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Pesticides are largely used at worldwide level to improve food production, fulfilling the needs of the global population which is increasing year by year. Although pesticides are beneficial for crop production, their extensive use has serious consequences for the pollution of the produced food as well as for soil and groundwaters. Indeed, it is reported that 50% of sprayed pesticides reach different destinations other than their target species, including soil, surface waters, and groundwaters. For this reason, we developed a flower-like origami paper-based device for pesticides detection in aerosol phase for precision agriculture. In detail, the paper-based electrochemical platform detects paraoxon, 2,4-dichlorophenoxyacetic acid, and glyphosate at ppb levels by measuring their inhibitory activity towards three different enzymes namely butyrylcholinesterase, alkaline phosphatase, and peroxidase enzyme, respectively. This integrated electrochemical device is composed of three office paper-based screen-printed electrodes and filter paper-based pads loaded with enzymes and enzymatic substrates. The pesticide detection is carried out by measuring through chronoamperometric technique the initial and residual enzymatic activity by using a smartphone-assisted potentiostat and evaluating the percentage of inhibition, proportional to the amount of aerosolized pesticides. This paper-based device was able to detect the three classes of pesticides in aerosol phase with limits of detection equal to 30 ppb, 10 ppb, and 2 ppb, respectively for 2,4-D, glyphosate, and paraoxon.

In EU, electronic equipment generated 9 mill tons of waste in 2005, and it is expected to grow to more than 12 million tons by 2020. To decrease the environmental pollutions of electronics, the development of sustainable sensors, including paper-based electrochemical devices, are attracting growing interest thanks to their cost-effectiveness, suitability for in situ analysis, and environmentally friendly. The development of the paper-based devices as point of care is a paramount issue, since this type of systems meets the requirements of the ASSURED criteria coined by WHO, which describe the ideal characteristics of a diagnostic test. As a matter of fact, paper-based (bio)sensors with electrochemical detection practically match this criteria, as they are Affordable (by those at risk of infection), Sensitive (low false-negatives), Specific (few false-positives), User-friendly (simple to perform and requiring minimal training), Rapid (to give useful information at first visit) and robust (do not require refrigerated storage), Equipment-free, Delivered to those who need it. This chapter covers the recent progresses on paper-based electrochemical (bio)sensors for biomedical field, giving an overview of the different papers and techniques used for the fabrication of paper-based devices as well as the different configurations designed. The main section encompasses the description of several paper-based sensors and biosensors (i.e. enzymatic, immuno- and nucleic-acid based sensors) with biomedical applications as well. The last section describes the future perspectives for eco-designed (bio)sensors, being a hot topic in the field of analytical sensing tools.

Herein we demonstrated, for the first time, the possibility to use the paper employed in printed electronics (i.e. p_e:smart) as substrate to develop a paper-based sensor. To improve the electrochemical performances of the inkjet-printed sensor, a dispersion based on carbon black nanoparticles was used to modify the working electrode, allowing for a highly performant nanomodified electrochemical sensor platform. This disposable sensor was characterized both electrochemically and morphologically, and it has been successively challenged towards a model analyte namely ascorbic acid. It has been evidenced that the presence of carbon black as nanomodifier decreased the overpotential for ascorbic acid oxidation (from 0.47 V to 0.28 V) with respect to the unmodified sensor and boosted the sensitivity (ca. 3-times). The applicability of this printed electrochemical sensor was demonstrated for the detection of ascorbic acid in a dietary supplement, quantifying 999 ± 130 mg with respect to the 1000 mg reported on the label.

A paramount research is focused nowadays on agrifood analysis, to ensure the commercialisation of safe products that meet the requirements of consumer perception. Food manufacturing processes might be threaten by contamination or lack of quality at each stage of the food supply chain while growing, processing, packaging, or distributing. Therefore, there is an increasing demand for fast and automatic analytical tools suitable for real-time control of food quality and safety through the whole chain. (Bio)sensors have high potential to this concern, being fast and sensitive analytical methods for the analysis of food composition and contamination, as well as for online process control. In this review, commercial (bio)sensors available for the agrifood sector are reported and compared in terms of their crucial features tailored for the different agrifood sector segments, including food analysis, process control, intelligent packaging, and smart agriculture. Moreover, an overview on the last trends in biosensor technologies is reported with the aim to enhance the biosensor performance and to develop newer sensor design and construction, fostering food production processes at high-quality standards.

The characterization of an economic and ease-to-use carbon paste acetylcholinesterase (AChE) based biosensor to determine the concentration of pesticides Paraoxon and Dichlorvos is discussed. AChE hydrolyses acetylthiocholine (ATCh) in thiocoline (TC) and acetic acid (AA). When AChE is immobilized into a paste carbon working electrode kept at +410 mV vs. Ag/AgCl electrode, the enzyme reaction rate using acetylthiocholine chloride (ATCl) as substrate is monitored as a current intensity. Because Paraoxon and Dichlorvos inhibit the AChE reaction, the decrease of the current intensity, at fixed ATCl concentration, is a measure of their concentration. Linear calibration curves for Paraoxon and Dichlorvos determination have been obtained. The detection limits resulted to be 0.86 ppb and 4.2 ppb for Paraoxon and Dichlorvos, respectively, while the extension of the linear range was up 23 ppb for the former pesticide and up to 33 ppb for the latter. Because the inhibited enzyme can be reactivated when immediately treated with an oxime, the biosensor reactivation has been studied when 1,1'-trimethylene bis 4-formylpyridinium bromide dioxime (TMB-4) and pyridine 2-aldoxime methiodide (2-PAM) were used. TMB-4 resulted more effective. The comparison with the behavior of similar AChE based biosensors is also presented.

A thionine-modified carbon paste electrode for catechol and Bisphenol A (BPA) detection is presented. Graphite powder was modified by adsorbing thionine as electrochemical mediator. The electrochemical response of the modified carbon paste electrode (CPE) was determined before electrode modification with tyrosinase. Then, tyrosinase was added in order to assemble a biosensor. Once established the best operative conditions, an interelectrode reproducibility around 7% was obtained and the resulting biosensor showed improved sensitivities and (S = 139.6±1.1 nA/*M for catechol and S = 85.4±1.5 nA/*M for BPA) in comparison with the biosensor constructed without thionine (S = 104.4±0.5 nA/*M for catechol and S = 51.1±0.6 nA/*Mfor BPA) and low detection limits (0.15*Mfor both the electrodes and analytes). Also the comparison with the results reported in the literature showed higher sensitivity and lower detection limit for our biosensor. Moreover the functioning of the thionine-tyrosinase CPE was validated following a biodegradation process of water polluted by BPA and comparing the time changes of BPA concentration inferred by the biosensor calibration curve and those determined by means of HPLC measurements