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A metal-free thiol-modified graphene derivative introduces a reusable approach to alleviate mutual interference in electrochemical heavy metal detection.

A method based on a CO2 laser plotter to produce 2D/2D heterostructure films (LIHTs) composed of rGO and group VI TMDs is proposed. The freestanding transferable LIHTs were employed to construct lab-made nitrocellulose self-contained sensors.

Altres ajuts: ICN2 is funded by CERCA programme, Generalitat de Catalunya. A.R.-M. acknowledges Universitat Autonoma de Barcelona (UAB) for the possibility of performing this work inside the framework of Biotechnology PhD Programme. Introduction: Since the COVID-19 pandemic, some of the routine methods for clinical diagnosis of infectious diseases have become closer to the general population and terms like "PCR" (polymerase chain reaction) and "antigen rapid diagnostic test" (RDT) are not restricted only to the scientific community but now also commonly appear in everyday language. Given the emergency, the pandemic also raised awareness about supply politics and regulation of the market for diagnostic tests [e.g., Emergency Use Authorization (EUA) from the Food and Drug Administration (FDA); or the "Conformité Européenne" marking (CE marking) from the European Union, EU]. PCR and RDT are two major techniques currently used in clinical practice for diagnosis of diseases. On the one hand, PCR is a highly sensitive method, but it relies on expensive equipment and qualified personnel. On the other hand, rapid diagnostic tests, despite being less sensitive, are faster, cheaper, portable, and battery/instrument-free. In this review, we will discuss the advantages and disadvantages of rapid antigen tests and different nucleic acid amplification techniques (NAATs), such as PCR, both as in vitro diagnostic devices. To do so, our review explains the working principle of each method, classifies the different subtypes, and analyzes the impact that the introduction of isothermal amplification methods will have in the diagnostic field. In addition, this review gives an overview of the current available products in the market and the new trends generated as a result of combining the strengths of NAAT and RDT.

Biomarkers are nucleic acids, peptides, proteins, lipids metabolites, or other small molecules in human tissues or biological fluids whose accurate detection contributes to the prediction and determination of diseases and their status. In recent years, platforms that allow the detection of important biomarkers at the point-of-care (PoC) are moving the field of diagnostics towards personalized medicine. In order to comply with the REASSURED criteria stated by the WHO, the most efficient solution is to integrate PoC devices with smartphones. Without a doubt the smartphone camera is a “smart detector,” and almost all the optical-based methods have been integrated, including absorbance, fluorescence, microscopic bio-imaging, surface plasmon resonance, chemiluminescence, bioluminescence, and photoluminescence. In this chapter, we explain how smartphones can be used as smart detectors in diagnostic devices and we will provide an overview of recent developments of smartphone-based optical PoC devices., A.M. acknowledge FEDER/Ministerio de Ciencia, Innovación y Universidades - Agencia Estatal de Investigación/_Project MAT2017-87202-P. A.M. also acknowledge ICN2 which is funded by the CERCA programme/Generalitat de Catalunya and supported by the Severo Ochoa Centres of Excellence programme that is funded by the Spanish Research Agency (AEI, grant no. SEV-2017-0706). A.M, L.H., A.I., C.P., R.A. and E.C. acknowledge Autonomous University of Barcelona (UAB) for their support. E.C. acknowledges Ministerio de Ciencia e Innovación of Spain and Fondo Social Europeo for the Fellowship PRE2018–084856 under the framework of “Plan Estatal de Investigación Científica y Técnica y de Innovación 2017–2020. L. H. acknowledges China Scholarship Council which is a non-profit institute affiliated with the Ministry of Education of the P. R. China. A.I. was supported by PROBIST postdoctoral fellowship funded by European Research Council (Marie Skłodowska-Curie grant agreement No. 754510).

Access to clean water for drinking, sanitation, and irrigation is a major sustainable development goal of the United Nations. Thus, technologies for cleaning water and quality-monitoring must become widely accessible and of low-cost, while being effective, selective, sustainable, and eco-friendly. To meet this challenge, hetero-bifunctional nanographene fluorescent beacons with high-affinity pockets for heavy metals are developed, offering top-rated and selective adsorption for cadmium and lead, reaching 870 and 450 mg g, respectively. The heterobifunctional and multidentate pockets also operate as selective gates for fluorescence signal regulation with sub-nanomolar sensitivity (0.1 and 0.2 nm for Pb and Cd, respectively), due to binding affinities as low as those of antigen-antibody interactions. Importantly, the acid-proof nanographenes can be fully regenerated and reused. Their broad visible-light absorption offers an additional mode for water-quality monitoring based on ultra-low cost and user-friendly reagentless paper detection with the naked-eye at a limit of detection of 1 and 10 ppb for Pb and Cd ions, respectively. This work shows that photoactive nanomaterials, densely-functionalized with strong, yet selective ligands for targeted contaminants, can successfully combine features such as excellent adsorption, reusability, and sensing capabilities, in a way to extend the material's applicability, its life-cycle, and value-for-money., The work was supported by the ERDF/ESF project “Nano4Future” (No. CZ.02.1.01/0.0/0.0/16_019/0000754). R.Z. and A.B. acknowledge the funding from the Czech Science Foundation, GA CR–EXPRO, 19-27454X. D.P., L.Z., V.Š., M.L., and V.H. thank the Internal Student Grant Agency of the Palacký University in Olomouc, Czech Republic (IGA_PrF_2022_019). M.O. acknowledges the ERC grant 2D-CHEM, No 683024 from H2020. Operation of XPS and TEM facilities was partly funded by the Research Infrastructure NanoEnviCz, supported by the Ministry of Education, Youth and Sports of the Czech Republic under Project No. LM2018124. N.C. gratefully acknowledges the IKY foundation for the financial support. N.C. and A.B.B. also thank the European Social Fund-ESF (co-financed by Greece and the European Union) through the Operational Programme “Human Resources Development, Education and Lifelong Learning” in the context of the project “Strengthening Human Resources Research Potential via Doctorate Research” (MIS-5000432), implemented by the State Scholarships Foundation (IKY). Computational resources were supplied by the project “e-Infrastruktura CZ” (e-INFRA CZ LM2018140) supported by the Ministry of Education, Youth, and Sports of the Czech Republic. This work was supported by the Ministry of Education, Youth, and Sports of the Czech Republic through the e-INFRA CZ (ID:90140). ICN2 is funded by CERCA programme, Generalit de Catalunya. Grant SEV-2017-0706 by MCIN/AEI/10.13039/501100011033. The authors also acknowledge the project MAT2017-87202-P funded by MCIN/AEI/10.13039/501100011033 and FEDER Una manera de hacer Europa. R.A.-D. acknowledges funding from the European Union Horizon 2020 Programme under Grant No. 881603 (Graphene Flagship Core 3).

This manuscript aims at raising the attention of the scientific community to the need for better characterised bioreceptors for fast development of point-of-care diagnostic devices able to support mass frequency testing. Particularly, we present the difficulties encountered in finding suitable antibodies for the development of a lateral flow assay for detecting the nucleoprotein of SARS-CoV-2., We acknowledge Consejo Superior de Investigaciones Científicas (CSIC) for the project “COVID19-122” granted in the call “Nuevas ayudas extraordinarias a proyectos de investigación en el marco de las medidas urgentes extraordinarias para hacer frente al impacto económico y social del COVID-19 (Ayudas CSIC-COVID-19)”. We acknowledge also the MICROB-PREDICT project that has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No. 825694. Financial support from the EU Graphene Flagship Core 3 Project (No. 881603) is also acknowledged. This article reflects only the authors' view, and the European Commission is not responsible for any use that may be made of the information it contains. ICN2 is funded by the CERCA programme/Generalitat de Catalunya. ICN2 is supported by the Severo Ochoa Centres of Excellence programme, funded by the Spanish Research Agency (AEI, grant no. SEV-2017-0706). E. C. acknowledges Ministerio de Ciencia e Innovación of Spain and Fondo Social Europeo for the Fellowship PRE2018-084856 awarded under the call ‘Ayudas para contratos predoctorales para la formación de doctores, Subprograma Estatal de Formación del Programa Estatal de Promoción del Talento y su Empleabilidad en I+D+i’, under the framework of ‘Plan Estatal de Investigación Científica y Técnica y de Innovación 2017–2020’. L. H. acknowledges the China Scholarship Council. L. H., E. C. and C. F.-C. acknowledge the Autonomous University of Barcelona (UAB) for their support. C. P. (ISGlobal) also acknowledges support from the Spanish Ministry of Science and Innovation and State Research Agency through the “Centro de Excelencia Severo Ochoa 2019–2023” Program (CEX2018-000806-S), and support from the Generalitat de Catalunya through the CERCA Program. A. I. was supported by a PROBIST postdoctoral fellowship funded by the European Research Council (Marie Skłodowska-Curie grant agreement No. 754510).

Adenosine-5'-triphosphate (ATP) is the primary energy carrier in all living organisms, and its detection in living cells represents a well-established approach. ATP-driven bioluminescence (BL) relying on the D-luciferin-luciferase reaction is a bioanalytical tool widely employed for monitoring hygiene and microbial contamination of foods.Here, we report a straightforward method for ATP BL detection using an ATP sensing paper fabricated with an alternative freeze-dry procedure. The assay can be easily implemented in laboratories equipped with (i) freeze-drying, wax printing, and 3D printing technologies and (ii) instrumentation for BL detection such as benchtop luminometers and portable light detectors including a smartphone camera without the need for additional equipment.

Signal amplification strategies are widely used for improving the sensitivity of lateral flow immunoassays (LFiAs). Herein, the artificial miniaturized peroxidase Fe(III)-MimochromeVI*a (FeMC6*a), immobilized on gold nanoparticles (AuNPs), is used as a strategy to obtain catalytic signal amplification in sandwich immunoassays on lateral flow strips. The assay scheme uses AuNPs decorated with the mini-peroxidase FeMC6*a and anti-human-IgG as a detection antibody (dAb), for the detection of human-IgG, as a model analyte. Recognition of the analyte by the capture and detection antibodies is first evidenced by the appearance of a red color in the test line (TL), due to the accumulation of AuNPs. Subsequent addition of 3,3',5,5'-tetramethylbenzidine (TMB) induces an increase of the test line color, due to the TMB being converted into an insoluble colored product, catalyzed by FeMC6*a. This work shows that FeMC6*a acts as an efficient catalyst in paper, increasing the sensitivity of an LFiA up to four times with respect to a conventional LFiA. Furthermore, FeMC6*a achieves lower limits of detection that are found in control experiments where it is replaced with horseradish peroxidase (HRP), its natural counterpart. This study represents a significant proof-of-concept for the development of more sensitive LFiAs, for different analytes, based on properly designed artificial metalloenzymes.

The majority of lateral flow assays (LFAs) use single-color optical labels to provide a qualitative naked-eye detection, however this detection method displays two important limitations. First, the use of a single-color label makes the LFA prone to results misinterpretation. Second, it does not allow the precise modulation of the sensitivity and dynamic range of the test. To overcome these limitations, a ratiometric approach is developed. In particular, using anti-HIgG functionalized red-fluorescent quantum dots on the conjugate pad (as target dependent labels) and blue-fluorescent nanoparticles fixed on the test line (as target independent reporters), it is possible to generate a wide color palette (blue, purple, pink, red) on the test line. It is believed that this strategy will facilitate the development of LFAs by easily adjusting their analytical properties to the needs required by the specific application., The authors acknowledge financial support from NACANCELL project PCIN-2016-066 (program Euronanomed 2). This work was also funded by the CERCA Program/Generalitat de Catalunya. The ICN2 was funded by the CERCA program/Generalitat de Catalunya. ICN2 acknowledges the support of the Spanish MINECO for the Project MAT2017-87202-P and through the Severo Ochoa Centres of Excellence Program under Grant SEV2201320295. A.I. was supported by PROBIST postdoctoral fellowship funded by European Research Council (Marie Sklodowska Curie) grant agreement No. 754510). C.P. acknowledges support from the Spanish Ministry of Science and Innovation and State Research Agency through the “Centro de Excelencia Severo Ochoa 2019-2023” Program (CEX2018-000806-S), and support from the Generalitat de Catalunya through the CERCA Program.

Because of numerous inherent and unrivaled features of nanofibers made of chitin, the second most plentiful natural-based polymer (after cellulose), including affordability, abundant nature, biodegradability, biocompatibility, commercial availability, flexibility, transparency, and extraordinary mechanical and physicochemical properties, chitin nanofibers (ChNFs) are being applied as one of the most appealing bionanomaterials in a myriad of fields. Herein, we exploited the beneficial properties offered by the ChNF paper to fabricate transparent, efficient, biocompatible, flexible, and miniaturized optical sensing bioplatforms via embedding/immobilizing various plasmonic nanoparticles (silver and gold nanoparticles), photoluminescent nanoparticles (CdTe quantum dots, carbon dots, and NaYF4:Yb3+@Er3+&SiO2 upconversion nanoparticles) along with colorimetric reagents (curcumin, dithizone, etc.) in the 3D nanonetwork scaffold of the ChNF paper. Several configurations, including 2D multi-wall and 2D cuvette patterns with hydrophobic barriers/walls and hydrophilic test zones/channels, were easily printed using laser printing technology or punched as spot patterns on the dried ChNF paper-based nanocomposites to fabricate the (bio)sensing platforms. A variety of (bio)chemicals as model analytes were used to confirm the efficiency and applicability of the fabricated ChNF paper-based sensing bioplatforms. The developed (bio)sensors were also coupled with smartphone technology to take the advantages of smartphone-based monitoring/sensing devices along with the Internet of Nano Things (IoNT)/the Internet of Medical Things (IoMT) concepts for easy-to-use sensing applications. Building upon the unrivaled and inherent features of ChNF as a very promising bionanomaterial, we foresee that the ChNF paper-based sensing bioplatforms will emerge new opportunities for the development of innovative strategies to fabricate cost-effective, simple, smart, transparent, biodegradable, miniaturized, flexible, portable, and easy-to-use (bio)sensing/monitoring devices., Financial support from the Chemistry & Chemical Engineering Research Centre of Iran (Tehran, Iran), Iran’s National Elites Foundation (INEF), Nano Novin Polymer Co. (Iran), and the Nano Match program of Iran Nanotechnology Initiative Council (INIC) are gratefully acknowledged. The ICN2 is funded by the CERCA Programme/Generalitat de Catalunya. The ICN2 is supported by the Severo Ochoa program of the Spanish Ministry of Economy, Industry and Competitiveness (MINECO; grant nos. SEV-2017-0706 and MAT2017-87202-P). The financial support of “the Czech Science Foundation (No. 19-00676S)” is also greatly appreciated.

Significant levels of infectious diseases caused by pathogenic bacteria are nowadays a worldwide matter, carrying considerable public health care challenges and huge economic concerns. Because of the rapid transmission of these biothreat agents and the outbreak of diseases, a rapid detection of pathogens in early stages is crucial, particularly in low-resources settings. To this aim, we developed for the first time a new sensing approach carried out in a single step for Escherichia coli O157:H7 detection. The detection principle is based on Förster resonance energy transfer using gold nanoclusters as a signal reporter and gold nanoparticles conjugated with antibodies as a quencher. The sensing platform includes an ultraviolet-light-emitting diode to provide the proper excitation and consists of a microtube containing two pieces of fiber glass; one of them is embedded with label-free gold nanoclusters and the other one with gold nanoparticles conjugated with antibodies. Upon the addition of the sample containing bacteria, the florescence of gold nanoclusters is recovered. The assay was evaluated by the naked eye (on/off) and quantitatively with use of a smartphone camera. The biosensor proved to be highly specific and sensitive, achieving a limit of detection as low as 4.0 cfu mL–1. Additionally, recoveries of 110% and 95% were obtained when the platforms in spiked river and tap water, respectively, were evaluated., The ICN2 is funded by the CERCA Programme/Generalitat de Catalunya. The ICN2 is supported by the Severo Ochoa program of the Spanish Ministry of Economy, Industry and Competitiveness (MINECO, gGrant No. SEV-2017-0706). Financial support was obtained under the MINECO Project MAT2017-87202-P. N.A. acknowledges the Food and Drug Laboratory Research Center, Food and Drug Organization of Iran, and Ministry of Science, Research and Technology of Iran for scholarships during this research time. A.S.T. acknowledges Universitat Autònoma de Barcelona for the possibility of carrying out this work inside the framework of its PhD Programme in Biotechnology.

The quantitative detection of different molecular targets is of utmost importance for a variety of human activities, ranging from healthcare to environmental studies. Bioanalytical methods have been developed to solve this and to achieve the quantification of multiple targets from small volume samples. Generally, they can be divided into two different classes: point of care (PoC) and laboratory-based approaches. The former is rapid, low-cost, and user-friendly; however, the majority of the tests are semiquantitative, lacking in specificity and sensitivity. On the contrary, laboratory-based approaches provide high sensitivity and specificity, but the bulkiness of experimental instruments and complicated protocols hamper their use in resource-limited settings. In response, here we propose a smartphone-based device able to support laboratory-based optical techniques directly at the point of care. Specifically, we designed and fabricated a portable microplate reader that supports colorimetric, fluorescence, luminescence, and turbidity analyses. To demonstrate the potential of the device, we characterized its analytical performance by detecting a variety of relevant molecular targets (ranging from antibodies, toxins, drugs, and classic fluorophore dyes) and we showed how the estimated results are comparable to those obtained from a commercial microplate reader. Thanks to its low cost (, ICN2 is funded by CERCA programme, Generalitat de Catalunya. Grant SEV-2017-0706 funded by MCIN/AEI/10.13039/501100011033. The authors acknowledge Consejo Superior de Investigaciones Científicas (CSIC) for the project “COVID19-122” granted in the call “Nuevas ayudas extraordinarias a proyectos de investigación en el marco de las medidas urgentes extraordinarias para hacer frente al impacto económico y social del COVID-19 (Ayudas CSIC-COVID-19)” and the research project INTCATCH 2020, Development and application of novel, integrated tools for monitoring and managing catchments supported by the European Union’s Horizon 2020 research and innovation program (Grant 689341). The authors also acknowledge the project MAT2017-87202-P funded by MCIN/AEI/10.13039/501100011033/and FEDER Una manera de hacer Europa. R.A.-D. acknowledges funding from the European Union Horizon2020 Programme under Grant No. 881603 (Graphene Flagship Core 3). A.I. was supported by PROBIST postdoctoral fellowship funded by the European Research Council (Marie Skłodowska-Curie grant agreement no. 754510).

Lateral flow assays (LFAs) are currently the most used point-of-care sensors for both diagnostic (e.g., pregnancy test, COVID-19 monitoring) and environmental (e.g., pesticides and bacterial monitoring) applications. Although the core of LFA technology was developed several decades ago, in recent years the integration of novel nanomaterials as signal transducers or receptor immobilization platforms has brought improved analytical capabilities. In this Review, we present how nanomaterial-based LFAs can address the inherent challenges of point-of-care (PoC) diagnostics such as sensitivity enhancement, lowering of detection limits, multiplexing, and quantification of analytes in complex samples. Specifically, we highlight the strategies that can synergistically solve the limitations of current LFAs and that have proven commercial feasibility. Finally, we discuss the barriers toward commercialization and the next generation of LFAs., We acknowledge financial support to the project AC21_2/00044 (GLEBIOASSAY), funded by Instituto de Salud Carlos III (ISCIII) and cofunded by the European Union, MICROBPREDICT project (European Union Horizon 2020 research and innovation program under grant agreement 825694), and Graphene Flagship Core 3 (European Union Horizon 2020 research and innovation program under grant agreement 881603). ICN2 is funded by CERCA programme, Generalitat de Catalunya. Grant SEV-2017-0706 is funded by MCIN/AEI/10.13039/501100011033. The authors also acknowledge the Project PID2021-124795NB-I00 funded by MCIN/AEI/10.13039/501100011033/and FEDER Una manera de hacer Europa and the project PAPYRUS: Grant PLEC2021-007972 funded by MCIN/AEI/10.13039/501100011033 and by the “European Union NextGenerationEU/PRTR”. The authors acknowledge Consejo Superior de Investigaciones Científicas (CSIC) for the project “COVID19-122” granted in the call “Nuevas ayudas extraordinarias a proyectos de investigación en el marco de las medidas urgentes extraordinarias para hacerfrente al impacto económico y social del COVID-19” (Ayudas CSIC-COVID-19). A.S.-T. acknowledges MINECO for the Juan de la Cierva Formación fellowship (FJC2020-043927-I). C.P. acknowledges the Marie Skłodowska-Curie Actions Individual Fellowship; this project received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement 795635. C.P. (ISGlobal) also acknowledges support from the Spanish Ministry of Science and Innovation** and State Research Agency through the “Centro de Excelencia Severo Ochoa 2019−2023” Program (CEX2018-000806-S).

With the increased demand for beef in emerging markets, the development of quality-control diagnostics that are fast, cheap and easy to handle is essential. Especially where beef must be free from pork residues, due to religious, cultural or allergic reasons, the availability of such diagnostic tools is crucial. In this work, we report a label-free impedimetric genosensor for the sensitive detection of pork residues in meat, by leveraging the biosensing capabilities of graphene acid - a densely and selectively functionalized graphene derivative. A single stranded DNA probe, specific for the pork mitochondrial genome, was immobilized onto carbon screen-printed electrodes modified with graphene acid. It was demonstrated that graphene acid improved the charge transport properties of the electrode, following a simple and rapid electrode modification and detection protocol. Using non-faradaic electrochemical impedance spectroscopy, which does not require any electrochemical indicators or redox pairs, the detection of pork residues in beef was achieved in less than 45 min (including sample preparation), with a limit of detection of 9% w/w pork content in beef samples. Importantly, the sample did not need to be purified or amplified, and the biosensor retained its performance properties unchanged for at least 4 weeks. This set of features places the present pork DNA sensor among the most attractive for further development and commercialization. Furthermore, it paves the way for the development of sensitive and selective point-of-need sensing devices for label-free, fast, simple and reliable monitoring of meat purity., We acknowledge funding from the European Union Horizon2020 Programme under Grant No. 881603 (Graphene Flagship Core 3). This article reflects only the author's view, and the European Commission is not responsible for any use that may be made of the information it contains. ICN2 is funded by the CERCA programme, Generalitat de Catalunya. The ICN2 is supported by the Severo Ochoa Centres of Excellence programme, funded by the Spanish Research Agency (AEI, grant no. SEV-2017-0706). J. M. R. Flauzino is grateful for the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior scholarship (CAPES-PRINT, Brazil, Grant number: 88887.371591/2019–00). D. Panáček acknowledges the Internal Student Grant Agency of the Palacký University in Olomouc, (IGA_PrF_2021_031). A. G. Brito-Madurro acknowledges the funding from Conselho Nacional de Desenvolvimento Científico e Tecnológico - CNPq (310782/2018–0). J. M. Madurro acknowledges the funding from Fundação de Amparo à Pesquisa do Estado de Minas Gerais – FAPEMIG (CEX-APQ-02902-17) and Conselho Nacional de Desenvolvimento Científico e Tecnológico – CNPq (311737/2018–8). A. Bakandritsos acknowledges the funding from the Czech Science Foundation, (project GA CR – EXPRO, 19–27454X). M. Otyepka acknowledges the ERC grand 2D-CHEM (No 683024 from H202). The work was supported also by the ERDF/ESF project “Nano4Future” (No.CZ.02.1.01/0.0/0.0/16_019/0000754).

Simplicity is one of the key feature for the spread of any successful technological product. Here, a method for rapid and low-cost fabrication of electrochemical biosensors is presented. This “plug, print & play” method involves inkjet-printing even in an office-like environment, without the need of highly specialized expertise or equipment, guaranteeing an ultra-fast idea to (scaled) prototype production time. The printed biosensors can be connected to a smartphone through its audio input for their impedance readout, demonstrating the validity of the system for point-of-care biosensing. Proper electrodes layout guarantees high sensitivity and is validated by finite element simulations. The introduction of a passivation method (wax printing) allowed to complete the devices fabrication process, increasing their sensitivity. Indeed, the wax allowed reducing the interference related to the parasitic currents flowing through the permeable coating of the employed substrates, which was used for the chemical sintering, thus avoiding the common thermal treatment after printing. As a case study, we used the devices to develop an electrochemical aptamer-based sensor for the rapid detection of neutrophil gelatinase-associated lipocalin (NGAL) in urine – a clinically important marker of acute kidney injury. The aptasensor platform is capable of detecting clinically relevant concentrations of NGAL with a simple and rapid smartphone readout. The developed technology may be extended in the future to continuous monitoring, taking advantage of its flexibility to integrate it in tubes, or to other diagnostic applications where cost/efficiency and rapidity of the research, development and implementation of point of care devices is a must., The MICROB-PREDICT project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 825694. This reflects only the author's view, and the European Commission is not responsible for any use that may be made of the information it contains. We thank Dr Alex Chamorro and Prof. Kevin Plaxco for the NGAL aptamers sequence used for the case study of our biosensors. E. P. N. acknowledges funding through the EU's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 754510. C.C.C.S. acknowledges funding through CAPES – PRINT (Programa Institucional de Internacionalização; grant #88887.310281/2018-00 and 88887.467442/2019-00) and Mackpesquisa-UPM. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 101008701 (Project acronym: EMERGE)

After the 1st Edition, this 2d one on COVID-19 biosensing technologies offers to the Biosensors and Bioelectronics readers the recent efforts of the biosensors community about the development of advanced biosensors for COVID-19 related biomarkers and their applications in real clinical scenarios and other settings. This issue includes 19 contributions from authors from various laboratories around the world. The developed biosensors are interested in detecting the virus or related biomarkers in different physiological fluids and other samples, including virus presence in the air. The reported devices are based on various detection technologies ranging from optical to electrical ones and involve different platforms, nano/micromaterials and are offered (mostly) as fully integrated biosensing systems.

Detecting the ultra-low abundance of analytes in real-life samples, such as biological fluids, water, soil, and food, requires the design and development of high-performance biosensing modalities. The breakthrough efforts from the scientific community have led to the realization of sensing technologies that measure the analyte's ultra-trace level, with relevant sensitivity, selectivity, response time, and sampling efficiency, referred to as Attomolar Analyte Sensing Techniques (AttoSens) in this review. In an AttoSens platform, 1 aM detection corresponds to the quantification of 60 target analyte molecules in 100 μL of sample volume. Herein, we review the approaches listed for various sensor probe design, and their sensing strategies that paved the way for the detection of attomolar (aM: 10-18 M) concentration of analytes. A summary of the technological advances made by the diverse AttoSens trends from the past decade is presented. This journal is, SPU is grateful to the Science and Engineering Research Board – Department of Science and Technology (SERB – DST), India (Grant no. PDF/2018/000079) for the National Postdoctoral Fellowship. VVRS and RD gratefully acknowledge the financial support by the Department of Science and Technology (DST), India. VVRS acknowledges the funding from Indo-German Science and Technology Centre (IGSTC), New Delhi under the DEMO-Multi-WAP project (IGSTC/Call 2015-Extension/Multi-WAP/09/2019-20). ICN2 is funded by the CERCA programme, Generalitat de Catalunya. The ICN2 is supported by the Severo Ochoa Centres of Excellence programme, funded by the Spanish Research Agency (AEI, grant no. SEV-2017-0706). The authors are grateful to Ms Volga Muthukumar, Mr Divagar Murugan, Ms Kuzhandai Shamlee James and Mr Rohan. S for their help in the manuscript preparation.

Electrochromism (EC) is a unique property of certain materials that undergo an electrochemical-induced change in colouration. During the last decades, electrochromic materials (ECMs) have been applied in a variety of technologies ranging from smart windows to information displays and energy storage devices. More recently, ECMs have attracted the attention of the (bio)sensing community thanks to their ability to combine the sensitivity of electrochemical methods with the intuitive readout of optical sensors. Although still a nascent technology, EC-based sensors are on the rise with several targets (e.g. cancer biomarkers, bacteria, metabolites and pesticides), which have already been detected by (bio)sensors using ECMs as transducers. In this review, we provide the reader with all the information to understand EC and its use in the development of EC-based biosensors., We acknowledge the MICROB-PREDICT project that has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 825694. Financial support from the EU Graphene Flagship Core 2 Project (No. 785219) is also acknowledged. This article reflects only the author’s view, and the European Commission is not responsible for any use that may be made of the information it contains. ICN2 is funded by the CERCA programme, Generalitat de Catalunya. The ICN2 is supported by the Severo Ochoa Centres of Excellence programme, funded by the Spanish Research Agency (AEI, grant no. SEV-2017-0706). E.P.N. acknowledges funding through the EU’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 754510.

The interaction of drugs with DNA has been searched thoroughly giving rise to an endless number of findings of undoubted importance, such as a prompt alert to harmful substances, ability to explain most of the biological mechanisms, or provision of important clues in targeted development of novel chemotherapeutics. The existence of some drugs that induce oxidative damage is an increasing point of concern as they can cause cellular death, aging, and are closely related to the development of many diseases. Because of a direct correlation between the response, strength/ nature of the interaction and the pharmaceutical action of DNA‐targeted drugs, the electrochemical analysis is based on the signals of DNA before and after the interaction with the DNA‐targeted drug. Nowadays, nanoscale materials are used extensively for offering fascinating characteristics that can be used in designing new strategies for drug‐DNA interaction detection. This work presents a review of nanomaterials (NMs) for the study of drug‐nucleic acid interaction. We summarize types of drug‐DNA interactions, electroanalytical techniques for evidencing these interactions and quantification of drug and/or DNA monitoring., The ICN2 is funded by the CERCA programme/Generalitat de Catalunya. ICN2 acknowledges the support of the Spanish MINECO for the Project MAT2017‐87202‐P and through the Severo Ochoa Centers of Excellence Program under Grant SEV2201320295. KDCM thank the CONACyT for the support through the scholarship #817447.

Solid-phase isothermal recombinase polymerase amplification (RPA) offers many benefits over the standard RPA in homogeneous phase in terms of sensitivity, portability, and versatility. However, RPA devices reported to date are limited by the need for heating sources to reach sensitive detection. With the aim of overcoming such limitation, we propose here a label-free highly integrated in situ RPA amplification/detection approach at room temperature that takes advantage of the high sensitivity offered by gold nanoparticle (AuNP)-modified sensing substrates and electrochemical impedance spectroscopic (EIS) detection. Plant disease (Citrus tristeza virus (CTV)) diagnostics was selected as a relevant target for demonstration of the proof-of-concept. RPA assay for amplification of the P20 gene (387-bp) characteristic of CTV was first designed/optimized and tested by standard gel electrophoresis analysis. The optimized RPA conditions were then transferred to the AuNP-modified electrode surface, previously modified with a thiolated forward primer. The in situ-amplified CTV target was investigated by EIS in a Fe(CN6)4–/Fe(CN6)3– red–ox system, being able to quantitatively detect 1000 fg μL–1 of nucleic acid. High selectivity against nonspecific gene sequences characteristic of potential interfering species such as Citrus psorosis virus (CPsV) and Citrus caxicia viroid (CCaV) was demonstrated. Good reproducibility (RSD of 8%) and long-term stability (up to 3 weeks) of the system were also obtained. Overall, with regard to sensitivity, cost, and portability, our approach exhibits better performance than RPA in homogeneous phase, also without the need of heating sources required in other solid-phase approaches., The ICN2 is funded by the CERCA programme/Generalitat de Catalunya. ICN2 acknowledges the support of the Spanish MINECO for the Project MAT2017-87202-P and the Severo Ochoa Centers of Excellence Program under Grant SEV2201320295. M.K. thanks Autonomous University of Barcelona for the opportunity of performing this work inside the framework of Biotechnology PhD Programme.

In this study, a novel photoluminescence material for the detection of tributyltin (TBT) was developed by using a paper-based nanocomposite system. For this purpose, molecularly imprinted polymeric nanoparticles (MIN) were synthesized with mini-emulsion polymerization technique. Graphene quantum dots obtained by the hydrothermal pyrolysis were immobilized to the nanoparticle surface via EDC-NHS coupling. The fabrication of sensing platform for TBT can be divided into two steps that are the preparation of nanocomposite and the applying the nanocomposite onto nitrocellulose membrane. The selectivity constant and association kinetics were calculated to analyze the interaction of TBT with immobilized MINs. The results proved that the developed nanosensor is promising for the determination of TBT with high selectivity and sensitivity reaching a detection limit of 0.23 ppt in seawater. This novel photoluminescent nanosensor has the potential to pave the way for further studies and applications., Recep Üzek thanks to TUBITAK for the given scholarship. We acknowledge the support from European Commission through the Graphene Flagship Core 2 project and from Ministerio de Economıa, Industria y Competitividad (MINECO), Agencia Estatal de Investigacion (AEI) for the project MAT2017-87202-P. The ICN2 is funded by the CERCA Programme/Generalitat de Catalunya. ICN2 is supported by the Severo Ochoa program from Spanish MINECO (Grant No. SEV2017-0706).

Proteins and antibodies are key biomarkers for diagnosing and monitoring specific medical conditions. Currently, gold standard techniques used for their quantification require laborious multi-step procedures, involving high costs and slow response times. It is possible to overcome these limitations by exploiting the chemistry and programmability of DNA to design a reagentless electrochemical sensing platform. Specifically, three DNA single strands are engineered that can self-assemble into a Y-shaped DNA nanostructure that resembles one of the IgGs. In order to convert this DNA nanostructure into a responsive DNA-scaffold bioreceptor, it is modified including two recognition elements, two redox tag molecules, and a thiol group. In the absence of the target, the scaffold receptor can efficiently collide with the electrode surface and generate a strong electrochemical signal. The presence of the target induces its bivalent binding, which produces steric hindrance interactions that limit the receptor's collisional activity. In its bound state, the redox tags can therefore approach the surface at a slower rate, leading to a signal decrease that is quantitatively related to the target concentration. The Y-shape DNA scaffold sensor can detect nanomolar concentrations of antibodies and proteins in, ICN2 was funded by the CERCA programme, Generalitat de Catalunya. ICN2 was supported by the Severo Ochoa Centres of Excellence programme and funded by the Spanish Research Agency (AEI, grant no. SEV-2017-0706). The authors acknowledge Consejo Superior de Investigaciones Científicas (CSIC) for the project “COVID19-122” granted in the call “Nuevas ayudas extraordinarias a proyectos de investigación en el marco de las medidas urgentes extraordinarias para hacer frente al impacto económico y social del COVID-19 (Ayudas CSIC-COVID-19)”. A.I. was supported by PROBIST postdoctoral fellowship funded by the European Research Council (Marie Skłodowska-Curie grant agreement no. 754510). C.P. acknowledges the Marie Skłodowska-Curie Actions Individual Fellowship; this project received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 795635. C.P. (ISGlobal) also acknowledges support from the Spanish Ministry of Science and Innovation** and State Research Agency through the “Centro de Excelencia Severo Ochoa 2019–2023” Program (CEX2018-000806-S), and support from the Generalitat de Catalunya through the CERCA Program. R.A.D. received financial support from the EU Graphene Flagship Core 3 Project (No. 881603)., With funding from the Spanish government through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2018-000806-S)

Water is the most important ingredient of life. Water fecal pollution threatens water quality worldwide and has direct detrimental effects on human health and the global economy. Nowadays, assessment of water fecal pollution relies on time-consuming techniques that often require well-trained personnel and highly-equipped laboratories. Therefore, faster, cheaper, and easily-used systems are needed toin situmonitor water fecal pollution. Herein, we have developed colorimetric lateral flow strips (LFS) able to detect and quantifyEscherichia colispecies in tap, river, and sewage water samples as an indicator of fecal pollution. The combination of LFS with a simple water filtration unit and a commercially available colorimetric reader enhanced the assay sensitivity and enabled more accurate quantification of bacteria concentration down to 10CFU mLin 10 minutes, yielding recovery percentages between 80% and 90% for all water samples analyzed. Overall, this system allows for monitoring and assessing water quality based onE. colispecies as a standard microbiological indicator of fecal pollution. Furthermore, we have developed a novel bioluminescent, bacteria-based method to quickly characterize the performance of a great variety of LFS materials. This new method allows evaluating the flow rate of big analytes such as bacteria through the LFS materials, as a suggestive means for selecting the appropriate materials for fabricating LFS targeting big analytes (≈2 μm). As a whole, the proposed approach can accelerate and reduce the costs of water quality monitoring and pave the way for further improvement of fecal pollution detection systems., This work was supported by the European Commission Program, H2020-WATER, INTCATCH Project (689341). We acknowledge all the INTCATCH partners for their support during the monitoring campaign in river Ter and the collection of the sewage water samples. ICN2 is supported by the Severo Ochoa Centres of Excellence programme, funded by the Spanish Research Agency (AEI, grant no. SEV-2017-0706). A. H. A. Hassan acknowledges the short-term fellowship (Grant 25347) funded by the Science and Technology Development Fund (STDF), Egypt.

Smart monitoring has been studied and developed in recent years to create faster, cheaper, and more user-friendly on-site methods. The present study describes an innovative technology for investigative monitoring of heavy metal pollution (Cu and Pb) in surface water. It is composed of an autonomous surface vehicle capable of semiautonomous driving and equipped with a microfluidic device for detection of heavy metals. Detection is based on the method of square wave anodic stripping voltammetry using carbon-based screen-printed electrodes (SPEs). The focus of this work was to validate the ability of the integrated system to perform on-site detection of heavy metal pollution plumes in river catchments. This scenario was simulated in laboratory experiments. The main performance characteristics of the system, which was evaluated based on ISO 15839 were measurement bias (Pb 75%, Cu 65%), reproducibility (in terms of relative standard deviation: Pb 11–18%, Cu 6–10%) and the limit of detection (4 µg/L for Pb and 7 µg/L for Cu). The lowest detectable change (LDC), which is an important performance characteristic for this application, was estimated to be 4–5 µg/L for Pb and 6–7 µg/L for Cu. The life span of an SPE averaged 39 measurements per day, which is considered sufficient for intended monitoring campaigns. This work demonstrated the suitability of the integrated system for on-site detection of Pb and Cu emissions from large and medium urban areas discharging into small water bodies., Open access funding provided by University of Natural Resources and Life Sciences Vienna (BOKU). The research leading to the presented results received funding from the research project INTCATCH 2020, “Development and application of Novel, Integrated Tools for monitoring and managing Catchments” supported by the European Union’s Horizon 2020 research and innovation programme, under the grant agreement No. 689341. The ICN2 is funded by the CERCA Programme/Generalitat de Catalunya. The ICN2 is supported by the Severo Ochoa program of the Spanish Ministry of Economy, Industry, and Competitiveness (MINECO, Grant No. SEV-2017–0706).

Inkjet printing of electrochemical sensors using a highly loaded mildly edge‐oxidized graphene nanosheet (EOGN) ink is presented. An ink with 30 mg/mL EOGNs is formulated in a mixture of N‐methyl pyrrolidone and propylene glycol with only 30 min of sonication. The absence of additives, such as polymeric stabilizers or surfactants, circumvents reduced electrochemical activity of coated particles and avoids harsh post‐printing conditions for additive removal. A single light pulse from a xenon flash lamp dries the printed EGON film within a fraction of a second and creates a compact electrode surface. An accurate coverage with only 30.4 μg of EOGNs per printed layer and cm2 is achieved. The EOGN films adhere well to flexible polyimide substrates in aqueous solution. Electrochemical measurements were performed using cyclic voltammetry and differential pulse voltammetry. An all inkjet‐printed three‐electrode living bacterial cell detector is prepared with EOGN working and counter electrodes and silver‐based quasi‐reference electrode. The presence of E. coli in liquid samples is recorded with four electroactive metabolic activity indicators.

Point-of-care (PoC) tests are practical and effective diagnostic solutions for major clinical problems, ranging from the monitoring of a pandemic to recurrent or simple measurements. Although, in recent years, a great improvement in the analytical performance of such sensors has been observed, there is still a major issue that has not been properly solved: The ability to perform adequate sample treatments. The main reason is that normally sample treatments require complicated or long procedures not adequate for deployment at the PoC. In response, a sensing platform, called paperbased electrophoretic bioassay (PEB), that combines the key characteristics of a lateral flow assay (LFA) with the sample treatment capabilities of electrophoresis is developed. In particular, the ability of PEB to separate different types of particles and to detect human antibodies in untreated spiked whole blood is demonstrated. Finally, to make the platform suitable for PoC, PEB is coupled with a smartphone that controls the electrophoresis and reads the optical signal generated. It is believed that the PEB platform represents a much-needed solution for the detection of low target concentrations in complex media, solving one of the major limitations of LFA and opening opportunities for point-of-care sensors., We acknowledge financial support from the NACANCEL project PCIN-2016-066 (program Euronanomed 2). This work is also funded by the CERCA Program/Generalitat de Catalunya. The ICN2 is funded by the CERCA program/Generalitat de Catalunya. ICN2 acknowledges the support of the Spanish MINECO for the Project MAT2017-87202-P and through the Severo Ochoa Centers of Excellence Program under Grant SEV2201320295. R.A.-D. acknowledges the financial support from the EU Graphene Flagship Core 3 Project (No. 881603). A.S.-T. acknowledges the Autonomous University of Barcelona (UAB) for the possibility of performing this work inside the framework of Biotechnology Ph.D. Program. C.P. acknowledges Marie Skłodowska-Curie Actions Individual Fellowship, and this project has received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement No. 795635. We also acknowledge Prof. Artur Xavier Roig from the Veterinary faculty in UAB for providing whole blood.

COVID-19 has become a worldwide pandemic. Despite dramatic advances in diagnostic technologies, all countries continue to face an unmet need in achieving decentralised biosensor technologies that will, in a rapid, sensitive, selective, and reliable way, tackle the global and urgent problem. In this context, the great potential of using biosensors together with Internet of Things (IoT) opens up tremendous opportunities for the biosensing community to develop novel strategies not only for diagnosis but also for aiding in the prevention and treatment of COVID-19.

The COVID-19 pandemic made clear how our society requires quickly available tools to address emerging healthcare issues. Diagnostic assays and devices are used every day to screen for COVID-19 positive patients, with the aim to decide the appropriate treatment and containment measures. In this context, we would have expected to see the use of the most recent diagnostic technologies worldwide, including the advanced ones such as nano-biosensors capable to provide faster, more sensitive, cheaper, and high-throughput results than the standard polymerase chain reaction and lateral flow assays. Here we discuss why that has not been the case and why all the exciting diagnostic strategies published on a daily basis in peer-reviewed journals are not yet successful in reaching the market and being implemented in the clinical practice., We acknowledge funding from the European Union Horizon2020 Programme under Grant No. 881603 (Graphene Flagship Core 3). We acknowledge Consejo Superior de Investigaciones Científicas (CSIC) for the project “COVID19-122” granted in the call “Nuevas ayudas extraordinarias a proyectos de investigación en el marco de las medidas urgentes extraordinarias para hacer frente al impacto económico y social del COVID-19 (Ayudas CSIC–COVID-19)”. We acknowledge the MICROB-PREDICT Project for partially supporting the work. The MICROB-PREDICT project has received funding from the European Union’s Horizon 2020 research and innovation programme under Grant No. 825694. This reflects only the author’s view, and the European Commission is not responsible for any use that may be made of the information it contains. We also acknowledge Agencia Estatal de Investigación (AEI) and Fondo Europeo de Desarrollo Regional (FEDER) for the project MAT2017-87202-P. A.I. was supported by a PROBIST postdoctoral fellowship funded by European Research Council (Marie Skłodowska-Curie Grant No. 754510). C.C.C.S. acknowledges funding through CAPES–PRINT (Programa Institucional de Internacionalização; Grant Nos. 88887.310281/2018-00 and 88887.467442/2019-00) and Mackpesquisa-UPM. L.H. acknowledges funding through the China Scholarship Council. ICN2 is funded by the CERCA Programme/Generalitat de Catalunya and supported by the Severo Ochoa programme (MINECO Grant No. SEV-2017-0706).

Recently, many bioluminescence-based applications have arisen in several fields, such as biosensing, bioimaging, molecular biology, and human health diagnosis. Among all bioluminescent organisms, Aliivibrio fischeri (A. fischeri) is a bioluminescent bacterium used to carry out water toxicity assays since the late 1970s. Since then, several commercial A. fischeri-based products have been launched to the market, as these bacteria are considered as a gold standard for water toxicity assessment worldwide. However, the aforementioned commercial products rely on expensive equipment, requiring several reagents and working steps, as well as high-trained personnel to perform the assays and analyze the output data. For these reasons, in this work, we have developed for the first time a mobile-phone-based sensing platform for water toxicity assessment in just 5 min using two widespread pesticides as model analytes. To accomplish this, we have established new methodologies to enhance the bioluminescent signal of A. fischeri based on the bacterial culture in a solid media and/or using graphene oxide. Finally, we have addressed the biocompatibility of graphene oxide to A. fischeri, boosting the sensitivity of the toxicity assays and the bacterial growth of the lyophilized bacterial cultures for more user-friendly storage., This work was supported by the European Commission Program, H2020-WATER, INTCATCH Project (No. 689341). ICN2 acknowledges support from the Severo Ochoa Program (MINECO, Grant SEV-2013-0295). The Nanobiosensors and Bioelectronics Group acknowledges the support from the Generalitat de Cataluña (Grant 2014 SGR 260). R.A. acknowledge the financial support from the EU Graphene Flagship Core 3 Project (No. 881603).

The main properties of graphene derivatives facilitating optical and electrical biosensing platforms are discussed, along with how the integration of graphene derivatives, plastic, and paper can lead to innovative devices in order to simplify biosensing technology and manufacture easy-to-use, yet powerful electrical or optical biosensors. Some crucial issues to be overcome in order to bring graphene-based biosensors to the market are also underscored., The authors acknowledge the support from H2020-EU (INTCATCH Project, Ref. 689341), MINECO (Spain, MAT2014-52485-P, RTC-2014-2619-7 and Severo Ochoa Program, Grant SEV-2013-0295) and Secretaria d'Universitats i Recerca del Departament d'Economia i Coneixement de la Generalitat de Catalunya (2014 SGR 260).

A low-cost strategy for the simple and rapid detection of bacterial cells in biological matrixes is presented herein. Escherichia coli and Salmonella typhimurium were chosen as model bacteria for the development of an electrochemical assay based on hollow AuAg nanoshells (NSs). By taking advantage of their electrocatalytic properties for the in situ generation of the electrochemical signal without the need of any other kind of reagent, substrate, or redox enzyme, high sensitivities (down to 102 CFU/mL) were achieved. Moreover, the recognition and discrimination of the model bacterial cells in the sample matrix was possible by relying solely on nonspecific affinity interactions between their cell walls and AuAg NSs surface, avoiding the use of expensive and fragile biological receptor. Compared to traditional, laboratory-based analytical tests available, this assay provides a promising proof-of-concept alternative that allows to obtain good sensitivities and selectivity in very short times in addition to the low cost., This work was carried out within the “Doctorat en Quìmica” PhD programme of Universitat Autònoma de Barcelona, supported by the Spanish MINECO (MAT2015-70725-R) and from the Catalan Agència de Gestió d’Ajuts Universitaris i de Recerca (AGAUR) (2017-SGR-143). Financial support from the HISENTS (685817) Project financed by the European Community under H20202 Capacities Programme is gratefully acknowledged. It was also funded by the CERCA Program/Generalitat de Catalunya. ICN2 acknowledges the support of the Spanish MINECO through the Severo Ochoa Centers of Excellence Program under Grant SEV2201320295.

Determination of the levels of heavy metal ions would support assessment of sources and pathways of water pollution. However, traditional spatial assessment by manual sampling and off-site detection in the laboratory is expensive and time-consuming and requires trained personnel. Aiming to fill the gap between on-site automatic approaches and laboratory techniques, we developed an autonomous sensing boat for on-site heavy metal detection using square-wave anodic stripping voltammetry. A fluidic sensing system was developed to integrate into the boat as the critical sensing component and could detect ≤1 μg/L Pb, ≤6 μg/L Cu, and ≤71 μg/L Cd simultaneously in the laboratory. Once its integration was completed, the autonomous sensing boat was tested in the field, demonstrating its ability to distinguish the highest concentration of Pb in an effluent of a galena-enriched mine compared to those at other sites in the stream (Osor Stream, Girona, Spain)., An autonomous sensing boat for heavy metal spatial assessment can distinguish the highest concentration of Pb in an effluent of a galena-enriched mine compared with those of other sites in the stream.