Screen-printed Electrodes Research Articles

A novel miniaturized potentiometric electrode based on carbon nanotubes and molecularly imprinted polymer for the determination of lidocaine.

A novel miniaturized, solid-contact potentiometric screen-printed electrode was developed for highly sensitive and selective determination of lidocaine anesthetic. The electrode integrated single-walled carbon nanotubes as a solid-contact material and a molecularly imprinted polymer as a recognition sensory material. The performance characteristics of the electrode were evaluated and optimized to display a Nernstian slope of 58.92 ± 0.98mV/decade over a linear concentration range of 4.53 × 10-7 to 6.18 × 10-3mol/l within < 6s. Thedetection limit was 7.75 × 10-8mol/l (18.16ng/ml) of lidocaine. The use of the molecularly imprinted polymer significantly enhanced the selectivity of the electrode, and carbon nanotubes increased the sensitivity, accuracy, and potential stability. The electrode was successfully used for determining lidocaine in pharmaceutical preparations and human urine. The results favorably compared with data obtained by liquid chromatography-tandem mass spectrometry.

Optimizing Carbon Structures in Laser-Induced Graphene Electrodes Using Design of Experiments for Enhanced Electrochemical Sensing Characteristics.

In this study, we explored the morphological and electrochemical properties of carbon-based electrodes derived from laser-induced graphene (LIG) and compared them to commercially available graphene-sheet screen-printed electrodes (GS-SPEs). By optimizing the laser parameters (average laser power, speed, and focus) using a design of experiments response surface (DoE-RS) approach, binder-free LIG electrodes were achieved in a single-step process. Traditional trial-and-error methods can be time-consuming and may not capture the interactions between all variables effectively. To address this, we focused on linear resistance and substrate delamination to streamline the DoE-RS optimization process. Two LIGs, designated LIG A and LIG B, were fabricated using distinct and optimized laser settings, which resulted in a sheet resistance of 25 ± 2 Ω/sq and 21 ± 1 Ω/sq, respectively. These LIGs, characterized by scanning electron microscopy, Raman spectroscopy, and contact angle analysis, exhibited a highly porous morphology with 13% pore coverage and a contact angle <50°, which significantly increased their hydrophilicity when compared to the GS-SPE. For the electrochemical studies, the oxidation of NO2- ion by the graphene-based working electrodes was investigated, as it allowed for the direct comparison of the LIGs to the GS-SPE. These included cyclic voltammetry, electrochemical impedance spectroscopy, and differential pulsed voltammetry studies, which revealed that LIG electrodes displayed a remarkable 500% increase in peak current during NO2- oxidation compared to the GS-SPE. The LIGs also demonstrated improved stability and sensitivity (420 ± 30 and 570 ± 10 nAμM-1 cm-2) compared to the GS-SPE (73 ± 4 nAμM-1 cm-2) in the oxidation of NO2- ions; however, LIG B was more susceptible to ionic interference than LIG A. These findings highlight the value of applying statistical approaches such as DoE-RS to systematically improve the LIG fabrication process, enabling the rapid production of optimized LIGs that outperform conventional carbon-based electrodes.

Highly conducting Laser-Induced Graphene-Ag nanoparticle composite as an effective supercapacitor electrode with anti-fungal properties.

This study presents a simple and an environmentally friendly approach to make Laser-Induced Graphene (LIG) based supercapacitor electrodes anchored with abundant Silver Nanoparticles (AgNPs). LIG, was synthesized using a CO2 laser writing technique on polyimide substrate. The LIG-Ag composite was prepared using two techniques, drop-coating, and screen-printing. Ag nanoparticles prepared using the plant extract of Swietenia Macrophylla was utilized to drop-coat AgNP on LIG substrate. Screen-printing was done by using a commercial Ag-ink and a suitable mesh. The supercapacitor made from screen-printed electrodes and supercapacitor made form drop-coated electrodes showed a high specific capacitance of 118 mF/cm2, 38 mF/cm2, and a high energy density of 2.42 mWh/cm2, 0.05 mWh/cm2 respectively. The screen-printed composite of LIG and AgNP was further studied for its anti-fungal properties and proved to be effective against Candida sp.

Construction of Mo-Doped CuO Incorporated on Carbon Black Modified Disposable Sensor for the Voltammetric Detection of Metol in Environmental Samples

Abstract In this study, a molybdenum-doped copper oxide (Mo–CuO) composite was synthesized via a hydrothermal method and combined with carbon black (CB) to form Mo–CuO@CB. This composite was used to modify a screen-printed carbon electrode (SPCE) for the detection of Metol (MT), an industrial pollutant harmful to both human health and the environment. Structural and surface characterization was performed using high-resolution transmission electron microscopy, field-effect scanning electron microscopy, energy-dispersive spectroscopy, Raman spectroscopy, X-rssy photoelectron spectroscopy, and X-ray diffraction. Electrochemical techniques, including differential pulse voltammetry and cyclic voltammetry, were used to assess the sensor's performance. The Mo–CuO@CB@SPCE sensor exhibited a low detection limit of 2.7 nM, and limit of quantification is 82 nM, a broad linear range (5.0 × 10−9 – 170 mol L-1), and high sensitivity (4.148 μA μM⁻¹ cm⁻²), benefiting from the catalytic activity of Mo–CuO and the large surface area of CB. With recovery rates ranging from 96 % to 100.6% in pond, river, and tap water, the sensor effectively detects MT in environmental samples, ensuring reliable monitoring of this persistent pollutant.

Multilayer textile-based concept for non-invasive biosensor platform

AbstractThe surface area of the working electrode plays a crucial role in determining the sensor’s performance, especially in enzymatic sensors. Increasing the surface area of the working electrode has a significant impact on the sensor’s functionality. This research focused on developing textile-based sensors using a multi-layer concept, employing the direct coating method. Two different sensors which are multilayer textile-based sensor (MTBS) and single-layer textile-based sensor (STBS) were prepared, while commercial screen-printed carbon electrode (SPCE) was also used as a comparison. The measurements were carried out using potassium ferricyanide solutions with concentrations of 0.01 M, 0.02 M, 0.03 M, 0.04 M, and 0.05 M at a voltage of 1 V, with a maximum duration up to the end of the measurement and a time interval of 0.5 s. According to the research findings, the fluid spreading speed of the SPCE is the lowest when compared to the spreading speeds of the MTBS and STBS. Specifically, the fluid spreading speed of the SPCE is 4.3 times slower than that of the STBS and 51 times slower than that of the MTBS. Utilizing a multi-layer concept with specific coatings can lead to better-performing sensors in terms of stability and sensitivity. The MTBS exhibits the greatest sensitivity, as indicated by its linear equation slope of 717.230 µA µM−1 cm−2.

Amino-functionalized vertically ordered mesoporous silica film on electrochemically polarized screen-printed carbon electrodes for the construction of gated electrochemical aptasensors and sensitive detection of carcinoembryonic antigens

Disposable electrochemical biosensors with high sensitivity are very fit for point-of-care testing in clinical diagnosis. Herein, amino-functionalized, vertically ordered mesoporous silica films (NH2-VMSF) attached to an electrochemically polarized screen-printed carbon electrode (p-SPCE) are prepared using a simple electrochemical method and then utilized to construct a gated electrochemical aptasensor for rapid and sensitive determination of carcinoembryonic antigen (CEA). After being treated with the electrochemical polarization procedure, p-SPCE has plentiful oxygen-containing groups and improved catalytic ability, which help promote the stability of NH2-VMSF on SPCE without the use of an adhesive layer and simultaneously generate a highly electroactive sensing interface. Owing to the numerous uniform and ultrasmall nanopores of NH2-VMSF, CEA-specific aptamer anchored on the external surface of NH2-VMSF/p-SPCE serves as the gatekeeper, allowing the specific recognition and binding of CEA and eventually impeding the ingress of electrochemical probes [Fe(CN)63−/4−] through the silica nanochannels. The declined electrochemical responses of Fe(CN)63−/4− can be used to quantitatively detect CEA, yielding a wide detection range (100 fg/mL to 100 ng/mL) and a low limit of detection (24 fg/mL). Moreover, the proposed NH2-VMSF/p-SPCE-based electrochemical aptasensor can be applied to detect the amount of CEA in spiked human serum samples, which extends the biological application of a disposable NH2-VMSF/p-SPCE sensor by modulating the biological recognition species.

CoWO4/Reduced Graphene Oxide Nanocomposite-Modified Screen-Printed Carbon Electrode for Enhanced Voltammetric Determination of 2,4-Dichlorophenol in Water Samples

Water pollution with phenolic compounds is a serious environmental issue that can pose a major threat to the water sources. This pollution can come from various agricultural and industrial activities. Phenolic compounds can have detrimental effects on both human health and the environment. Therefore, it is essential to develop and improve analytical methods for determination of these compounds in the water samples. In this work, the aim was to design and develop an electrochemical sensing platform for the determination of 2,4-dichlorophenol (2,4-DCP) in water samples. In this regard, a nanocomposite consisting of CoWO4 nanoparticles (NPs) anchored on reduced graphene oxide nanosheets (rGO NSs) was prepared through a facile hydrothermal method. The formation of the CoWO4/rGO nanocomposite was confirmed via different characterization techniques. Then, the prepared CoWO4/rGO nanocomposite was used to modify the surface of a screen-printed carbon electrode (SPCE) for enhanced determination of 2,4-DCP. The good electrochemical response of the modified SPCE towards the oxidation of 2,4-DCP was observed by using cyclic voltammetry (CV) due to the good properties of CoWO4 NPs and rGO NSs along with their synergistic effects. Under optimized conditions, the CoWO4/rGO/SPCE sensor demonstrated a broad linear detection range (0.001 to 100.0 µM) and low limit of detection (LOD) (0.0007 µM) for 2,4-DCP determination. Also, the sensitivity of CoWO4/rGO/SPCE for detecting 2,4-DCP was 0.3315 µA/µM. In addition, the good recoveries for determining spiked 2,4-DCP in the water samples at the surface of CoWO4/rGO/SPCE showed its potential for determination of this compound in real samples.

A highly sensitive and selective label-free impedimetric immunosensor for the detection of interleukin-6 based on AuNPs@pDA@NiCo2S4@MoS2 nanocomposite.

A highly sensitive and selective label-free impedimetric immunosensor based on AuNPs@pDA@NiCo2S4@MoS2 nanocomposite modified on the surface of a screen-printed electrode (SPE) was designed for the detection of interleukin-6 (IL-6). The distribution of NiCo2S4 nanoparticles on MoS2 nanosheets was able to prevent them from agglomerating. The polydopamine (pDA) layer was coated on the surface of NiCo2S4@MoS2 nanosheets by self-polymerization, which improved the stability and biocompatibility of the nanomaterial. The excellent reduction ability of pDA promoted the synthesis of gold nanoparticles (AuNPs), which increased the amount of antibody adsorption and the conductivity of the material. Finally, the antibody (Ab) of IL-6 was immobilized on the surface of AuNPs@pDA@NiCo2S4@MoS2 nanocomposite. Electrochemical impedance spectroscopy (EIS) was used to detect the change of impedance before and after the immune response between Ab and IL-6 antigen (IL-6). Under the optimal experimental conditions, the relative change in impedance and the logarithmic concentration of IL-6 showed a good linear relationship in the range 1.00 to 1.00 × 106pg/mL, with a low detection limit of 0.97pg/mL. In addition, the proposed immunosensor performed with good reproducibility, stability, and specificity. It was successfully applied to the determination of IL-6 in patient's serum samples of head and neck carcinoma with recoveries of 98.40% to 106.5%. To sum up, the proposed label-free impedimetric immunosensor was successfully constructed for IL-6 detection in real samples.

α-Synuclein plastic antibody applied to monitor monomeric structures and discriminate aggregated forms in human CSF

Aggregation of alpha-synuclein (aSyn) occurs in presynaptic neurons and constitutes a key factor for the progression of Parkinson's disease, emphasising the urgency of early detection to support effective treatment. Unfortunately, a reliable, sensitive and cost-effective diagnostic tool has so far been lacking.Thus, this work presents a novel biosensor for detecting aSyn using plastic antibodies coupled to electrochemical detection. This biosensor was designed for portability and compatibility with point-of-care devices and exploits the electropolymerization of methylene blue (MB) together with aSyn on the carbon working electrode of screen-printed electrodes (SPEs). By electrochemical impedance spectroscopy (EIS) measurements, the sensor showed exceptional analytical performance in detecting aSyn monomers in human CSF samples. It showed a linear trend of response from 1 fM to 10 pM with an impressively low limit of detection of 69 aM. Selectivity tests confirmed the predominant response to aSyn monomers, a less intense response to oligomers and insensitivity to fibrils.Overall, this plastic antibody-based electrochemical sensor represents a significant breakthrough as it is the first of its kind to accurately, sensitively and selectively detect aSyn monomers with a partial response to oligomers. Its simplicity and reproducibility promise to contribute to the early and effective diagnosis of Parkinson's disease.

Tailoring Atomic Ordering Uniformity Enables Selectively Leached Nanoporous Pd-Ni-P Metallic Glass for Enhanced Glucose Sensing.

Constructing nanostructures, such as nanopores, within metallic glasses (MGs) holds great promise for further unlocking their electrochemical capabilities. However, the MGs typically exhibit intrinsic atomic-scale isotropy, posing a significant challenge in directly fabricating anisotropic nanostructures using conventional chemical synthesis. Herein a selective leaching approach, which focuses on tailoring the uniformity of atomic ordering, is introduced to achieve pore-engineered Pd-Ni-P MG. This innovative approach significantly boosts the number of exposed active sites, thereby enhancing the electrochemical sensitivity for glucose detection. Electrochemical tests reveal that the nanoporous Pd-Ni-P MG exhibits high sensitivity (3.19mA mm⁻¹ cm⁻2) and remarkable stability (97.7% current retention after 1000 cycles). During electrochemical cycling, synchrotron X-ray pair distribution function and X-ray absorption fine structure analyses reveal that the distance between active sites decreases, enhancing electron transport efficiency, while the medium-range ordered structure of the Pd-Ni-P MG remains stable, contributing to its exceptional glucose sensing capabilities. A microglucose sensor is successfully developed by integrating the nanoporous Pd-Ni-P MG with a screen-printed electrode, demonstrating the practical applicability. This study not only offers a new avenue for the design of highly active nanoporous MGs but also sheds light on the mechanisms behind the high electrochemistry performance of MGs.

Electroanalysis of Statin Drugs: A Review on the Electrochemical Sensor Architectures Ranging from Classical to Modern Systems.

An overview of the latest advances in the design of electrochemical sensor architectures dedicated to the determination of drugs from the statin class is presented in this review. Statins are drugs widely consumed for cholesterol control, and their determination in different matrices through the application of electroanalysis is growing considering advantages such as operational simplicity, lower cost and ease of sample preparation. Within the context of statins, electrochemical sensor architectures can be subdivided into conventional/classical electrodes such as glassy carbon electrodes, carbon paste electrodes, pencil graphite electrodes, boron-doped diamond electrodes and metallic electrodes, and more modern electrode systems, including the screen-printed electrodes and 3D-printed electrodes. Thus, different aspects related to the preparation of these electrochemical sensors and analytical performance are presented, also reflecting advances in terms of designs of new architectures and possible improvements not previously reviewed. Analyzed samples, advantages and disadvantages of different implemented sensor's modification strategies and perspectives for the electroanalysis of statins are also included throughout the work.

Enhanced 3D-printed Matrix for Electrocatalytic Detection: A Practical and Simple Electrochemical Platform

AbstractIn this work, we proposed a novel 3D-printed manufactured electrode system. A project was developed and optimized, compatible with commercially available potetiostats. Additive manufacturing included the modification of the pseudo-reference electrode by electrodeposition of silver and its subsequent oxidation to the Ag/AgCl form. Then the system was tested using electrochemical techniques to check the application as a universal electroactive platform. As an example, we checked the detection of paracetamol as a common substance from non-steroidal anti-inflammatory drugs (NSAIDs). Finally, the system was compared to available commercial carbon electrodes, considering the screen-printed electrode (SPE no.1 and SPE no.2) and the glassy carbon electrode (GCE), showing higher sensitivity and linearity range compared to commercial screen-printed systems. The novelty of the proposed platform unveils a new way of common, simple, budget, and fast obtaining a universal electroactive platform for electrochemical research, keeping high-performance parameters.

Graphene quantum dots modified electrodes as electrochemical sensing tool towards the detection of codeine in biological fluids and soft drinks.

An electroanalytical method based on disposable screen-printed carbon electrodes modified with non-toxic carbonaceous nanodots is proposed as a reliable and effective device for codeine determination in biological fluids and soft drinks. Graphene quantum dots (GQDs), carbon quantum dots (CQDs) and carbon nanodots (CNDs) were evaluated as electrode modifiers for the determinationof the drug. The electroactive areas of the modified electrodes were assessed by cyclic voltammetry using potassium ferricyanide. Results demonstrated that GQDs provided the best analytical response for codeine, displaying an intense and well-defined anodic wave approximately 0.9V vs reference electrode. The method exhibits an acceptable linear dynamic range, low limits of detection and quantification (0.21 and 0.73µM, respectively), and satisfactory precision (below 3.9% expressed as relative standard deviation (RSD)) in saliva. Only the analysis of biofluids requires a simple extraction protocol. The feasibility and applicability of this novel approach were assessed by determining codeine in different matrices, with recoveries ranging from 69 to 112%. This cost-effective, simple, easily miniaturised and portable method was applied not only to biofluids but also for the direct detection of codeine in soft drinks combined with a codeine-enriched syrup, a medication that is being used to adulterate beverages, particularly at specific events (drinking and nightclub parties). There is no need forany sample treatment, demonstrating its versatility in analysing beverages for potential adulteration as well.

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.

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.

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 (&lt; 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.

Advanced label-free electrochemical immunosensor for a minimally invasive detection of proteins in paintings

In recent decades, scientific methodologies applied in theCultural Heritage field have been growing, due to their pivotal role in guiding informed decisions concerning conservation strategies and daily maintenance. To achieve this goal, minimally/non-invasive quantitative and qualitative analyses are needed. However, the non-invasive and selective identification of proteinaceous binders and coatings in artworks represent an open issue in Cultural Heritage science.Herein, a novel miniaturized system is introduced, which consists of a label-free electrochemical immunosensor integrated with biocompatible Gellan gel. This method is intended to selectively and minimally invasively identify ovalbumin (OVA) on-site in paintings. The label-free immunosensor is made up on screen-printed electrodes (SPEs) by functionalizing the working electrode (WE) with a primary antibody (anti-ovalbumin) for the specific recognition of OVA. The presence of OVA produces antigen-antibody reaction, which results in the development of a bulky immunocomplex on the WE. This complex is quantified using square wave voltammetry (SWV) and a reversible redox probe: the current measured is inversely proportional to the OVA concentrations. The developed immunosensors showed good analytical performances when applied directly to painted mock-ups, exhibiting a limit of detection (LOD) of 1.6 ng/mL, a limit of quantification (LOQ) equal to 16 ng mL-1, a working range between 0.01-0.4 μg/mL and selectivity for OVA over other protein components commonly present in painted artworks, including bovine serum albumin (BSA), collagen, and casein.The outcomes highlighted the dependability of the immunosensor in detecting OVA and the efficacy of Gellan gel as a streamlined method for extracting the target protein while preventing residue accumulation on the painting surface. This advancement suggests the potential of Gellan gel-coupled immunosensor systems as viable diagnostic alternatives for artwork management and preservation.

Electrochemical enrichment of a community of weak electricigens and characterisation of three halotolerant electroactive isolates: Micrococcus sp. YH-1, Gordonia sp. RH-1 and Stutzerimonas sp. CH-1

Microbial electroactivity in elevated salt conditions is seldom studied, despite both fundamental and applied relevance. This work reports the enrichment of electroactive microorganisms under saline conditions (2% NaCl), performed on screen-printed carbon electrodes with applied anodic potential. From the weakly electroactive enriched community, three halotolerant electroactive isolates were obtained in pure culture and identified via 16S rRNA gene sequencing. Two isolates were Gram positive (proposed names Micrococcus sp. YH-1 and Gordonia sp. RH-1) and one was Gram negative (proposed name Stutzerimonas sp. CH-1). The isolates were electrochemically characterised on conventional carbon felt electrodes using chronoamperometry. After two days of growth, a current density of 8.29 ± 0.85 μA/cm2 was observed in Micrococcus sp. YH-1, comparable to reported values for the model electroactive microorganism Shewanella oneidensis. Gordonia sp. RH-1 and Stutzerimonas sp. CH-1 appeared to be weak electricigens due to their low current output (2.19 ± 0.46 μA/cm2 and 1.73 ± 0.47 μA/cm2, respectively). The isolates are notable as there are very limited reports of electroactivity in the genera Micrococcus and Gordonia. Cyclic voltammetry revealed prominent redox peaks in Micrococcus sp. YH-1 and Stutzerimonas sp. CH-1. Scanning electron microscopy demonstrated colonisation of the electrode by each isolate, along with thin cellular appendages in Micrococcus sp. YH-1 and Stutzerimonas sp. CH-1. This work extends the catalogue of characterised halotolerant electroactive microbes while also enhancing our understanding of weak electricigens, extracellular electron transfer in Gram positives, and the inherent electroactivity of the natural environment.

Nanosilver and Graphene Oxide Modified Screen-Printed Carbon Electrode for Electrochemical Detection of Bisphenol A

Nanosilver and Graphene Oxide Modified Screen-Printed Carbon Electrode for Electrochemical Detection of Bisphenol A

Enzymatic bimetallic Cu-Ni micromotor sensor for xanthine detection

Enzymatic bimetallic Cu-Ni micromotors modified screen-printed electrodes were designed for the determination of xanthine. The bimetallic Cu-Ni micromotors were prepared by electrochemical template deposition. Morphological and structural characterization revealed that the smaller size and active mobility of the particles contribute to a larger specific surface area. The increase in surface area enhances electro-catalytic activities and sensitivity. These improved properties enable the newly created xanthine oxidase-modified Cu-Ni micromotors to function effectively as a high-performance sensor. Designed specifically for detecting xanthine, this sensor boasts high sensitivity, a broad measurement range, low detection limits, and excellent reproducibility and stability. The enzymatic bimetallic micromotor-based sensor was also successfully employed to measure xanthine levels. The limits of detection were determined to be 15.7 nM and 21.53 μM for xanthine concentration ranges of 0.1 μM–1 μM and 10 μM–300 μM, respectively, based on electrochemical signals under a magnetic field. Besides, the detection limit was calculated as 9.02 μM for xanthine concentrations ranging from 0.3 μM to 20 μM, based on the speed of the micromotors under a magnetic field (S/N = 3). The impressive results highlight the significant potential of bimetallic Cu-Ni micromotors as sensors, suggesting their promising applications in monitoring food freshness and enhancing security technology.