Electrochemical Sensor Research Articles

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.

Needle-in-needle electrochemical sensor for in-vivo monitoring of anticancer drug etoposide

Therapeutic drug monitoring (TDM) serves as a potent tool for adjusting drug concentration within a reasonable range. However, continuous monitoring of anticancer drugs in-vivo presents a significant challenge. Herein, we propose a needle-in-needle electrochemical sensor based on an acupuncture needle electrode, capable of monitoring the anticancer drug etoposide in the peritoneal cavity of living rats. The acupuncture needle was modified with Au nanoparticles and etoposide-templated molecularly imprinted polymer (MIP), resulting in high sensitivity and selectivity in the electrochemical detection of etoposide. The modified acupuncture needle (0.16 mm diameter) was anchored inside a syringe needle (1.40 mm diameter), allowing the outer syringe needle to protect the modified materials of the inner acupuncture needle during skin piercing. Due to the unique needle-in-needle design, high stability was obtained during in-vivo etoposide monitoring. Connecting to a smartphone-controlled portable electrochemical workstation, the needle-in-needle sensor offers great convenience in point-of-care TDM. Moreover, the electrode materials on the acupuncture needle were carefully characterized and optimized. Under the optimized conditions, low detection limits and wide linear range were achieved. This work provides new insights into acupuncture needle electrochemical sensors and further expands the feasibility for real-time and in-vivo detection.

Highly sensitive methyl parathion electrochemical sensor designed from expired mung bean-derived porous carbon embellished with cerium oxide nanoparticles

Methyl parathion (MP) is one kind of highly toxic, efficient, and broad-spectrum organic phosphorus insecticides, which may prevent and control various pests on crops. However, the unscientific usage of MP has caused serious harm to humans and ecological environment. It is very necessary to design a sensitive and selective MP analysis method to ensure the food safety and life health. In this work, we reported a low-cost and environmental-friendly strategy to prepare the expired mung bean derived porous carbon (EMBPC) with interconnected carbon conductive network and large specific surface area, which was further decorated by cerium oxide (CeO2) nanoparticles. EMBPC possessed good conductivity property and electrochemical active area, which effectively boosted the charge transfer efficiency. CeO2 nanoparticles with good biocompatibility and high catalytic capacity promoted the efficient adsorption of MP on the surface of sensing electrode due to the affinity of CeO2 nanoparticles towards the phosphate groups of MP. Furthermore, EMBPC with porous carbon conductive structure could effectively make up for the inherent disadvantage of CeO2 nanoparticles in the term of electrical conductivity. The fabricated EMBPC@CeO2/GCE sensor showed highly sensitive MP detection property with low limit of detection (LOD) of 9.028 nM. The satisfactory repeatability, reproducibility, and anti-interference ability could be achieved at the fabricated MP electrochemical sensor. For the detection of MP in food samples, the EMBPC@CeO2/GCE sensor showed satisfactory recovery rates of 95.25–112.31 % and low RSD of 1.76–4.05 %, which suggested the good application prospect of the EMBPC@CeO2/GCE sensor.

Perovskite materials advance the potent sensor exploration

AbstractPerovskite materials with unique crystal structure have developed rapidly in recent years owing to their special physical and chemical properties, such as high light absorption and extraordinary electrocatalytic properties. Metal halide perovskites are quite attractive in various fields because of their simple manufacturing process, adjustable band gap, good charge transfer performance, and high theoretical photoelectric conversion efficiency. Therefore, perovskite oxides mixed with metal elements become ideal samples for studying the surface and catalytic performance of catalysts. In this review, various metal perovskites are clearly classified and introduced according to the corresponding synthesis methods, including hydrothermal method, sol–gel method, and high‐temperature solid phase, as well as coprecipitation. The excellent properties of perovskite make it extensively used in nanotechnology, chemistry, environmental protection, and material science, especially in solar cells and sensors. In particular, the nanosized perovskite materials are becoming more and more popular in sensors, which was reviewed in detail here. Most importantly, the design of electrochemical sensors using perovskite nanomaterials with low detection limit and high sensitivity will bring new insight into the detection of biomolecules. Both challenges and prospects of metal perovskites were discussed for promoting the development of biosensors in the end.

Development of a C3N4-based electrochemical sensing platform for the detection of circulating tumor cells in blood

This study presents a cancer diagnostics method through the development of a graphitic carbon nitride (g-C3N4)-based electrochemical sensor for detecting circulating tumor cells (CTCs) in blood. Utilizing the unique properties of g-C3N4 nanosheets combined with gold nanoparticles functionalized with DNA aptamers, the sensor exhibits remarkable sensitivity and selectivity in CTC detection. The aptamers specifically target cell surface biomarkers, enabling the precise capture and quantification of CTCs. The sensor's detection limit is an impressive 5 cells/mL, with a broad detection range from 10 to 105 cells/mL. This high-performance sensing platform not only achieves rapid and accurate quantification of CTCs but also demonstrates robustness against interference from other cell types, making it highly suitable for clinical applications. The optimized conditions for aptamer-functionalized nanoparticle concentration and incubation time ensure the sensor's efficacy, as validated in spiked blood samples. This work provides a practical and efficient approach for non-invasive cancer diagnostics, offering significant improvements over existing methods in terms of simplicity, sensitivity, and specificity for early detection and monitoring of cancer progression.

A Non‐Enzymatic Electrochemical Sensor Based on Cerium Oxide Nanocubes for the Rapid Detection of Hydrogen Peroxide Residues in Food Samples†

The rapid and simple detection methods of hydrogen peroxide (H2O2) residues is highly required for food safety. Herein, an electrochemical H2O2 sensor is developed with cerium oxide nanocubes as highly active non‐enzymatic catalyst. Combined with carbon black to improve conductivity, the disposable sensor can determine H2O2 in the range from 100 to 100 μM with a limit of detection (LOD) of 100 nM. This sensor also shows good selectivity and reproducibility, which is enabled to detect H2O2 in real food samples without any pretreatment in 100 s, providing a new solution for the direct quantitative measurement of H2O2 residues for food safety. © 2024 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC.

Electrochemical Sensing Device for Carboplatin Monitoring in Proof-of-Concept Drug Delivery Nanosystems.

(1) Background: Carboplatin (CBP) is a chemotherapeutic drug widely used in the treatment of a variety of cancers. Despite its efficiency, CBP is associated with side effects that greatly limit its clinical use. To mitigate these effects, CBP can be encapsulated in targeted delivery systems, such as liposomes. Ensuring the adequate loading and release of CBP from these carriers requires strict control in pharmaceutical formulation development, demanding modern, rapid, and robust analytical methods. The aim of this study was the development of a sensor for the fast and accurate quantification of CBP and its application on proof-of-concept CBP-loaded nanosomes. (2) Methods: Screen-printed electrodes were obtained in-lab and the electrochemical behavior of CBP was tested on the obtained electrodes. (3) Results: The in-lab screen-printed electrodes demonstrated superior properties compared to commercial ones. The novel sensors demonstrated accurate detection of CBP on a dynamic range from 5 to 500 μg/mL (13.5-1350 μM). The method was successfully applied on CBP loaded and released from nanosomes, with strong correlations with a spectrophotometric method used as control. (4) Conclusions: This study demonstrates the viability of electrochemical techniques as alternative options during the initial phases of pharmaceutical formulation development.

Ion-selective paper-based chromogenic strip and electrochemical sensor for the detection of ammonium ions

The fraudulent practice of adding ammonium salts to milk in order to enhance the nitrogen content has serious health implications including renal failure. Ammonium ion detection has been targeted through the conventional analytical methods however, lack of portability, and complex operation limits their use for field applications. In this scenario, paper-based test strips and electrochemical sensors can provide strategies for point-of-test applications. Here, an ion-selective paper-based chromogenic strip and electrochemical sensor has been developed for detection and quantification of ammonium ions. The developed paper-based chromogenic strip showed detection limit of 0.008 % (w/v) for ammonium ions, whereas, electrochemical sensor showed an LOD of 0.0062 ± 0.0023 % (w/v) with a sensitivity of 1.6 × 10−5 A.% −1.mm−2. The developed paper-based chromogenic strip and electrochemical sensor can be employed by regulatory bodies and dairy industries to ensure the safety and quality of milk.

MnO2 nanosheets based catechol oxidase mimics for robust electrochemical sensor: Synthesis, mechanism and its application for ultrasensitive and selective detection of dopamine

Nanozymes have favorable activity and good stability, which are potential alternatives to natural enzymes and widely applied in biosensing. However, nanozymes based electrochemical sensors are fewer, because many nanozymes are not easy to form efficient electrocatalytic interface and experience interference from the possible oxidizable species. Herein, ultrathin MnO2 nanosheets (MnO2 NSs) were synthesized by reduction of KMnO4 in acidic environment by chemical precipitation method. The MnO2 NSs show excellent catechol oxidase mimicking activity. The steady-state kinetics of MnO2 NSs shows a higher Vmax of 3.441 µM s−1. Additionally, the catalytic mechanism is that in the presence of oxygen, catechol or its analogues are oxidized to quinone or quinoids, while oxygen is reduced to H2O. Afterwards, the possible mechanism of dopamine (DA) at MnO2 NSs-modified electrode is investigated. DA is first catalytically oxidized to dopamine quinone (DQ) by MnO2 NSs based catechol oxidase, which further undergoes irreversible electrochemical reduction to DA involving two protons and two electrons transfer during the process. On the basis of this, a selective and ultrasensitive amperometric detection of DA at 0.0 V (vs. SCE) was explored, which have two linear parts, 0.01–20 μM and 20–100 μM DA with the LOD of 4.1 nM (S/N = 3). Most importantly, the presence of oxidizable species including ascorbic acid, uric acid and cysteine may coexist with DA in biological systems do not exhibit any appreciable interference. The as-proposed method was applicable to detect DA in human serum samples with good satisfactory accuracy and recovery. This research casts prospect to apply nanozymes for electrochemical sensor with excellent analytical performance.

A structure-switching electrochemical aptamer sensor for mercury ions based on an orderly assembled gold nanorods-modified electrode

In this paper, an electrochemical aptamer sensor with high sensitivity and selectivity was proposed for the detection of mercury ion (Hg2+). The orderly assembled gold nanorods-modified screen-printed electrode (AuNRs/SPE) was used to improve the sensor with higher sensitivity and data reproducibility. The sensor was designed based on the specific recognition of Hg2+ with aptamer to form T-Hg2+-T binding structure. Two aptamer chains were applied in the designed sensor, aptamer S1 with terminal thiolate group was self-assembled on the AuNRs/SPE via Au-S bond, and complementary S2 labeled with ferrocene (Fc) would generate a strong redox electrical signal. The addition of Hg2+ would mediate the folding of the T-base of S1 to form a hairpin structure, resulting in the dissociation of the Fc-labelled S2 from the sensing system and a significant reduction in the redox current. The electrochemical properties of the sensor were further investigated using cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). The effects of aptamer reaction time, concentration, and target incubation time on the sensor response were also investigated. The results showed that the sensor had a sensitive response to Hg2+ at concentrations ranging from 1 pM to 1 μM, with a detection limit of 0.3 pM. Furthermore, the proposed sensor was applied in the determination of Hg2+ in real samples, demonstrating its potential practical value.

A Physical Insight of Phase-Dependent Electron Transfer Kinetic Behaviors and Electrocatalytic Activity of an Iron Oxide-Based Sensing Nanoplatform Towards Chloramphenicol

Insight into the phase-dependent electron transfer kinetics and electrocatalytic activity of metal oxide nanostructures is important in the rational design of functional nanostructures for realizing high-performance electrochemical sensors. This study focuses on elucidating the effect of the crystalline phase on the electron transfer kinetics and electrocatalytic activity of iron(III) oxide. The α-FeOOH, γ-Fe2O3, and α-Fe2O3 nanorods were designed by using a simple chemical method and calcining process. The phase-dependent difference in the electron transfer kinetics and electrocatalytic activity toward the sensitive response of chloramphenicol (CAP) is observed by the transformation from α-FeOOH to γ-Fe2O3, and from α-FeOOH to α-Fe2O3 nanorods. We found that the oxygen vacancies formed in phase transformation from α-FeOOH to α-Fe2O3 is a key factor in promoting the electrochemical reduction of chloramphenicol. The α-Fe2O3 nanorods-based electrochemical sensors showed a linear response in the CAP concentration range from 0.1 to 75 μM with a limit of detection of 60 nM and an electrochemical sensitivity of 2.86 μA μM−1 cm−2. This work further provides valuable physical insight into the phase-dependent electron transfer kinetics and electrocatalytic activity of metal oxide nanostructures for the rational design of sensing interface.

An o-Phenylenediamine and MWCNT-Based Electrochemical Sensor for the Detection of Triclosan by Cyclic Voltammetry

Selectivity and sensitivity are the two key parameters for construction of a sensor. In this work, a novel electrochemical sensor based on molecularly-imprinted composites synthesized from o-phenylenediamine (o-PD) and multiwalled carbon nanotube (MWCNT) to detect triclosan is reported. Two different sensors were developed MIC/GC and MIC/cf-MWCNT/GC. To fabricate MIC/GC, molecularly imprinted composite (MIC) was synthesized by cyclic voltammetry using o-PD, COOH-functionalized MWCNT (cf-MWCNT) and triclosan on glassy carbon (GC) electrode, following removal of surface triclosan. MIC/cf-MWCNT/GC was fabricated by synthesizing MIC on cf-MWCNT coated GC. Template removal was performed using NaOH solution. MIC/GC could detect triclosan till 40 ppb while using MIC/cf-MWCNT/GC, 10 ppb of limit of detection (LOD) was achieved. Adsorption isotherms were constructed for both the films. Langmuir adsorption isotherm gave the best fit for MIC/cf-MWCNT/GC with -ΔGads value of 54.952 kJ mol−1 indicating stronger chemisorption. To understand the role of cf-MWCNT in detection of triclosan, electrochemical band gap studies, electrochemical impedance spectroscopy, and cyclic voltammetry studies were conducted. Both the sensors were found to be efficient for detection of triclosan in the presence of interfering ions.

A Novel MXene@MOF@Pt NPs-Based Enzyme-Free Electrochemical Sensor for Highly Sensitive Detection of Hydrogen Peroxide Released from Living Cells

Rapid and accurate detection of hydrogen peroxide (H2O2), an important reactive oxygen species (ROS) released from living cells, is of great significance for early diagnosis of tumors. Here, a high sensitive enzyme-free electrochemical sensor for the detection of H2O2 released from living cells was constructed based on MXene@ZIF-8@Pt NPs nanocomposites. Through the characterization of physical and chemical properties, it was observed that Pt NPs with excellent catalytic activity were uniformly supported on MXene@ZIF-8, which exhibited excellent conductivity and large specific surface area. Thanks to the significantly enhanced catalytic activity derived from the successful integration of MXene, ZIF-8 and Pt NPs, under the optimal conditions, the sensing platform based on MXene@ZIF-8@Pt NPs exhibited a wide linear range from 355.4 nM to 21.75 mM, with a limit of detection as low as 120.9 nM, while showing satisfactory reproducibility and selectivity. Furthermore, the developed electrochemical sensor enables real-time monitoring of H2O2 released from living Hela cells under N-formylmethionyl-leucyl-phenylalanine stimulation. Overall, the MXene@ZIF-8@Pt NPs developed in this article will become a promising candidate in monitoring physiological processes.

An electrochemical sensor based on molecularly imprinted poly(o-phenylenediamine) for the detection of thymol

A molecularly imprinted electrochemical sensor was facilely fabricated for the detection of thymol (THY). o-Phenylenediamine (oPD) was used as the functional monomer and electropolymerized on the surface of the glassy carbon electrode (GCE) by using THY as the templates. After the THY templates were removed with 50 % (v/v) ethanol, imprinted cavities complementary to the templates were formed within the poly(o-phenylenediamine) (PoPD) films. The resultant molecularly imprinted PoPD/GCE (MI-PoPD/GCE) was used for the detection of THY, and a wide linear range from 0.5 to 100 μM with a low limit of detection (LOD) of 0.084 μM were obtained under the optimal conditions. The developed MI-PoPD/GCE also displays high selectivity, reproducibility and stability for THY detection. Finally, the content of THY in the real samples was accurately determined by the as-fabricated MI-PoPD/GCE, demonstrating its high practicability and reliability.

Portable electrochemical aptasensor for highly sensitive detection of 3,3′,4,4′-tetrachlorobiphenyl

Aptamer-based electrochemical sensors are frequently used as independent, surface-functionalized, passive electrodes. However, their sensitivity and detection limits become limited, particularly when the electrode area is reduced to facilitate miniaturization. A mobile phone-based microfluidic electrochemical aptamer sensing platform for 3,3′,4,4′-tetrachlorobiphenyl (PCB77) detection was developed in this work. This aptamer sensor utilized Exonuclease I (Exo I) and DNA/AuNPs/horseradish peroxidase (DNA/AuNPs/HRP) nanoprobes as a merged signal amplification method, which resulted in an increase in the electrochemical sensing performance. Sensitive detection of PCB77 was accomplished by functionalizing the hierarchically structured Au@MoS2/CNTs/GO modified working/sensing electrode with the specific aptamer. The aptamer sensor was tested with different concentrations of PCB77 within the microfluidic platform. Afterward, the differential pulse voltammograms were recorded using a wireless integrated circuit device. Subsequently, the collected data was transmitted to a smartphone using Bluetooth communication. A detection limit of 0.0085 ng/L was obtained for PCB77 detection, with a detection range from 0.1 to 1000 ng/L. In addition, the detection of PCB77 in spiked water samples validated the possibility of using this aptamer sensor in a real environment, and the aptamer sensor demonstrated high selectivity in distinguishing PCB77 from other potential interfering species. The merging of electrochemical aptamer sensors with purposefully engineered microfluidic and integrated devices in this study is a novel and promising method that provides a dependable platform for on-site applications.

Aminosilane assisted deposition of gold nanoparticles on Zn(OH)2 nanosheets and their application in electrochemical sensor

A facile and efficient method for systematical deposition of gold nanoparticles (AuNPs) on Zn(OH)2 nanosheets (NS) with different Zn and Au ratios was established in the presence of N-[3-(trimethoxysilyl)propyl]diethylenetriamine (TPDT silane), without adding any external reducing agents, at room temperature. Here, TPDT silane behaves as both a stabilizing and reducing agent. UV–vis absorption spectroscopy, transmission electron microscopy, high-angle annular dark-field scanning transmission electron microscopy-energy dispersive X-ray spectroscopy, X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscopy were used to confirm the formation of AuNPs on Zn(OH)2 NS. As the concentration of AuNPs increased, a proportional increase in both the number and size of deposited AuNPs on Zn(OH)2 NS was observed. To understand how the variation in the number and size of AuNPs affects their catalytic activity, the electrocatalytic activity of different composition ratios of Zn(OH)2-Au NS toward nitrite ions was studied using cyclic voltammetry and amperometric technique. The TPDT-stabilized Zn(OH)2-Au NS showed high electrocatalytic activity, attributed to the effective electron transfer from Zn(OH)2 NS to AuNPs, creating a synergistic effect that enhances the overall activity. The optimal Zn(OH)2-Au NS modified electrode showed an amperometric sensitivity of 5.72 nA/µM and a limit of detection of 1.2 µM for nitrite ions in water sample well below the guideline value of WHO. This demonstrates the practical applicability of this method for real-world water analysis.

Development of an efficient electrochemical sensor based on CuAl-LDH using an electrostatic repulsion approach for the selective determination of dopamine in the presence of uric acid and ascorbic acid species

This study provides a unique electrochemical sensor that exhibits both excellent sensitivity and selectivity, while also being environmentally friendly. The CuAl-LDH/GCE sensor, proposed as the recommended sensor, was synthesized using a straightforward one-step co-precipitation procedure. It was first used to measure dopamine levels using differential pulse voltammetry. At the ideal pH level of 8, dopamine has a positive charge, but ascorbic acid and uric acid have a negative charge. LDH, on the other hand, carries a negative charge and exhibits high electrostatic attraction towards dopamine, but is electrostatically repelled by negatively charged ascorbic acid and uric acid. Hence, CuAl-LDH/GCE has the potential to specifically ascertain the existence of dopamine in the presence of these particular species. The examination of the composition and morphology of CuAl-LDH was conducted using various analytical techniques, including scanner electron microscopy (FESEM), transmission electron microscope (TEM), element mapping (MAP), Fourier transform infrared (FTIR), energy-dispersive X-ray spectroscopy (EDX), Brunauer Emmett Teller (BET), X-ray photoelectron diffraction (XRD), and Raman techniques. Under ideal circumstances, the calibration graph of dopamine was generated using differential pulse voltammetry. A linear range of 4.194–1151.54 μM was achieved for dopamine, with a limit of detection of 0.33 μM. The findings of the study indicate that the sensor created for dopamine determination has exceptional stability, repeatability, and reproducibility. The sensor that was presented was effectively used for the measurement of dopamine in both pharmaceutical ampoules and human plasma samples.

Graphene quantum dots (GQDs)-modified screen-printed electrode for the determination of cannabidiol (CBD) in hemp seeds flour

In this work, the development of a graphene quantum dots (GQDs)-modified screen-printed carbon (SPCE) electrode for the determination of cannabidiol (CBD), a cannabinoid present in the Cannabis L. Sativa (hemp) plant, is reported. This cannabinoid is non-intoxicating and non-psychoactive, thus CBD-containing drugs as well as CBD-containing foods, are now on the market in many countries due to their health-beneficial effects and pharmacological activities. Because of the increasing interest in analyzing CBD in these real samples, we analyzed here a sample of hemp flour that was used for testing the developed CBD electrochemical sensor. Preliminary work devoted to optimizing the analysis conditions, allowed to development of a GQDs-modified electrode with promising characteristics for the simple screening of CBD. The electroanalytical tests for CBD detection showed a sensitivity of 0.98 μAμM-1 cm−2, which is increased by 2-folder compared to bare SPCE, and a limit of detection (LOD) equal to 0.277 μM. The developed GQDs/SPCE sensor and the analysis procedure were then applied for the CBD analysis in a hemp seeds flour sample. Based on the results obtained, the advantages/disadvantages evidenced by operating with the developed electrochemical sensor in the analysis of CBD in real samples were discussed.

Application of Graphdiyne Confined Gold Nanoparticles Modified Electrode as A Robust Sensing Platform for The Detection of 7-Hydroxy-6-Methoxy-Hydrocoumarin

A graphdiyne (gdy) and gold nanoparticles (aunps) nanocomposite was formed with aunps growing on the surface and between the layers of gdy, which was used as the sensing interface on carbon ionic liquid electrode (cile) to detect 7-hydroxy-6-methoxy-hydrocoumarin (7–6-hdc) that isolated from the noni juice. The GDY-Au nanocomposite was characterized by different spectroscopic techniques, which exhibited corrugated and folded morphology with large specific surface area. The GDY-Au nanocomposite modified electrode displayed excellent performance which is attributed to the highly conductive nanocomposite, where gdy structure with defects could immobilize more aunps to decrease the electron transfer resistance. In addition, the reaction mechanism of 7–6-hdc at GDY-Au surface was deduced based on the electrochemical kinetics investigations. Combined with density functional theory calculation, it was verified that the active site of 7–6-hdc and the presence of aunps enhanced the electrocatalytic capacity of GDY-Au nanocomposite. Under optimal conditions, the modified electrode displayed a wider linear range from 10.0 nm to 1.0 mm for 7–6-hdc analysis with a detection limit of 3.22 nm (3s0/s). This work provides a promising material to realize accurate analysis for 7–6-hdc, and the discovered sensing mechanism provides method guidance for the exploration of other novel electrochemical sensors.

Enzyme-Free Glucose Detection via Scalable and Economical Fabrication of Nickel-Polyvinylpyrrolidone-Modified Multi-Walled Carbon Nanotubes

Development of accurate, reliable, and affordable glucose detection tools remains a top scientific priority. Nanotechnology is frequently utilized for this purpose. In this study, polyvinylpyrrolidone (PVP)-modified nickel (Ni) nanoparticles on multi-walled carbon nanotube (MWCNT) were prepared using a unique microwave synthesis technique. The synthesized particles were investigated by transmission electron microscopy (TEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). TEM analysis revealed that well-dispersed Ni nanoparticles with an average size of about 4.11 nm were uniformly dispersed on the MWCNT surface in the presence of PVP particles. The obtained NiPVP@MWCNT was used for the glucose sensor and its performance was investigated. According to the results, the limit of detection (LOD) and limit of quantification (LOQ) values for NiPVP@MWCNT nanocomposite in the linear range of 0.1 mM - 1 mM were calculated as 0.364 mM and 1.215 mM, respectively. As a result of the selectivity test, it was observed that it was highly selective for glucose and the current values increased with increasing concentration. Our study shows that the cost of platinum, which is widely used in electrochemical sensors, can be reduced by the application of polymeric structures. This leads to a more stable structure. The developed nanostructures are efficient, highly stable, discriminative, and sensitive and have the potential to be used as glucose sensors in the market.