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The fast-growing healthcare demand for user-friendly and affordable analytical tools is driving the efforts to develop reliable platforms for the customization of therapy based on individual health conditions. In this overall scenario, we developed a paper-based electrochemical sensor for the quantification of iron ions in serum as a cost-effective sensing tool for the correct supplement administration. In detail, the working electrode of the screen-printed device has been modified with a nanocomposite constituted of carbon black and gold nanoparticles with a drop-casting procedure. Square wave voltammetry has been adopted as an electrochemical technique. This sensor was further modified with Nafion for iron quantification in serum after sample treatment with trifluoroacetic acid. Under optimized conditions, iron ions have been detected with a LOD down to 0.05 mg/L and a linearity up to 10 mg/L in standard solution. The obtained results have been compared with reference methods namely commercial colorimetric assay and atomic absorption spectroscopy, obtaining a good correlation within the experimental errors. These results demonstrated the suitability of the developed paper-based sensor for future applications in precision medicine of iron-deficiency diseases., (© 2023. Springer-Verlag GmbH Germany, part of Springer Nature.)

In the last few decades, nanomaterials have made great advances in the biosensor field, thanks to their ability to enhance several key issues of biosensing analytical tools, namely, sensitivity, selectivity, robustness, and reproducibility. The recent trend of sustainability has boosted the progress of novel and eco-designed electrochemical paper-based devices to detect easily the target analyte(s) with high sensitivity in complex matrices. The huge attention given by the scientific community and industrial sectors to paper-based devices is ascribed to the numerous advantages of these cost-effective analytical tools, including the absence of external equipment for solution flow, thanks to the capillary force of paper, the fabrication of reagent-free devices, because of the loading of reagents on the paper, and the easy multistep analyses by using the origami approach. Besides these features, herein we highlight the multifarious aspects of the nanomaterials such as (i) the significant enlargement of the electroactive surface area as well as the area available for the desired chemical interactions, (ii) the capability of anchoring biorecognition elements on the electrode surface on the paper matrix, (iii) the improvement of the conductivity of the cellulose matrix, (iv) the functionality of photoelectrochemical properties within the cellulose matrix, and (v) the improvement of electrochemical capabilities of conductive inks commonly used for electrode printing on the paper support, for the development of a new generation of paper-based electrochemical biosensors applied in the biomedical field. The state of the art over the last ten years has been analyzed highlighting the various functionalities that arise from the integration of nanomaterials with paper-based electrochemical biosensors for the detection of biomarkers.

The RNA programmed non-specific (trans) nuclease activity of CRISPR-Cas Type V and VI systems has opened a new era in the field of nucleic acid-based detection. Here, we report on the enhancement of trans-cleavage activity of Cas12a enzymes using hairpin DNA sequences as FRET-based reporters. We discover faster rate of trans-cleavage activity of Cas12a due to its improved affinity (Km) for hairpin DNA structures, and provide mechanistic insights of our findings through Molecular Dynamics simulations. Using hairpin DNA probes we significantly enhance FRET-based signal transduction compared to the widely used linear single stranded DNA reporters. Our signal transduction enables faster detection of clinically relevant double stranded DNA targets with improved sensitivity and specificity either in the presence or in the absence of an upstream pre-amplification step., (© The Author(s) 2022. Published by Oxford University Press on behalf of Nucleic Acids Research.)

The increasing demand for food and the need for a sustainability vision in the agri-food sector have boosted novel approaches for food management, enhancing the valorization of wastes and by-products belonging to the food industry. Herein, we present a novel paper-based origami device to assess the amount of both glucosinolate and glucose in a food waste product belonging to Brassicaceae plants, to evaluate the quality value and the correct management of waste samples. The device has been designed as an origami paper-based platform constituted of two paper-based biosensors to work synergistically in a multiplexed detection. In detail, a monoenzymatic biosensor and a bienzymatic biosensor were configured for the detection of glucose and glucosinolates, respectively, using filter paper pads preloaded with glucose oxidase and/or myrosinase. To complete the paper-based platform, the enzyme-preloaded pads were combined with office paper-based electrodes modified with Carbon black/Prussian Blue nanoparticles for the measurement of enzymatic by-product at a low applied potential (i.e., 0 V versus Ag/AgCl). Overall, this paper-based platform measured glucose and glucosinolate (i.e., sinigrin) with a linear range up to 2.5 and 1.5 mM, and detection limits of 0.05 and 0.07 mM, respectively. The repeatability corresponded to an RSD% equal to 5% by testing 10 mM of glucose, and 10% by testing 1 mM of sinigrin. The accuracy of the developed multiplex device was evaluated by recovery studies at two different levels of sinigrin, i.e., 0.25 and 0.5 mM, obtaining recoveries values equal to (111 ± 3) % and (86 ± 1) %, respectively. The multiplex detection of both glucose and glucosinolate in Brassicaceae samples evaluates the quality values of the waste sample, ensuring the quality of the re-used food product waste by using an eco-designed analytical tool. The combination of paper-based devices for quality control of food waste with the re-use of these food products represents a sustainable approach that perfectly matches sustainable agrifood practices as well as the overall approach of the circular economy., (© 2022. The Author(s).)

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., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Coronavirus disease 2019 (COVID-19) has been recognized as a global pandemic outbreak, opening the most severe socio-economic crisis since World War II. Different scientific activities have been emerged in this global scenario, including the development of innovative analytical tools to measure nucleic acid, antibodies, and antigens in the nasopharyngeal swab, serum, and saliva for prompt identification of COVID-19 patients and to evaluate the immune response to the vaccine. The detection of SARS-CoV-2 in saliva remains a challenge for the lack of sufficient sensitivity. To address this issue, we developed a novel paper-based immunoassay using magnetic beads to support the immunological chain and 96-well wax-printed paper plate as a platform for color visualization by using a smartphone combined with Spotxel free-charge app. To assess the reliability of the measurement of SARS-CoV-2 in saliva, untreated saliva was used as a specimen and the calibration curve demonstrated a dynamic range up to 10 μg/mL, with a detection limit equal to 0.1 μg/mL. The effectiveness of this sustainable analytical tool in saliva was evaluated by comparing the data with the nasopharyngeal swab specimens sampled by the same patients and tested with Real-Time PCR reference method, founding 100% of agreement, even in the case of high Cycle Threshold (CT) numbers (low viral load). Furthermore, the positive saliva samples were characterized by the next-generation sequencing method, demonstrating the capability to detect the Delta variant, which is actually (July 2021) the most relevant variant of concern., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Point-of-care devices have attracted a huge interest by the scientific community because of the valuable potentiality for rapid diagnosis and precision medicine through cost-effective and easy-to-use devices for on-site measurement by unskilled personnel. Herein, we reported a smartphone-assisted electrochemical device consisted of a screen-printed electrode modified with carbon black nanomaterial and a commercially available smartphone potentiostat i.e. EmStat3 Blue, for sensitive detection of tyrosine. Once optimized the conditions, tyrosine was detected in standard solutions by square wave voltammetry, achieving a linear range comprised between 30 and 500 μM, with a detection limit equal to 4.4 μM. To detect tyrosine in serum, the interference of another amino acid i.e. tryptophan was hindered using a sample treatment with an extraction cartridge. The agreement of results analyzing serum samples with HPLC reference method and with the developed smart sensing system demonstrated the suitability of this smartphone-assisted sensing tool for cost-effective and rapid analyses of tyrosine in serum samples., (Copyright © 2021 Elsevier B.V. All rights reserved.)

An Enzyme Linked ImmunoMagnetic Electrochemical assay (ELIME) was developed for the detection of the hepatitis A virus (HAV). This system is based on the use of new polydopamine-modified magnetic nanobeads as solid support for the immunochemical chain, and an array of 8 screen-printed electrodes as a sensing platform. Enzymatic-by-product is quickly measured by differential pulse voltammetry. For this purpose, all analytical parameters were optimized; in particular, different blocking reagents were evaluated in order to minimize the nonspecific interaction of bioreagents. Using the ELIME assays, a quantitative determination of HAV can be achieved with a detection limit of 1·10 -11 IU mL -1 and a working range between 10 -10 - 5 × 10 -7 IU mL -1 . The cross-reactivity of the commercial monoclonal antibodies against HAV used in ELIME assays was tested for Coxsackie B4, resulting very low. The sensitivity was also investigated and compared with spectrophotometric sandwich ELISA. The average relative standard deviation (RSD) of the ELIME method was less than 5% for the assays performed on the same day, and 7% for the measurements made on different days. The proposed system was applied to the cell culture of HAV, which title was quantified by Real-Time Quantitative Reverse Transcription PCR (RT¬qPCR). To compare the results, a correlation between the units used in ELIME (IU mL -1 ) and those used in RT¬qPCR (genome mL -1 ) was established using a HAV-positive sample, resulting in 1 IU mL -1 -10 -4 gen mL -1 (R 2  = 0.978). The ELIME tool exhibits good stability and high biological selectivity for HAV antigen detection and was successfully applied for the determination of HAV in tap water., (Copyright © 2021 Elsevier B.V. All rights reserved.)

In the last 10 years, paper-based electrochemical biosensors have gathered attention from the scientific community for their unique advantages and sustainability vision. The use of papers in the design the electrochemical biosensors confers to these analytical tools several interesting features such as the management of the solution flow without external equipment, the fabrication of reagent-free devices exploiting the porosity of the paper to store the reagents, and the unprecedented capability to detect the target analyte in gas phase without any sampling system. Furthermore, cost-effective fabrication using printing technologies, including wax and screen-printing, combined with the use of this eco-friendly substrate and the possibility of reducing waste management after measuring by the incineration of the sensor, designate these type of sensors as eco-designed analytical tools. Additionally, the foldability feature of the paper has been recently exploited to design and fabricate 3D multifarious biosensors, which are able to detect different target analytes by using enzymes, antibodies, DNA, molecularly imprinted polymers, and cells as biocomponents. Interestingly, the 3D structure has recently boosted the self-powered paper-based biosensors, opening new frontiers in origami devices. This review aims to give an overview of the current state origami paper-based biosensors, pointing out how the foldability of the paper allows for the development of sensitive, selective, and easy-to-use smart and sustainable analytical devices.

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 Ag 4 [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%., (Copyright © 2021 Elsevier B.V. All rights reserved.)

The recent global events of COVID-19 in 2020 have alerted the world to the risk of viruses and their impacts on human health, including their impacts in the social and economic sectors. Rapid tests are urgently required to enable antigen detection and thus to facilitate rapid and simple evaluations of contagious individuals, with the overriding goal to delimitate spread of the virus among the population. Many efforts have been achieved in recent months through the realization of novel diagnostic tools for rapid, affordable, and accurate analysis, thereby enabling prompt responses to the pandemic infection. This review reports the latest results on electrochemical and optical biosensors realized for the specific detection of SARS-CoV-2 antigens, thus providing an overview of the available diagnostics tested and marketed for SARS-CoV-2 antigens as well as their pros and cons.

Botulinum neurotoxins (BoNTs) produced by soil bacterium Clostridium botulinum are cause of botulism and listed as biohazard agents, thus rapid screening assays are needed for taking the correct countermeasures in a timely fashion. The gold standard method relies on the mouse lethality assay with a lengthy analysis time, i.e., 2-5 days, hindering the prompt management of food safety and medical diagnosis. Herein, we propose the first paper-based antibody-free sensor for reliable and rapid detection of BoNT/A and BoNT/C, exploiting their cleavage capability toward a synthetic peptide able to mimic the natural substrate SNAP-25. The peptide is labelled with the electroactive molecule methylene blue and immobilized on the paper-based electrode modified with gold nanoparticles. Because BoNT/A and BoNT/C can cleave the peptide with the removal of methylene blue from electrode surface, the presence of these neurotoxins in the sample leads to a signal decrease proportional to BoNT amount. The biosensor developed with the selected peptide and combined with smartphone assisted potentiostat is able to detect both BoNT/A and BoNT/C with a linearity up to 1 nM and a detection limit equal to 10 pM. The applicability of this biosensor was evaluated with spiked samples of orange juice, obtaining recovery values equal to 104 ± 6% and 98 ± 9% for 1 nM and 0.5 nM of BoNT/A, respectively., (Copyright © 2021 Elsevier B.V. All rights reserved.)

The outbreak of COVID-19 is caused by high contagiousness and rapid spread of SARS-CoV-2 virus between people when an infected person is in close contact with another one. In this overall scenario, the disinfection processes have been largely improved. For instance, some countries have approved no-touch technologies by vaporizing disinfectants such as hydrogen peroxide, with the overriding goal to boost the safety of the places. In the era of sustainability, we designed an electrochemical paper-based device for the assessment of hydrogen peroxide nebulized by a cost-effective ultrasonic aroma diffuser. The paper-based sensor was fabricated by modifying via drop-casting a filter paper-based screen-printed electrode with a dispersion of carbon black-Prussian Blue nanocomposite, to assess the detection of hydrogen peroxide at -0.05 V vs Ag/AgCl. The use of paper-based modified screen-printed electrode loaded with phosphate buffer allowed for monitoring the concentration of hydrogen peroxide in aerosol, without any additional sampling instrument to capture the nebulized solution of hydrogen peroxide at a concentration up to 7% w/w. Hydrogen peroxide, a reconverted ultrasonic aroma diffuser, and the paper-based electrochemical sensor assisted by smartphone have demonstrated how different low-cost technologies are able to supply an useful and cost-effective solution for disinfection procedures., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2021 Elsevier B.V. All rights reserved.)

Herein, we report a novel paper-based electrochemical sensor for on-site detection of sulphur mustards. This sensor was conceived combining office paper-based electrochemical sensor with choline oxidase enzyme to deliver a sustainable sensing tool. The mustard agent detection relies on the evaluation of inhibition degree of choline oxidase, which is reversibly inhibited by sulphur mustards, by measuring the enzymatic by-product H 2 O 2 in chronoamperometric mode. A nanocomposite constituted of Prussian Blue nanoparticles and Carbon Black was used as working electrode modifier to improve the electroanalytical performances. This bioassay was successfully applied for the measurement of a sulphur mustard, Yprite, obtaining a detection limit in the millimolar range (LOD = 0.9 mM). The developed sensor, combined with a portable and easy-to-use instrumentation, can be applied for a fast and cost-effective detection of sulphur mustards.

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.

The wide spectrum of unique needs and strengths of Autism Spectrum Disorders (ASD) is a challenge for the worldwide healthcare system. With the plethora of information from research, a common thread is required to conceptualize an exhaustive pathogenetic paradigm. The epidemiological and clinical findings in ASD cannot be explained by the traditional linear genetic model, hence the need to move towards a more fluid conception, integrating genetics, environment, and epigenetics as a whole. The embryo-fetal period and the first two years of life (the so-called 'First 1000 Days') are the crucial time window for neurodevelopment. In particular, the interplay and the vicious loop between immune activation, gut dysbiosis, and mitochondrial impairment/oxidative stress significantly affects neurodevelopment during pregnancy and undermines the health of ASD people throughout life. Consequently, the most effective intervention in ASD is expected by primary prevention aimed at pregnancy and at early control of the main effector molecular pathways. We will reason here on a comprehensive and exhaustive pathogenetic paradigm in ASD, viewed not just as a theoretical issue, but as a tool to provide suggestions for effective preventive strategies and personalized, dynamic (from womb to adulthood), systemic, and interdisciplinary healthcare approach.

The diffusion of novel SARS-CoV-2 coronavirus over the world generated COVID-19 pandemic event as reported by World Health Organization on March 2020. The huge issue is the high infectivity and the absence of vaccine and customised drugs allowing for hard management of this outbreak, thus a rapid and on site analysis is a need to contain the spread of COVID-19. Herein, we developed an electrochemical immunoassay for rapid and smart detection of SARS-CoV-2 coronavirus in saliva. The electrochemical assay was conceived for Spike (S) protein or Nucleocapsid (N) protein detection using magnetic beads as support of immunological chain and secondary antibody with alkaline phosphatase as immunological label. The enzymatic by-product 1-naphtol was detected using screen-printed electrodes modified with carbon black nanomaterial. The analytical features of the electrochemical immunoassay were evaluated using the standard solution of S and N protein in buffer solution and untreated saliva with a detection limit equal to 19 ng/mL and 8 ng/mL in untreated saliva, respectively for S and N protein. Its effectiveness was assessed using cultured virus in biosafety level 3 and in saliva clinical samples comparing the data using the nasopharyngeal swab specimens tested with Real-Time PCR. The agreement of the data, the low detection limit achieved, the rapid analysis (30 min), the miniaturization, and portability of the instrument combined with the easiness to use and no-invasive sampling, confer to this analytical tool high potentiality for market entry as the first highly sensitive electrochemical immunoassay for SARS-CoV-2 detection in untreated saliva., (Copyright © 2020 Elsevier B.V. All rights reserved.)

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., (Copyright © 2020 Elsevier B.V. All rights reserved.)

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., (Copyright © 2020 Elsevier B.V. All rights reserved.)

In the overall scenario of precision medicine, we propose a novel paper-based lab-on-a-chip to deliver a cost-effective and easy to use sensing tool for customized administration of drugs in Alzheimer's disease. Among several drugs, we designed the device for evaluating the efficacy of compounds (e.g. physostigmine, rivastigmine, donepezil) which are able to inhibit in a reversible way the cholinesterase enzyme. Because cholinesterase activity is peculiar to each patient, the administration of customized amount of the drug can improve the treatment efficacy and the quality of patient life, avoiding side effects due to the overdosage. In detail, we exploited Vivid™ Plasma Separation membrane to threat the whole blood sample, filter paper to load the reagents needed for the measurement, and office paper to print electrodes able to measure the butyrylcholinesterase activity, delivering a reagent free analytical tool. The calibration curve of butyrylcholinesterase obtained in blood sample provided linearity between 2 and 12 U/mL, with sensitivity of 0.050 ± 0.004 μA mL/U. The physostigmine, rivastigmine, and donepezil inhibition activities toward the butyrylcholinesterase enzyme were also measured in blood sample with linearity up to respectively 0.5 μM, 25 μM, 30 μM, and detection limits of 0.009 μM, 0.4 μM, 0.3 μM. These results demonstrate the capability of paper-based origami sensors as point of care devices to customize the drug administration in Alzheimer's disease., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Bisphenol A is one the most relevant endocrine disruptors for its toxicity and ubiquity in the environment, being largely employed as raw material for manufacturing processes of a wide number of compounds. Furthermore, bisphenol A is released in the drinking water when plastic-based bottles are incorrectly transported under sunlight, delivering contaminated drinking water. For the health of human beings and the environment, rapid and on site detection of bisphenol A in drinking water is an important issue. Herein, we report a novel and cost-effective printed electrochemical sensor for an enzymatic-free bisphenol A detection. This sensor encompasses the entire electrochemical cell printed on filter paper and the reagents for the measurement loaded in the cellulose fiber network, for delivering a reagent-free analytical tool. The working electrode was printed using ink modified with carbon black, a cost effective nanomaterial for sensitive and sustainable bisphenol A determination. Several parameters including pH, frequency, and amplitude were optimized allowing for a detection limit of 0.03 μM with two linear ranges 0.1-0.9 μM and 1 μM-50 μM, using square wave voltammetry as electrochemical technique. The satisfactory recovery values found in river and drinking water samples demonstrated the suitability of this sensor for screening analyses in water samples. These results revealed the attractiveness of this paper-based device thanks to the synergic combination of paper and carbon black as cost-effective materials., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020. Published by Elsevier B.V.)

A novel amperometric algae-based biosensor was developed for the detection of photosynthetic herbicides in river water. The green photosynthetic algae Chlamydomonas reinhardtii was immobilized on carbon black modified screen-printed electrodes, exploiting carbon black as smart nanomaterial to monitor changes in algae oxygen evolution during the photosynthetic process. The decrease of oxygen evolution, occurring in the presence of herbicides, results in a decrease of current signals by means of amperometric measurements, in an analyte concentration dependent manner. Atrazine as case study herbicide was detected in a concentration range of 0.1 and 50 μM, with a linear range from 0.1 to 5 μM and a detection limit of 1 nM. No interference was observed in presence of 100 ppb arsenic, 20 ppb copper, 5 ppb cadmium, 10 ppb lead, 10 ppb bisphenol A, and 1 ppb paraoxon, tested as safety limits. A ~25% matrix effect and satisfactory recovery values of 107 ± 10% and 96 ± 8% were obtained in river water for 3 and 5 μM of atrazine, respectively. Stability studies were also performed obtaining a high working stability up to 10 h and repeatability with an RSD of 1.1% (n = 12), as well as a good storage stability up to 3 weeks., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Herein we report a multiplated and biopolymeric-based optical bioassay for organophosphate detection based on the use of acetylcholinesterase (AChE) as biocomponent and biopolymeric electrospun fibrous mats as eco-designed supports for AChE immobilisation. The principle of the detection relays on the decrease of enzymatic activity due to the capability of the organophosphorus pesticides to irreversibly inhibit AChE, which is optically detected using Ellman colorimetric method. The proposed bioassay consists in a novel, cost-effective, and multiplex-based 96-well system, in combination with customised biopolymeric membranes modified with AChE, with the aim to deliver a sustainable analytical tool. Indeed, the designed set-up should provide and guarantee several advantages, including: i) the re-use of plastic multi-plate with the only replacement of polymer dishes in the case of inhibition absence; ii) the exploiting of the properties of the immobilised enzyme, i.e. multiple analysis using the same amount of enzyme, reducing the AChE amount for analysis. In detail, three different biopolymers (i.e. polylactic acid (PLA), polycaprolactone (PCL), and poly-hydroxybutyrate-co-hydroxyvalerate (PHBV)) were investigated and morphologically characterised, as supports for enzyme immobilisation, to identify the optimal one. Among them, PHBV was selected as the best support to immobilise AChE by cross-linking method. The analytical features of the bioassay were then assessed by measuring standard solutions of paraoxon in a range of concentrations between 10 and 100 ppb, achieving a linear range up to 60 ppb and a detection limit of 10 ppb. Thus, the suitability of this sustainable bioassay to detect organophosphate at ppb level was demonstrated., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

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)., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

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., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

The current international pharmaceutical scenario encompasses several steps in drug production, with complex and extremely long procedures. In the last few decades, scientific research has been trying to offer valid and reliable solutions to replace or support conventional techniques, in order to facilitate drug development procedures. These innovative approaches may have extremely positive effects in the production chain, supplying fast, and cost-effective quality as well as safety tests on active pharmaceutical ingredients (APIs) and their excipients. In this context, the exploitation of electrochemical paper-based analytical devices (ePADs) is still in its infancy, but is particularly promising in the detection of APIs and excipients in tablets, capsules, suppositories, and injections, as well as for pharmacokinetic bioanalysis in real samples., (Copyright © 2020 Antonacci, Scognamiglio, Mazzaracchio, Caratelli, Fiore, Moscone and Arduini.)

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.

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 <1 h.

In this study we reported the development of a paper-based algal biosensor for the optical detection of nanoencapsulated-atrazine, a forefront nanoformulated herbicide with a high effective post-emergence herbicidal activity. In particular, the unicellular green photosynthetic algae Chlamydomonas reinhardtii was immobilised on a paper substrate soaked with an agar thin film and placed in a glass optical measurement cell, obtaining a totally environmental-friendly device. Nanoencapsulated-atrazine was detected by following the variable fluorescence (1-V J ) parameter, which decreased inversely proportional to the herbicide concentrations, in a range between 0.5 and 200 nM, indicating a linear relationship in the measured dose-response curves and a detection limit of 4 pM. Interference studies resulted in a very slight interference in presence of 2 ppm copper and 10 ppb arsenic at safety limits, as well as a slight matrix effect and a satisfactory recovery value of 96 ± 5% for 75 nM nanoencapsulated-atrazine in tap water. Stability studies were also performed obtaining a good storage stability up to 3 weeks. Results demonstrated the suitability of the proposed paper-based optical biosensor as a valid support in smart agriculture for on site, environmental friendly, cost effective and sensitive nanoencapsulated-atrazine analysis., (Copyright © 2019 Elsevier B.V. All rights reserved.)

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., (Copyright © 2019 Elsevier B.V. All rights reserved.)

The synthesis and employment of volatile toxic compounds as chemical weapons with a large-scale destructive power has introduced a new insidious threat over the last century. In this framework, the development of wearable sensing tools represents a critical point within the security field, in order to provide early alarm systems. Herein, a novel wearable electrochemical biosensor was developed for the rapid and on-site detection of mustard agents. Since a chemical attack is typically carried out by spraying these volatile agents into air, the sensor was designed in order to be able to measure mustard agents directly in the aerosol phase, further than in the liquid phase. The electrodes were screen-printed onto a filter paper support, which allowed to harness the porosity of paper to pre-load all the needed reagents into the cellulose network, and hence to realise an origami-like and reagent-free device. Mustard agent detection was carried out by monitoring their inhibitory effects toward the choline oxidase enzyme, through the amperometric measurement of the enzymatic by-product hydrogen peroxide. A carbon black/Prussian blue nanocomposite was used as a bulk-modifier of the conductive graphite ink constituting the working electrode, allowing for the electrocatalysis of the hydrogen peroxide reduction. After having verified the detecting capability toward a mustard agent simulant, the applicability of the resulting origami-like biosensor was demonstrated for the rapid and real-time detection of real sulfur mustard, obtaining limits of detection equal to 1 mM and 0.019 g·min/m 3 for liquid and aerosol phase, respectively., (Copyright © 2019 Elsevier B.V. All rights reserved.)

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., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Herein, we report an impedimetric DNA-based aptamer sensor for a single-step detection of B. anthracis spore simulant (B. cereus spore). Specifically, we designed a miniaturized label-free aptasensor for B. cereus spores based on a gold screen-printed electrode functionalized with B. cereus spores-binding aptamer (BAS-6R). Several parameters were optimized to fabricate the aptasensor such as the concentration of DNA aptamer solution (0.5 µM), the time (48 h), the temperature (4 °C), and the pH (7.5) for aptamer immobilization on the working electrode surface. Once the aptasensor was developed, it was tested against B. cereus spores 14579 evaluating the effect of incubation time and MgCl 2 concentration. Under the optimized conditions (incubation time equal to 3 h and absence of MgCl 2 ), B. cereus spores 14579 were detected with a linear range between 10 4 CFU/ml and 5 × 10 6 CFU/ml and a detection limit of 3 × 10 3 CFU/ml. Furthermore, the study of selectivity toward B. cereus 11778, B. subtilis, Legionella pneumophila, and Salmonella Typhimurium has demonstrated the capability of this sensor to detect B. cereus spores, proving the suitability of the DNA-based sensing element combined with a portable instrument for a label-free measurement on site of B. anthracis spore simulant., (Copyright © 2018 Elsevier B.V. All rights reserved.)

The article presents an original analysis which combines use-wear, 3D modelling and spatial analyses to experimental archaeology in order to investigate Early Upper Palaeolithic flint-knapping gestures and techniques involving the use of macro-lithic tools. In particular, the methodological framework proposed in this paper was applied to the study of Protoaurignacian and Aurignacian macro-tools from Fumane Cave (Verona, Italy). Combining spatial analysis and use wear investigation, both at low and high magnifications, permitted the identification and detailed description of the use-related traces affecting both the hammerstones and retouchers which, at Fumane Cave, were used at different stages during flint tool production. Several experimental activities were performed including core reduction, maintenance, and blank production together with different types of edge retouching. From a methodological perspective, the protocol of analysis permitted to codify specific traces and to produce quantitative data related to their geometry and distribution over the tool's surface, according to the activities and gestures performed. The results obtained allowed a careful investigation of the function and the gestures associated to the use of the macro-lithic tools coming from the Protoaurignacian and Aurignacian levels of Fumane Cave while providing a methodological tool for interpreting different archaeological samples., Competing Interests: The authors have declared that no competing interests exist.

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.