lg[nM]−1 and 1.28 μA lg[nM]−1), and exceptional stability and selectivity. The flexible MIP sensors could continuously and dynamically monitor changes in sweat cortisol and lactate concentrations, thus contributing to the advancement of next‐generation flexible sweat electrochemical sensors and providing a crucial tool for monitoring exercise fatigue.

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.

Development of Lab-made Flexible Screen-printed Electrode based on S-Graphene Enriched with AuNPs and CuO for Electrochemical Detection of Tyrosine

Tyrosine (Tyr) is an amino acid that serves as a precursor for the synthesis of numerous neurotransmitters in the human body. This study aimed to design paper-based lab-made screen-printing electrodes (SPE) for tyrosine determination using a flexible electrochemical sensor. To achieve this, conductive inks with this composition were developed for the first time in the literature by incorporating sulfur (S)-doped graphene, synthesized using Yucel’s method, as well as gold nanoparticles and copper oxide (CuO) as conductive fillers, which were then integrated into flexible paper substrates. The optimized electrodes (CuO/S-G/AuNPs/SPE) were used to investigate the best oxidation response to tyrosine. Characterization of CuO/S-G/AuNPs/SPE was performed using electrochemical impedance spectroscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and field emission scanning electron microscopy. The sensor had a limit of detection of 0.024 μM and a limit of quantitation of 0.08 μM. In addition, the sensor’s affordability and ease of use make it advantageous for practical applications. The results demonstrate the sensor’s stability and reproducibility in measuring tyrosine. It is anticipated that the proposed sensor can effectively detect tyrosine in sweat samples and serve as a non-invasive, wearable, flexible sensor in the future.

A flexible self-supported electrochemical sensor Co-NC/PS@CC for real-time detection of cell-released H2O2

BackgroundHydrogen peroxide (H2O2) is an important reactive oxygen species (ROS) molecule involved in cell metabolism regulation, transcriptional regulation, and cytoskeleton remodeling. Real-time monitoring of H2O2 levels in live cells is of great significance for disease prevention and diagnosis. ResultsWe utilized carbon cloth (CC) as the substrate material and employed a single-atom catalysis strategy to prepare a flexible self-supported sensing platform for the real-time detection of H2O2 secreted by live cells. By adjusting the coordination structure of single-atom sites through P and S doping, a cobalt single-atom nanoenzyme Co-NC/PS with excellent peroxidase-like activity was obtained. Furthermore, we explored the enzyme kinetics and possible catalytic mechanism of Co-NC/PS. Due to the excellent flexibility, high conductivity, strong adsorption performance of carbon cloth, and the introduction of non-metallic atom-doped active sites, the developed Co-NC/PS@CC exhibited ideal sensing performance. Experimental results showed that the linear response range for H2O2 was 1–17328 μM, with a detection limit (LOD) of 0.1687 μM. Additionally, the sensor demonstrated good reproducibility, repeatability, anti-interference, and stability. SignificanceThe Co-NC/PS@CC prepared in this study has been successfully applied for detecting H2O2 secreted by MCF-7 live cells, expanding the application of single-atom nanoenzymes in live cell biosensing, with significant implications for health monitoring and clinical diagnostics.

A novel flexible electrochemical sensor with multi-level carbon nano-array for in-situ real-time monitoring of H2O2 secreted by cells

Developing ultra-sensitive sensors for in-situ real-time monitoring of low-level cell secretions is of paramount importance in understanding various biological processes, and it is still a challenge. Herein, for the first time, we constructed a novel flexible Au-Co@C-CNT/CC sensing electrode with nano-array structures by in-situ synthesis, catalytic pyrolysis and electrochemical deposition, and successfully realized the real-time monitoring of H2O2 released by cells. The 3D leaf-like structure of the electrode not only provided a large electroactive surface area (7.66 cm2) but also exhibited a microvilli structure of carbon nanotubes (CNT) on the surface, which further enhanced the presence of active sites. Moreover, the Co-Nx sites generated by catalytic pyrolysis can promote the adsorption and catalysis of H2O2 on the surface of sensing electrode. The introduction of Au NPs facilitated the transfer of electrons, thereby enhancing the electrical conductivity and electrocatalytic performance of Au-Co@C-CNT/CC. Benefiting from these unique superiorities, this sensing platform displayed excellent performance for H2O2 determination with a wide linear range (10–27080 μM) and low detection limit (0.13 μM). Notably, the good biocompatibility and flexibility of this sensing platform allowed direct culture of human lung cancer cells (A549 cells) on the electrodes, which can realize dynamic in-situ real-time detection of H2O2 released by cells, showing great potential in the diagnosis of related diseases.

Enzyme-chitosan hydrogels for high sensitivity flexible silk-based electrochemical glucose sensor

Developing enzymatic glucose sensors with high stability and excellent sensing performance is beneficial for the diagnosis and real-time monitoring of diabetes. In this study, we developed an enzymatic glucose sensor with the RGO (Reduced Graphene Oxide) /SF (Silk Fibroin) composite membrane as a flexible and conductive substrate, and then PB (Prussian Blue) was deposited on the surface of RGO/SF. To enhance the stability of GOD (Glucose Oxidase) and enzymatic glucose sensor, enzyme-chitosan hydrogel electropolymerized on the PB/RGO/SF electrode surface and at last a Nafion layer was coated on the hydrogel to prevent hydrogel detachment and mitigate the effects of interferent. This developed GOD/PB/RGO/SF sensor exhibits good sensing performance in glucose detection, with a response time of less than 10 s, a sensitivity as high as 230.96 μA mM−1 cm−2 at low concentration, and a linear range of 65.57 μM–10 mM, and it also shows good anti-interference feature and reproducibility, providing the reliable sensing performance for detecting glucose levels in human organisms and drinks. In conclusion, the GOD/PB/RGO/SF flexible sensor developed in this study has good prospects for application in glucose real-time monitoring and flexible sensing device.