Paper-based devices as new smart analytical tools for sustainable detection of environmental pollutants

The use of paper as a multifunctional material in electrochemical sensing has been intensively explored over the last decade. The combination among different kinds of paper as well as their coupling with different electro chemical cell configurations have been demonstrated, disclosing innovative sensing performances and features that are still to be fully investigated. This ongoing research has found applications in a variety of fields, including the biomedical, agri-food, security, and environmental ones, thanks to the high versatility and adaptability of the paper material. In this review, we report a critical and comparative analysis of electrochemical devices based on paper published within 2010–2021 and applied for the detection of pollutants of environmental interest in fresh water, seawater, and other real environmental matrices. Several paper types, from common office paper to Whatman filter paper with different filtering grades, were proved to be useful in this field. In detail, the multifarious roles played by the paper are discussed, highlighting how the paper can be a suitable material for electrochemical sensing while being capable of simplifying the measurement of complex real matrices or real izing programmable origami-like structures. Among the most important pollutants, a special focus is dedicated to the emerging pollutants. Furthermore, the unique advantages achieved by the paper have been analyzed and highlighted, reporting the future perspectives regarding the use of this surprising material

Paper as smart support for bioreceptor immobilization in electrochemical paper-based devices

The use of paper as a smart support in the field of electrochemical sensors has been largely improved over the last 15 years, driven by its outstanding features such as foldability and porosity, which enable the design of reagent and equipment-free multi-analysis devices. Furthermore, the easy surface engineering of paper has been used to immobilize different bioreceptors, through physical adsorption, covalent bonding, and electrochemical poly-merization, boosting the fine customization of the analytical performances of paper-based biosensors. In this review, we focused on the strategies to engineer the surface of the paper for the immobilization of (bio)recog-nition elements (eg., enzymes, antibodies, DNA, molecularly imprinted polymers) with the overriding goal to develop accurate and reliable paper-based electrochemical biosensors. Furthermore, we highlighted how to take advantage of paper for designing smart configurations by integrating different analytical processes in an eco-designed analytical tool, starting from the immobilization of the (bio)receptor and the reagents, through a designed sample flow along the device, until the analyte detection

Heavy metal accumulation capacity of Axinella damicornis (Esper, 1794) (Porifera, Demospongiae): a tool for bioremediation of polluted seawaters

A wide range of contaminants are continuously introduced into the aquatic environment and among these, heavy metals con- stitute one of the most dangerous groups because of their persistent nature, toxicity, tendency to accumulate in organisms and more still, they are non-degradable. Marine organisms such as sponges represent target species for the monitoring of heavy metal contamination due their filtering activity. This study aims to evaluate the retention capacity of lead and cadmium by the sponge Axinella damicornis under laboratory conditions. The sponges were exposed for 144 h to seawaters artificially polluted with lead (Pb) and cadmium (Cd) separately and with a mixture of the two metals. The final goal of the experiments was to evaluate the met- al uptake in the sponge body and efficiency of the sponge in removing the metals from seawater. In particular, the highest values of metal concentration in the sponges were recorded for Pb: this metal was found to be 6 times and 9 times more concentrated than Cd, respectively in the case of exposure to the single metal and to the combination of both metals. The metal concentrations found, especially for Pb, were much higher in A. damicornis than in other organisms investigated in the sea. Remarkable signs of stress and necrosis were recorded in the specimens when exposed to the combination of Pb and Cd, evidencing a synergistic effect of the metals mixture. This study paves adds knowledge on the contamination effects by heavy metals on the marine organisms and on the contribution from A. damicornis as efficient tool for bioremediation of polluted seawaters

Why ammonium detection is particularly challenging but insightful with ionophore-based potentiometric sensors - an overview of the progress in the last 20 years

The monitoring of ammonium ion concentration has gained the attention of researchers from multiple fields since it is a crucial parameter with respect to environmental and biomedical applications. For example, ammonium is considered to be a quality indicator of natural waters as well as a potential biomarker of an enzymatic byproduct in key physiological reactions. Among the classical analytical methods used for the detection of ammonium ions, potentiometric ion-selective electrodes (ISEs) have attracted special attention in the scientific community because of their advantages such as cost-effectiveness, user-friendly features, and miniaturization ability, which facilitate easy portable measurements. Regarding the analytical performance, the key component of ISEs is the selective receptor, labelled as an ionophore in ISE jargon. Indeed, the preference of an ionophore for ammonium amongst other ions (i.e., selectivity) is a factor that primarily dictates the limit of detection of the electrode when performing measurements in real samples. A careful assessment of the literature for the last 20 years reveals that nonactin is by far the most employed ammonium ionophore to date. Despite the remarkable cross-interference of potassium over the ammonium response of nonactin-based ISEs, analytical applications comprising water quality assessment, clinical tests in biological fluids, and sweat monitoring during sports practice have been successfully researched. Nevertheless, there is evident difficulty in the determination of close-to-micromolar levels of ammonium in real samples with a significant potassium background level (i.e., millimolar concentration). This fact has fostered the search for a large variety of ammonium ionophores over the years, which are critically inspected herein. Overall, we provide an easily readable state of the art accompanied by a comprehensive description of other types of ammonium electrodes, including commercially available units. We conclude that newer breakthroughs are still required in the field to reach the desired analytical applications.QC 20211129</p

Monitoraggio della corrosione nelle barre di rinforzo per le strutture in cemento armato

In Italia l'interesse per il monitoraggio strutturale è recentemente aumentato, anche in conseguenza di alcuni drammatici crolli di importanti infrastrutture. Spesso la valutazione della salute di una struttura è il risultato della valutazione visiva da parte di esperti, almeno inizialmente. Il cemento armato è uno dei materiali da costruzione più adottati per le infrastrutture e gli edifici, nell'ultimo mezzo secolo, ma la sua durabilità è in grande discussione, anche perché legata alla condizione delle barre metalliche dell’armatura. In condizioni normali le barre sono protette dalla corrosione in quanto circondate dalla matrice di calcestruzzo. Ma quando l’alcalinità del calcestruzzo diminuisce rispetto al suo valore ottimale, per vari motivi, le barre di armatura sono a rischio corrosione. Questo documento si propone di mostrare come sia possibile monitorare le condizioni delle barre di rinforzo in acciaio utilizzando sensori elettrochimici stampati miniaturizzati ed economici combinati con strumentazione portatile. Sebbene tale attività non fornisca al momento una valutazione quantitativa del danno strutturale, sembra almeno fornire informazioni particolarmente rilevanti per monitoraggi ulteriori sulle condizioni del materiale, sollecitando le contromisure di ripristino per estendere la durata e la sicurezza della struttura

Screen-printed electrode as a cost-effective and miniaturized analytical tool for corrosion monitoring of re-inforced concrete

Herein, we report the first electrochemical sensor based on a screen-printed electrode designed to evaluate the corrosion level in iron-reinforced concrete specimens. The combination of an Ag pseudoreference electrode with a gel polymeric electrolyte allows for fast, stable and cost-effective potentiometric measurements, suitable for evaluating the corrosion of iron bars embedded in concrete samples. The sensor was found to be capable of discriminating between a standard non-corroded sample and samples subject to corrosion due to the presence of chloride or carbonate in the concrete matrix. The potential in concrete-based specimens containing carbonate (pH 9, - 0.35 +/- 0.03 V) or chloride (4% w/w, - 0.52 +/- 0.01 V) was found to be more negative than in a standard concrete-based sample ( - 0.251 +/- 0.003 V), in agreement with the ASTM standard C876 method which uses a classical Cu/CuSO4 solid reference electrode. Our results demonstrate that a printed Ag pseudoreference electrode combined with KC1 agar provides an efficient and reliable electrochemical system for evaluating the corrosion of iron bars embedded in concrete-based structures

Nuovi elettrodi stampati paper-based per il monitoraggio dei processi degradativi del cemento armato

LA presente invenzione riguarda nuovi sensori “paper based”, questo termi-ne verrà chiarito di seguito, comprendenti almeno un elettrodo stampato su di un supporto flessibile scelto nel gruppo comprendente: poliestere, kapton, nylon, tedlar, mylar, carta da ufficio, carta cromatografica o carta da filtro; 5 per la misura della corrosione della barra metallica presente all’interno del-la struttura di cemento, del pH del cemento o dei cloruri contenuti nel cemento; caratterizzati dal fatto che detti sensori comprendono almeno una parte in carta; in cui: - detta parte in carta prima dell’uso deve essere inumidita; 10 - le misurazioni vengono effettuate su di un supporto solido (sul cement

A paper-based device for glyphosate electrochemical detection in human urine: A case study to demonstrate how the properties of the paper can solve analytical issues

In the ever-growing demand for agricultural production, the use of pesticides and the consequential health risks is an issue that remains in the spotlight. The biomonitoring of pesticides in biological matrices is a mandatory task to point out the adverse effects on those people that are particularly exposed (i.e., occupational exposure) and to customize the use of pesticides for safer and more aware agricultural practices (i.e., precision agriculture). To overcome the bottleneck of costs and long sample treatments, we conceived a paper-based analytical device for the fast and smart detection of glyphosate in human urines, which is still the most widespread pesticide. Importantly, we demonstrate how to face the analytical interference given by uric acid to develop an electrochemical sensor for glyphosate detection using paper as a multifunctional material. To this purpose, a sample treatment was pointed out and integrated into a paper strip to decrease the level of uric acid in urines, finally delivering a ready-to-use device that combines lateral and vertical flow. The effective decrease of uric acid after the paper-integrated treatment is verified by direct oxidation in differential pulse voltammetry, whereas glyphosate detection can be carried out by enzyme inhibition assay in chronoamperometry. The system showed a limit of detection for glyphosate of 75 μg/L and a linear range of 100 - 700 μg/L. Additionally, the sustainability of the paper device was assessed and compared with reference chromatographic methods. Overall, this work provides an example of how to design green sensing solutions for addressing analytical challenges in line with the White Analytical Chemistry principles