Electrochemical Sensor Research Articles

Cost‐effective amperometric sensor for monitoring levofloxacin in groundwater

AbstractThe presence of water micropollutants, such as antibiotics, has proved the necessity to develop novel and cost‐effective devices for their identification and quantification. These devices aim to save time, reagent usage, and costs associated with conventional analytical methods. In this work, we introduce poly(methylene blue) based screen‐printed electrodes (SPE‐PMB) as electrochemical sensors designed for the quantification of levofloxacin (LVX), given its current prevalence as a micropollutant. Integrating the fabrication and measurement processes into a single electrochemical device is a significant step in creating affordable detection tools. The proposed sensor was assessed using LVX solutions prepared in real groundwater samples, demonstrating its selectivity and achieving a detection limit of 3.3 μM. Finally, we compared the SPE‐PMB sensor and high‐performance liquid chromatography (HPLC) to validate its operation and performance. Consequently, our results suggest that the sensor can be a viable alternative to chromatographic methods for identifying and quantifying micropollutants at very low concentrations in complex matrices.

A portable and sensitive DNA-based electrochemical sensor for detecting piconewton-scale cellular forces

BackgroundCell-generated forces are a key player in cell biology, especially during cellular shape formation, migration, cancer development, and immune response. The measurement of forces exerted and experienced by cells is fundamental in understanding these mechanosensitive cellular behaviors. While cell-generated forces can now be detected based on techniques like fluorescence microscopy, atomic force microscopy, optical/magnetic tweezers, however, most of these approaches rely on complicated instruments or materials, as well as skilled operators, which could limit their potential broad applications in regular biological laboratories. ResultsA new type of smartphone-based electrochemical sensor is developed here for cellular force measurement. In this system, a double-stranded DNA-based force probe, known as tension gauge tether, is attached to the surface of a gold screen-printed electrode, which is then incorporated into a portable smartphone-based electrochemical device. Cellular force-induced DNA detachment on the sensor surface results in multiple redox reporters to reach the surface of the electrode and generate enhanced electrochemical signals. To further improve the sensitivity, a CRISPR-Cas12a system has also been incorporated to cleave the remaining surface-attached anchor DNA strand. Using integrin-mediated tension as an example, piconewton-scale adhesion forces generated by ≤ 10 HeLa cells could now be reliably detected. Meanwhile, the threshold forces of these electrochemical sensors can also be modularly tuned to detect different levels of cellular forces. SignificanceThese novel DNA-based highly sensitive, portable, cost-efficient, and easy-to-use electrochemical sensors can be potentially powerful tools for detecting different cell-generated molecular forces. Functioning as complementary tools with traction force microscopy and fluorescent probes, these electrochemical sensors can be straightforwardly applied in regular biological laboratories for understanding the basic mechanical principles of cell signaling and for developing novel strategies and materials in tissue engineering, regenerative medicine, and cell therapy.

A Wearable Electrochemical Sensor Based on Single-Atom Pt Anchored on Activated NiCo-LDH/Ti3C2Tx for Real-Time Monitoring of Glucose.

Wearable, noninvasive sweat sensors enable real-time monitoring of metabolites in human health management. However, the commercial enzyme-based and currently nonenzymatic glucose sensor represents sluggish glucose oxidation kinetics and a narrow sensing range. Rational design of sensitive materials is significant yet faces a huge challenge. Herein, we construct a single-atom Pt supported on NiCo-LDH/Ti3C2Tx heterostructures (Pt1-NiCo-LDH/Ti3C2Tx) as the nonenzymatic electrochemical glucose sensor sensitive materials for selective detection of glucose level in human sweat. The obtained Pt1-NiCo-LDH/Ti3C2Tx with improved structural stability and enhanced charge transfer efficiency shows a low oxidation peak potential of 0.49 V, high sensitivity of 506.6 μA mM-1 cm-2, a low detection limit of 0.035 μM, and long-term stability toward the glucose detection. The wearable sensor, coupled with a wireless transmission module and a signal processing chip, is used for real-time perspiration glucose monitoring during outdoor exercise. The result is comparable to that of high-performance liquid chromatography (HPLC). This research provides a new paradigm for designing a wearable nonenzymatic electrochemical glucose sensor, enabling noninvasive real-time monitoring of glucose concentrations in human sweat.

Improved MnO2 based electrode performance arising from step by step heat treatment during electrodeposition of MnO2 for determination of paracetamol, 4-aminophenol, and 4-nitrophenol

The design of electrochemical sensors is crucial considering important factors such as efficiency, low cost, biocompatibility, and availability. Manganese oxides are readily available, low-cost, and biocompatible materials, but their low conductivity limits their efficiency as sensors. Today, morphology engineering of manganese oxide has been one of the most common research topics, because manganese oxides’ electrochemical properties are highly dependent on their morphologies. In this study, a method for reducing the charge transfer resistance (Rct) of MnO2-based electrodes was established by the cyclic voltammetry technique accompanied by step-by-step heat treatment to electrodeposition MnO2 nanofilm, which remarkably improved the Rct. Next, the sensing performance of MnO2/FTO for two separate measurements was examined, one for the simultaneous measurement of paracetamol (PAR) and 4-aminophenol (4-APh), and the other for the measurement of 4-nitrophenol (4-NP). Under the optimum conditions, the linear ranges of 4-APh, PAR, and 4-NP, were 0.8 to 22.0 µM, 2.0 to 55.0 µM, and 0.1–250 µM, with limits of detection (LOD) of 0.19 µM, 0.60 µM, and 0.01 µM, respectively. It also was unaffected by a 200-fold excess of interferences. In addition, the designed sensor was successfully applied to the analysis of real samples.

Metal–Organic Framework-Derived CeO2/Gold Nanospheres in a Highly Sensitive Electrochemical Sensor for Uric Acid Quantification in Milk

In this work, CeBTC (a cerium(III) 1,3,5-benzene-tricarboxylate), was used as a precursor for obtaining CeO2 nanoparticles (nanoceria) with better sensor performances than CeO2 nanoparticles synthesized by the solvothermal method. Metal–organic framework-derived nanoceria (MOFdNC) were functionalized with spheric gold nanoparticles (AuNPs) to further improve non-enzymatic electrode material for highly sensitive detection of prominent biocompound uric acid (UA) at this modified carbon paste electrode (MOFdNC/AuNPs&CPE). X-ray powder diffraction (XRPD) and transmission electron microscopy (TEM) analysis were used for morphological structure characterization of the obtained nanostructures. Cyclic voltammetry and electrochemical impedance spectroscopy, both in an [Fe(CN)6]3−/4− redox system and uric acid standard solutions, were used for the characterization of material electrocatalytic performances, the selection of optimal electrode modifier, and the estimation of nature and kinetic parameters of the electrode process. Square-wave voltammetry (SWV) was chosen, and the optimal parameters of technique and experimental conditions were established for determining uric acid over MOFdNC/AuNPs&CPE. Together with the development of the sensor, the detection procedure was optimized with the following analytical parameters: linear operating ranges of 0.05 to 1 µM and 1 to 50 µM and a detection limit of 0.011 µM, with outstanding repeatability, reproducibility, and stability of the sensor surface. Anti-interference experiments yielded a stable and nearly unchanged current response with negligible or no change in peak potential. After minor sample pretreatment, the proposed electrode was successfully applied for the quantification of UA in milk.

Development of a sustainable and disposable modified Bi-CdFe2O4 electrode for electrochemical sensing of lead (II) and Acetaminophen drug molecule

The study of research proposes a systematic pattern for optimization and fabrication of a sustainable-cost effective electrochemical sensor made by Bi-CdFe2O4 (BCDF) nanoparticle and graphite powder. The structural examinations of synthesized BCDF materials were analyzed by specific spectral techniques viz.; P-XRD, SEM-EDX, TEM, XPS, FT-IR and DRS techniques. The modified sensor electrode offer a significant electrochemical properties that can improve the material selectivity and sensitivity actions measured by Cyclic Voltammetric (CV) and Electrochemical Impedance Spectral (EIS) plots. We demonstrated a developed highly-purity BCDF-graphite paste electrode for sensing actions on Paracetamol and Lead (Pb2+) ions under 0.1 M KCl. The excellent sensing activity towards Lead ions and Paracetamol confirmed by its redox potential peaks at scan rate of 1–5 V/s with maximum sensitivity of -0.61 V and 0.69 V respectively. The excellent photo-dye-degradation action of BCDF (98.2%) than those of host CDF (81.6%) on Rose Bengal (RB) dye was demonstrated. Its kinetic study reveals that this process follows first order kinetics and rate constants of the host (18.1 × 10−3 min−1) and BCDF (39.2 × 10−3 min−1) were measured. Thus, the synthesized BCDF electrode provides a new perception for developing specific nano-sensor towards detection of toxic metals.

Bio-carbon-derived porous reduced graphene oxide photo- and electrochemical sensor for ultra-sensitive detection of testosterone hormone

Bio-carbon-derived porous reduced graphene oxide photo- and electrochemical sensor for ultra-sensitive detection of testosterone hormone

Electrochemical Sensor Fabrication Based on Nanocomposite of ZIF-8/ZnO Decorated with Poly(L-Cysteine) for Trace Analysis of Morphine

Electrochemical Sensor Fabrication Based on Nanocomposite of ZIF-8/ZnO Decorated with Poly(L-Cysteine) for Trace Analysis of Morphine

All-solid-state electrochemical marine sensors based on Na3V2(PO4)3@Na4Zr2Si3O12 solid-state reference electrodes

In this study, Na4Zr2Si3O12 (NZS) solid electrolyte was prepared using an elevated-temperature solid-state method. After heating under supercritical conditions (i.e., 400 °C and 40 MPa), the structure and performance stability of the as-fabricated NZS solid electrolyte were evaluated applying scanning electron microscopy (SEM), X-ray diffraction (XRD), and electrochemical impedance spectroscopy (EIS). A new all-solid-state reference electrode, combining Na3V2(PO4)3(NVP) with NZS (NVP@NZS), was developed, and its electrochemical properties were investigated. The prepared reference electrode demonstrated steady potential in both simulated seawater and buffer solutions across a range of pH values and different salt solutions. The reference electrode, integrated with an Ir/IrO2 working electrode, was used to construct an all-solid-state potentiometric pH sensor. This sensor demonstrated a strong linear related response when measuring the pH of both aqueous solutions and simulated seawater samples. Additionally, an ion sensor based on anodic stripping voltammetry, constructed with the assembled solid-state reference electrode, a platinum counter electrode, and a gold-mercury working electrode, was utilized to measure Cu2+ and S2− ions in both aqueous solutions and simulated seawater samples. These all-solid-state electrochemical sensors, incorporating the NVP@NZS solid-state reference electrode, demonstrated a small detection threshold, excellent linear correlation (R2 > 0.99), and a broad detection range, making them well-suited for chemical analysis in challenging marine environments.

Silver Nanoparticles Formed Directly on a Screen-Printed Electrode/Graphene Oxide: A One-Step Electrochemical Synthesis and an Effective 2,4,6-Trichlorophenol Electrochemical Sensor

Abstract A graphene oxide/silver nanoparticles (GO/AgNPs) nanocomposite was synthesized directly onto a screen-printed electrode (SPE) using a one-step electrochemical synthesis process. The obtained result is that the SPE electrode was modified by AgNPs with an average diameter of 11.5 nm which distributed evenly on GO sheets. A 0.01 M AgNO3 solution dropped onto the SPE/GO electrode and a chronoamperometry (CA) method with a potential of −1.2 V and a time period of 10 seconds were the optimal synthesis conditions. Then, the SPE/GO/AgNPs electrode was applied in developing an electrochemical sensor to detect 2,4,6-trichlorophenol (2,4,6-TCP) using a square wave voltammetry method. A reasonable cost, a wide linear range (0.05–1.0 mM), a low detection limit (0.85 μM), a high repeatability, a good selectivity, a high durability, and especially, a rapid detection time (< 1 minute) thanks to the ability to directly detect 2,4,6-TCP were the outstanding advantages of the fabricated electrochemical sensor. Moreover, the electrochemical sensor based on the SPE/GO/AgNPs electrode was also applied to detect 2,4,6-TCP in a tap water sample using a standard addition method.

Simultaneous detection of moxifloxacin and gatifloxacin by Cu-TCPP/rGO electrochemical sensor

Moxifloxacin (MOX) and gatifloxacin (GAT) are structurally similar and possess close oxidation peak potentials, making it difficult for simultaneous detection by electrochemical methods. To address this, an electrochemical sensor was constructed with reduced graphene oxide (rGO) and copper porphyrin complex (Cu-TCPP), achieving signal amplification and simultaneous detection of MOX and GAT. The linear relation range from 5.00 to 600.00 μmol·L−1 for MOX (LOD is 1.34 μmol·L−1) and 10 to 300 μmol·L−1 for GAT (LOD is 0.59 μmol·L−1). When applied to water samples, it achieved recoveries of 100.09–112.02 % with a relative standard deviation (RSD) of less than 6 % for MOX, and 97.27–110.72 % with an RSD of less than 4 % for GAT. Further calculations indicated that the electro-oxidation of GAT involved two protons and two electrons.

Novel Zn-based Metal Coordination Polymer for Ultrafast Capture and Electrochemical Sensing of Hg(Ⅱ)

The electrochemical sensor shows great promise in the detection of trace Hg(Ⅱ), of which the performance could be significantly enhanced by the functionalized material with the merits of effective and ultrafast capture for Hg(Ⅱ). In this study, the novel metal coordination polymers (MCPs) was synthesized by the 2-thio-barbituric acid as the organic ligand to modify the electrochemical sensor to address this issue. The as-prepared material was composed of regular flakes with a polyhedral and well-defined crystal structure, the successful loading of the abundant sulfurous group (7.49% of the total mass) endowed the Zn-TBA with the capability to efficiently uptake (97.4-99.9%) Hg(Ⅱ) at 500mg/L under a wider pHs as well as the high content of coexisting cations and anions, highlighted the excellent capacity, strong environmental adaptability, and selectivity. Notably, the superfast mass transfer was revealed in the adsorption kinetics test, in which the Hg(Ⅱ) content was effectively reduced from 50mg/L to 14 μg/L within 20s to meet the national emission standards. Based on this, Zn-TBA modified the carbon cloth (Zn-TBA/CC) and the glass carbon electrode (Zn-TBA/GCE) was prepared, thereinto, the current response of Zn-TBA/CC was approximately 60 times that of the pristine electrode. A strong positive correlation (R2=0.998) relationship could be attained across the content of 0.25-3μM, achieving the detection limit to be 0.29μM. The impressive performance was maintained in the complex matrices and regeneration test. In addition, Zn-TBA/CC exhibited better physical properties, charge transfer ability, and sensing properties than Zn-TBA/GCE, highlighting the advantages of CC as a flexible sensor substrate. Finally, the stable recovery (90-98.5%) in the spiked actual surface water confirmed that the two established methods possessed a promising application potential in capturing and detecting the trace Hg(Ⅱ) with high accuracy and precision. This study extended the application of MCPs in the electrochemical sensor and provided an available analysis method to trap and determine the metal content.

Highly sensitive electrochemical detection of ciprofloxacin using MXene (Ti3C2Tx)/poly (rutin) composite as an electrode material

Ciprofloxacin is a widely used antibiotic for treating numerous bacterial infections and it is also considered by the world health organization (WHO) to be extremely vital for human medicine. Therefore, accurate, simple, and cost-effective detection of ciprofloxacin, a commonly used antibiotic, is critical for treating various bacterial infectious diseases. In this work, glassy carbon electrode/poly (rutin)/Ti3C2Tx, is developed for the detection of ciprofloxacin antibiotic. The electrochemical sensor was modified with rutin hydrate monomer and Ti3C2Tx via electro-polymerization of rutin hydrate and drop-casting of Ti3C2Tx. The modified electrode surface was characterized using scanning electron microscopy, high-resolution transmission electron microscopy, attenuated total reflectance- Fourier transform infrared spectroscopy, and electrochemical impedance spectroscopy. The oxidation of ciprofloxacin was performed in 0.01molL−1 of phosphate buffer at a pH level of 5.0. This medium established a linear range of 1.0 × 10−9-1.0 × 10−4 molL−1, limit of detection at 1.0 × 10−9 molL−1 and sensitivity of 0.49 μA/μMcm2. Finally, the modified electrode displayed high selectivity when tested in inorganic-organic mixtures as well as in real sample medium such as blood serum. To the best of our knowledge the current work is the first to report the use of MXene/rutin composite for electrochemical sensing mechanism. The proposed electrochemical sensor has high potential for the formation of therapeutic drug doses application via monitoring of CIP patient intake (clinical settings of CIP).

Construction of calcium zirconate nanoparticles confined on graphitic carbon nitride: An electrochemical detection of diethofencarb in food samples

A well-known fungicide designated diethofencarb (DFC) is used on crops to eradicate fungal infections and increase agricultural production. However, the National Food Safety Standard has established an overall maximum residual limit of 1 mg/kg for DFC, and excessive usage of this chemical has detrimental effects on the environment in real-time. In this work, an improved electrochemical sensor based on hydrothermally synthesized CaZrO3 is incorporated into a g-C3N4 sheet and developed to quickly and accurately screen DFC, a well-known carbamate fungicide. The electrochemical sensor that was successfully designed demonstrated good conductivity, high ion diffusion parameters, a high electro-active surface area, and a quick electron transport ratio when used for DFC detection. The structure, crystalline accuracy, and purity of the as-prepared CaZrO3@g-C3N4 were examined using various analytical and microscopic techniques. Additionally, the cyclic voltammetry technique examined the electrochemical investigations of the CaZrO3@g-C3N4 modified glassy carbon electrode (GCE). A robust synergistic interaction between the CaZrO3 and g-C3N4 makes large surface areas and improved DFC detection possible. The fabricated sensor exhibits a wide linear range of 0.01–230.04 μM, a low detection limit of 1.8 nM, and excellent stability according to the results of the DPV technique. Remarkably, our proposed sensor has proven to be feasible for real-time analysis and can distinguish DFC-spiked various food samples with a good recovery range.

An Antibiofouling Electrochemical Sensor Consisting of Amphiphilic Copolymer on CNT-COOH Electrodes for Point-of-Care Monitoring of Propofol Blood Concentration in Surgical Patients

The monitoring of propofol (PPF) blood concentration is vital for the safety of intravenous anesthesia. Electrochemical sensors represent a powerful tool for the detection of PPF. Our previous research has demonstrated that CNT-COOH electrodes exhibit advantages in resisting electrochemical fouling from PPF oxidation products. Nevertheless, biofouling remains a critical challenge hindering the clinical transformation of PPF electrochemical sensors. To address this issue, we employed in-situ electrodeposition to deposit zwitterionic sulfobetaine methacrylate (SBMA) and overoxidation polydopamine (OPDA) onto CNT-COOH screen-printed electrodes (SPEs) and proposed an innovative CNT-COOH/OPDA-SBMA (CNT-COOH/OPS) amphiphilic antifouling biosensor. This amphiphilic electrode, featuring both hydrophilic and hydrophobic properties, demonstrated excellent antifouling performance through electrochemical characterization in ex-vivo blood assays, coupled with commendable sensitivity, stability, and selectivity. CNT-COOH/OPS SPEs were also applied in point-of-care monitoring of the PPF blood concentrations in animals and clinical surgical patients and exhibited good accuracy and linearity (Ipa=0.0084c+0.4458, R2=0.995) with a limit of detection of 2.948μM. Further, the electrodes demonstrated a high recovery and the blood concentrations determined by electrochemical detection had robust negative correlation with the depth of anesthesia. Therefore, CNT-COOH/OPS SPEs hold promise as a significant tool in point-of-care monitoring of PPF, offering patients safer and more personalized medical care.

Enhanced ePAD-DNA biosensor incorporating ZnO-NRs: Rapid and reliable electrochemical detection of field-isolated Pasteurella multocida

An electrochemical sensor has received much attention due to its importance for early infection identification, hinting at its critical relevance in diagnostic applications. For the detection of field-isolated strains of Pasteurella multocida, this paper reports the development and fabrication of a DNA-based electrochemical biosensor by integrating zinc oxide (ZnO) nanorods (NRs) into an electrochemical paper-based analytical device (ePAD). One significant improvement over the state-of-the-art features of the sensor is the using paper, an economically viable substrate that can be manufactured in large numbers. These sensors, being categorized under precision instruments with an ecologically friendly design, are ideal for mass production of eco-sensitive substrates. The biosensor is more sensitive and specific as compared to the conventional PCR-based sensing techniques. Moreover, the biosensor exploits the inherent properties of ZnO-NRs to amplify the signal output, whereas ePAD limits detection cost. In addition, a probe targeting the KMT gene of P. multocida was first characterized using conventional PCR and then immobilized onto the ZnO nanorods-modified ePAD surface, which improved the biosensor's ability for the rapid and selective genetic material of the pathogen detection. In addition, the sensor was validated using the methods of Cyclic Voltammetry (CV) and Linear Sweep Voltammetry (LSV). The reported biosensor it provides Linear Response of 0.001-10 μg/ml with LOD 0.001 μg/ml within a response time of 30 s. Subsequently, the biosensor reveals fast kinetics of the reaction as a powerful tool for timely and accurate diagnostics, pointing to its contribution to further development in biosensing technologies in the diagnostic area of infectious diseases at hospitals and clinics.

Synthesis, crystal structure and exploration of N,N'-(ethane-1,2-diyl)bis(4-acetylbenzenesulfonamide) (EDBABS) fabricated glassy carbon electrode as highly sensitive barium (Ba2+) sensor: An electrochemical approach

Environmental pollution spurred by dint of noxious chemicals and heavy metals has popped up as a pressing threat for present day community. In this study, we synthesized the N,N'-(ethane 1,2-diyl)bis(4-acetylbenzene-1-sulfonamide) (EDBABS) and N,N'-(cyclohexane-1,2-diyl)bis(4-acetylbenzenesulfonamide) (CDBABS) as bidentate chelating agents with the intention to detect the heavy metal cations in water systems. Conventional spectroscopic techniques such as UV-Vis spectroscopy, Fourier transform-infra red (FT-IR) spectroscopy, 1H-NMR and 13C-NMR in addition to single crystal X-ray diffraction studies were performed to expound structural characterization data of these newly synthesized non-reported bidentate chelating agents. After Characterization, a novel electrochemical current – potential (I-V) approach based on their modified GCEs was applied to detect the toxic cations in water systems. For this purpose, Keithley electrometer was employed as a constant voltage source. On the trail of fabricating an efficient as well as selective electrochemical sensor, for the detection of heavy metal cations in phosphate buffer system of pH = 7.0, EDBABS and CDBABS coupled with nafion as adhesive conducting binder were coated separately onto the Glassy Carbon Electrodes (GCEs). it was delineated that newly designed EDBABS/Nafion/GCE induced a high current response for Ba2+ cations in the presence of other interfering heavy metal cations (Y3+, Sn2+, Sb3+, Mn2+, Hg2+, Cr3+, As3+ and Ag+) than CDBABS/Nafion/GCE and found to be selective and sensitive towards Ba2+ cations, predominantly contributing towards environmental pollution. In order to optimize this newly designed EDBABS/Nafion/GCE as selective electrochemical Ba2+ cationic sensor, different analytical parameters such as sensitivity, limit of detection (LOD) at S/N of 3, limit of quantification (LOQ), and linear dynamic range (LDR) turned out to be satisfactory towards Ba2+ cations. The calibration curve emerged to be linear with a broad concentration range of Ba2+ cations from 0.1 nM to 0.01M and sensitivity was estimated as 3.481 × 10−3µAµM−1cm−2 in addition to (r2) as 0.9834, limit of detection (LOD) as 0.027nM (at S/N=3) and limit of quantification (LOQ) as 0.091nM. Within the realm of extensive environmental protection and public health care field, this work inducts a reliable and effective way for the fabrication of sensitive as well as selective cationic electrochemical sensors based on chelating agents which can be launched as an advanced approach for quick probing of heavy metal cations in water systems, reliably and effectively.

Non-Destructive Integration of Spark-Discharge Produced Gold Nanoparticles onto Laser-Scribed Graphene Electrodes for Advanced Electrochemical Sensing Applications

Gold nanoparticles (AuNPs) decorated graphene materials are preferable materials in a wide range of electrochemical applications, however, the current methods for preparing them have several limitations. Herein, we have developed a green, solution-free, and non-destructive method for the in-situ generation of AuNPs on laser-scribed graphene electrodes (LSGEs), addressing the limitations of traditional preparation methods. This novel technique, contrasting with the conventional solution-based electrochemical deposition, utilizes spark discharge to modify LSGEs, demonstrating superior performance in sensors and biosensors applications. Through comprehensive characterizations (scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), Raman spectra, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Kelvin probe force microscopy (KPFM)), we observed significant distinctions in particle size, metal loading, stability, surface-to-volume ratio, and graphene quality between spark-discharge produced AuNPs (SP-AuNPs) and electrodeposition produced AuNPs (EC-AuNPs). The average particle sizes of the SP-AuNPs and EC-AuNPs are 10 nm and 38 nm, respectively. The SP-AuNPs modified LSGEs demonstrate exceptional electroanalytical performance in dopamine detection, with a broad detection range (0.6–90 µM) and low LOD (0.40 µM), further validated in human neuroblastoma cells SH-SY5Y. Our findings suggest that the spark discharge method represents a significant advancement in the synthesis of metal nanoparticle enhanced LSG electrodes, with broad implications for electrochemical sensing, biosensing, and biomedical applications.

Molecular displacement approach for the electrochemical detection of protein-bound propofol

Propofol is one of the principal drugs used for the sedation of patients undergoing mechanical ventilation in intensive care units. The correct dosage of such sedative drugs is highly important, but current methods of determining infusion rates are limited and there is a lack of suitable methods for directly determining patient blood propofol concentrations. A significant challenge for the development of propofol sensors is that propofol demonstrates very high protein binding, leading to a low free fraction in blood. Here we present a method for improving the efficacy of an electrochemical propofol sensor by increasing the free fraction via a molecular displacement approach. When used in conjunction with a carbon nanotube/graphene oxide/iron oxide nanoparticle functionalised screen-printed electrode, it was found that this approach dramatically improved the sensor's sensitivity towards propofol. Ibuprofen was found to be the most effective displacement agent, with an optimal concentration of 30 mM. The resultant sensitivity was 2.82 nA/μg/ml/mm2 with a coefficient of variation of 0.07, and the limit of detection was 0.2 μg/ml. This approach demonstrates high specificity towards drugs commonly administered to intensive care patients.

Air quality monitoring system based on low power wide area network technology at public transport stops

<span>Mass migration from rural areas to urban areas has caused problems of traffic congestion, high industrial concentration and inequity in the distribution of housing in the world's capitals, generating a significant threat to sustainable development and public health due to air pollution air. In the Peruvian context, the importance of real-time monitoring of air quality is highlighted according to the standards established by the government. Several studies propose real-time environmental monitoring systems using internet of thing (IoT) technologies, electrochemical and optical sensors to measure pollutants, highlighting the need for data analysis. The objective of the paper is to show the implementation of IoT devices called sensor nodes, with long range wide area network (LoRaWAN) transmission technology for continuous monitoring of polluting gas concentrations. In addition, they are integrated into a central node called gateway to perform real-time monitoring through a web application. As an initial result, IoT devices demonstrated their effectiveness for real-time monitoring. Despite being a prototype-level result, the next stage involves its deployment at public transport stops in Lima. Overcoming the limitations of the solution, this paper establishes the foundation for future research on pollution and public health.</span>