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Malaria elimination is a major goal to be reached in the next decade. Significant progress were made in the past, and the prevalence decreased in many areas while the positive trend stalled in the last years. The exact number of asymptomatic carriers of Plasmodium parasites is unknown since this population is not detected by conventional diagnosis methods and participate in the maintenance of transmission. Molecular methods to detect low parasitemia are not available at point-of-care in low-income countries of malaria endemic areas. Adaptation of molecular methods such as loop-mediated isothermal amplification of DNA may provide effective tools but it required simplification of DNA detection. Square waves voltammetry, easily imbedded in small device such as cell phone, was largely described for DNA detection but support for reaction was an issue to address. Here we used an efficient functionalization method of paper-based material to facilitate the interactions between isothermal amplification product and methylene blue for easy-to-use DNA detection. The proof-of-concept of qualitative detection of very low parasitemia from malaria infected patients using newly chemically treated paper for square waves voltammetry was obtained with a sensitivity and specificity of 100% and a limit-of-detection of 0.1 parasite. μL−1 corresponding to a parasitemia of 0.000002%. [Display omitted] • Asymptomatic carriers of Plasmodium parasites participate in the maintenance of malaria transmission. • Molecular methods to detect low parasitemia are not available at point-of-care in malaria endemic areas. • Detection of Plasmodium DNA using square waves voltammetry and methylene blue required innovative paper functionalization. • The proof-of-concept of low parasitemia diagnosis using chemically grafted paper for square waves voltammetry was obtained. [ABSTRACT FROM AUTHOR]

This work presents an all-in-one origami paper-based electrochemical platform for simple and inexpensive l -cysteine (Cys) detection using Cys as a monomer for modifying electrode surfaces. The proposed method combines the steps of electropolymerization and detection into a single device to offer a highly convenient method for the end-user. In comparison, the sensitivity toward Cys detection is a significantly increased using this modified electrode. The developed device provided a linear concentration range of 10–800 μM with a limit of detection of 5.5 μM. For application, the device was successfully applied to detect Cys in different food products such as wheat flour, bread, and cake with satisfactory results, yielding excellent intra-day and inter-day relative standard deviations (1.5–4.9%) and recoveries (84.2–110.8%). This discovery is important from the viewpoint of the development of Cys detection in other applications in the future. [Display omitted] • A novel self-modification of poly(cysteine) for l -cysteine detection was proposed. • New all-in-one origami paper-based analytical device coupled with a novel sensor was developed to offer a convenient procedure over previous methods. • Good selectivity, accuracy, and precision for l -cysteine detection in food samples were demonstrated. [ABSTRACT FROM AUTHOR]

Additive manufacturing is a technique that allows the construction of prototypes and has evolved a lot in the last 20 years, innovating industrial fabrication processes in several areas. In chemistry, additive manufacturing has been used in several functionalities, such as microfluidic analytical devices, energy storage devices, and electrochemical sensors. Theophylline and paracetamol are important pharmaceutical drugs where overdosing can cause adverse effects, such as tachycardia, seizures, and even renal failure. Therefore, this paper aims at the development of miniaturized electrochemical sensors using 3D printing and polylactic acid-based conductive carbon black commercial filament for theophylline and paracetamol detection. Electrochemical characterizations of the proposed sensor were performed to prove the functionality of the device. Morphological characterizations were carried out, in which chemical treatment could change the surface structure, causing the improvement of the analytical signal. Thus, the detection of theophylline at a linear range of 5.00–150 μmol L−1 with a limit of detection of 1.2 μmol L−1 was attained, and the detection of paracetamol at a linear range of 1.00–200 μmol L−1 with a limit of detection of 0.370 μmol L−1 was obtained, demonstrating the proposed sensor effectively detected pharmaceutical drugs. [Display omitted] • A simple and easy printing miniaturized electrochemical device has been developed. • A 3D-printed sensor based on PLA and carbon black filament is constructed. • DMF chemical treatment was effective for exposing carbon black agglomerates. • The optimized method was applied for theophylline detection. • Drug monitoring is performed in pharmaceutical and artificial biological samples. [ABSTRACT FROM AUTHOR]

Rapid and sensitive determination of pesticide residues in fruits and vegetables is critical for human health and ecosystems. This paper used an Ag-modified CuO sphere-cavity array (CuO@Ag) electrode as a thiram SERS/electrochemical dual readout detection platform. Numerous Raman "hotspots" generated by uniformly distributed silver nanoparticles, charge transfer at the CuO@Ag interface, and the formation of Ag-thiram complexes contribute to the significant enhancement of this SERS substrate, which results in excellent SERS performance with an enhancement factor up to 1.42 × 106. When using SERS as the readout technique, the linear range of the substrate for thiram detection was 0.05–20 nM with a detection limit (LOD) of up to 0.0067 nM. Meanwhile, a correlation between the value of change in current density and thiram concentration was established due to the formation of stable complexes of thiram with Cu2+ generated at specific potentials. The linear range of electrochemical detection was 0.05–20.0 μM, and the detection limit was 0.0167 μM. The newly devised dual-readout sensor offers notable sensitivity and stability. The two signal readout methods complement each other in terms of linear range and detection limit, making it a convenient tool for assessing thiram residue levels in agro-food. At the same time, the combination of commercially available portable equipment makes on-site monitoring possible. Ag-modified CuO cavity arrays have been established as SERS-electrochemical dual-signal platforms for thiram detection. [Display omitted] • CuO@Ag cavity arrays were used as SERS/electrochemical dual-signal sensors. • The EM and CT synergistic effect endow CuO@Ag with excellent SERS performance. • The highly ordered array structure ensures excellent SERS signal reproducibility. • The complex between the electrode and thiram enhances the electrochemical response. • The sensor demonstrated the feasibility of detecting thiram in real samples. [ABSTRACT FROM AUTHOR]

The electrochemical method is commonly applied in diagnosing and monitoring diseases. When used in conjunction with optical disease detection systems, it can broaden the detection range, lower the limit of detection and create mutual confirmation. Utilizing the electrochemical-optical dual-mode detection method for disease diagnosis is non-invasive, low-cost, easy-to-use, efficient and accurate compared with the traditional single-mode method. This paper reviews the reports of electrochemistry and optical methods combined in recent years, such as colorimetry, fluorescence, Surface Enhanced Raman Spectroscopy (SERS), surface plasmon resonance (SPR) and spectroelectrochemistry. We cover researches on several electrochemical-optical dual-mode detection methods for identifying disease markers, including biochemistry, cancer, infection, cardiovascular and cerebrovascular disease, and neurological diseases as well. These studies demonstrate the feasibility of electrochemical-optical dual-mode detection and its broad application prospects in the field of disease detection. This paper reviews the popular schemes of electrochemical dual-mode detection in disease diagnosis recently. First of all, five electrochemical dual-mode disease detection are discussed, such as electrochemical-colorimetry mode, electrochemical-fluorescence mode, electrochemical-SERS mode, electrochemical-SPR mode and electrochemical-microfluidics mode. Secondly, we investigate the schemes of various electrochemical dual-mode detection methods for the detection of different types of diseases, such as biochemical detection, cancer detection, infection detection, detection of cardiovascular and cerebrovascular and neurological disease detection. Finally, alternative electrochemical dual-mode detection methods are compared. We also evaluate their detection qualities across a variety of disorders and recommend research avenues that researchers may favor in the future. [Display omitted] • Introducing the research progress of electrochemical-optical dual-mode detection in different kinds of diseases. • Stating the excellent schemes of combining electrochemistry with different kinds of optical methods in disease detection. • An in-depth analysis of the benefits and drawbacks of several electrochemical-optical dual-mode detection methods. • The future prospect of different electrochemical-optical dual-mode detections in disease diagnosis are discussed. [ABSTRACT FROM AUTHOR]

A properly designed sensing interface is crucial for the accurate and sensitive detection of biologically active molecules. Single-atom nanozymes from transition metal and nitrogen-doped carbon materials (M-N-C) have caught attention owing to their large surface area and strong bionic enzyme activity. Herein, a three-dimensional layered electrochemical electrode consisting of a Co–N–C nanoenzyme embedded in a reduced graphene oxide aerogel was prepared for the detection of hydrogen peroxide (H 2 O 2), dopamine (DA) and uric acid (UA). Due to its unique three-dimensional layered structure, rGA has excellent electrical conductivity and high material loading and is used to enhance the electrocatalytic performance of Co–N–C. The combination of single-atom nanozymes and electrochemical detection shows unique advantages in catalytic activity and selectivity. The limit of detection and detection range are 0.74 μM and 3–2991 μM respectively for H 2 O 2. Furthermore, it has been successfully implemented for the in-situ detection of H 2 O 2 in living cells. In addition, their simultaneous detection is also realized by the sensors for DA and UA. And it can accurately capture the signal of UA and DA in the urine. Meanwhile, the electrode displays satisfactory stability and repeatability. Therefore, this paper provides a new detection strategy for a variety of bioactive molecules, showing great potential in cell biology, pathophysiology and diagnostics. A novel electrochemical sensor based on single-atom nanozymes Co–N–C for bioactive molecules detection. [Display omitted] • Single-atom nanozymes Co–N–C exhibited peroxidase activity. • Co–N–C/rGA was used to detect H 2 O 2 in living cells, and successfully realized the simultaneous detection of DA and UA. • It provides a new method for the detection of bioactive molecules. [ABSTRACT FROM AUTHOR]