The need to deliver high performant and miniaturised electrochemical sensors has boosted the use of carbon nanomaterials as smart modifiers of working electrode surface. Among the carbon nanomaterials, the common and cost-effective carbon black has recently attracted the attention from the scientific community for its outstanding features as electrode nanomodifier for analyte detection. Herein, we report the structural and morphological characterisation of several types of carbon blacks, namely HP 160, HS20, MTN 990, N115, N220, N375, N660, PL6, Super P, and XE2B, by means of Raman spectroscopy, transmission electron microscopy (TEM) and scanning electron microscopy (SEM) analyses. Furthermore, the electrochemical characterisation of screen-printed electrodes modified with these carbon blacks was carried out by cyclic voltammetry and electrochemical impedance spectroscopy with ferro/ferricyanide as redox probe, highlighting the advantage to use carbon black as nanomodifier in respect to the bare electrode. Among several tested carbon black types, the lowest peak-to-peak separation and resistance to electron transfer values were achieved using screen-printed electrodes modified with CB N115, N375, HP 160 and PL6. The electrodes modified with these types of CB were successively tested in cyclic voltammetry towards epinephrine, benzoquinone, ascorbic acid, cysteine, catechol, and caffeic acid, observing a remarkable improvement of electrochemical performances in respect to the bare electrode, even when the amperometric mode was used. The results obtained demonstrated that several types of CB can remarkably improve the electrochemical performances of the sensors in terms of the decrease of applied potential or peak-to-peak separation, the improvement of the peak intensity, and the decrease of the resistance of the electron transfer due to several key features, including nanodimensions, the onionlike carbon structure, and the high number of defect sites.

Paper-based devices are always more gaining a relevant position in the field of sensors. The continuous demand for affordable, simple, sustainable, and portable devices, is making paper as the ideal basis towards the realization of analytical tools for the easy self-testing. In this work, we demonstrate, for the first time, the development of a disposable paper-based printed electroanalytical strip for reliable, rapid, and high-throughput detection of glutathione in blood. The detection is based on the thiol-disulfide exchange reaction, which produces a detectable compound easily oxidizable at a Prussian Blue/carbon black nanocomposite involving a favorable low-interference overpotential. This nanocomposite is mixed within a carbon-based conductive ink and successively screen-printed onto a wax-patterned filter paper. The employment of paper provides a reagent-free device, as a consequence of the reagents pre-loading within the testing area. After the experimental conditions have been optimized, glutathione has been detected up to 10 mM, with a detection limit of 60 μM, and a sensitivity of (0.102 ± 0.005) μA/mM. This sensor showed satisfactory repeatability (relative standard deviation equal to 10%, for detection of glutathione 1 mM), especially by considering the hand-made manufacturing process. The "real-world" applicability of this strip has been evaluated by quantifying blood glutathione at physiological levels and by recovery studies achieving satisfactory values.

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The recent trend of using sustainable disinfectants in water treatment sector boosted the employment of chlorine dioxide (ClO2) as green disinfectant. Indeed, this disinfectant is characterised by several attractive features such as the working capability in a wide range of pH and the absence of harmful by‐products. These characteristics confer to chlorine dioxide a prominent position between the disinfectants, thus analytical tools for on‐site detection are needed to customize the water treatment. Herein, we described the development of an innovative and cost‐effective carbon black modified screen‐printed electrode for amperometric quantification of chlorine dioxide in standard solution and in swimming pool water. The carbon black as working electrode nanomodifier allowed for the detection of chlorine dioxide at low applied potential, with linear range of 0.05–20 ppm, and a detection limit of 0.01 ppm. The matrix effect evaluation as well as the recovery study demonstrated the capability of this sensor for a cost‐effective detection of chlorine dioxide in swimming pool water, paving the way for the use of miniaturised electrochemical sensors in water treatment field.