Screen-printed Electrodes Research Articles

Simple and low-cost thrombin activity assay using screen-printed electrodes with portable electrochemiluminescence device

Real-time monitoring of thrombin activity is essential for preventing, diagnosing, and treating coagulation-related diseases. Herein, we present a simple, disposable electrochemiluminescence (ECL) biosensor for thrombin activity assay based on screen-printed electrodes (SPE). The thrombin-specific peptide substrate Mpr (4-Methoxybenzyl group)-GGRK-Fc (ferrocene) was identified from four candidates using molecular docking and specificity constant experiments. Mpr-GGRK-Fc exhibited the highest apparent specificity constant (kcat/KM) of 2.09 × 1012 M−1 s−1, indicating superior affinity and specificity for thrombin. Thrombin catalyzes the cleavage of Mpr-GGRK-Fc, resulting in the detachment of Fc from the electrode surface, which leads to an increase in ECL intensity. Under optimal conditions, the biosensor exhibits a wide linear range from 1.0 × 10−4 U/mL to 1.0 U/mL, with a low detection limit of 4.02 × 10−5 U/mL. The biosensor shows high specificity for thrombin among a range of proteins. Compared to commercial fluorescence kits, our biosensor offers superior sensitivity, selectivity, and stability in detecting thrombin activity in whole blood, making it a promising tool for bedside clinical applications.

Graphene oxide modified screen printed electrodes based sensor for rapid detection of E. coli in potable water

A sensitive and rapid electrochemical sensor has been developed to detect Escherichia coli (E. coli) bacteria that is crucial for ensuring safe drinking water. E. coli significantly contributes to waterborne contamination, driven by overexploitation and insufficient cleanliness around water bodies. This work incorporates synthesis and characterization of graphene oxide (GO), sensor preparation, and sensor testing in the presence of varying E. coli dilutions via H2O2 decomposition. GO is used as a sensing layer and drop casted on the working electrode of screen printed electrode (SPE). The sensor is exposed to different bacterial solutions using varied bacterial concentrations and fixed percent solution of H2O2. The interface of GO and bacterial solution results in a change in potential. The cross-sensitivity tests have also been performed in the presence of chemical compounds found in waste water samples, Pseudomonas aeruginosa and Citrobacter youngae. The sensor demonstrates a detection limit of 2.8 CFU/mL, with a sensitivity of 5.1 mV-mL/CFU, fast response time and excellent repeatability when tested with E. coli. Its performance has also been assessed by comparing the sensing results for regular tap water, reverse osmosis (RO) water, and deionized water samples. This work paves the way for developing a chip-based system to detect E. coli.

Surfactant-assisted electrochemical sensor for phytocannabinoids

The Cannabis sativa plant is known to be a complex source of phytocannabinoids with diverse applications across medicinal, recreational, and industrial domains. However, the proliferation of cannabidiol (CBD)-based or low- Δ9-tetrahydrocannabinol (Δ9-THC) content products has posed challenges for law enforcement agencies due to the complexity of distinguishing lawful from illicit usage. As legislation around cannabis evolves, precise and reliable analytical methods are urgently needed. Traditional techniques, while accurate, are time-consuming and resource intensive. Portable field tests lack specificity and often need follow-up confirmatory tests. Herein, an innovative electrochemical sensor for accurate and efficient identification of phytocannabinoids is presented. The study focuses on the detection of tetrahydrocannabinolic acid (THCA), Δ9-THC, cannabidiolic acid (CBDA), CBD, cannabichromene (CBC) and cannabinol (CBN), employing unmodified carbon screen-printed electrodes (SPEs) as the platform. Additionally, the integration of a cationic surfactant, hexadecyltrimethylammonium bromide (CTAB), is investigated to enhance the sensitivity. This electrochemical sensor demonstrates successful qualitative and semi-quantitative identification of the main phytocannabinoids in seizures. Ultimately, our sensor benefits harm and supply reduction agencies by facilitating quality control and addressing the complexities of varied cannabis products.

IDENTIFICATION OF WHITE WINE ADULTERATION WITH APPLE JUICE AND APPLE CIDER USING CYCLIC VOLTAMMETRY ON A SCREEN-PRINTED ELECTRODE AIDED BY CHEMOMETRIC ANALYSIS

An electroanalytical approach has been developed for the identification and quantification of adulteration of white wine with apple juice and apple cider. After addition of LiClO4 as electrolyte and deoxygenation, the sample was analysed via cyclic voltammetry conducted on a screen-printed carbon electrode modified with gold nanoparticles. Cyclic voltammograms (CVs) of white wine samples displayed consistency regardless of their grape variety, mono-, bi- or multi-varietal status as well as geographical origin. In contrast, CVs of apple juice and apple cider exhibited similarities but were distinct from those of white wine. They were particularly characterized by the presence of a cathodic peak at about -0.50V, attributed to sugars and organic acids, predominantly malic acid. Subsequently, cyclic voltammograms were exported into data points and they were subjected to chemometric analysis. Principal Component Analysis effectively grouped samples into two clusters: white wine and apple juice/ apple cider. Class-modelling demonstrated the ability to detect adulteration in white wine samples, with a detection threshold of 5% v/v or lower, contingent upon the adulterant type (apple juice or apple cider). Partial Least Squares regression facilitated quantification of the adulteration level with acceptable accuracy. This approach is both cost-effective and straightforward, necessitating minimal sample preparation.

Detection of highly sensitive Escherichia coli (E. coli) bacteria using an electrochemical sensor based on zinc oxide/polyvinyl alcohol nanocomposite

Escherichia coli (E. coli) bacteria is found in various water and food sources, posing a significant threat to human health by potentially causing several diseases. Therefore, this study aimed to explore the fabrication of electrochemical sensor based on ZnO/PVA nanocomposite. The fabrication was carried out using a screen-printed carbon electrode (SPCE), with ZnO/PVA nanocomposite serving as a modifying material on the working electrode through the drop-casting method. ZnO/PVA nanocomposite was characterized using Field Emission Scanning Electron Microscopy (FESEM), Transmission Electron Microscope (TEM), X-ray diffraction (XRD), I-V, and cyclic voltammetry electrochemistry. The results of FESEM characterization showed an even distribution of ZnO in PVA matrix with an average of 59 nm particle size. The modification of the working electrode with ZnO/PVA nanocomposite showed an improved current response. Furthermore, a response time of approximately 3–5 min was achieved with a limit of detection (LOD) of 1.97 × 106 CFU during E. coli detection testing. This phenomenon enabled the prototype sensor to detect the presence of E. coli, shown by an increase in current generated during cyclic voltammetry testing. Based on the potential for further development, electrochemical sensor based on ZnO/PVA nanocomposite showed promise in becoming a leading option for E. coli detection.

Ultrasensitive electrochemical detection of miDNA-21 in human serum based on synergistic signal amplification by conducting polymers and bimetallic nanoparticles

MicroRNA-21 (miRNA-21) is a class of small non-coding RNAs that play a crucial role in the regulation of post-transcriptional gene expression. By leveraging the principle of base complementary pairing, the detection of miRNA-21 can be achieved through its analogue, MicroDNA-21 (miDNA-21), which possesses an identical sequence. Utilizing screen-printed carbon electrodes (SPCE), a conducting polymer (polypyrrole, Ppy), and metal nanocomposites (gold-platinum nanoparticles, Au@Pt NPs) were sequentially electrodeposited to create an electrochemical biosensor for the detection of miDNA-21. This biosensor employed ferrocyanide/ferricyanide (Fe(CN)63−/4−) as the electrochemical signaling probe, and its structure was elucidated via field emission scanning electron microscopy (FESEM) and Energy Dispersive Spectrometer (EDS). Quantitative detection was facilitated through differential pulse voltammetry (DPV), yielding a concentration range and linear fitting equation of 10.00–7.00 × 10.00−14 mol/L: ΔI = 0.5143 lgc + 9.191, R2 = 0.9986. The limit of detection (LOD) was determined to be 2.90 × 10−15 mol/L, with a sensitivity of 9.42 μA/μmol/L·cm2. Subsequent performance assessments confirmed the sensor’s excellent selectivity, reproducibility, and stability. Evaluation using the standard addition method, with normal human serum as the matrix, yielded recoveries ranging from 98.97 % to 102.70 %, and relative standard deviation (RSD) values below 1.00 %. These results demonstrate the method’s viability for practical application in detecting miRNA in human serum.

Electrochemical paper-based sensor based on molecular imprinted polymer and nitrogen-doped graphene for tetracycline determination

In this work, an electrochemical paper-based analytical device (ePAD) based on molecular-imprinted polymer (MIP) and nitrogen-doped graphene (NG) was developed for sensitive electrochemical detection of tetracycline in wastewater. The NG was in-situ synthesized on the paper-based screen-printed carbon electrode (pSPCE) by potentiostatic method to improve the conductivity of the sensor. Subsequently, the MIP were electropolymerized on NG using o-phenylenediamine (oPD) as a functional monomer and tetracycline (TC) as template molecule by cyclic voltammetry (CV) to deliver the specific recognition of TC. The electrode modification process was highly controllable, and the detection efficiency was improved. The electrochemical properties of MIP/NG/ePAD were evaluated by CV, differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS). Under optimized conditions, the fabricated ePAD sensor showed a good linear relationship with TC concentration ranging from 5 × 10−9 to 1 × 10−5 mol/L with a correlation coefficient (R2) of 0.995 and a detection limit of 3.29 × 10−9 mol/L. The ePAD sensor was successfully applied to TC detection in real water samples with satisfied recoveries from 94.0 % to 106.9 %. The low-cost, portable, high specificity, and reliable ePAD sensor proposed here has promising potential for application in point-of-care testing (POCT) in environmental monitoring.

Innovative dual-mode miniaturized nitrite sensor: Incorporating colorimetric and electrochemical detectors for comprehensive monitoring on a single platform

This study introduces a novel, miniaturized analytical platform for a comprehensive range of founded nitrite concentrations on a single, portable device. Nitrites, essential for extending shelf life and enhancing color, are commonly found in both natural and industrial environments. In environmental settings, it is important to detect low nitrite concentrations, industrial applications, such as in the food industry, require handling higher concentrations effectively. This groundbreaking approach combines colorimetry and electrochemical detection for nitrite monitoring in a single portable paper-based device (PAD). Utilizing potassium permanganate (KMnO4) as a chromogenic agent, the device enables rapid, visual detection and quantification of high nitrite concentrations via smartphone-based color intensity analysis. For sensitive detection of low-level nitrite, it incorporates a cellulose acetate-modified screen-printed electrode (CA/SPCE) with differential pulse voltammetric detection. Under optimal conditions, the proposed dual-detection platform effectively detects nitrite concentrations ranging from 0.05 to 12.5 mM. Specifically, it covers (0.05 to 0.6 mM using electrochemical detection and 0.5 to 12.5 mM through colorimetric analysis. High nitrite levels produce a faded color in the test zone, while low or undetectable color changes trigger electrochemical analysis for enhanced precision. This PAD platform is portable, cost-effective, and minimizes reagent usage. Importantly, the method’s detection limit aligns with the World Health Organization’s acceptable daily nitrite intake in drinking water (3 mg L−1, approximately 65 µM), making it a practical tool for nitrite screening.

Development and evaluation of a nontargeted electrochemical surface-enhanced Raman spectroscopy (EC-SERS) screening method applied to forensic seized drug casework samples

Screening tests in forensic laboratories are a critical step in ensuring an efficient and effective analytical scheme for presumptive identification. Electrochemical surface-enhanced Raman spectroscopy (EC-SERS) represents a novel workflow that can be applied both in the laboratory and on-site as a fast, inexpensive, and selective approach to seized drug screening. Using cyclic voltammetry and a 785 nm Raman spectrometer, a nontargeted screen was developed using silver screen-printed electrodes and tested on a panel of common drugs of abuse and adulterants. Following characterization of the analyte panel, in-house binary and tertiary mixtures were assessed and the effectiveness of the developed EC-SERS method was tested using common score-based algorithms including correlation, hit-quality-index, spectral angle mapper, and correlation of the 1st derivative. For in-house blind samples, this approach allowed for positive identification of at least one compound in 100 % of samples. Identification of all compounds was lower at 52 %. Seized drug samples from adjudicated casework were tested on-site at the Maryland State Police laboratory as a fit-for-purpose study. EC-SERS provided an accurate screening result of 86 % using the 1st derivative correlation. Applying knowledge of both the local drug landscape and the prevalence of specific adulterants, this value improved to a positive screening of 93 % for the authentic samples. EC-SERS represents a novel approach to drug screening that could impact forensic laboratories, customs and border patrol, public health, and scene investigations. Future work should focus on improved data processing and chemometric tools for data generated in EC-SERS methods.

Low-Cost Electrochemical Determination of L-Ascorbic Acid Using Screen-Printed Electrodes and Development of an Electronic Tongue for Juice Analysis

Low-cost electrochemical methodologies for the determination of L-ascorbic acid (vitamin C) and the analysis of juices are developed based on its electro-oxidation on carbon screen-printed electrodes. A novel chronoamperometric methodology is developed for the quantification of L-ascorbic acid in fruit juices. The proposed method stands out for its simplicity and rapidity, demonstrating its efficacy in determining L-ascorbic acid content in various fruit juices. Notably, the results obtained with this chronoamperometric approach are compared with those yielded by chromatography, with no significant differences between the two methods being found. Additionally, an electronic tongue is developed for the differentiation of juices based on the square wave voltammetric signals.

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.