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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)

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.

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 molecularly imprinted fluorescent sensors have gained more attention due to their impressive detection performance for the early diagnosis and treatment of diseases in body fluids, foods, and environmental samples. In clinic laboratories and point of care analysis systems, these sensors have the potential to perform the routine analyses due to their features such as low-cost, sensitive, easy to operate, etc. that increase the researches in this field. There are four types of fluorophores (organic fluorescent dye, QDs, GQDs, and rare earth materials), which are mainly used for preparing molecularly imprinted fluorescent sensors. In this chapter, we will give more details about the application of molecularly imprinted fluorescent sensors based on these fluorophores.

ATP-driven bioluminescence relying on the D-luciferin-luciferase reaction is widely employed for several biosensing applications where bacterial ATP detection allows to verify microbial contamination for hygiene monitoring in hospitals, food processing and in general for cell viability studies. Several ATP kit assays are already commercially available but an user-friendly ATP biosensor characterized by low-cost, portability, and adequate sensitivity would be highly valuable for rapid and facile on site screening. Thanks to an innovative freeze-drying procedure, we developed a user-friendly, ready-to-use and stable ATP sensing paper biosensor that can be combined with smartphone detection. The ATP sensing paper includes a lyophilized “nano-lantern” with reaction components being rapidly reconstituted by 10 μL sample addition, enabling detection of 10−14 mol of ATP within 10 min. We analysed urinary microbial ATP as a biomarker of urinary tract infection (UTI), confirming the capability of the ATP sensing paper to detect the threshold for positivity corresponding to 105 colony-forming units of bacteria per mL of urin, This research was sponsored in part by PRIN 2015 “Multifunctional nanotools for advanced cancer diagnostics” (Prot. 2015TWP83Z) and the NATO Science for Peace and Security Programme under Grant No. 985042. The ICN2 is funded by the CERCA Programme/Generalitat de Catalunya and also supported by the Severo Ochoa program of the Spanish Ministry of Economy, Industry and Competitiveness (MINECO, grants No. SEV-2017-0706 and MAT2017-87202-P).

Lateral flow assays (LFAs) are paper-based analytical devices that allow for the performance of in situ diagnostic tests with good sensitivity, specificity, repeatability and low limit of detection. The application of different kinds of nanoparticles with different properties have made LFAs compatible with different detection methods (e.g. colorimetry, photoluminescence, magnetism, heating, electroactivity), thus showing their versatility. Even though LFA technology is well-established, research on the topic is more alive than ever due to the advances in the study of nanomaterials, the implementation of smartphone technology for signal readout and the creativity in finding new strategies for signal enhancement. In this chapter, the applications of LFAs using different kind of nanoparticles as labels are compiled, demonstrating their use in a range of fields such as clinical diagnostics, environmental monitoring, food safety and veterinary. Given the relevance of nanoparticles in the performance of LFAs, a section of the chapter is dedicated to biofunctionalisation strategies.

Lateral flow biosensors are paper-based devices that allow the detection of different types of analytes with quickness, robustness and selectivity, without leaving behind paper sensors benefits as low-cost, recyclability and sustainability. Nanomaterials have been widely reported in lateral flow biosensors, offering new sensing strategies based on optical or electrical detection techniques. Looking for other advantageous nanomaterials, we propose for the first time the use of iridium oxide (IV) nanoparticles in lateral flow assays for the detection of human immunoglobulin as a model protein. These nanoparticles can be easily prepared and conjugated with biomarkers. Their dark blue color gives a high contrast against the white background of the strips being in this way excellent labels., We acknowledge support from MINECO (Spain) MAT2017-87202-P and project PCIN-2016-066 (program Euronanomed 2). This work is also funded by the CERCA Programme / Generalitat de Catalunya. ICN2 is supported by the Severo Ochoa program from Spanish MINECO (Grant No. SEV-2017-0706). Daniel Quesada-González and Amadeo Sena-Torralba acknowledge Autonomous University of Barcelona (UAB) for the possibility of performing this work inside the framework of Chemistry and Biotechnology Ph.D. Programmes, respectively.

Lateral flow paper-based biosensors merge as powerful tools in point-of-care diagnostics since they are cheap, portable, robust, selective, fast and easy to use. However, the sensitivity of this type of biosensors is not always as high as required, often not permitting a clear quantification. To improve the colorimetric response of standard lateral flow strips (LFs), we have applied a new enhancement strategy that increases the sensitivity of LFs based on the use of cellulose nanofibers (CNF). CNF penetrate inside the pores of LFs nitrocellulose paper, compacting the pore size only in the test line, particularly near the surface of the strip. This modification retains the bioreceptors (antibodies) close to the surface of the strips, and thus further increasing the density of selectively attached gold nanoparticles (AuNPs) in the top part of the membrane, in the test line area, only when the sample is positive. This effect boosts in average a 36.6% the sensitivity of the LFs. The optical measurements of the LFs were carried out with a mobile phone camera whose imaging resolution was improved by attaching microscopic lens on the camera objective. The characterization of CNF into paper and their effect was analyzed using atomic force microscope (AFM) and scanning electron microscope (SEM) imaging techniques., 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). Financial support was obtained under MAT2017-87202-P, funded by Agencia Estatal de Investigación and Fondo Europeo de Desarrollo Regional, and MINECO project FIS2015-73932-JIN. This work was partially funded by 2017-SGR-579 project from the Generalitat de Catalunya. D.Q.G. acknowledges Universitat Autònoma de Barcelona for the possibility of carrying out this work inside the framework of its PhD Programme in Chemistry. Ch.S. thanks the BIST for a preBIST Grant (No. 754558).

The development of nanomaterials for use as bio-recognition elements is important in the evolution of biosensing systems. In the present article we present a sensing system based on copper oxide nanoparticles (CuO NPs) for the detection of phenolic compounds and pesticides. This sensor takes advantage of the interactions of CuO NPs with toxic compounds that in turn generate an electrochemical signal related to the concentration of the pollutants., ICN2 acknowledges support from the Severo Ochoa Program (MINECO, Grant SEV-2013-0295) and MICINN for the Project MAT2011–25870 and Generalitat de Cataluña for SGR support.

Enzymatic biosensors based in electrochemical responses are one of the most developed and studied devices for quantitative analysis. The combination of both electroanalytical methods and enzyme characteristics makes biosensors a very powerful technology for fast, selective, and low-cost analysis with applications in environmental, food, and clinical studies. In the present article, a brief description of these devices including their classification and the different construction strategies is given. Enzymatic activity and the various variables that might affect it are discussed along with strategies such as the use of nanomaterials to solve some drawbacks that such kind of biosensors uses to present.

In this work, a novel biosensor based on electrochemically reduced graphene oxide and iridium oxide nanoparticles for the detection of angiotensin-converting enzyme inhibitor drug, captopril, is presented. For the preparation of the biosensor, tyrosinase is immobilized onto screen printed electrode by using 1-Ethyl-3-(3-dimethylaminopropyl)-carbodiimide and N-Hydroxysuccinimide coupling reagents, in electrochemically reduced graphene oxide and iridium oxide nanoparticles matrix. Biosensor response is characterized towards catechol, in terms of graphene oxide concentration, number of cycles to reduce graphene oxide, volume of iridium oxide nanoparticles and tyrosinase solution. The designed biosensor is used to inhibit tyrosinase activity by Captopril, which is generally used to treat congestive heart failure. It is an angiotensin-converting enzyme inhibitor that operates via chelating copper at the active site of tyrosinase and thioquinone formation. The captopril detections using both inhibition ways are very sensitive with low limits of detection: 0.019 µM and 0.008 µM for chelating copper at the active site of tyrosinase and thioquinone formation, respectively. The proposed methods have been successfully applied in captopril determination in spiked human serum and pharmaceutical dosage forms with acceptable recovery values., S. Kurbanoglu acknowledges the support given by Ankara University BAP14L0237002 for her PhD thesis project. Nanobiosensors and Bioelectronics Group acknowledges the support from MINECO (project MAT2014-52485-P 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).

Graphene-based materials (GBM) are an exceptional type of materials that offer unprecedented application capabilities to the scientific and technologic community. The encapsulation of different materials such as drugs, nanoparticles, polymers, oxides and cells by GBM is leading to outstanding hybrid materials with unprecedented behaviours promising a myriad of advantageous applications, including micro/nanomotors, biosensing platforms, bio/imaging agents, drug delivery systems, potential tumour treatment alternatives, environmental remediation platforms, advanced batteries and novel supercapacitors. We present an overview on graphene-encapsulated materials and their most important synthesis pathways. In addition, we explore the synergistic functionalities provided by these composites and highlight the state-of-the-art related to energy, environmental and bio-applications, among others. Finally, we discuss their challenges and future outlooks., This work was supported by: The European Commission Program, FP7-OCEAN, SMS Project (613844) and MINECO (Spain, MAT2014-52485-P, BIO2013-49464-EXP, RTC-2014-2619-7). ICN2 acknowledges support from the Severo Ochoa Program (MINECO, Grant SEV-2013-0295). Nanobiosensors and Bioelectronics Group acknowledges the support from Secretaria d’Universitats i Recerca del Departament d’Economia i Coneixement de la Generalitat de Catalunya (2014 SGR 260). The author SASM thanks FAPESP (Proc. No. 2013/17053-0) and CNPq (Proc. No. 302762/2013-2) for the financial support. The author LFS thanks FAPESP (Proc. No. 2012/08750-6 and 2013/20701-3).

Both carbon nanotubes (CNTs) and graphene are important pillars in the ongoing efforts to devise new applications in nanotechnology. One of their most promising applications is building devices such as sensors and biosensors, which is important step for the development of personalized medical healthcare devices. Mediators are usually used and sought to modify the physicochemical properties of these materials. In this review, we highlight the importance of the functionalization of CNT and graphene derivatives with redox molecules taking ferrocene derivatives as a model molecule. The employed techniques during (bio)sensing measurements using various functionalization strategies are also described. In addition, we discuss various aspects related to the applications of ferrocene–modified CNTs and graphene in electrochemical sensors and biosensors with a focus on the explanation of both CNTs/graphene and ferrocene contributions in the catalytic systems, which in turn enhance the analytical performance of the (bio)sensing devices., ICN2 acknowledges support from the Severo Ochoa Program (MINECO, Grant SEV–2013–0295) and MICINN for the Project MAT2011–25870 and Generalitat de Cataluña for SGR support. The Ministry of Higher Education and Scientific Research of Tunisia (MHESR), UTM University, LCAE laboratory (LR99ES15) and TWAS (grant #: RG–13–413 RG/PHA/AF/AC_C) are also acknowledged for research funds and mobility grants for AR.

A novel ferrocene-functionalized reduced graphene oxide (rGO)-based electrode is proposed. It was fabricated by the drop casting of ferrocene-functionalized graphene onto polyester substrate as the working electrode integrated within screen-printed reference and counter electrodes. The ferrocene-functionalized rGO has been fully characterized using FTIR, XPS, contact angle measurements, SEM and TEM microscopy, and cyclic voltammetry. The XPS and EDX analysis showed the presence of Fe element related to the introduced ferrocene groups, which is confirmed by a clear CV signal at ca. 0.25 V vs. Ag/AgCl (0.1 KCl). Mediated redox catalysis of HO and bio-functionalization with glucose oxidase for glucose detection were achieved by the bioelectrode providing a proof for potential biosensing applications., ICN2 acknowledges support from the Severo Ochoa Program (MINECO, Grant SEV-2013-0295) and MICINN for the Project MAT2011–25870 and Generalitat de Cataluña for SGR support. The Ministry of Higher Education and Scientific Research of Tunisia (MHESR), the UTM University and the LCAE Laboratory are also acknowledged for research and travel funds granted for AR (LR99ES15).

This chapter revises the recent trends in the use and applications of nanomaterials (NMs) in analytical detections with special interest in food quality control. The most important NMs such as gold nanoparticles, quantum dots, carbon-related nanomaterials and their properties are introduced. We show how analytical science is taking advantage of such materials to either develop new analytical methods or improve the existing technologies. Biosensing, in both batch and lab-on-a-chip formats, is one of the most important analytical technologies that is in the forefront of such interesting applications. The use of these materials in some conventional analytical techniques such as chromatography between others also is discussed. Examples related to such NMs application in real food samples with interest for quality control as well as detection of various interesting compounds such as glucose, amino acids, DNA (normally present in food) or other species that are usually of interest to be detected for safety reasons (bacteria, toxins) are discussed. Aspects related to the improvements of analytical performance in terms of detection limits, stability, selectivity, etc. using various NMs and detection technologies also are discussed.

Parathyroid hormone-like hormone (PTHLH) exerts relevant roles in progression and dissemination of several tumors. However, factors influencing its production and secretion have not been fully characterized. The main limitation is the lack of specific, sensitive and widely available techniques to detect and quantify PTHLH. We have developed a lateral flow immunoassay using gold nanoparticles label for the fast and easy detection of PTHLH in lysates and culture media of three human cell lines (HaCaT, LA-N-1, SK-N-AS). Levels in culture media and lysates ranged from 11 to 20 ng/mL and 0.66 to 0.87 μg/mL respectively. Results for HaCaT are in agreement to the previously reported, whereas LA-N-1 and SK-N-AS have been evaluated for the first time. The system also exhibits good performance in human serum samples. This methodology represents a helpful tool for future in vitro and in vivo studies of mechanisms involved in PTHLH production as well as for diagnostics., [From the Clinical Editor]: Parathyroid Hormone-like Hormone (PTHLH) is known to be secreted by some tumors. However, the detection of this peptide remains difficult. The authors here described their technique of using gold nanoparticles as label for the detection of PTHLH by Lateral-flow immunoassays (LFIAs). The positive results may also point a way to using the same technique for the rapid determination of other relevant cancer proteins., Grant/Funding Support: ICN2 acknowledges support of the Spanish MINECO under Project MAT2014-52485-P and through the Severo Ochoa Centers of Excellence Program under Grant SEV-2013-0295 and from the Secretaria d’Universitats i Recerca del Departament d’Economia i Coneixement de la Generalitat de Catalunya (Grant 2014 SGR 260). The authors also wish to acknowledge funding from the Spanish Ministry of Health (FIS PI14/00040 to CdT), and Fundació Privada Cellex.

This review shows the recent trends on the use of both single and array nanochannels for electrical biosensing applications. Some general considerations on the principles of the stochastic sensing, together with an overview about the common routes for nanochannels preparation before focusing on the applications for DNA, protein, virus, toxin and other analytes detection are given. Emerging materials used to obtain nanochannels, such as graphene and its analogues as well as novel systems based on the use of nanoparticles in combination with nanochannels are discussed. Aspects related to the analytical performance of the developed devices are also discussed. Finally prospects for future improvements and applications of this technology are included., We acknowledge the support of the Spanish MINECO under Project MAT2014-52485-P and through the Severo Ochoa Centers of Excellence Program under Grant SEV-2013-0295. The support from Secretaria d'Universitats i Recerca del Departament d'Economia i Coneixement de la Generalitat de Catalunya (Grant 2014 SGR 260) and from the E.C. under FP7-OCEAN 2013.1 contract number 613844 “SMS” are also acknowledged.

A nanobiosensor based on the use of porous magnetic microspheres (PMM) as efficient capturing/pre-concentrating platform is presented for detection of Alzheimer's disease (AD) biomarkers. These PMMs prepared by a multistep swelling polymerization combined with iron oxide precipitation afford carboxyl functional groups suitable for immobilization of antibodies on the particle surface allowing an enhanced efficiency in the capturing of AD biomarkers from human serum samples. The AD biomarkers signaling is produced by gold nanoparticle (AuNP) tags monitored through their electrocatalytic effect towards hydrogen evolution reaction (HER). Novel properties of PMMs in terms of high functionality and high active area available for enhanced catalytic activity of the captured AuNPs electrocatalytic tags are exploited for the first time. A thorough characterization by scanning transmission electron microscope in high angle annular dark field mode (STEM-HAADF) demonstrates the enhanced ability of PMMs to capture a higher quantity of analyte and consequently of electrocatalytic label, when compared with commercially available microspheres. The optimized and characterized PMMs are also applied for the first time for the detection of beta amyloid and ApoE at clinical relevant levels in cerebrospinal fluid (CSF), serum and plasma samples of patients suffering from AD., We acknowledge MINECO (Madrid) for the project MAT2011-25870 and the EU′s support under FP7 contract number 246513 “NADINE”.

Carbon-nanotube (CNT)-modified glassy carbon electrodes exhibiting strong and stable electrocatalytic response toward NADH are described. A substantial (490 mV) decrease in the overvoltage of the NADH oxidation reaction (compared to ordinary carbon electrodes) is observed using single-wall and multi-wall carbon-nanotube coatings, with oxidation starting at ca. −0.05 V (vs. Ag/AgCl; pH 7.4). Furthermore, the NADH amperometric response of the coated electrodes is extremely stable, with 96% and 90% of the initial activity remaining after 60 min stirring of 2×10−4 and 5×10−3M NADH solutions, respectively (compared to 20% and 14% at the bare surface). The CNT-coated electrodes thus allow highly sensitive, low-potential, stable amperometric sensing. Such ability of carbon nanotubes to promote the NADH electron-transfer reaction suggests great promise for dehydrogenase-based amperometric biosensors. Keywords: NADH, Carbon nanotubes, Fouling, Electrocatalysis, Biosensors

The effect of graphene oxidative grades upon the conductivity and hydrophobicity and consequently the influence on an enzymatic biosensing response is presented. The electrochemical responses of reduced graphene oxide (rGO) have been compared with the responses obtained from the oxide form (oGO) and their performances have been accordingly discussed with various evidences obtained by optical techniques. We used tyrosinase enzyme as a proof of concept receptor with interest for phenolic compounds detection through its direct adsorption onto a screen-printed carbon electrode previously modified with oGO or rGO with a carbon-oxygen ratio of 1.07 or 1.53 respectively. Different levels of oGO directly affect the (bio)conjugation properties of the biosensor due to changes at enzyme/graphene oxide interface coming from the various electrostatic or hydrophobic interactions with biomolecules. The developed biosensor was capable of reaching a limit of detection of 0.01. nM catechol. This tuning capability of the biosensor response can be of interest for building several other biosensors, including immunosensors and DNA sensors for various applications. © 2014 Elsevier B.V., MEC (Spain) for MAT2011-25870 grant is acknowledged.

The aim of these authors is to offer to the reader the general basis of lateral flow technology and overall of that based on the use of gold nanoparticles, its design, and various useful analytical applications. The historical progress of this technology discussed first is followed by a detailed description of the basic principles, formats, and components including its advantages and limitation. The use of gold nanoparticles as unique labels and their application for detection of different analytes such as proteins, DNA, mycotoxins, pesticides, and heavy metal detection is thoroughly detailed. Finally, new trends on lateral flow technology involving the use of new strategies and materials for improving its sensitivity are also presented and discussed.

The rapid determination of trace phenolic compounds is of great importance for evaluating the total toxicity of contaminated water samples. Nowadays, electrochemical tyrosinase (Tyr) based biosensors constitute a promising technology for the in situ monitoring of phenolic compounds because of their advantages such as high selectivity, low production cost, promising response speed, potential for miniaturization, simple instrumentation and easy automatization. A mediator-free amperometric biosensor for phenolic compounds detection based on the combination of bismuth nanoparticles (BiNPs) and Tyr for phenol detections will be hereby reported. This is achieved through the integration of BiNPs/Tyr onto the working electrode of a screen printed electrode (SPE) by using glutaraldehyde as a cross-linking agent. BiNPs/Tyr biosensor is evaluated by amperometric measurements at –200 mV DC and a linear range of up to 71 μM and 100 μM and a correlation coefficient of 0.995 and 0.996 for phenol and catechol, respectively. The very low DC working potential ensures the avoidance of interferences making this biosensor an advantageous device for real sample applications. In addition, the response mechanism including the effect of BiNPs based on electrochemical studies and optical characterizations will be also discussed. The obtained results may open the way to many other BiNPs applications in the biosensing field., This work was supported by grants from MICINN through the Spain-Japan International Bilateral Project, PIB2010JP-00278 and MAT2011-25870. M. C. thanks the Universitat Autònoma de Barcelona for the predoctoral fellowship (PIF 2009). The financial support from the Spanish Ministry of Science and Innovation through project MAT2008-03079/NAN and predoctoral fellowship (BES-2009-023939 given to M. G.) is also acknowledged.

The use of gold nanoparticles (AuNPs) as labeling carriers in combination with the enzymatic activity of the horseradish peroxidase (HRP) in order to achieve an improved optical lateral flow immunoassay (LFIA) performance is presented here. Briefly in a LFIA with an immune-sandwich format AuNPs are functionalized with a detection antibody already modified with HRP, obtaining an 'enhanced' label. Two different detection strategies have been tested: the first one following just the red color of the AuNPs and the second one using a substrate for the HRP (3 different substrates are evaluated), which produces a darker color that enhances the intensity of the previous red color of the unmodified AuNPs. In such very simple way it is gaining sensitivity (up to 1 order of magnitude) without losing the simplicity of the LFIA format, opening the way to other LFIA applications including their on-demand performance tuning according to the analytical scenario. © 2012 Elsevier B.V., We acknowledge the MEC (Madrid) for the Project no. MAT2011-25870, the E.U.'s support under FP7 Contract no. 246513 “NADINE” and the NATO Science for Peace and Security Program's support under the Project no. SfP 983807.

The synthesis and characterization of gold nanoparticles (AuNPs 20. nm sized) modified with k-casein derived peptides in order to monitor the peptide effect as bacterial adhesion inhibitor, thanks to the carrier/concentrator effect of the AuNPs is here presented. Some aspects related to the stability of AuNP/peptide conjugates for a potential application in the design of an electrochemical biosensor for pathogen bacteria detection are also discussed. This peptide based nanoparticle assay takes advantage of the dual character of the AuNPs: as carrier of the biorecognition molecule and also as electrocatalytic label, allowing the evaluation of the pathogen bacteria-peptide interaction in a simple and rapid way through the chronoamperometric monitoring of the hydrogen evolution reaction on screen-printed carbon electrodes. The developed proof of concept theranostic system may open the way to therapeutic and biosensing applications with interest for various fields. © 2012 Elsevier B.V., We acknowledge MEC (Madrid) for the projects AGL2009-07328 and MAT2011-25870 and the NATO Science for Peace and Security Programme's support under the project SfP983807.

14 páginas, 16 figuras, 1 tabla.-- Trabajo seleccionado para: "The World Congress on Biosensors,Glasgow, Scotland, UK May 26-28, 2010"., The need for novel biosensing systems has increased enormously in the last few years. In this context nanoparticles with special optical and electrochemical properties are bringing significant advantages in fields such as clinical analysis, environmental monitoring, food and safety/security control. Biosensor technology represents an interesting alternative for the development of efficient, fast, low-cost and user-friendly biosensing devices. Between different biosensing alternatives the nanotechnology and nanomaterial oriented biosensors represent very attractive and cost-efficient tools for real sample applications. The developed devices are based on the use of various platforms which allows their future applications and extension in several fields. Optical detection alternatives based on light absorption and scattering, surface plasmon resonance enhancement, fluorescence (including its quenching strategies) between other methods will be discussed. In addition, a special emphasis on electrical methods (electromechanical, stripping analysis, potentiometric etc.) that use nanoparticles as tracers for biomolecules detection will be given. In most of the examples nanoparticle-based biosensing systems are being offered as excellent screening and advantageous alternatives to existing conventional strategies/assays and the corresponding equipments., We acknowledge funding from the MEC (Madrid) for the projects MAT2008-03079/NAN, CSD2006-00012 “NANOBIOMED” (Consolider-Ingenio 2010).

4 páginas, 3 figuras., A label-free bioelectronic detection of aptamer–thrombin interaction based on electrochemical impedance spectroscopy (EIS) technique is reported. Multiwalled carbon nanotubes (MWCNTs) were used as modifiers of screen-printed carbon electrotransducers (SPCEs), showing improved characteristics compared to the bare SPCEs. 5′amino linked aptamer sequence was immobilized onto the modified SPCEs and then the binding of thrombin to aptamer sequence was monitored by EIS transduction of the resistance to charge transfer (Rct) in the presence of 5 mM [Fe(CN)6]3−/4−, obtaining a detection limit of 105 pM. This study represents an alternative electrochemical biosensor for the detection of proteins with interest for future applications., We acknowledge funding from the MEC (Madrid) for the projects MAT2008-03079/NAN, CSD2006-00012 “NANOBIOMED” (Consolider-Ingenio 2010) and the Juan de la Cierva scholarship (A. de la Escosura-Muñiz).

4 páginas, 3 figuras., The catalytic ability of gold nanoparticles (AuNPs) toward the formation of H2 in the electrocatalyzed Hydrogen Evolution Reaction (HER) is thoroughly studied, using screen-printed carbon electrodes (SPCEs) as electrotransducers. The AuNPs on the surface of the SPCE, provide free electroactive sites to the protons present in the acidic medium that are catalytically reduced to hydrogen by applying an adequate potential, with a resulting increment in the reaction rate of the HER measured here by the generated catalytic current. This catalytic current is related with the concentration of AuNPs in the sample and allows their quantification. Finally, this electrocatalytic method is applied for the first time, in the detection of AuNPs as labels in a magnetoimmunosandwich assay using SPCEs as electrotransducers, allowing the determination of human IgG at levels of 1 ng/mL., We acknowledge funding from the MEC (Madrid) for the projects MAT2008-03079/NAN, CSD2006-00012 “NANOBIOMED” (Consolider- Ingenio 2010) and the Juan de la Cierva scholarship (A. de la Escosura- Muñiz)

7 páginas, 5 figuras, 6 tablas.-- Trabajo presentado a: "The 13th International Symposium on Olfaction and Electronic Nose — ISOEN 2009"., An automated potentiometric electronic tongue (ET) was developed for the quantitative determination of Cd2+, Cu2+ and Pb2+ heavy metal mixtures. The Sequential Injection Analysis (SIA) technique was used in order to automate the obtaining of input data. The combined response was modelled by means of Artificial Neural Networks (ANNs). The sensor array was formed by four Ion Selective Electrode (ISE) sensors: two based on chalcogenide glasses, Cd sensor and Cu sensor, and the rest on poly(vinyl chloride) membranes, Pb sensor and Zn sensor. The sensors were first characterized with respect to one and two analytes, by means of high-dimensionality calibrations, aided by the use of the SIA flow system; this characterization enabled an interference study of great practical utility. To take profit of the dynamic nature of the sensors response, each kinetic profile was compacted by Fast Fourier Transform (FFT) and the extracted coefficients used as inputs for the ANN in the multidetermination application. Finally, analyses were performed employing synthetic samples to validate obtained results., This work was supported by European Community project FP6- IST No. 034472, “WARMER: Water risk management in Europe” and by Spanish Ministry of Science and Innovation, project TEC2007- 68012-C03-02/MIC.

Publisher Summary This chapter presents a procedure for the construction of a graphite–epoxy composite electrode (GECE) and the analysis of lead and cadmium in contaminated soils and water samples. One of the key points in the preparation of the GECE is the well homogenization of all the components before curing of the composite pastes. The homogenized distribution will ensure a good reproducibility of the electrodes after each renewing surface procedure (mechanical polishing as described in the procedures). The same graphite epoxy composite pastes can be used to prepare thick-film electrodes by using screen-printed technology. By this way, a better reproducibility of the electrodes will be achieved.

Publisher Summary This chapter presents a procedure to construct a magnetic graphite epoxy composite electrode (M-GECE) and detect DNA hybridization electrochemically by labeling with gold nanoparticles and using an M-GECE. Construct the transducer body include soldering of female connector to the copper disc, introduction this connection into the cylindrical PVC sleeve, at the other end graphite–epoxy composite composite and the permanent magnet is placed. Further, neodymium magnet is incorporated and cured at 40˚C during week. Experiments for the detection of a single, three-base mismatch and non-complementary DNA were carried out in two strand assays format. The results demonstrated an efficient discrimination. The chapter presents a figure that displays these results in sandwich assay, where the difference in current intensities is observed—that is, higher for target DNA (CF-T), which represents the efficient hybridization electrochemical response on the M-GECE, and lower responses for one base mismatch.

Publisher Summary Several free-mercury sensors for stripping analysis of heavy metals have been developed. The first strategy, graphite-epoxy composite electrodes (GECE) without any modification brings several advantages such as avoidance of the use of harmful mercury or other time-consuming procedures to modify glassy carbon or other electrodes. Additionally the metal stripping can be performed without oxygen removal. Graphite-epoxy electrodes are cheaper and easy to be prepared in the laboratory. Although, a higher detection limit compared to the mercury-film electrode has been found, this kind of electrode can be envisioned as an attractive alternative for mercury-free detection of heavy metals. The second strategy, the use of bismuth solution to form bismuthfilm GECE (Bi-GECE) for the determination of cadmium, lead, and zinc is also demonstrated. This strategy combines the GECE with bismuthfilm formation in situ during the stripping analysis of metals. The coupling of GECE with bismuth film results in sensitive, well-defined, and undistorted peaks especially for cadmium and lead. The third strategy, a novel GECE that incorporates Bi(NO3)3 salt in the sensing matrix is also developed. The resultant Bi(NO 3 ) 3 – GECE is compatible with BiFEs for use in stripping analysis of heavy metals.

Publisher Summary This chapter overviews the progress that has been made toward the development of portable microfluidic device for on-site and fast detection of nitrated explosives and to describes the major developments in this field. Microfluidic device for detection of five trinitrotpulene-related explosive compounds with exchangeable carbon thick-film screen-printed amperometric detector has been described. This detection design permitted convenient and rapid replacement of the detector. The need to improve detection limits of nitroaromatic explosives on microfluidic platform led several researchers to explore other electrode materials such as gold-wire electrode in end-column walljet configuration, gold electrode fabricated on the channel outlet, thick-film carbon detector, and mercury/gold amalgam electrode. A single-channel chip-based analytical microsystem that allowed rapid flow injection measurements of the total content of organic explosive compounds, as well as detailed micellar chromatographic identification of the individual ones have also been utilized. Indirect laser-induced fluorescence was used to detect explosive compounds after their separation by micellar electrokinetic chromatography. To achieve indirect detection, a low concentration of a dye was added to the running buffer as a visualizing agent. Pushing detection limits of nitroaromatic explosives into the parts per trillion (ppt) level requires sample preconcentration. Solid-phase extraction of explosives is used from sea water which was followed by rapid on-chip separation and detection.

Publisher Summary This chapter presents a procedure to setup microchip electrophoresis/electrochemical detector system and the use of this system for separating and detecting four important organic explosives. A figure of microchip electrophoretic system with electrochemical detection is presented to assist in its construction. The use of commercial capillary electrophoresis high-voltage power supply is recommended. The home-made high-voltage power supply (output from 0 to 4000 V) can be constructed. Gel electrophoresis power supplies are not recommended. The high-voltage power supply and related open connections should be handled with extreme care to avoid electrical shock. Nitroaromatic explosives are toxic and mutagenic compounds and should be handled with extra care. Skin and eye contact and accidental ingestion or inhalation should be avoided.

Publisher Summary This chapter discusses the application of gold nanoparticles (NPs) (AuNPs) in electrochemical genosensors and immunosensors and some of the trends in their use for environmental and biomedical diagnostics among other application fields. Electrochemical methods used for AuNPs label detection are promising taking into account their high sensitivity, low detection limit, selectivity, simplicity, low cost and availability of portable instruments. The sensitivity of AuNPs detection is usually improved by the silver enhancement method. In this procedure, silver ions are reduced to silver metal by a reducing agent, at the surface of a gold NP, causing it to grow and so facilitating the detection. Many strategies based on DNA hybridization assays using AuNPs have been developed. Most of them rely on capturing the NP to the hybridised target in a three-component ‘sandwich’ format. technologies such as DNA sensors and immunosensors based on AuNPs might be exploited to fill specific niche applications in the environmental monitoring area. The analysis of trace substances in environmental science, pharmaceutical and food industries is a challenge because many of these applications demand a continuous monitoring mode. The use of immunosensors based on AuNPs in these applications should also be appropriate.

Publisher Summary Conducting composites and biocomposites are interesting alternatives for the construction of electrochemical sensors. The possibility of integrating various materials is one main advantage. Some materials that are incorporated within the composite result in enhanced sensitivity and selectivity. Composite and biocomposite electrodes offer many potential advantages compared to more traditional electrodes consisting of a surface-modified single conducting phase. Composite electrodes can often be fabricated with great flexibility in size and shape of material, permitting easy adaptation to a variety of electrode configurations. Another advantage of composite electrodes is the higher signal-to-noise (S/N) ratio (when compared with the corresponding pure conductors) that accompanies an improved (lower) detection limit. Also there is the possibility of obtaining composite electrodes from precious metals in a form with less weight and lower cost compared to their pure conductor counterparts. The development of composite-based electrodes may lead to important advances in analytical electrochemistry, particularly in sensor devices.