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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 growth of (bio)sensors in analytical chemistry is mainly attributable to the development of affordable, effective, portable, and user-friendly analytical tools. In the field of sensors, paper-based devices are gaining a relevant position for their outstanding features including foldability, ease of use, and instrument-free microfluidics. Herein, a multifarious use of filter paper to detect copper ions in bodily fluids is reported by exploiting this eco-friendly material to (i) synthesize AuNPs without the use of reductants and/or external stimuli, (ii) print the electrodes, (iii) load the reagents for the assay, (iv) filter the gross impurities, and (v) preconcentrate the target analyte. Copper ions were detected down to 3 ppb with a linearity up to 400 ppb in standard solutions. The applicability in biological matrices, namely, sweat and serum, was demonstrated by recovery studies and by analyzing these biofluids with the paper-based platform and the reference method (atomic absorption spectroscopy), demonstrating satisfactory accuracy of the novel eco-designed analytical tool.

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.

Despite substantial advances in sensing technologies, the development, preparation, and use of self-testing devices is still confined to specialist laboratories and users. Decentralized analytical devices will enormously impact daily lives, enabling people to analyze diverse clinical, environmental, and food samples, evaluate them and make predictions to improve quality of life, particularly in remote, resource-scarce areas. In recent years, paper-based analytical tools have attracted a great deal of attention; the well-known properties of paper, such as abundance, affordability, lightness, and biodegradability, combined with features of printed electrochemical sensors, have enabled the development of sustainable devices that drive (bio)sensors beyond the state of the art. Their blindness toward colored/turbid matrices (i.e., blood, soil), their portability, and the capacity of paper to autonomously filter/purge/react with target species make such devices powerful in establishing point-of-need tools for use by non-specialists. This protocol describes the preparation of a voltammetric phosphate sensor and an amperometric nerve agent biosensor; both platforms produce quantitative measurements with currents in the range of microamperes. These printed strips comprise three electrodes (graphite for working and counter electrodes and silver/silver chloride (Ag/AgCl) for the reference electrode) and nanomodifiers (carbon black and Prussian blue) to improve their performance and specificity. Depending on analytical need, different types of paper (filter, office) and configurations (1D, 2D, 3D) can be adopted. The protocol, based on the use of cost-effective manufacturing techniques such as drop casting (to chemically modify the substrate surface) and wax/screen printing (for creating the channels and electrodes), can be completed in

In this work, a wax-patterned chromatographic paper has been utilized as a holistic platform to 1) synthesize Prussian Blue Nanoparticles (sensing species), 2) load the reagents for the assay, 3) concentrate the sample through multistep, and 4) visualize the determination of silver ions. Waters are continuously affected by changes in the composition, thus the utilization of reagent-free analytical tools is of huge interest for smart drinking water monitoring. Herein, we report the characterization and application of a multi-array paper-based platform for the colorimetric determination of silver ions based on the conversion from Prussian Blue to its silver-based analogue, namely Ag4[Fe(CN)6]. In particular, the platform highlights the increase of sensitivity due to paper pre-concentration of sample, that can be easily adapted to the analytical necessities. Within the proposed experimental setup, Ag+ is visualized down to a detection limit of 0.9 μM, with high repeatability and satisfactory recoveries in the range comprised between 90 and 113%.

Nowadays, environmentally friendly synthesis pathways for preserving the environment and minimizing waste are strongly required. Herein, we propose filter paper as a convenient scaffold for chemical reactions. To demonstrate this novel approach, Prussian Blue Nanoparticles (PBNPs) were synthesized on filter paper by utilizing few μL of its precursors without external inputs, i.e. pH, voltage, reducing agents, and without producing waste as well. The functional paper, named “Paper Blue”, is successfully applied in the sensing field, exploiting the reduction of hydrogen peroxide at low applied potential. The eco-designed “Paper Blue” was combined with wax- and screen-printing to manufacture a reagentless electrochemical point-of-care device for diabetes self-monitoring, by using glucose oxidase as the biological recognition element. Blood glucose was linearly detected for a wide concentration range up to 25 mM (450 mg/dL), demonstrating its suitability for management of diabetes and glucose-related diseases. The Paper Blue-based biosensor demonstrated a correlation coefficient of 0.987 with commercial glucose strips (Bayer Contour XT). The achieved results demonstrated the effectiveness of this approach, which is also extendible to other (bio)systems to be applied in catalysis, remediation, and diagnostics.

Advances in cutting-edge technologies including nanotechnology, micmfluidics, 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 (sic)/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).

Pancreatic ductal adenocarcinoma is the predominant neoplastic disease of the pancreas and it represents the fourth most frequent cause of death in cancer-related disease, with only 8% of survivors after 5-year to the diagnosis. The main issues of this type of cancer rely on fast progress (i.e. 14 months from T1 to a T4 stage), nonspecific symptoms with delay in diagnosis, and the absence of effective screening strategies. To address the lack of early diagnosis, we report a cost-effective paper-based biosensor for the detection of miRNA-492, which is recognised as a biomarker for pancreatic ductal adenocarcinoma. To design a miniaturised, sensitive, and robust paper-based platform, an electrochemical sensor was screen-printed on office paper previously wax-patterned via wax-printing technique. The paper-based sensor was then engineered with a novel and highly specific peptide nucleic acid (PNA) as the recognition element. The formation of PNA/miRNA-492 adduct was evaluated by monitoring the interaction between the positively charged ruthenium (III) hexamine with uncharged PNA and/or negatively charged PNA/miRNA-492 duplex by differential pulse voltammetry. The paper-based biosensor provided a linear range up to 100 nM, with a LOD of 6 nM. Excellent selectivity towards one- and two-base mismatches (1MM, 2MM) or scrambled (SCR) sequences was highlighted and the applicability for biomedical analyses was demonstrated, measuring miRNA-492 in undiluted serum samples.

Altres ajuts: the ICN2 is funded by the CERCA Programme/Generalitat de Catalunya. The development of paper-based electroanalytical strips as powerful diagnostic tools has gained a lot of attention within the sensor community. In particular, the detection of nucleic acids in complex matrices represents a trending topic, especially when focused toward the development of emerging technologies, such as liquid biopsy. DNA-based biosensors have been largely applied in this direction, and currently, there are two main approaches based on target/probe hybridization reported in the literature, namely Signal ON and Signal OFF. In this technical note, the two approaches are evaluated in combination with paper-based electrodes, using a single strand DNA relative to H1047R (A3140G) missense mutation in exon 20 in breast cancer as the model target. A detailed comparison among the analytical performances, detection protocol, and cost associated with the two systems is provided, highlighting the advantages and drawbacks depending on the application. The present work is aimed to a wide audience, particularly for those in the field of point-of-care, and it is intended to provide the know-how to manage with the design and development stages, and to optimize the platform for the sensing of nucleic acids using a paper-based detection method.

Biosensor development exploiting various transduction principles is characterized by a strong competition to reach high detectability, portability and robustness. Nevertheless, a literature-based comparison is not possible, as different conditions are employed in each paper. Herein, we aim at evaluating which measurement, photons or electrons, yields better biosensor performance. Upon outlining an update in recent achievements to boost analytical performance, amperometry and chemiluminescence (CL)-based biosensors are directly compared employing the same biospecific reagents and analytical formats. Horseradish peroxidase (HRP) and hydrogen peroxide concentrations were directly measured, while glucose and mouse IgG were detected employing an enzyme paper-based biosensor and an immunosensor, respectively. Detectability was down to picomoles of hydrogen peroxide (4 pmol for CL and 210 pmol for amperometry) and zeptomoles of HRP (45 zmol for CL and 20 zmol for amperometry); IgG was detected down to 12 fM (CL) and 120 fM (amperometry), while glucose down to 17 μM (CL) and 40 μM (amperometry). Results showed that amperometric and CL biosensors offered similar detectability and analytical performance, with some peculiarities that suggest complementary application fields. As they generally provided slightly higher detectability and wider dynamic ranges, CL-based biosensors appear more suitable for point-of-care testing of clinical biomarkers, where detectability is crucial. Nevertheless, as high detectability in CL biosensors usually requires longer acquisition times, their rapidity will allocate electrochemical biosensors in real-time monitoring and wearable biosensors. The analytical challenge demonstrated that these biosensors have competitive and similar performance, and between photons and electrons the competition is still open.

In the last decades, there is a growing search for analytical strategies to ensure clinical analysis without the need of laboratory set-up and skilled personnel. Indeed, user-friendly and low-cost devices are highly valued in the era of sustainability for their capability to be applied in low-resource contexts, such as developing countries. To address this issue, herein we report a 96-well paper-based and laboratory setup-free optical platform for the detection of butyrylcholinesterase enzyme (BChE) activity in human serum. We used chromatographic paper to realize a novel analytical tool exploiting its porous structure for reagentless synthesize Prussian Blue Nanoparticles (the sensing element), as well to load all the reagents required for the measurement. The principle of BChE activity detection relies on the reaction between the enzymatic product thiocholine and Prussian Blue, giving the Prussian White with subsequently Prussian Blue's fading, detected by a common office scanner supported by ImageJ software. Using this novel paper-based optical platform, BChE activity was linearly detected in the 2–15 U/mL range with a detection limit down to 0.8 U/mL. The accuracy was successfully demonstrated by recovery study with spiked serum and by comparing the data with the gold standard method.

Herein, we propose the first three-dimensional origami paper-based device for the detection of several classes of pesticides by combining different enzyme-inhibition biosensors. This device was developed by integrating two different office paper-based screen-printed electrodes and multiple filter paper-based pads to load enzymes and enzymatic substrates. The versatile analysis of different pesticides was carried by folding and unfolding the filter paper-based structure, without any addition of reagents and any sample treatment (i.e. dilution, filtration, pH adjustment). The paper-based platform was employed to detect paraoxon, 2,4-dichlorophenoxyacetic acid, and atrazine by exploiting the capability of these different types of pesticides (i.e. organophosphorus insecticides, phenoxy-acid herbicides, and triazine herbicide) to inhibit butyrylcholinesterase, alkaline phosphatase, and tyrosinase, respectively. The degree of inhibition correlating to the quantity of pesticides was evaluated by chronoamperometrically monitoring the enzymatic activity in the absence and in the presence of pesticides by using a portable potentiostat. To improve the sensitivity, the paper-based electrodes were modified with carbon black alone in the case of platforms for 2,4-dichlorophenoxyacetic acid and atrazine detection, or decorated with Prussian blue nanoparticles for the detection of paraoxon. The paper-based device was applied for the detection of paraoxon, 2,4-dichlorophenoxyacetic acid, and atrazine at ppb level in both standard solutions and river water sample. The accuracy of this origami multiple paper-based electrochemical biosensor was evaluated in river water by recovery studies, obtaining satisfactory values (e.g. for paraoxon 90 ± 1% and 88 ± 2%, for 10 and 20 ppb, respectively). The proposed three-dimensional origami paper device allows for rapid, cost-effective and accurate pesticide detection in surface water as a result of combining filter and office papers, screen-printing, wax-printing and nanomaterial technology.

The detection of double stranded DNA (dsDNA) is often associated with the use of laboratory-bound approaches and/or with the prior generation of single stranded DNA (ssDNA), making these methods not suitable for in situ monitoring, i.e., point-of-care diagnostics. Screen-printed technology, coupled to the use of triplex forming oligonucleotides (TFO) as the recognizing probes, offers a great possibility toward the development of portable analytical tools. Moreover, the continuous demand for sustainable processes and waste lowering have highlighted the role of paper-based substrates for manufacturing easy-to-use, low-cost, and sustainable electrochemical devices. In this work, filter paper and copy paper have been utilized to produce E-DNA strips. Gold nanoparticles (AuNPs) have been exploited to immobilize the methylene blue (MB)-tagged TFO and to enhance the charge transfer kinetics at the electrode surface. Both paper-based substrates have been electrochemically characterized, and in addition, the effect of the amount of waxed layers has been evaluated. The paper-based E-DNA strips have been challenged toward the detection of three model targets, obtaining 3 and 7 nM as the detection limit, respectively, for single and double stranded sequences. The repeatability of the manufacturing (homemade) process has been evaluated with a relative standard deviation of approximately 10%. The effectiveness of the filter paper-based platform has been also evaluated in undiluted serum obtaining a similar value of the detection limit (compared to the measurements carried out in buffer solution). In addition, a synthetic PCR amplified dsDNA sequence, related to HIV, has been detected in serum samples.

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.

Herein we describe a novel reagentless paper-based electrochemical phosphate sensor, manufactured with a simple and inexpensive approach. By following three easy steps, consisting of wax patterning, paper chemical modification, and electrode screen-printing, the filter paper provides an effective electroanalytical platform to sense phosphate ions in standard solutions and real samples (river water). The electrochemical properties of the paper-based platform were evaluated, firstly, by using ferricyanide as a redox mediator, proving no analyte-entrapment due to the cellulose lattice. Then, the reference colorimetric method for phosphate ions, which is based on the formation of phosphomolybdic complex, was successfully adapted to a reagentless electrochemically paper-based platform. This novel and highly sustainable configuration readily allows for the determination of phosphate ions with high reproducibility and long storage stability, achieving a detection limit of 4 μM over a wide linear range up to 300 μM. This in-house approach would be able to generically develop an affordable in situ and user-friendly sensing device without the addition of any reagent, to be applied for a broad range of analytes.

A facile ⿿one-step⿿ route to produce a homogenous and highly stable cobalt phthalocyanine (CoPc)-based dispersion by using carbon black (CB) as supporting material is reported. Herein, CB is proposed as effective material to load CoPc in order to obtain a CB/CoPc hybrid nanocomposite dispersion suitable for modifying screen-printed electrodes (SPEs) by an easy and automatable drop casting approach. CoPc resulted anchored to CB by a non-covalent physisorption, confirmed by IR and UV-visible spectroscopies, allowing to preserve the electrochemical performances of CoPc. The resulting CB/CoPc-modified SPE was tested as sensing tool to detect thiocholine, an enzymatic product of butyrylcholinesterase (BChE). The use of CB/CoPc leads to a highly sensitive thiocholine detection by applying a low potential (+0.05 V vs. internal reference) without fouling problem, a typical drawback that affects the thiol electrochemical detection. The favorable characteristics of the sensor were exploited for an easy BChE biosensor fabrication that renders this biosensor well suitable for mass-production. This electrochemical monoenzymatic biosensor was then challenged towards paraoxon, chosen as model organophosphorous pesticide, obtaining a low detection limit (18 nM). The suitability of the biosensor was tested in a waste water sample obtaining satisfactory recovery values, thus demonstrating its capability in such complex matrix.

A screen-printed electrode (SPE) modified with a carbon black (CB)-Au nanoparticles (AuNPs) composite is assembled and tested. Electrochemical and morphological investigations highlight the physico-chemical properties of the resulting AuNP-CB-SPE amperometric device with respect to SPEs modified with a single component of the nanocomposite. The effective performance of such a modified electrode in activating electrocatalytic processes, consisting both in oxidation and reduction reactions, is demonstrated. In particular, electrochemical tests on analytes such as glucose, hydrogen peroxide, hydroquinone, and ascorbic acid, evidence that the composite possesses electrocatalytic performance well superior with respect to the relevant mono-component modified SPE. As a consequence, a meaningful lowering of the peak potentials and improvement of the sensor sensitivities is observed when using AuNP-CB-SPEs with respect to both CB-SPEs and AuNP-SPEs. In the case of H2O2 reduction, the occurrence of the electrochemical process at less negative potentials is coupled to an improvement of sensor sensitivity of about one order of magnitude. Concurrently, lower limit of detections, ranging from 20 to 99% less, have been obtained for the major part of the analytes studied, i.e. glucose, hydrogen peroxide and hydroquinone. Preliminary results reported here indicate that AuNP-CB-SPE can be proposed as an efficient amperometric sensor to be used in many analytical applications.

Bioassays based on enzyme inhibition are analytical tools widely employed for inhibitor analysis. Beside the conventional analytical techniques such as chromatography and mass spectrometry, these bioassays are cost-effective, easy to use, and suitable for in situ measurement but they are often characterised by a quite narrow linear range. Herein, we report a novel graphical method based on integrated Michaelis-Menten equation, valid for all types of reversible inhibition, which provides an extended linear range. The suitability of this innovative approach was demonstrated in the case of fluoride quantification using a colorimetric bioassay based on acetylcholinesterase inhibition. The “half time reaction”, estimated by the progress curve of cholinesterase inhibition, was plotted versus the fluoride inhibitor concentration, observing an extended linear range up to 5 mM, instead of 0.6 mM using initial rate measurements. The applicability of this new concept was further demonstrated in the case of catalase enzyme inhibited by cyanide. Furthermore, it was demonstrated that fixed substrate conversion at level of 10–50% allows determination of inhibitor concentration in a wide linear range with high precision and in short time of analysis. This novel theoretical and practical approach allows for the extension of the linear range without any further experiments, with several advantages including low reagent consumption, reduced waste generation and time of measurement.

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.

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%.

Graphene has been emphasized by researchers as the most promising nanomaterial for many application fields, including energy, catalysis, electronics, remediation, and sensing. In the field of analytic sciences, the continuous demand of sensitive, portable, user-friendly, low-cost, and low-volume analyses has highlighted graphene and graphene-related nanocomposites as key components toward the implementation of graphene-based (bio)sensors. This chapter provides the opportunity to summarize and critically evaluate the recent developments of graphene-based electrochemical devices that have been applied in biomedical field, for the detection of a wide variety of analytes of interest ranging from small compounds to nucleic acids, antibodies, proteins, and bacteria. Particular focus will interest graphene-based lab-on-a-chip (LOC) devices that have been (or will be) capable to answer the important query introduced by the World Health Organization (WHO) toward the development of affordable, sensitive, specific, user-friendly, rapid and robust, equipment-free and deliverable to end users (ASSURED) devices and to replace traditional approaches in the biomedical self-diagnostic field.

The recent goal of sustainability in analytical chemistry has boosted the development of eco-designed analytical tools to deliver fast and cost-effective analysis with low economic and environmental impact. Due to the recent focus in sustainability, we report the use of low-cost filter paper as a sustainable material to print silver electrodes and to load reagents for a reagent-free electrochemical detection of chloride in biological samples, namely serum and sweat. The electrochemical detection of chloride ions was carried out by exploiting the reaction of the analyte (i.e. chloride) with the silver working electrode. During the oxidation wave in cyclic voltammetry the silver ions are produced, thus they react with chloride ions to form AgCl, while in the reduction wave, the following reaction occurs: AgCl + e- -->Ag + Cl-. These reactions at the electrode surface resulted in anodic/cathodic peaks directly proportional to the chloride ions in solution. Chloride ions were detected with the addition of only 10 μL of the sample on the paper-based electrochemical cell, obtaining linearity up to 200 mM with a detection limit equal to 1 mM and relative standard deviation lower than 10%. The accuracy of the sensor was evaluated in serum and sweat samples, with percentage recoveries between 93 ± 10 and 108 ± 8%. Moreover, the results achieved with the paper-based device were positively compared with those obtained by using the gold standard method (Ion Selective Electrode) adopted in routine clinical analyses.

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.

Through the years, scientists have developed cutting-edge technologies to make (bio)sensors more convenient for environmental analytical purposes. Technological advancements in the fields of material science, rational design, microfluidics, and sensor printing, have radically shaped biosensor technology, which is even more evident in the continuous development of sensing systems for the monitoring of hazardous chemicals. These efforts will be crucial in solving some of the problems constraining biosensors to reach real environmental applications, such as continuous analyses in field by means of multi-analyte portable devices. This review (with 203 refs.) covers the progress between 2010 and 2015 in the field of technologies enabling biosensor applications in environmental analysis, including i) printing technology, ii) nanomaterial technology, iii) nanomotors, iv) biomimetic design, and (v) microfluidics. Next section describes futuristic cutting-edge technologies that are gaining momentum in recent years, which furnish highly innovative aspects to biosensing devices.

Paper-based microfluidic devices are gaining large popularity because of their uncontested advantages of simplicity, cost-effectiveness, limited necessity of laboratory infrastructure and skilled personnel. Moreover, these devices require only small volumes of reagents and samples, provide rapid analysis, and are portable and disposable. Their combination with electrochemical detection offers additional benefits of high sensitivity, selectivity, simplicity of instrumentation, portability, and low cost of the total system. Herein, we present the first example of an integrated paper-based screen-printed electrochemical biosensor device able to quantify nerve agents. The principle of this approach is based on dual electrochemical measurements, in parallel, of butyrylcholinesterase (BChE) enzyme activity towards butyrylthiocholine with and without exposure to contaminated samples. The sensitivity of this device is largely improved using a carbon black/Prussian Blue nanocomposite as a working electrode modifier. The proposed device allows an entirely reagent-free analysis. A strip of a nitrocellulose membrane, that contains the substrate, is integrated with a paper-based test area that holds a screen-printed electrode and BChE. Paraoxon, chosen as nerve agent simulant, is linearly detected down to 3µg/L. The use of extremely affordable manufacturing techniques provides a rapid, sensitive, reproducible, and inexpensive tool for in situ assessment of nerve agent contamination. This represents a powerful approach for use by non-specialists, that can be easily broadened to other (bio)systems.

Herein, we describe a sustainable and inexpensive approach to monitor Zn(II) in biological fluids by fabricating an office paper-based electrochemical sensor. By following two easy steps, consisting of wax patterning and electrode screen-printing, the office paper provides an effective electroanalytical tool that is easily extensible to a broad range of analytes. This approach would be able to develop affordable user-friendly sensing devices, tackling the lack of resources in regions with poor-settings/facilities. In order to provide more details regarding the screen-printed electrodes fabrication, office paper, Whatman #1 chromatrographic paper, and polyester have been characterized with electrochemical, morphological, and mechanical tests and compared. Using office paper, Zn(II) has been detected linearly up to 2 μg/mL with a detection limit equal to 25 ng/mL and a relative standard deviation of 8%. To highlight the feasibility, reliability, and easiness of the proposed electrochemical sensor, Zn(II) has been detected in serum and sweat at physiological level (μg/mL), and the accuracy of the method has been verified by satisfactory recoveries close to 100%.

Herein, we report the first example of a paper-based screen-printed biosensor for the detection of ethanol in beer samples. Common office paper was adopted to fabricate the analytical device. The properties of this paper-based screen-printed electrode (SPE) were investigated by cyclic voltammetry, electrochemical impedance spectroscopy, and scanning electron microscopy, and they were compared with the well-established polyester-based SPEs as well. Paper demonstrated similar properties when compared with polyester, highlighting suitability towards its utilization in sensor development, with the advantages of low cost and simple disposal by incineration. A nanocomposite formed by Carbon Black (CB) and Prussian Blue nanoparticles (PBNPs), namely CB/PBNPs, was utilized as an electrocatalyst to detect the hydrogen peroxide generated by the enzymatic reaction between alcohol oxidase (AOx) and ethanol. After optimizing the analytical parameters, such as pH, enzyme, concentration, and working potential, the developed biosensor allowed a facile quantification of ethanol up to 10 mM (0.058 %vol), with a sensitivity of 9.13 μA/mM cm2 (1574 μA/%vol cm2) and a detection limit equal to 0.52 mM (0.003%vol). These satisfactory performances rendered the realized paper-based biosensor reliable over the analysis of ethanol contained in four different types of beers, including Pilsner, Weiss, Lager, and alcohol-free. The proposed manufacturing approach offers an affordable and sustainable tool for food quality control and for the realization of different electrochemical sensors and biosensors as well.

This overview (with 114 refs.) covers the progress made between 2010 and 2015 in the field of nanomaterial based electrochemical biosensors for pesticides in food. Its main focus is on strategies to analyze real samples. The review first gives a short introduction into the most often used biorecognition elements. These include (a) enzymes (resulting in inhibition-based and direct catalytic biosensors), (b) antibodies (resulting in immunosensors), and (c) aptamers (resulting in aptasensors). The next main section covers the various kinds of nanomaterials for use in biosensors and includes carbonaceous species (carbon nanotubes, graphene, carbon black and others), and non-carbonaceous species in the form of nanoparticles, rods, or porous materials. Aspects of sample treatment and real sample analysis are treated next before discussing vanguard technologies in tailor-made food analysis. [Figure not available: see fulltext.]

In this work a comparative study using Screen-Printed Electrodes (SPEs) modified by drop casting with Carbon Black, Single Walled Carbon Nanotubes[BOND]COOH, Graphene Oxide, and reduced Graphene Oxide is reported. The carbon nanomaterials employed were characterized by X-ray photoelectron and Raman spectroscopy, while the modified SPEs have been morphologically and electrochemically characterized. Nanoengineered SPEs have been tested with ferricyanide, NADH, ascorbic acid and cysteine. We observed valuable electroanalytical performances of Carbon Black with the advantage to be i) cost-effective ii) suitable to obtain stable and homogenous dispersion and iii) mass-producible following a well established route.

An automatable flow system for the continuous and long-term monitoring of the phosphate level has been developed using an amperometric detection method based on the use of a miniaturized sensor. This method is based on the monitoring of an electroactive complex obtained by the reaction between phosphate and molybdate that is consequently reduced at the electrode surface. The use of a screen-printed electrode modified with carbon black nanoparticles (CBNPs) leads to the quantification of the complex at low potential, because CBNPs are capable of electrocatalitically enhancing the phosphomolybdate complex reduction at +125 mV versus Ag/AgCl without fouling problems. The developed system also incorporates reagents and waste storage and is connected to a portable potentiostat for rapid detection and quantification of phosphate. Main analytical parameters, such as working potential, reagent concentration, type of cell, and flow rate, were evaluated and optimized. This system was characterized by a low detection limit (6 μM). Interference studies were carried out. Good recovery percentages comprised between 89 and 131.5% were achieved in different water sources, highlighting its suitability for field measurements.

Here we describe the construction and optimization of a cholesterol biosensor based on screen-printed electrodes (SPEs) modified with inkjet-printed Prussian blue nanoparticles (PBNPs). The deposition of PBNPs using inkjet printing led to the highly facile fabrication of sensors with excellent sensitivity and reproducibility for the measurement of H 2 O 2 . Further integration of the sensor with a microfabricated low volume (4 μL) sample cell allowed the measurement of cholesterol in serum with the addition of cholesterol oxidase. The biosensor exhibited a sensitivity to cholesterol of 2.1 μA/mM cm 2 ( r 2 = 0.97, n = 5) and was linear in the range of 0–15 mM.

A screen-printed electrode (SPE) modified with a carbon black and Au nanoparticles bilayer was developed and proposed as an amperometric sensor for ascorbic acid quantification in pharmaceutical products and for dopamine estimation in the presence of large excess of ascorbic acid. Electrochemical investigations highlight the performances of the resulting modified electrode with respect to SPEs modified with a single component of the nano-composite.

The final aim of this work is the realization of an automatic system based on amperometric measurements able to detect the phosphate in absence of the operator, thus in remote mode control, using automatic valves leaded by a software. The SPEs (screen-printed electrodes) thank to their small size and long term stability, can be easily embedded in a flow system for continuous in situ analysis. Gold nanoparticles (AuNPs), carbon black (CB) and both of them have been used to obtain “composite” (CB/AuNPs) for modifying the SPEs. The different types of sensor (SPE-AuNPs, SPE-CB and SPE-CB/AuNPs), obtained by drop casting technique, were challenged towards phosphate in order to investigate the electrochemical performances. The optimization of the operative parameters for the phosphate detection has been carried out first via batch measurements and in the second step, the flow system has been assembled and re-optimized. The amperometric method developed in this work is able to detect phosphate in a linear range from 20 to 80 µM with detection limit equal to 6 µM (calculated as 3σ/ slope). Moreover, the system was challenged toward tap, river and lake water samples and compared to the colorimetric reference method; a good concordance of the results confirmed that the method is able to detect phosphate also in a complex matrix such as River water.

A sensor for the simple and sensitive measurement of hydrogen peroxide has been developed which is based on screen printed electrodes (SPEs) modified with Prussian blue nanoparticles (PBNPs) deposited using piezoelectric inkjet printing. PBNP-modified SPEs were characterized using physical and electrochemical techniques to optimize the PBNP layer thickness and electroanalytical conditions for optimum measurement of hydrogen peroxide. Sensor optimization resulted in a limit of detection of 2 × 10(-7) M, a linear range from 0 to 4.5 mM and a sensitivity of 762 μA ∙ mM(-1) ∙ cm(-2) which was achieved using 20 layers of printed PBNPs. Sensors also demonstrated excellent reproducibility (