Sustainable materials for the design of forefront printed (bio)sensors applied in agrifood sector

The search for sustainability has now become a duty for all those entities, nations or people who intend to combat poverty in the world, safeguard the environment and bridge the gap of disparities that unfortunately still exist between underdeveloped countries and medium-high developed nations.The agrifood sector plays an important role in this vision, and the development of sustainable analytical devices at low cost and easy to use for everyone, suitable for being adopted by those countries whose technological development does not allow them to take up expensive and sophisticated laboratory techniques, may constitute a contribution towards achieving the objectives listed above.In this review we illustrate some examples of electrochemical devices realized utilizing sustainable materials, such as paper, as support for disposable and reagent-free (bio)sensors applied to the monitoring of food quality and safety. We also mention the first applications of new carbonaceous materials obtained from the recycling of agrifood waste products, which promise interesting features for electrochemical applications. (C) 2020 Elsevier B.V. All rights reserved

All-solid state ion-selective carbon black-modified printed electrode for sodium detection in sweat

The synergic combination of printed electronics and printed electrochemical sensors has recently emerged as a new route for developing smart chemical wearable devices applied to sweat monitoring. Sodium ion is one of electrolytes monitored in sweat to evaluate sweating level for electrolyte replacement recommendations. Herein, we report the development of new designed screen-printed electrodes, in which working electrode has been easily modified by drop-casting with the nanomaterial carbon black and a selective membrane cocktail, and the reference electrode with a polyvinyl butyral-based membrane. Once optimised all conditions, the screen-printed electrochemical sensor demonstrated no aqueous layer formation between working electrode and selective membrane, long-term potential stability, good shelf life, and resistance to interferences from oxygen and light. The carbon black-based sensor allowed for the detection of sodium ions in range 10(-4) M e 1 M with a slope of 58 +/- 3 mV/decade and a detection limit of 63 mu M. The applicability for sweat analysis was evaluated by analysing three sweat samples collecting during running activity, obtaining concentrations of 44 +/- 4 mM, 55 +/- 6 mM, and 47 +/- 3 mM, values in agreements with sodium ions content in healthy people, as well as using artificial sweat with recovery values of 90 +/- 3%, 94 +/- 2%, and 94 +/- 5%

A lab-on-a-tip approach to make electroanalysis user-friendly and de-centralized: Detection of copper ions in river water

The development of portable and user-friendly sensing platforms is a hot topic in the field of analytical chemistry. Among others, electroanalytical approaches exhibit a high amenability for reaching this purpose, i.e. the commercial strips for diabetes care are an obvious success. However, providing fully-integrated and user-friendly methods is the leitmotiv. In this work we evaluate the use of a disposable pipette tip, opportunely configured, to realize the first example of lab-on-a-tip. The combination of a pipette tip, wire electrodes, and cotton wool filter, highlights the suitability of producing a novel one-shot electroanalytical platform that does not require expertise-required tasks. To demonstrate the feasibility of this novel method, copper (Cu2+) is detected in water samples by means of anodic stripping voltammetry. The quantification is performed directly into the tip that contains a cotton wool filter: the filter has the double function of purifying the matrices from gross impurities and releasing all the pre-loaded reagents necessary for the assay. After optimizing the experimental parameters, the lab-on-a-tip was capable of detecting Cu2+ linearly up to 300 μg/L with a detection limit of 6.3 μg/L. The effectiveness of the platform was confirmed by testing 50, 100, and 150 ppb Cu-spiked river water sample with recovery value comprised between 92 and 103%

Carbon black as an outstanding and affordable nanomaterial for electrochemical (bio)sensor design

Advances in cutting-edge technologies including nanotechnology, microfluidics, electronic engineering, and material science have boosted a new era in the design of robust and sensitive biosensors. In recent years, carbon black has been re-discovered in the design of electrochemical (bio)sensors thanks to its interesting electroanalytical properties, absence of treatment requirement, cost-effectiveness (c.a. 1 €/Kg), and easiness in the preparation of stable dispersions. Herein, we present an overview of the literature on carbon black-based electrochemical (bio)sensors, highlighting current trends and possible challenges to this rapidly developing area, with a special focus on the fabrication of carbon black-based electrodes in the realisation of sensors and biosensors (e.g. enzymatic, immunosensors, and DNA-based)

Carbon Black-Modified Electrodes Screen-Printed onto Paper Towel, Waxed Paper and Parafilm M®

Herein, we evaluated the use of paper towel, waxed paper, and Parafilm M® (Heathrow Scientific, Vernon Hills, IL, USA) as alternative substrates for screen-printed sensor manufacturing. Morphological study was performed to evaluate the adhesion of the ink on these uncommon substrates, as well as the morphology of the working electrode. The electrochemical characterization was carried out using ferricyanide/ferrocyanide as redox couple. To enhance the electrochemical properties of the developed sensors, the nanomaterial carbon black was used as nanomodifier. The modification by drop casting of the working electrode surface, using a stable dispersion of carbon black, allows to obtain a sensor with improved electrochemical behavior in terms of peak-to-peak separation, current intensity, and the resistance of charge transfer. The results achieved confirm the possibility of printing the electrode on several cost-effective paper-based materials and the improvement of the electrochemical behavior by using carbon black as sustainable nanomaterial

Facile development of cost effective and greener for all solid-state supercapacitor on paper substrate

The introduction of paper-based platforms for developing novel energy storage devices such as supercapacitors (SCs) highlights new promising opportunities in the field of flexible electronics. Herein, the use of paper-based substrate has shown reduced manufacturing cost and simplified coating process by screen-printing technology, as well as an improvement of the multilayer structure adhesion. The SC manufactured with Graphite ink mixed with Carbon Black (CB)/Prussian blue (PB) at different weight ratios (0, 3, 4, 5, 7, and 10 wt %) shows good performances. An optimum weight ratio of carbon black/prussian blue. 4 wt % is consistent with the following features: i) specific capacitance of 253 mF/cm² at 0.01 V/s, ii) specific energy density of 0.5 mWh/cm², iii) specific power density of 0.1 mW/cm², and iv) good cycling stability (94%) after 5000 cycles. The proposed fabrication approach exhibits a simple scale-up, a low environmental impact and a decrease of manufacturing costs: it provides self-supporting electrodes based on a mixture of graphite ink and CB/PB nanocomposite

Novel bio-lab-on-a-tip for electrochemical glucose sensing in commercial beverages

The development of portable and user-friendly sensing platforms is a hot topic in the field of analytical chemistry. Among others, electroanalytical approaches exhibit a high amenability for reaching this purpose, i.e. the commercial strips for diabetes care are an obvious success. However, providing fully-integrated and reagent-free methods is always a leitmotiv. In this work, we evaluated the use of a disposable pipette tip, opportunely configured to demonstrate the first example of an electrochemical biosystem in a pipette tip, namely bio-lab-on-a-tip. The combination of a pipette tip, wire electrodes, enzyme, and cotton wool filter, allows the fabrication of a novel electroanalytical platform that does not need expertise-required tasks. To demonstrate the feasibility of this novel method, glucose is detected in beverages by means of chronoamperometry. The experimental setup, entirely built inside the pipette tip, is able to 1) block impurities/interferences from matrix, 2) load/release reagents for the bio-assay, 3) reduce the operating task to zero, and 4) perform electrochemical detection. With optimized experimental parameters, the bio-lab-on-a-tip is able to detect glucose linearly up to 10 mM with a detection limit of 170 μM. The effectiveness of the platform was confirmed by testing commercial beverages, e.g. Coca-Cola and Coca-Cola Zero, with high accuracy. In addition, the shelf-life of the novel device was evaluated, highlighting the role of cotton wool filter for providing a suitable environment for glucose oxidase stability. The novel concept can be easily generalized for further applications in the field of non-invasive clinical diagnostics and in-situ environmental monitoring