μA μM Research Articles

High-Density Dual-Structure Single-Atom Pt Electrocatalyst for Efficient Hydrogen Evolution and Multimodal Sensing.

Herein, we report a high-density dual-structure single-atom catalyst (SAC) by creating a large number of vacancies of O and Ti in two-dimensional (2D) Ti3C2 to immobilize Pt atoms (SA Pt-Ti3C2). The SA Pt-Ti3C2 showed excellent performance toward the pH-universal electrochemical hydrogen evolution reaction (HER) and multimodal sensing. For HER catalysis, compared to the commercial 20 wt % Pt/C, the Pt mass activities of SA Pt-Ti3C2 at the overpotentials of ∼30 and 110 mV in acid and alkaline media are 45 and 34 times higher, respectively. More importantly, during the alkaline HER process, an interesting synergetic effect between Pt-C and Pt-Ti sites that dominated the Volmer and Heyrovsky steps, respectively, was revealed. Moreover, the SA Pt-Ti3C2 catalyst exhibited high sensitivity (0.62-2.65 μA μM-1) and fast response properties for the multimodal identifications of ascorbic acid, dopamine, uric acid, and nitric oxide under the assistance of machine learning.

A simple and efficient electrochemical sensor for folic acid determination on Ti(OH)4 modified carbon paste electrode

Folic acid (FA) has a crucial function in pregnant women and anemic patients. Having adequate FA prior to and during the gestation period can protect the brain of the child and spine from significant birth abnormalities. It reduces the risk of stroke, heart disease and some types of cancers, etc. Thus, FA is employed as a reliable biomarker in the early identification of various disorders. In the present study, we synthesized titanium tetra hydroxide [Ti(OH)4] nanoparticles (NPs) by precipitation method with annealing at 100 °C, which is used to modify carbon paste electrode (Ti(OH)4 /MCPE). FA is detected here by voltammetry method using Ti(OH)4/MCPE in the phosphate buffer of pH 6 and compared with bare and TiO2-400, TiO2-600 and TiO2-800 °C NPs MCPE. Based on ac-impedance spectra, the conductivity of Ti(OH)4/MCPE was found to be higher, and consequently this electrode showed excellent sensitivity of 5.5 µA µM−1 cm−2. Lower detection limit (1.3 nM) was observed in the concentration range of 0.4–30 μM by differential pulse voltammetry. The Ti(OH)4/MCPE was also effective for the determination of FA in real samples such as orange, banana, spinach and tablet. The electrochemical sensor investigated here showed excellent stability (92 %) up to 30 days.

Manganese tetraphenylporphyrin and carbon nanocoil interface-based electrochemical sensing of tyrosine.

Tyrosine is one of the essential metabolites present in the human body for nutritional maintenance and normal physiological functioning. Its concentration in the body is crucial in predicting various hereditary, emotional, and physiological disorders. Therefore, quantitative monitoring of tyrosine in clinical samples is indispensable. We state the use of carbon nanocoils/manganese tetraphenylporphyrin convened glassy carbon electrode (CNC/MnTPP/GC) for the streamlined electrochemical sensing of tyrosine. Cutting-edge analytical techniques were employed to perform a comprehensive physicochemical analysis of the synthesized materials. To investigate the electrochemical properties, various techniques such as cyclic voltammetry (CV), differential pulse voltammetry (DPV), electrochemical impedance spectroscopy, and chronocoulometry were employed. CNC/MnTPP/GC displayed an optimal response at pH 5 and exhibited remarkable linearity within the concentration range of 0.05 to 100 μM for tyrosine. Using DPV, it demonstrated a low limit of detection (21 nM ± 1.17) and a sensitivity of 0.12 μA μM-1 cm-2. CNC/MnTPP/GC displayed excellent performance in terms of repeatability, reproducibility, and stability for up to 30 days, making it suitable for real-time analysis, particularly in the analysis of tyrosine in blood serum. Notably, CNC/MnTPP/GC showcased a superior detection limit compared to previously reported methods.

Electrochemical Detection of Ammonia in Water Using NiCu Carbonate Hydroxide-Modified Carbon Cloth Electrodes: A Simple Sensing Method.

Excessive ammonia nitrogen can potentially compromise the safety of drinking water. Therefore, developing a rapid and simple detection method for ammonia nitrogen in drinking water is of great importance. Nickel-copper hydroxides exhibit strong catalytic capabilities and are widely applied in ammonia nitrogen oxidation. In this study, a self-supported electrode made of nickel-copper carbonate hydroxide was synthesized on a carbon cloth collector via a straightforward one-step hydrothermal method for rapid ammonia nitrogen detection in water. It exhibits sensitivities of 3.9 μA μM-1 cm-2 and 3.13 μA μM-1 cm-2 within linear ranges of 1 μM to 100 μM and 100 μM to 400 μM, respectively, using a simple and rapid i-t method. The detection limit is as low as 0.62 μM, highlighting its excellent anti-interference properties against various anions and cations. The methodology's simplicity and effectiveness suggest broad applicability in water quality monitoring and environmental protection, particularly due to its significant cost-effectiveness.

Development of tungsten trioxide nano-flakes intercalated on tannic acid-functionalized reduced graphene oxide for flexible acebutolol sensors

Acebutolol (ACE) is commonly used to treat hypertension and high blood pressure. Large doses of ACE can have adverse effects with potentially life-threatening consequences. It is, therefore, essential to develop a simple, low-cost, reliable, and reproducible device for detecting ACE in biofluids. This study explores the potential of unique two-dimensional nano-flakes, such as tungsten trioxide (WO3). Graphene oxide (GO) typically exhibits lower electrical conductivity than pristine graphene due to the presence of oxygen-containing functional groups that interfere with the π-conjugated structure. Functionalizing GO with tannic acid (TA) can partially reinstate the π-conjugation and limit the amount of oxygen, resulting in enhanced electrical conductivity. Ultrasonic techniques were utilized to create WO3 NFs@TA-rGO, and a range of spectroscopic and microscopic methods were applied to examine the formation of the resulting WO3 NFs@TA-rGO nanocomposites. Under optimal conditions, modified sensors resulted in lower limits of detection (0.0055 μM) and good sensitivity (0.40 μA μM−1 cm−2). They also exhibited a broad linear range spanning from 0.009 to 568.6 μM. Fabricated sensors have significant anti-interference properties with high specificity and excellent storage stability (RSD = 4.3 %), reproducibility (RSD = 3.9 %), and repeatability (RSD = 3.3 %). Ultimately, the sensor's efficacy was confirmed through the successful detection of ACE in biological samples (with recoveries ranging from 99.1 to 99.6 %). Lastly, this study highlights the substantial potential of ACE detection and extends its applications in biomedical diagnostics and pharmaceutical research.

A Biosensor for Simultaneous Detection of Epinephrine and Ascorbic Acid Based on Fe(III)-Polyhistidine-Functionalized Multi-Wall Carbon Nanotube Composites.

Epinephrine (EP) is a very important chemical transmitter in the transmission of nerve impulses in the central nervous system of mammals. Ascorbic acid (AA) is considered to be the most important extracellular fluid antioxidant and has important antioxidant properties in the cell. In this study, a series of transition metal-polyhistidine-carboxylated multi-wall carbon nanotube nanocomposites were synthesized, and their simultaneous catalytic effects on epinephrine and ascorbic acid were investigated. The results showed that nanocomposites based on iron ions had the highest catalytic activity. The prepared biosensor expressed high selectivity toward EP and AA with LOD values of 0.1 μΜ (AA) and 0.01 μΜ (EP), and sensitivity values of 4.18 μA mM-1 with a range of 0.001-5 mM (AA), 50.98 μA mM-1 with a range of 0.2-100 μM (EP), and 265.75 μA mM-1 with a range of 0.1-1.0 mM (EP). Moreover, it showed good stability, good repeatability and high selectivity in real sample detection. This work is a reference for the design of new electrochemical enzyme-free biosensors and the detection of biomarkers.

Assembly of Gold Nanostar Cores Within Silica Shells and Its Impact on Solid-State SERS and Nonenzymatic Catalytic Sensing.

Metal core and dielectric shell nanoparticles (NPs) have garnered considerable attention for their multifaceted properties and extensive applications across diverse fields of nanoscience and nanotechnology. However, a literature gap exists regarding the impact of assembled metallic nanostar cores within a single shell, particularly concerning surface-enhanced Raman scattering (SERS) and electrochemical sensing. In this study, we have demonstrated the better performance of assemblies of gold nanostars (AuNSs) enclosed in single silica shell for SERS enhancement and electrocatalytic activity, particularly in the fields of ascorbic acid (AA) and glucose sensing. We have devised a method to isolate and passivate nanostar assemblies, ranging from 2 to 30 nanostars per assembly, with a functionalized silica (SiO2) shell, facilitating their preservation. The engineered thickness of the silica shell ensures unhindered optical measurements while elucidating the influence of multiple AuNS cores. Due to the formation of nanogaps and nanojunctions between AuNSs within assembly, we have achieved a maximum SERS enhancement factor (EF) of 1.416 × 1010 for the rhodamine 6G analyte. Utilizing assembled AuNS cores within a single silica shell, we have demonstrated AA (sensitivity of 5.278 × 10-5 μA μM-1 cm-2) and glucose (sensitivity of 7.519 × 10-4 μA μM-1 cm-2) sensing via a nonenzymatic electrochemical pathway.

Design and performance analysis of double gate vertically stacked MoS2 nanosheet field effect transistor

In this work we report a vertically stacked nanosheet Field Effect Transistor (NSFET) in double gate configuration using transition metal dichalcogenide (TMD) based molybdenum disulphide (MoS2) as the conducting channel. The performance of the NSFET is analysed for number of channels, different channel thickness, different source/drain contacts. The performance of the device at different temperatures (T) also analysed. The proposed NSFET with three vertically stacked channels, exhibits a ON current (ION) of 30.6 μA μm−1, Subthreshold swing (SS) of 69 mV/dec and ON to OFF current ratio of more than 108 at Vds = 1V. Further the ION can be improved with multi-layer channel thickness. The performance of the vertically stacked MoS2 NSFET in junction less (JL) and inversion mode (IM) is compared, it is concluded from the simulations that JL vertically stacked MoS2 NSFET more immune to short channel effects such as threshold voltage (Vth) roll-off and drain induced barrier lowering (DIBL).

Paper-based Electrochemical Sensor Integrated with Gold Nanoparticle-Decorated Carbon Cloth as a Working Electrode for Nitric Oxide Detection in Artificial Tears.

Nitric oxide (NO) in human tears regulates numerous ocular surface processes, such as tear generation, corneal wound healing, conjunctival vascular tone, and so forth. Any deviation from its normal concentration is linked to various ocular syndromes, including microbial keratitis, conjunctivitis, pterygium, dry eye, retinitis, glaucoma, and so forth. Therefore, precise monitoring of NO in tears can be considered as a potential biomarker for ocular diseases. Here, we report a highly sensitive and selective electrochemical NO sensor using carbon ink-based electrodes. Counter, working (WE), and reference electrodes have been designed and painted on a butter paper by using carbon ink. To improve the sensing performance, the WE has been modified with a gold nanoparticle (Au NP)-deposited carbon cloth (CC). Such a paper-based sensor demonstrated high sensitivity of ∼0.34 μA μM-1 cm-2, ultralow detection limit of ∼2.35 nM, wide linear range of 10 nM-0.4 mM, and fast response time (0.35 s). The sensor also showed excellent stability and selectivity toward the interfering agents in human body fluids. Such a low-cost, flexible paper-based sensor was employed for the detection of NO in artificial tears.

Nanoarchitectonics of Fe single-atom catalyst modified with flexible wearable patch for sweat biomarker analysis

In personalized medical diagnostics and health monitoring, the analysis of biomarkers in sweat, such as uric acid (UA) and dopamine (DA), offers valuable insights into metabolic states. This study introduces a flexible wearable patch based on Fe single-atom catalysts (FeSAs) to simultaneously detect UA and DA in sweat for comprehensive health assessment. Our wearable patch demonstrated linear response ranges of 1–800 μM for UA and 1–500 μM for DA, with detection limits of 2.68 μM and 3.76 μM, and sensitivities of 0.015 μA μM−1 cm−2 and 0.0176 μA μM−1 cm−2, respectively. Additionally, we integrated agarose hydrogel into the wearable patches, optimizing sweat collection efficiency at agarose concentrations ranging from 2 % to 3.8 %. This innovation enables effective biomarker enrichment directly from the skin surface. In conclusion, our study presents an innovative FeSAs-based electrocatalyst capable of simultaneous detection of low-concentration UA and DA biomarkers.

A highly sensitive and selective electrochemical sensing probe for detection of Edoxaban anticoagulant drug residue in environmental water and drug formulations

ABSTRACT Anticoagulant drugs currently play a crucial role in preventing severe deep vein thrombosis, heart attacks, heart valve diseases and contribute to the regulation of blood flow. Thus, the existing study reports the redox behaviour of Edoxaban (EDX) anticoagulant drug at bare glassy carbon electrode (GCE) for establishing sensitive, and selective adsorptive square wave – cathodic stripping voltammtric (Ads SW-CSV) probe for EDX detection. Under the optimal analytical parameters, the probe displayed good linear dynamic range (LDR) of EDX from 1.0 × 10−6 − 1.0 × 10−5 M. The probe displayed probe sensitivity, limits of detection (LOD) and quantification (LOQ) of 18.5 µA µM−1 cm−2, 3.3 × 10−7 and 1.0 × 10−6 M, respectively. The probe offered quick response, good anti-interference ability towards multiple co-existing species, good recovery (99.21 ± 5.02), reproducibility, and repeatability with relative standard deviation (RSD) of ± 3.0% at 1.0 × 10−6 M of EDX (n = 3). Intraday and interday precisions of the probe were 99.8 ± 1.74 and 99.54 ± 2.08% at 1.0 × 10−6 M of EDX, respectively. The probe was fruitfully applied for EDX detection in its formulations and its residue in water samples with good recovery (99.76 ± 3.768–101.43 ± 0.09) and precision (RSD < 3%) at low and high EDX levels. The tabulated Student t test (t tab =2.78) was higher than the experimental t exp = 1.3–1.7 at 95% probability (n = 5). The probe exhibited good sensitivity and selectivity towards EDX detection in drug formulation and environmental water samples. The probe has long-term stability and high level of anti-interference performance towards EDX detection.

CuxO decorated Ti3C2Tx MXene composites for non-enzymatic glucose sensing with large linear ranges.

Ti3C2Tx MXene/CuxO composites were prepared by acid etching combined with electrochemical technique. The abundant active sites on the surface of MXene greatly increase the loading of CuxO nanoparticles, and the synergistic effect between the different components of the composite can accelerate the oxidation reaction of glucose. The results indicate that at the working potential of 0.55V (vs. Ag/AgCl), the glucose sensor based on Ti3C2Tx MXene/CuxO composite presents large linear concentration ranges from 1 µM to 4.655 mM (sensitivity of 361 µA mM-1 cm-2) and from 5.155 mM to 16.155 mM (sensitivity of 133 µA mM-1 cm-2). The limit of detection is 0.065 µM. In addition, the sensor effectively avoids the oxidative interference of common interfering species such as ascorbic acid, dopamine and uric acid. Thesensor has good reproducibility, stability and acceptable recoveries for the detection of glucose in human sweat sample (97.5-103.3%) with RSD values less than 4%. Based on these excellent properties it has great potential for the detection of glucose in real samples.

A home-made nanoporous gold microsensor for lead(II) detection in seawater with high sensitivity and anti-interference properties.

A nanoporous gold microelectrode (NPG-μE) was fabricated and used for Pb(II) detection in seawater samples via square wave anodic stripping voltammetry (SWASV). The Au microelectrode (Au-μE) was fabricated by embedding a gold microfiber into a Pasteur pipette, and its surface was further modified by an anodization-electrochemical reduction (A-ECR) method, yielding the NPG-μE. The fabricated electrodes were characterized by cyclic voltammetry (CV) and field emission scanning electron microscopy (FE-SEM) for electrochemical and structural morphological investigations. SWASV results show a Pb(II) stripping peak at around -0.05 V vs. Ag/AgCl, sat. KCl, which is unusual for common Pb(II) detection (typically occurring at around -0.40 V) in anodic stripping voltammetry (ASV) analysis. The Pb(II) detection at less negative stripping potential is more beneficial. Hence, it exhibited anti-interference properties with Cd(II), which is attributed to the preferential deposition and stripping of the target analyte on the low-indexed crystal planes of the NPG structure. The calibration plot obtained by SWASV was linear in the concentration range of 0.1-10 μM, and the detection limit was found to be 57 nM (correlation coefficient of 0.9974). The NPG microsensor presented a 15-fold enhanced current response compared to Au-μE, with excellent sensitivity (27.2 μA μM-1 cm-2). The application of the NPG microsensor was examined by detecting Pb(II) in seawater samples, and a satisfactory performance was obtained.

A symmetric heterogate dopingless electron-hole bilayer TFET with ferroelectric and barrier layers

In this paper, a symmetric heterogate dopingless electron–hole bilayer tunnel field-effect transistor with a ferroelectric layer and a dielectric barrier layer (FBHD-EHBTFET) is proposed. FBHD-EHBTFET can not only avoid random doping fluctuation and high thermal budget caused by doping, but also solve the issue that conventional EHBTFETs are unable to use the self-alignment process during device manufacturing. The simultaneous introduction of the symmetric heterogate and dielectric barrier layer can significantly suppress off-state current (I off). Ferroelectric material embedded in the gate dielectric layer can enhance electron tunneling, contributing to improving on-state current (I on) and steepening average subthreshold swing (SS avg). By optimizing various parameters related to the gate, ferroelectric layer, and dielectric barrier layer, FBHD-EHBTFET can obtain the I off of 1.11 × 10–18 A μm−1, SS avg of 12.5 mV/dec, and I on of 2.59 × 10–5 A μm−1. Compared with other symmetric dopingless EHBTFETs, FBHD-EHBTFET can maintain high I on while reducing its I off by up to thirteen orders of magnitude and SS avg by at least 51.2%. Moreover, investigation demonstrates that both interface fixed charge and interface trap can increase I off, degrading the off-state performance of device. The study on FBHD-EHBTFET-based dynamic random access memory shows that it has the high read-to-current ratio of 1.1 × 106, high sense margin of 0.42 μA μm−1, and long retention time greater than 100 ms, demonstrating that it has great potential in low-power applications.

Deep eutectic solvent-mediated synthesis of ZnCo2O4/MWCNT-COOH: Investigation of electrocatalytic activity for gatifloxacin detection

The overuse of gatifloxacin seriously pollutes the environment and cause potential harm to our health. Hence, it is imperative to develop a rapid and sensitive method for gatifloxacin determination. Herein, an efficient electrocatalyst was designed for the voltammetric determination of gatifloxacin based on carboxylated multiwalled carbon nanotubes warped ZnCo2O4 nanoparticles (ZnCo2O4/MWCNT-COOH). The ZnCo2O4 nanoparticles were synthesized by a green deep eutectic solvent-mediated ion-thermal route, and further composited with MWCNTs-COOH. The ZnCo2O4/ MWCNT-COOH combined the catalytic activity of ZnCo2O4 with the high electrical conductivity of MWCNT-COOH, aiming to improve the electrochemical sensing performance toward gatifloxacin. The synergistic interactions between ZnCo2O4 and MWCNT-COOH endowed the ZnCo2O4/MWCNT-COOH with extraordinary catalytic activity for gatifloxacin oxidation. Consequently, the ZnCo2O4/MWCNT-COOH displayed a wide linear response range (0.01–10 μM) for detecting gatifloxacin, with a high sensitivity (29.64 μA μM−1 cm−2) and low detection limit (2.0 nM). The ZnCo2O4/MWCNT-COOH showed robust voltammetric responses against potential interfering species, and maintained highly stable responses for at least two weeks. Moreover, the ZnCo2O4/MWCNT-COOH/GCE was successfully used to detect gatifloxacin in water samples with satisfactory recoveries (97.22 − 104.5 %). Together with its low cost, environment friendly and rapid response, the ZnCo2O4/MWCNT-COOH shows promising prospects in trace detection of gatifloxacin.

Efficient and environmentally friendly uric acid voltametric sensor based on Ni-MOF and carboxylated multi-walled carbon nanotubes nanocomposites

Uric acid (UA) levels are significant in the monitoring of human health, making their detection very important. In this paper, a simple and innovative electrochemical method for the detecting UA was established, using a sensing platform based on hybrid electrodes of Nickel-Metal Organic Framework (Ni-MOF) and carboxylated multi-walled carbon nanotubes (MWCNTs-COOH). Detailed investigations into the electrocatalytic activity of Ni-MOF/MWCNTs-COOH/GCE for The Ni-MOF/MWCNTs-COOH exhibited remarkable catalytic activity for UA oxidation. The detection limit was 0.005 μM, with a sensitivity calculation result of 6.377 µA µM−1, and a wide linearity interval (0.03–10 μM, 10–300 μM). Utilizing its high sensitivity and selectivity, this sensor was used for the measurement of UA in biological fluids, including human serum and urine samples, recovery amounts being 96.6–100.8 %, and 98.9–101.3 %. This work is highly significant; offering new perspectives for the application of Ni-MOF based chemical sensors in the realms of environmental monitoring and healthcare.

Ultrasensitive tadalafil detection with eco-friendly CeO2/Al-pillared clay incorporated pencil graphite paste electrode

In this study, we have constructed a novel voltammetric sensor based on montmorillonite clay (MMT) incorporated with CeO2 nanoparticles using a composite graphite paste electrode as a cross linker (MMT-CeO2NPs/GPG-PE) for the trace determination of tadalafil (TAD) drug. The characterization of CeO2 nanoparticles has been conducted using various analytical techniques, including X-ray diffraction, transmission electron microscopy, and high-resolution transmission electron microscopy. The morphology of the composite of CPG and MMT-CeO2NPs/CPG was elucidated through scanning electron microscopy (SEM). The newly developed sensor (MMT-CeO2NPs/CPG-PE) exhibited remarkable efficiency towards TAD oxidation using adsorptive stripping square-wave voltammetry (AdS-SWV) in Mcllvaine buffer solution (pH 8.0). A highly selective and sensitive method for TAD detection has been successfully applied based on MMT-CeO2NPs/CPG-PE, showing two different linear concentration ranges of 0.005−0.1 and 0.1–9.9 µM. The LOD and LOQ were determined to be 1.97 × 10−10 and 6.57 × 10−10 M, respectively, with a sensitivity of 3916 µA µM−1 cm−2. Interestingly, the sensing electrode exhibited excellent reproducibility, reusability, and stability even after 30 days. Moreover, the newly developed nano-sensor (MMT-CeO2NPs/CPG-PE) has been effectively utilized for the accurate detection of TAD in pharmaceutical formulations and spiked human blood serum and urine samples, demonstrating no interference from other substances.

A novel polycaprolactone film-coated electrode incorporating aluminum nanoparticles for pyruvate biosensing in clinical diagnosis

Pyruvate is an important parameter that is measured in a wide range of fields, from healthcare to environmental monitoring. Accurate and rapid measurement of pyruvate is therefore essential. Biosensors are well suited for this purpose. A novel, simple, and reliable biosensor was developed by modifying a polycaprolactone film with aluminum nanoparticles and used for the first time to detect pyruvate. The electrochemical properties and surface characteristics of the aluminum nanoparticle-modified film-coated gold electrode were investigated using cyclic voltammetry, scanning electron microscopy, and energy dispersive X-ray spectroscopy. The biosensor responded to pyruvate within a concentration range of 1 μM to 1000 μM with a sensitivity of 2.30 µA µM−1 cm−2 at an applied potential of + 0.4 V. The obtained accuracy was 99.5 % ± 0.002 with a relative standard deviation of only 0.041 %. The limit of detection was calculated to be 0.45 μM. The accuracy of spiked pyruvate measurement in a complex medium was highly accurate, with a result of 105.11 ± 0.02 % when tested using human serum from male AB plasma. The initial response was maintained at 98 % and 87 % after 10 and 20 days, respectively.

Laser chemical vapor deposition of nitrogen-doped SiC electrode for electrochemical detection of uric acid

Reasonable design and construction of high-performance electrodes are desirable for developing non-enzymatic electrochemical sensors for uric acid (UA). Herein, N-doped SiC film was prepared as an electrochemical electrode using a novel laser chemical vapor deposition (LCVD) method. Compared with its undoped counterpart, the doped electrode exhibited a low detection limit of 0.77 μM and a high detection sensitivity of 9.75 µA µM−1 cm−2 owing to its large active sites and fast electron transfer rate. Furthermore, the as-developed electrode clearly exhibited immunity towards the coexisting interfering species, such as dopamine and ascorbic acid, and facilitated the quantitative analysis of UA in real-world samples. In addition, the effects of N doping on electrochemical sensing were verified via theoretical calculations by investigating adsorption energy and Bader charge. Our works verify the feasibility of introducing N into SiC to enhance UA sensing performance and fabricating on-chip electrochemical sensors, which may spur the development of advanced and portable SiC-based biosensors for health monitoring.

Electrode modified with CO2 laser-reduced graphene oxide-silver nanoparticles for determination of nitrite in water

Intercalation of rGO with AgNPs was achieved photothermally through CO2-assisted laser irradiation of GO and Ag+ precursors in the solid state. A uniform distribution of AgNPs was anchored on rGO (LrGO-AgNPs). The LrGO-AgNPs nanocomposite was structurally and electrochemically characterized. The parameters for the fabrication of LrGO-AgNPs and electrochemical NO2− detection were optimized. Under optimal conditions, the glassy carbon electrode (GCE) modified with LrGO-AgNPs showed a high diffusion coefficient and electron transfer rate constant for NO2− oxidation. Aditionally, the modified electrode displayed outstanding electrocatalytic activity toward NO2− oxidation with a sensitivity of 114.6 μA μM−1 cm−2 and an estimated response time of 7 s. The linear concentration range, LOD, and LOQ were 0.1–10,000, 0.039, and 0.131 μM, respectively. The proposed amperometric sensor was applied to detect carcinogenic nitrite in water samples and obtained recoveries between 93 ± 3 % and 103.3 ± 0.3 %. The results of the proposed method and the UV–vis spectrophotometric method showed no significant differences, indicating the potential of the proposed sensor for wider applications.