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Early detection and effective treatment are crucial to reduce the physical, emotional, and financial pressure exerted by growing cancer burden on individuals, families, communities, and health systems. Currently, it is clear that the accurate analysis of emerging cancer epigenetic and metastatic-related biomarkers at different molecular levels is envisaged as an exceptional solution for early and reliable diagnosis and the improvement of therapy efficiency through personalized treatments. Within this field, electrochemical biosensing has demonstrated to be competitive over other emerging and currently used methodologies for the determination of these biomarkers accomplishing the premises of user-friendly, multiplexing ability, simplicity, reduced costs and decentralized analysis, demanded by clinical oncology, thus priming electrochemical biosensors to spark a diagnostic revolution for cancer prediction and eradication. This review article critically discusses the main characteristics, opportunities and versatility exhibited by electrochemical biosensing, through highlighting representative examples published during the last two years, for the reliable determination of these emerging biomarkers, with great diagnostic, predictive and prognostic potential. Special attention is paid on electrochemical affinity biosensors developed for the single or multiplexed determination of methylation events, non-coding RNAs, ctDNA features and metastasis-related protein biomarkers both in liquid and solid biopsies of cancer patients. The main challenges to which further work must be addressed and the impact of these advances should have in the clinical acceptance of these emerging biomarkers are also discussed which decisively will contribute to understand the molecular basis involved in the epigenetics and metastasis of cancer and to apply more efficient personalized therapies. Electrochemical biosensing to move forward in cancer epigenetics and metastasis. Image 1 • Accurate analysis of cancer epigenetic and metastatic-related biomarkers. • User-friendly, multiplexing ability, simplicity, reduced costs and decentralized analysis. • Opportunities and versatility exhibited by electrochemical biosensing in this field. • Representative examples published during the last two years. • Main challenges to solve and future impact and prospects. [ABSTRACT FROM AUTHOR]

Constant progress in the identification of biomarkers at different molecular levels in samples of different natures, and the need to conduct routine analyses, even in limited-resource settings involving simple and short protocols, are examples of the growing current clinical demands not satisfied by conventional available techniques. In this context, the unique features offered by electrochemical biosensors, including affordability, real-time and reagentless monitoring, simple handling and portability, and versatility, make them especially interesting for adaptation to the increasingly challenging requirements of current clinical and point-of-care (POC) diagnostics. This has allowed the continuous development of strategies with improved performance in the clinical field that were unthinkable just a few years ago. After a brief introduction to the types and characteristics of clinically relevant biomarkers/samples, requirements for their analysis, and currently available methodologies, this review article provides a critical discussion of the most important developments and relevant applications involving electrochemical biosensors reported in the last five years in response to the demands of current diagnostic, prognostic, and therapeutic actions related to high prevalence and high mortality diseases and disorders. Special attention is paid to the rational design of surface chemistry and the use/modification of state-of-the-art nanomaterials to construct electrochemical bioscaffolds with antifouling properties that can be applied to the single or multiplex determination of biomarkers of accepted or emerging clinical relevance in particularly complex clinical samples, such as undiluted liquid biopsies, whole cells, and paraffin-embedded tissues, which have scarcely been explored using conventional techniques or electrochemical biosensing. Key points guiding future development, challenges to be addressed to further push the limits of electrochemical biosensors towards new challenging applications, and their introduction to the market are also discussed. [ABSTRACT FROM AUTHOR]

The debated question on the possible relation between the Earth’s magnetic field and climate has been usually focused on direct correlations between different time series representing both systems. However, the physical mechanism able to potentially explain this connection is still an open issue. Finding hints about how this connection could work would suppose an important advance in the search of an adequate physical mechanism. Here, we propose an innovative information-theoretic tool, i.e. the transfer entropy, as a good candidate for this scope because is able to determine, not simply the possible existence of a connection, but even the direction in which the link is produced. We have applied this new methodology to two real time series, the South Atlantic Anomaly (SAA) area extent at the Earth’s surface (representing the geomagnetic field system) and the Global Sea Level (GSL) rise (for the climate system) for the last 300 years, to measure the possible information flow and sense between them. This connection was previously suggested considering only the long-term trend while now we study this possibility also in shorter scales. The new results seem to support this hypothesis, with more information transferred from the SAA to the GSL time series, with about 90% of confidence level. This result provides new clues on the existence of a link between the geomagnetic field and the Earth’s climate in the past and on the physical mechanism involved because, thanks to the application of the transfer entropy, we have determined that the sense of the connection seems to go from the system that produces geomagnetic field to the climate system. Of course, the connection does not mean that the geomagnetic field is fully responsible for the climate changes, rather that it is an important driving component to the variations of the climate. [ABSTRACT FROM AUTHOR]

This work describes the development of a simple and ultrasensitive electroanalytical methodology for the determination of microribonucleic acids (miRNAs) making use of nanostructured disposable electrodes. The strategy involves direct hybridization of the target miRNA (miRNA–21) with a specific thiolated RNA probe self-assembled together with mercaptohexanol (MCH) onto gold nanoparticles (AuNP)-modified screen-printed electrodes (SH-RNA/MCH-AuNP-SPCEs). In addition, the resulting RNA/miRNA homoduplexes are recognized with the viral protein p19 and labeled with a HRP-conjugated anti-Maltose Binding Protein (MBP) monoclonal antibody. Amperometric detection was carried out at −0.20 V ( vs . the Ag pseudoreference electrode) using the H 2 O 2 /hydroquinone (HQ) system. The prepared biosensors showed a linear dependence between the measured cathodic current and the concentration of the target miRNA over the 0.5–50 pmol L −1 range with a calculated detection limit (LOD) of 142 fmol L −1 without any target miRNA amplification. The assay lasted 60 min once the SH-RNA/MCH-AuNP-SPCEs were prepared. The SH-RNA/MCH-AuNP-SPCEs bioplatforms exhibit at least 2 months-storage stability and possess attractive practical advantages compared with other methods involving either p19 protein or amplification techniques. The usefulness of the method was demonstrated by determining the endogenous level of the target miRNA in total RNA (RNA t ) extracted from healthy and cancerous breast cells. [ABSTRACT FROM AUTHOR]

A new method for the detection of miRNAs making use of a competitive RNA/RNA hybridization configuration is described in this work. A biotinylated miRNA (biotin-miRNA) of identical sequence to that of the target miRNA is mixed with the samples to be analyzed allowing competition to be accomplished with the target miRNA for a thiolated RNA probe assembled onto a gold nanoparticles (AuNPs) modified screen-printed electrode. After labeling the hybridized biotin-miRNA with streptavidin-HRP conjugates, amperometric detection at −0.20 V was carried out using the H 2 O 2 /hydroquinone (HQ) system. The decrease in the amperometric response was proportional to the concentration of model target miRNA-21 in the 100 fM to 25.0 pM range. The integrated sensor provided a very low detection limit (25 fM, 0.25 attomol in 10 μL sample) for miRNA-21 without any amplification step, a complete discrimination against single nucleotide mismatched sequences under practical conditions and high storage stability. The usefulness of the developed method was demonstrated by determining the endogenous levels of the mature target miRNA in total RNA (RNA t ) extracted from cancerous and non-cancerous cells. [ABSTRACT FROM AUTHOR]

Owing to the outstanding conductivity and biocompatibility as well as numerous other fascinating properties of two-dimensional (2D)-nanomaterials, 2D-based nanohybrids have shown unparalleled superiorities in the field of electrochemical biosensors. This review highlights latest advances in electrochemical immunosensors for clinical biomarkers based on different hybrid 2D-nanomaterials. Particular attention will be given to hybrid nanostructures involving graphene and other graphene-like 2D-layered nanomaterials (GLNs). Several recent strategies for using such 2D-nanomaterial heterostructures in the development of modern immunosensors, both for tagging or modifying electrode transducers, are summarized and discussed. These hybrid nanocomposites, quite superior than their rival materials, will undoubtedly have an important impact within the near future and not only in clinical areas. Current challenges and future perspectives in this rapidly growing field are also outlined. [ABSTRACT FROM AUTHOR]

A novel electrochemical approach for determination of miRNAs involving a sandwich hybridization assay onto streptavidin-magnetic beads (Strep-MBs), hybridization chain reaction (HCR) amplification and amperometric detection at disposable screen-printed carbon electrodes is reported. Using miRNA-21 as the target analyte, a dynamic linear range from 0.2 to 5.0 nM with a 60 pM (1.5 fmol in 25 μL) detection limit was obtained. The achieved sensitivity is 24-fold higher than a non-HCR amplification approach involving conventional sandwich type assay onto MBs. Moreover, the whole assay time lasted 1 h 45 min which is remarkably shorter than other reported methodologies. The methodology exhibited full selectivity against other non-complementary miRNAs as well as an acceptable discrimination between homologous miRNA family members. The applicability of this novel approach was demonstrated by determining mature miRNA-21 in total RNA (RNA t ) extracted from tumor cells and human tissues. [ABSTRACT FROM AUTHOR]

The development of electrochemical magnetobiosensors for the simultaneous determination of two biomarkers associated with salivary oral cancer, protein IL-8 and its messenger RNA (IL-8 mRNA) associated, in undiluted human saliva samples is reported in this work. The implemented methodology involves the use of functionalized magnetic beads, specific antibodies against IL-8 protein, a specific hairpin DNA sequence for IL-8 mRNA and amperometric detection at disposable dual screen printed carbon electrodes. This methodology exhibits high sensitivity and selectivity for the target analytes providing detection limits of 0.21 nM for IL-8 mRNA and 72.4 pg mL −1 (far below the clinical established cut-off of 600 pg mL −1 ) for IL-8 protein in undiluted saliva samples. The dual amperometric magnetobiosensor was applied to the direct determination of both biomarkers in spiked raw saliva samples and to determine the endogenous content of IL-8 protein in saliva samples from 7 healthy individuals. The obtained results were statistically in agreement with those provided by a commercial ELISA kit. [ABSTRACT FROM AUTHOR]

A highly sensitive disposable amperometric immunosensor based on the use of magnetic beads (MBs) is described for determination of Ara h 1, the major peanut allergen, in only 2 h. The approach uses a sandwich configuration involving selective capture and biotinylated detector antibodies and carboxylic acid-modified MBs (HOOC-MBs). The MBs bearing the immunoconjugates are captured by a magnet placed under the surface of a disposable screen-printed carbon electrode (SPCE) and the affinity reactions are monitored amperometrically at −0.20 V (vs a Ag pseudo-reference electrode) in the presence of hydroquinone (HQ) as electron transfer mediator and upon addition of H 2 O 2 as the enzyme substrate. The developed immunosensor exhibits a wide range of linearity between 20.8 and 1000.0 ng mL −1 Ara h 1, a detection limit of 6.3 ng mL −1 , a great selectivity, a good reproducibility with a RSD of 6.3% for six different immunosensors and a useful lifetime of 25 days. The usefulness of the immunosensor was demonstrated by determining Ara h 1 in different matrices (food extracts and saliva). The results correlated properly with those provided by a commercial ELISA method offering a reliable and promising analytical screening tool in the development of user-friendly devices for on-site determination of Ara h 1. [ABSTRACT FROM AUTHOR]

A novel magnetobiosensing approach for the rapid and simultaneous detection of two breast cancer-related miRs (miR-21 and miR-205) is reported. It involves the use of antimiR-21 and antimiR-205 specific probes, chitin-modified magnetic beads (Chitin-MBs), the p19 viral protein as capture bioreceptor and amperometric detection with the H 2 O 2 /hydroquinone (HQ) system at dual screen-printed carbon electrodes (SPdCEs). The use of SPdCEs allows the simultaneous independent amperometric readout for each target miR to be measured. The magnetosensor exhibited sensitive and selective detection with dynamic ranges from 2.0 to 10.0 nM and detection limits of 0.6 nM (6 fmol) for both target miRs without any amplification step in less than 2 h. The usefulness of the approach was evaluated by detecting the endogenous levels of both target miRs in total RNA (RNA t ) extracted from metastatic breast cancer cell lines and human tissues. [ABSTRACT FROM AUTHOR]

A very sensitive magnetoimmunosensor for the determination of β-lactoglobulin (β-LG) is reported in this work. A sandwich configuration involving covalent immobilization of the capture antibody (antiβ-LG) onto activated carboxylic-modified magnetic beads (HOOC-MBs) and incubation of the modified MBs with a horseradish peroxidase labeled antibody (HRP-antiβ-LG), is used. The resulting modified MBs are captured by a magnet placed under the surface of a disposable carbon screen-printed electrode (SPCE) and the amperometric responses are measured at −0.20 V (vs. Ag pseudo-reference electrode), upon addition of hydroquinone (HQ) as electron transfer mediator and H 2 O 2 as the enzyme substrate. The β-LG magnetoimmunosensor exhibited a wide range of linearity (2.8–100 ng mL −1 ) and a low detection limit of 0.8 ng mL −1 (20 pg in 25 μL sample). The magnetoimmunosensing platform was successfully applied for the detection of β-LG in different types of milk without any matrix effect after just a sample dilution. The results correlated properly with those provided by a commercial ELISA method offering a truthful analytical screening tool. These features make the developed methodology a promising alternative in the development of user-friendly devices for on-site determination of β-LG in dairy products. [ABSTRACT FROM AUTHOR]

The study of the temporal evolution of the dipole moment variations is a forefront research topic in Earth sciences. It constrains geodynamo simulations and is used to correct cosmogenic isotope production, which is evidence of past solar activity, and it is used to study possible correlations between the geomagnetic field and the climate. In this work, we have analysed the main error sources in the geomagnetic dipole moment computation from palaeomagnetic data: the influence of the non-dipole terms in the average approach, the inhomogeneous distribution of the current palaeomagnetic database, and the averaging procedure used to obtain the evolution of the dipole moment. To evaluate and quantify these effects, we have used synthetic data from a global model based on instrumental and satellite data, the International Geomagnetic Reference Field: 11th generation. Results indicate that the non-dipole terms contribute on a global scale of <6 % in the averaged dipole moment, whereas the regional non-dipole contribution can show deviations of up to 35 % in some regions such as Oceania, and different temporal trends with respect to the global dipole moment evolution in other ones, such as Europe and Asia. A regional weighting scheme seems the best option to mitigate these effects in the dipole moment average approach. But when directional and intensity palaeomagnetic information is available on a global scale, and in spite of the inhomogeneity of the database, global modelling presents more reliable values of the geomagnetic dipole moment. [ABSTRACT FROM AUTHOR]

A novel magnetobiosensing approach for the rapid, sensitive and selective miR-21 detection is reported involving the use of a specific RNA probe (antimiR-21), streptavidin-magnetic beads (Strep-MBs), the siRNA Binding Protein p19 as detector bioreceptor, and amperometric detection with the H2O2/hydroquinone (HQ) system at disposable screen-printed carbon electrodes. The magnetosensor exhibited a dynamic range from 1.4 to 10 nM and a detection limit of 4.2 fmol of synthetic target miR-21 without any amplification step in 75 min. The usefulness of the approach was evaluated by analyzing total RNA (RNAt) extracted from metastatic breast cancer cell lines, human tissues and breast cytologies. [ABSTRACT FROM AUTHOR]

Abstract: Two different fibrinogen (Fib) amperometric immunosensing designs based on the use of magnetic beads (MBs) and a novel specific nanobody (Nb) expressed in Escherichia coli are described for the first time. The immunological reaction for Fib detection was performed on COOH-MBs or His-Tag-Isolation-MBs as solid support for the immobilization of the antigen or the captured Nb. Direct and indirect competitive magnetoimmunosensing configurations have been tested and compared. In the former one, Fib and biotinylated Fib competed for the immobilized Nb binding sites while the latter configuration involved competition of free Fib in solution and immobilized Fib for binding to a fixed amount of the specific biotinylated Nb. Labeling of the captured biotinylated Nb or antigen was made with streptavidin-HRP. The modified magnetic beads were captured by a neodymium magnet on the surface of screen-printed carbon electrodes (SPCEs). Amperometric detection was accomplished at −0.20V (vs. Ag pseudo-reference electrode) by measuring the catalytic current arising upon addition of H2O2 and using hydroquinone (HQ) as redox mediator in solution. A better analytical performance was achieved with the indirect competitive immunoassay with a detection limit of 0.044μgmL−1 Fib. The usefulness of both approaches was successfully demonstrated by analyzing an international standard for Fib plasma. The assays could be carried out in diluted plasma samples in a total analysis time of 90min. [Copyright &y& Elsevier]

Highlights: [•] New electrochemical biosensing device for determining the blood's ethanol content (BAC). [•] Prototype based on bienzyme amperometric composite biosensors. [•] Determination of BAC by amperometric monitoring of ethanol in sweat. [•] BAC determination in single measurement or in continuous modes. [•] Successful validation with 40 volunteers. [Copyright &y& Elsevier]

The preparation, characterization and performance evaluation of an amperometric affinity disposable magnetosensor, based on the use of a recombinant penicillin-binding protein (PBP) and screen-printed carbon electrodes (SPCEs), for the specific detection and quantification of β-lactam antibiotic residues in milk are reported. The PBP was immobilized onto His-Tag-Isolation-modified magnetic beads (His-Tag-Isolation-MBs), and a direct competitive assay using a tracer with horseradish peroxidase (HRP) for the enzymatic labeling was performed. The amperometric response obtained at −0.20 V vs. the Ag pseudo-reference electrode of the SPCE after the addition of H2O2 in the presence of hydroquinone (HQ) was used as the transduction signal. The developed methodology showed very low detection limits (in the low ppb level) for the 6 antibiotics tested in untreated milk samples, and a good selectivity against other antibiotic residues frequently detected in milk and dairy products. Due to the bioreceptor employed, this methodology was able to detect only the active form of β-lactam antibiotics with high affinities for both penicillins and cephalosporins. Moreover, the analysis took only 30 min. [ABSTRACT FROM AUTHOR]

Abstract: Integrated amperometric biosensors for the determination of l-malic and l-lactic acids were developed by coimmobilization of the enzymes l-malate dehydrogenase (MDH) and diaphorase (DP), or l-lactate oxidase (LOX) and horseradish peroxidase (HRP), respectively, together with the redox mediator tetrathiafulvalene (TTF), on a 3-mercaptopropionic acid (MPA) self-assembled monolayer (SAM)-modified gold electrode by using a dialysis membrane. The electrochemical oxidation of TTF at +100mV (vs. Ag/AgCl), and the reduction of TTF+ at −50mV were used for the monitoring of the enzyme reactions involved in l-malic and l-lactic acid determinations, respectively. Experimental variables concerning the biosensors composition and the detection conditions were optimized for each biosensor. Good relative standard deviation values were obtained in both cases for the measurements carried out with the same biosensor, with no need of cleaning or pretreatment of the bioelectrodes surface, and with different biosensors constructed in the same manner. After 7 days of continuous use, the MDH/DP biosensor still exhibited 90% of the original sensitivity, while the LOX/HRP biosensor yielded a 91% of the original response after 5 days. Calibration graphs for l-malic and l-lactic were obtained with linear ranges of 5.2×10−7 to 2.0×10−5 and 4.2×10−7 to 2.0×10−5 M, respectively. The calculated detection limits were 5.2×10−7 and 4.2×10−7 M, respectively. The biosensors exhibited a high selectivity with no significant interferences. They were applied to monitor malolactic fermentation (MLF) induced by inoculation of Lactobacillus plantarum CECT 748T into a synthetic wine. Samples collected during MLF were assayed for l-malic and l-lactic acids, and the results obtained with the biosensors exhibited a very good correlation when plotted against those obtained by using commercial enzymatic kits. [Copyright &y& Elsevier]

Abstract: Lectin-based screen-printed gold electrodes are reported for the impedimetric label-free detection of bacteria. The selective interaction of lectins with carbohydrate components from microorganisms surface was used as the recognition principle for their detection and identification. Electrochemical impedance spectroscopy (EIS) was employed for the direct label-free transduction of the bacteria–lectin binding. Biotinylated Concanavalin A (Con A) and Escherichia coli were used for the evaluation of the lectin–bacteria complex formation. This complex was formed in solution, and then adsorbed onto the gold SPE surface. No bacteria immobilization was observed on the sensor prepared in the absence of ConA, demonstrating the absence of non-specific bacteria adsorption onto the gold SPE. On the contrary, the changes in electron transfer resistance allowed monitoring of E. coli–biotinylated Con A complex formation without any amplification step. Experimental variables such as the biotinylated-Con A concentration and the bacteria–lectin incubation time were optimized. The electron transfer resistance varied linearly with the logarithmic value of E. coli concentration over four orders of magnitude, 5.0×103 and 5.0×107 cfumL−1. The selectivity of the approach was evaluated by checking the impedimetric responses of gold SPE modified with the complexes formed between nine lectins and three different bacteria (E. coli, Staphylococcus aureus and Mycobacterium phlei). Different response profiles were found when the different lectins were used as recognition elements. principal component analysis (PCA) allowed classification and distinction among bacteria. Finally, electrochemical monitoring of β-galactosidase activity for the surface attached bacteria was demonstrated to be useful to distinguish between E. coli and S. aureus, which exhibit a similar affinity towards biotinylated-Con A. [Copyright &y& Elsevier]

Abstract: The construction and performance of integrated amperometric biosensors for the determination of glycerol are reported. Two different biosensor configurations have been evaluated: one based on the glycerol dehydrogenase/diaphorase (GDH/DP) bienzyme system, and another using glycerol kinase/glycerol-3-phosphate oxidase/peroxidase (GK/GPOx/HRP). Both enzyme systems were immobilized together with the mediator tetrathiafulvalene (TTF) on a 3-mercaptopropionic acid (MPA) self-assembled monolayer (SAM)-modified gold electrode by using a dialysis membrane. The electrochemical oxidation of TTF at +150mV (vs. Ag/AgCl), and the reduction of TTF+ at 0mV were used for the monitoring of the enzyme reactions for the bienzyme and trienzyme configurations, respectively. Experimental variables concerning both the biosensors composition and the working conditions were optimized for each configuration. A good repeatability of the measurements with no need of cleaning or pretreatment of the biosensors was obtained in both cases. After 51 days of use, the GDH/DP biosensor still exhibited 87% of the original sensitivity, while the GK/GPOx/HRP biosensor yielded a 46% of the original response after 8 days. Calibration graphs for glycerol with linear ranges of 1.0×10−6 to 2.0×10−5 or 1.0×10−6 to 1.0×10−5 M glycerol and sensitivities of 1214±21 or 1460±34μAM−1 were obtained with GDH/DP and GK/GPOx/HRP biosensors, respectively. The calculated detection limits were 4.0×10−7 and 3.1×10−7 M, respectively. The biosensors exhibited a great sensitivity with no significant interferences in the analysis of wines. The biosensors were applied to the determination of glycerol in 12 different wines and the results advantageously compared with those provided by a commercial enzyme kit. [Copyright &y& Elsevier]

Pd-zirconia-based monolithic catalysts were prepared with various commercial zirconia raw materials and a natural magnesium silicate binder, sepiolite, for the selective catalytic reduction (SCR) of NO with CH4 in oxygen excess. The different textural properties, metastable tetragonal zirconia phase stability, surface acidity, Pd dispersion and catalytic properties of these monoliths were compared to select the most suitable structured catalyst for NOx control in natural gas-fired power plants. The influence of operating temperature in the two reactions, NO reduction and CH4 combustion, with the monolithic catalysts was determined. A 0.4 wt.% Pd-zirconia catalyst, manufactured from a sulphated zirconium hydroxide raw material, was selected as the most appropriate in the reaction under study, reaching a maximum NO conversion at 400 °C. [Copyright &y& Elsevier]

Focuses on developmental parameters of cell death in the wing disc of Drosophila. Information on apoptotic cell death in wing imaginal discs; Results of experimentally induced apoptosis in single cells or territories; Details on normal Drosophila development.

Unraveling the short‐term behavior of the Earth's past geomagnetic field at regional scales is crucial for understanding its global behavior and, thus, the dynamics of the deep Earth. In this context, obtaining accurate full‐vector geomagnetic field records from regions where archeomagnetic data are absent becomes essential. Here, we present the first full‐vector archeomagnetic data from Central Asia, derived from the analysis of nine archeological kilns sampled in South Uzbekistan, dating back to the period between 200 BCE and 1429 CE. To obtain these new data, we conducted thermal and alternating field demagnetization procedures, along with Thellier‐Thellier paleointensity experiments, including partial thermoremanent magnetization checks, thermoremanent magnetization anisotropy and cooling rate corrections. The comparison between the new data, previous selected data from Central Asia, and available global models reveals important differences between approximately 400 BCE and 400 CE, especially concerning the geomagnetic field intensity element. In order to investigate this in detail, we have developed a regional update of the SHAWQ global models family by incorporating, for the first time, high‐quality data from Central Asia. The results suggest that this deviation is linked to non‐dipolar sources of the geomagnetic field in Central Asia reaching a maximum contribution around the first century BCE. According to the updated global paleoreconstruction, this non‐dipole feature, manifested at the Earth's surface as low intensities, is associated with the presence of a reversed flux patch at the core‐mantle boundary beneath this region. Plain Language Summary: The geomagnetic field is a global feature that changes over time and space. These changes are known over the last few centuries through direct observations collected by satellites and geomagnetic observatories. However, indirect measurements, based on the paleomagnetic study of archeological and geological materials, are needed to disentangle geomagnetic field behavior over longer time scales. In this context, archeomagnetism is the discipline that studies the direction and strength of the past geomagnetic field by investigating the magnetic properties of well dated archeological baked clay material. In order to properly describe the behavior of the Earth's magnetic field it is crucial to have a good temporal and spatial coverage of archeomagnetic data. In this work, we present the first full‐vector archeomagnetic data for Central Asia, a large region that remained unexplored from an archeomagnetic point of view. The new data were obtained from 9 kilns excavated in South Uzbekistan, with ages ranging from 200 BCE to 1429 CE. We then developed a regional update of the SHAWQ global models family by incorporating, for the first time, high‐quality archeomagnetic data from Central Asia. The results indicate a relevant non‐dipole feature presented over this region around the first century BCE. Key Points: First nine full‐vector archeomagnetic data for Central Asia for the last 2k yearsResults indicate a large non‐dipole contribution around the first century BCE in Central AsiaCentral Asia intensity data reveal a reversed flux patch at the core‐mantle boundary [ABSTRACT FROM AUTHOR]

An introduction to the journal is presented which discusses various papers published within the issue, including one on the development of electrochemical immunosensing scaffolds, one on the use of screen-printed electrodes, and another on control of electron transfer.

An integrated amperometric d -lactic acid biosensor involving a gold film deposited by sputtering on a stainless steel disk electrode where the enzymes d -lactic acid dehydrogenase (DLDH) and diaphorase (DP) as well as the redox mediator tetrathiafulvalene (TTF) are coimmobilized by using a dialysis membrane, is reported in this work. Amperometry in stirred solutions at a detection potential of +0.15 V (vs Ag/AgCl reference electrode) provided a linear calibration plot for d -lactic acid over the 1.0×10 −4 to 3.8×10 −3 g L −1 concentration range, with a limit of detection of 3.1×10 −5 g L −1 . The usefulness of the biosensor was demonstrated by determining d -lactic acid in beer samples with good results. Additionally, the biosensor was implemented together with a commercial l −lactic amperometric biosensor in a semiautomatic flow-injection analysis (FIA) system able to perform a rapid and simple stereo-specific determination of d - and d -lactic without a previous separation step. The operational characteristics of the biosensors under flow conditions were evaluated and its applicability was demonstrated through the simultaneous determination of both enantiomers in beer samples. [ABSTRACT FROM AUTHOR]

A non-destructive, rapid and simple to use sensing method for direct determination of glucose in non-processed fruits is described. The strategy involved on-line microdialysis sampling coupled with a continuous flow system with amperometric detection at an enzymatic biosensor. Apart from direct determination of glucose in fruit juices and blended fruits, this work describes for the first time the successful application of an enzymatic biosensor-based electrochemical approach to the non-invasive determination of glucose in raw fruits. The methodology correlates, through previous calibration set-up, the amperometric signal generated from glucose in non-processed fruits with its content in % (w/w). The comparison of the obtained results using the proposed approach in different fruits with those provided by other method involving the same commercial biosensor as amperometric detector in stirred solutions pointed out that there were no significant differences. Moreover, in comparison with other available methodologies, this microdialysis-coupled continuous flow system amperometric biosensor-based procedure features straightforward sample preparation, low cost, reduced assay time (sampling rate of 7 h −1 ) and ease of automation. [ABSTRACT FROM AUTHOR]

Highlights: [•] First disposable amperometric magnetobiosensor for screening of multiple antibiotics. [•] Discrimination between free and milk samples containing antibiotics at their MRLs. [•] Simple and short sample pretreatment and fast detection within 5min. [•] Useful and affordable alternative to classical assays for antibiotic screening in milk. [ABSTRACT FROM AUTHOR]

Highlights: [•] Nanostructured rough gold electrodes as general DNA biosensors platforms. [•] Electrode nanopatterning was accomplished by repetitive square-wave perturbing potential. [•] Hybridization was electrochemically monitored by using electrostatic or intercalative indicators. [•] PCR amplified real samples can be detected without complicated sample treatment procedures. [•] The genosensor exhibits a wide linear range, high sensitivity and remarkable long-term storage stability. [Copyright &y& Elsevier]

An integrated amperometric sucrose biosensor involving a 3-mercaptopropionic acid (MPA) self-assembled monolayer (SAM)-modified gold disk electrode (AuE) and coimmobilization of the enzymes invertase (INV) and fructose dehydrogenase (FDH) as well as the redox mediator tetrathiafulvalene (TTF) by means of a dialysis membrane is reported. Amperometry in stirred solutions at a detection potential of +0.10V provided a linear calibration plot for sucrose over the 1.2×10−6–3.0×10−3 molL−1 concentration range, with a limit of detection of 3.6×10−7 molL−1. The practical usefulness of the biosensor was demonstrated by determining sucrose in condensed milk and in an infant food reference material with good results. Additionally, the biosensor was implemented together with commercial fructose and glucose amperometric biosensors in a continuous flow system to perform the multiplexed quantification of sucrose, fructose and glucose in a single experiment. The operational characteristics of the biosensors in this novel flow system were evaluated and their applicability was demonstrated through the simultaneous determination of the three sugars in the above-mentioned reference material. [ABSTRACT FROM AUTHOR]

Periods of accelerated seismicity have been observed during the preparation process of many large earthquakes. This accelerating seismicity can be detected by the Accelerated Moment Release (AMR) method and its recent Revised version (R-AMR) when the two techniques are applied to earthquake catalogues. The main aim of this study is to investigate the seismicity preceding large mainshocks and possibly increase our comprehension of the underlying physics. In particular, we applied both the AMR and R-AMR to the seismicity preceding 14 large worldwide shallow earthquakes, i.e. with focal depth less than 40 km, with magnitude M > 6 for Mediterranean area, and M ≥ 6.4 in the rest of the world, occurred from 2014 to 2018. Twelve case studies were analysed in the framework of SwArm For Earthquake study project funded by ESA, comprising the period 2014–2016; two additional cases were also considered to confirm the goodness of the methodology outside the period of the project catalogues. In total, R-AMR shows better performances than AMR, in 11 cases out of 14. In particular, in four out of 14 cases (i.e. 28.6%), the R-AMR method shows that acceleration exists due to an evident clustering in time–space on the faults, thus guiding the convergence of the fit; in seven cases (i.e. 50%) the R-AMR discloses acceleration, although no clustering around the fault is present; the remaining three cases (i.e. 21.4%) show no emerging acceleration from background. Finally, when R-AMR is compared with simulations, we verify that in most of the cases the acceleration is real and not casual. [ABSTRACT FROM AUTHOR]

A shrimp tropomyosin (TPM) immunosensor has been developed and optimized to detect trace amounts of shrimp (in the ppm range), based on a combination of an amperometric transduction, magnetic particles and disposable screen-printed electrodes. The approach is based on the implementation of a sandwich immunoassay format on the surface of magnetic beads and their coupling onto disposable screen-printed electrodes to finally register the amperometric response at −200 mV vs. Ag pseudo-reference electrode, using H 2 O 2 as enzymatic substrate and hydroquinone as redox mediator. The use of carboxyl-functionalized magnetic microbeads (MBs) and in-house made magnetic nanoparticles (MNPs) as solid supports have been evaluated and compared. Our experimental results confirm that the use of MBs, in addition to simplifying the test protocol, improves the resulting sensitivity, so they were selected for the implementation of the immunosensor. In the optimized experimental conditions, the developed immunosensor offered a LOD of 47 pg mL−1 for amperometric determination of shrimp TPM standards and great selectivity against TPM from other sources, thus allowing differentiation between crustaceans (shrimp) and mollusks (squid). Applicability studies demonstrated successful determination both in crude and cooked samples using very simple protocols. Additionally, processed foods based on fish and mollusks that could potentially include crustaceans in their composition have been analyzed using the sensor and compared to the declared ingredients. The sensitivity and specificity showed by the sensor in the analysis of heterogeneous food samples without a previous purification or enrichment stage, also outperforms existing solutions in terms of time and cost effectiveness and permits its direct and smooth implementation in the food industry for routine allergen analyses. Representation of the TPM sensor configuration and the reactions involved in the amperometric transduction at a screen-printed carbon electrode. Image 1 • An amperometric immunosensor has been developed for the accurate detection of shrimp tropomyosin. • A limit of detection of 47 pg mL−1 has been obtained in under 3 h. • Crustacean and mollusk tropomyosin has been clearly differentiated, a relevant issue for the food processing industry. • The applicability of the sensor for the determination in both raw and cooked foods has been assessed. [ABSTRACT FROM AUTHOR]

Proper functionalization of electrode surfaces and/or nanomaterials plays a crucial role in the preparation of electrochemical (bio)sensors and their resulting performance. In this context, copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) has been demonstrated to be a powerful strategy due to the high yields achieved, absence of by-products and moderate conditions required both in aqueous medium and under physiological conditions. This particular chemistry offers great potential to functionalize a wide variety of electrode surfaces, nanomaterials, metallophthalocyanines (MPcs) and polymers, thus providing electrochemical platforms with improved electrocatalytic ability and allowing the stable, reproducible and functional integration of a wide range of nanomaterials and/or different biomolecules (enzymes, antibodies, nucleic acids and peptides). Considering the rapid progress in the field, and the potential of this technology, this review paper outlines the unique features imparted by this particular reaction in the development of electrochemical sensors through the discussion of representative examples of the methods mainly reported over the last five years. Special attention has been paid to electrochemical (bio)sensors prepared using nanomaterials and applied to the determination of relevant analytes at different molecular levels. Current challenges and future directions in this field are also briefly pointed out. [ABSTRACT FROM AUTHOR]

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has not been fixed in the paper. [ABSTRACT FROM AUTHOR]

Abstract This paper describes the reliable determination of progesterone (P4) in undiluted saliva making use of a disposable amperometric immunosensors implemented on low-cost and portable device/potentiostat constructed with commercial-off-the-shelf (COTS) components. The immunosensor allows the fast (45 min), selective and sensitive determination (5 pg mL−1 LOD) of P4 using amperometry in stirred solutions. The immunosensor was coupled to the COTS-based potentiostat and amperometry was made into drops of quiescent solutions. No significant differences were apparent between the analytical performance achieved with the immunosensor for P4 using both a conventional and the COST-based potentiostats. The practical applicability of the immunosensor coupled with the COTS-based potentiostat was demonstrated by determining the endogenous P4 content in different undiluted saliva samples with highly variable endogenous contents of the target hormone. The obtained results were in good agreement with those provided by the conventional ELISA methodology and with the contents reported in the literature for samples with similar characteristics. This validated the combined device for the reliable and minimally invasive determination of the target hormone involving a very simple protocol and taking only 45 min. Graphical abstract Image 1 Highlights • Reliable determination of progesterone (P4) in undiluted saliva with a disposable immunosensor. • Portable device/potentiostat constructed with commercial-off-the-shelf (COTS) components. • Fast (45 min) and sensitive determination of P4 using amperometry in stirred solutions or drops of quiescent solutions. • Determination of endogenous P4 in saliva with highly variable contents of the target hormone. [ABSTRACT FROM AUTHOR]

Abstract An amperometric immunosensor for the determination of the biomarker endoglin (CD105) to comply with the requirements of sensitivity and accuracy demanded in clinical practice is reported in this work. The immunosensing platform is implemented onto disposable electrodes modified with poly(pyrrolepropionic) acid (pPPA). The methodology involves a sandwich configuration and labeling of the biotinylated detector antibody with poly-HRP-streptavidin for signal amplification. Amperometric detection of hydrogen peroxide reduction in the presence of HQ was employed as analytical readout. The different steps involved in the immunosensor preparation were monitored by electrochemical impedance spectroscopy. The resulting immunosensor provided a linear range between 0.18 and 20 ng mL−1, adequate for the determination of CD105 in serum, with a detection limit (LOD) of 140 pg mL−1. These analytical characteristics improve those reported previously for other electrochemical immunosensors. A good reproducibility of the measurements, an excellent storage stability of the anti-CD105-pPPA/SPCE bioplatforms and an excellent selectivity of the resulting immunosensors were found. The usefulness of the immunosensors was tested by analyzing human serum samples collected from healthy individuals and patients of colorectal, breast and lung cancer and epidermolysis bullosa. The results were successfully validated against those provided by an ELISA kit. Graphical abstract Amperometric immunosensing platform, implemented onto a disposable electrode modified with pPPA and involving a sandwich configuration for sensitive and accurate determination of CD105 in serum samples from cancer or epidermolysis bullosa patients with minimal sample treatment. Image 1 [ABSTRACT FROM AUTHOR]

This paper describes the first immunosensor reported so far for the highly sensitive determination of the egg white allergen, ovomucoid (OM). The approach involves the selective capture of sandwich immunocomplexes formed by capture antibody-target protein allergen-HRP-labeled detector antibody onto carboxylic acid-functionalized magnetic beads (HOOC-MBs). The resulting magnetic bioconjugates were captured on the surface of disposable screen-printed carbon electrodes (SPCE) to perform amperometric detection at −0.20 V vs . the Ag pseudo-reference electrode in the presence of hydroquinone (HQ) and H 2 O 2 . The as prepared electrochemical immunoplatform showed a wide range of linearity (0.3–25 ng mL −1 ), a LOD of 0.1 ng mL −1 , which is much lower than those claimed for commercial ELISA kits, and a great selectivity against other white egg allergenic proteins. The developed immunosensor was successfully employed for the simple and accurate determination of trace amounts of OM in unprocessed (eggs and wheat flour) and baked (bread) food samples. [ABSTRACT FROM AUTHOR]

The production of cosmogenic isotopes offers a unique way to reconstruct solar activity during the Holocene. It is influenced by both the solar and Earth magnetic fields and thus their combined effect needs to be disentangled to infer past solar irradiance. Nowadays, it is assumed that the long-term variations of cosmogenic production are modulated by the geomagnetic field and that the solar field dominates over shorter wavelengths. In this process, the effects of the non-dipolar terms of the geomagnetic field are considered negligible. Here we analyse these assumptions and demonstrate that, for a constant solar modulation potential, the geomagnetic field exerts a strong modulation of multi-centennial to millennial wavelengths (periods of 800 and 2200 yr). Moreover, we demonstrate that the non-dipole terms derived from the harmonic degree 3 and above produce maximum differences of 7% in the global average radiocarbon production rate. The results are supported by the identification, for the first time, of a robust coherence between the production rates independently estimated from geomagnetic reconstructions and that inferred from natural archives. This implies the need to review past solar forcing reconstructions, with important implications both for the assessment of solar-climate relationships as well as for the present and future generation of paleoclimate models. [ABSTRACT FROM AUTHOR]

A sensitive amperometric immunosensor has been prepared by immobilization of capture antibodies onto gold nanoparticles (AuNPs) grafted on a screen-printed carbon electrode (SPCE) through aryl diazonium salt chemistry using 4-aminothiophenol (AuNPs-S-Phe-SPCE). The immunosensor was designed for the accurate determination of clinically relevant levels of B-type natriuretic peptide (BNP) in human serum samples. The nanostructured electrochemical platform resulted in an ordered layer of AuNPs onto SPCEs which combined the advantages of high conductivity and improved stability of immobilized biomolecules. The resulting disposable immunosensor used a sandwich type immunoassay involving a peroxidase-labeled detector antibody. The amperometric transduction was carried out at −0.20 V (vs the Ag pseudo-reference electrode) upon the addition of hydroquinone (HQ) as electron transfer mediator and H 2 O 2 as the enzyme substrate. The nanostructured immunosensors show a storage stability of at least 25 days, a linear range between 0.014 and 15 ng mL −1 , and a LOD of 4 pg mL −1 , which is 100 times lower than the established cut-off value for heart failure (HF) diagnosis. The performance of the immunosensor is advantageously compared with that provided with immunosensors prepared by grafting SPCE with p-phenylendiamine (H 2 N-Phe-SPCE) and attaching AuNPs by immersion into an AuNPs suspension or by electrochemical deposition, as well as with immunosensors constructed using commercial AuNPs-modified SPCEs. The developed immunosensor was applied to the successful analysis of human serum from heart failure (HF) patients upon just a 10-times dilution as sample treatment. [ABSTRACT FROM AUTHOR]

Electrochemical sandwich immunoassay strategies involving the use of carboxyl-functionalized magnetic microbeads (cMBs) and magnetic nanoparticles (cMNPs) have been evaluated and compared. The proteolytically cleaved soluble tyrosine kinase receptor sAXL was used as the target analyte. Antibodies against AXL were covalently immobilized on cMBs or cMNPs. Immunobinding of AXL was detected by means of a secondary biotinylated antibody and a streptavidin-horseradish peroxidase conjugate. The electrochemical transduction was accomplished by capturing the cMBs or cMNPs bearing the immunoconjugates onto screen-printed carbon electrodes (SPCEs) by using a small magnet. The amperometric response was measured at −0.20 V (vs the silver pseudo-reference electrode of the SPCE) upon the addition of HO in the presence of hydroquinone as the redox mediator. The calibration plots for AXL extended up to 7.5 ng mL when cMBs were used for the preparation of the immunosensor and up to 40 ng mL in the case of using cMNPs. The respective slope values were 158 (cMBs) and 43 nA mL ng (cMNPs), while the achieved LODs were 74 (cMBs) and 75 pg mL (cMNPs). Although the immunosensors prepared with cMBs provided a shorter range of linearity, they exhibited a 3.7-times larger sensitivity than those constructed with cMNPs. The successful application of the new strategies was demonstrated for the determination of the endogenous content of sAXL in real human serum samples (a cut-off value of 71 ng mL have been established for patients with risk of heart failure). The immunosensors constructed using cMBs or cMNPs can be advanta geously compared, in terms of sensitivity and fabrication time, with the only immunosensor for AXL previously reported. In addition, these new immunosensors took approximately half time than ELISA to perform the assay. [ABSTRACT FROM AUTHOR]

A sensitive and rapid method for the determination of the clinically relevant biomarker receptor tyrosine kinase AXL in serum involving amperometric disposable immunosensors is reported. The target protein was sandwiched between a specific capture antibody covalently immobilized on screen-printed carbon electrodes modified with electropolymerized poly(pyrrolepropionic acid) and a biotinylated detector antibody labeled with a streptavidin-horseradish peroxidase conjugate. The amperometric responses were measured at −0.20 V vs the Ag pseudo-reference electrode of the SPCE upon the addition of H 2 O 2 in the presence of hydroquinone (HQ) as mediator. This integrated immunosensing platform showed a low limit of detection (337 pg mL −1 ), a good selectivity against other non-target serum proteins, and provided results statistically in agreement with those obtained by using a commercial ELISA kit. These attractive features together with the simplicity and easy automation and miniaturization of the required instrumentation make the developed methodology a promising alternative in the development of devices for on-site clinical analysis. [ABSTRACT FROM AUTHOR]

An electrochemical magnetoimmunosensor for the determination of progesterone receptor (PR) making use of functionalized magnetic microbeads (MBs), a sandwich-type immunoassay and amperometric detection at disposable screen-printed carbon electrodes (SPCEs) was described for the first time in this work. This selective and sensitive magnetoimmunosensor, with a detection limit of 22 pg mL−1, was successfully applied to the determination of PR in raw cell lysates with just a dilution as sample treatment and exhibiting no matrix effect. The advantageous performance in terms of simplicity and assay time over commercial ELISAs makes it competitive with conventional strategies providing rapidly quantitative and reliable results on this biomarker currently used in the clinical practice for diagnosis, follow-up and monitoring of metastatic breast cancer. In addition, a dual magnetoimmunosensor using screen-printed dual carbon electrode (SPdCE) has been implemented for the simultaneous determination of PR and estrogen receptor α (ERα) in cell lysates. This dual receptor determination allows a more accurate diagnosis enabling a more efficient treatment. The usefulness of this dual magnetoimmunosensing platform was demonstrated by discriminating raw lysates of two types of cancer cells (MCF-7 and MDA-MB-436) with significantly different PR/ERα expression levels. [ABSTRACT FROM AUTHOR]

[Display omitted] • First dual immunoplatform for simultaneous determination of BAFF and APRIL cytokines. • Improved sensitivity and much shorter assay time compared with ELISA kits. • Patients with systemic lupus erythematosus or colorectal cancer can be discriminated. This work reports the first dual magnetic beads (MBs) assisted immunoplatform for the simultaneous determination of BAFF (B cell activation factor) and APRIL (a proliferation-induced ligand), two cytokines related to immunity and tumour invasion, growth and metastasis. The electrochemical immunoplatform involves sandwich-type immunoassays implemented on magnetic microparticles functionalized with neutravidin (NA-MBs) or carboxylic groups (HOOC-MBs), and amperometric detection (E app = − 0.20 V vs. Ag pseudo-reference electrode) at screen-printed dual carbon electrodes (SPdCE) using the H 2 O 2 /hydroquinone (HQ) system. The developed immunosensors provide improved sensitivity, with LOD values of 0.33 and 16.4 pg mL−1 for BAFF and APRIL, respectively, and much shorter assay time that those claimed for ELISA kits and allow their simultaneous determination. The dual immunosensor permits discrimination between healthy individuals and patients diagnosed with Systemic Lupus Erythematosus (SLE) or colorectal cancer (CRC) through the determination of both cytokines in 100-times diluted human sera with results in agreement with those provided by the individual ELISA methodologies. [ABSTRACT FROM AUTHOR]

A highly sensitive amperometric magnetoimmunosensor for the determination of ErbB2 protein, a well-known biomarker related to high-impact high-incidence diseases such as breast cancer, is described. A sandwich format involving the covalent immobilization of a specific capture antibody onto magnetic beads (MBs) and incubation of the modified MBs with a mixture solution of the antigen and a HRP-labeled detector antibody was used. The resulting modified MBs were captured on the surface of a disposable screen-printed carbon electrode (SPCE) and the amperometric responses at −0.20 V were measured. This ErbB2 magnetoimmunosensor exhibited a very low detection limit of 26 pg mL − 1 far below the established cut-off for this biomarker (15 ng mL −1 ) and was successfully applied to the quantitation of ErbB2 in human serum and cell lysates samples without any matrix effect. In addition, the developed assay allowed the assessment of ErbB2 status directly in intact breast cancer cells. The results correlated well with those obtained with a commercial ELISA method, thus demonstrating that the new magnetoimmunosensing platform offers a truthful and useful analytical tool to be easily applied in breast cancer diagnosis through either ErbB2 protein determination or breast cancer cell status detection. [ABSTRACT FROM AUTHOR]

An amperometric immunoassay for the determination of tumor necrosis factor alpha (TNFα) protein biomarker in human serum based on the use of magnetic microbeads (MBs) and disposable screen-printed carbon electrodes (SPCEs) has been developed. The specifically modified microbeads were magnetically captured on the working electrode surface and the amperometric responses were measured at -0.20 V (vs. Ag pseudo-reference electrode), upon addition of hydroquinone (HQ) as electron transfer mediator and H2O2 as the enzyme substrate. After a thorough optimization of the assay, extremely low limits of detection were achieved: 2.0 pg mL-1 (36 fM) and 5.8 pg mL-1 (105 fM) for standard solutions and spiked human serum, respectively. The simplicity, robustness and this clinically interesting LOD proved the developed TNFα immunoassay as a good contender for real clinical application. [ABSTRACT FROM AUTHOR]

• Electrochemical immunoplatform for NfL determination. • MBs-bearing sandwich immunocomplexes and amperometric detection at SPCEs. • Unlike ELISAs, appropriate sensitivity (LOD of 3 pg mL-1) for plasma samples analysis. • Accurate determination in plasma samples and brain tissues from non-demented control subjects and patients diagnosed with NDs. • Simple and 1 h protocol requiring small sample amounts. Alzheimer's disease (AD) is a common neurodegenerative disorder associated with massive degradation of neuronal cell structure due to aging. In recent years, neurofilament light chain (NfL) arises as one of the most promising blood biomarkers for AD. Bioassays available for NfL determination in blood (ELISA kits or Simoa assays) require multiple steps, specialized personnel and expensive instrumentation of application limited to centralized and high-resource environments. With the aim of overcoming these drawbacks, this work reports the first magnetic microbeads (MBs)-based electrochemical bioplatform developed so far for the determination of NfL. The developed platform relies in a sandwich type immunoassay involving an HRP-secondary antibody to enzymatically label the detector antibody on the surface of commercial MBs functionalized with carboxylic acids. Amperometric transduction is carried out at screen-printed carbon electrodes (SPCEs) upon deposition of the magnetic bioconjugates on the working electrode surface using the H 2 O 2 /hydroquinone (HQ) system. This MBs-based immunoplatform provides a LOD value of 3.0 pg mL−1. The analytical performance is appropriate for the determination of NfL in plasma and brain tissues from AD patients using simple and short protocols (60 min) and requiring low amount of samples (5 µL raw plasma and 0.1 µg tissue extracts). Image, graphical abstract [ABSTRACT FROM AUTHOR]

This paper describes the first biosensor reported to date for the determination of mustard seed traces. The biosensor consists of an amperometric immunosensing platform able to sensitively and selectively determine Sin a 1 content, the major allergen of yellow mustard and the most abundant protein of these seeds. The immunosensing platform exploits the coupling of magnetic microbeads (MBs) modified with sandwich-type immune complexes, comprising polyclonal and monoclonal antibodies, selective to the target protein for its capturing and detection, respectively. In addition, a HRP-conjugated secondary antibody was used for enzymatic labelling of the monoclonal antibody, and amperometric transduction was made at screen-printed carbon electrodes (SPCEs) using the hydroquinone (HQ)/H 2 O 2 system. The electrochemical immunosensor allows the simple and fast detection (a single 1-h incubation step) of Sin a 1 with a limit of detection of 0.82 ng mL−1 (20.5 pg of protein in 25 μL of sample) with high selectivity against structurally similar non-target allergenic proteins (such as Pin p 1 from pine nut). The developed immunoplatform was successfully used for the analysis of peanut, rapeseed, cashew, pine nut and yellow mustard extracts, giving only positive response for the yellow mustard extract with a Sin a 1 content, in full agreement with that provided by conventional ELISA methodology. First electrochemical bioplatform of mustard seeds through sensitive and selective amperometric determination of Sin a 1. Image 1 • First biosensor reported to date for the determination of mustard seed traces. • Amperometric determination of Sin a 1, the major allergen of yellow mustard seeds. • Sandwich immunosensing platform based on MBs and SPCEs. • Sensitive (LOD of 0.82 ng mL−1 for Sin a 1 standards) and selective determination. • Accurate determination in plant food extracts. [ABSTRACT FROM AUTHOR]

• Clinical details of NDD/AD and closely related genetic and proteomic biomarkers. • State-of-the art in electrochemical affinity biosensing methods for NDD/AD diagnosis. • Main features of proposed strategies, analytical performances and potential applications. • NDD/AD biomarkers determination in CSF, plasma and serum. • Challenges to solve, key steps and future research directions. Neurodegenerative disorders (NDD), and particularly Alzheimer's disease (AD), are one of the greatest challenges facing our current medicine and society because of its increasing incidence and the high burden imposed both on patients' families and health systems. Despite this, their accurate diagnosis, mostly conducted by cerebrospinal fluid (CSF) analysis or neuroimaging techniques, costly, time-consuming, and unaffordable for most of the population, remains a complex task. In this situation, electrochemical biosensors are flourishing as promising alternative tools for the simple, fast, and low-cost diagnosis of NDD/AD. This review article provides the relevant clinical details of NDD/AD along with the closely related genetic (genetic mutations, polymorphisms of ApoE and specific miRNAs) and proteomic (amyloid-β peptides, total and phosphorylated tau protein) biomarkers circulating mostly in CSF. In addition, the article systematically enlightens a general view of the electrochemical affinity biosensors (mostly aptasensors and immunosensors) reported in the past two years for the determination of such biomarkers. The different developed strategies, analytical performances and applications are comprehensively discussed. Recent advancements in signal amplification methodologies involving smart designs and the use of nanomaterials and rational surface chemistries, as well as the challenges that must be struggled and the prospects in electrochemical affinity biosensing to bring more accessibility to NDD/AD diagnosis, prognosis, and follow-up, are also pointed out. [ABSTRACT FROM AUTHOR]

Simultaneous determination of fertility hormones in saliva using disposable immunosensing platforms and a custom designed field-portable dual potentiostat. • Simultaneous determination of progesterone and luteinizing hormone in saliva samples. • Disposable immunoplatforms and custom designed field-portable dual potentiostat. • LODs of 1.7 pg mL−1 and 0.10 mIU mL-1 for P4 and LH, respectively, in less than 1 h. • Accurate determination of both target hormones in saliva samples. This work describes a new electroanalytical device for the simultaneous and reliable determination of two fertility relevant hormones (luteinizing hormone, LH, and progesterone, P4) in saliva. The device is constructed using a custom designed and field-portable potentiostat where dual disposable immunosensing platform are connected. The immunosensors are based on sandwich-type and competitive immunoassays implemented onto magnetic microbeads (MBs) functionalized with Neutravidin and Protein G for the determination of LH and P4, respectively. Amperometric detection performed at −0.20 V vs the Ag pseudo-reference electrode using the H 2 O 2 /hydroquinone (HQ) system was employed as the transduction technique after placing the MBs with immunocomplexes for each target hormone on the appropriate working electrode of screen-printed dual carbon electrodes (SPdCEs). The method exhibits high sensitivity and selectivity for the target hormones providing detection limits of 1.7 pg mL−1 and 0.10 mIU mL−1 for P4 and LH, respectively, with a 1 h test time. The applicability of the method was confirmed by determining both hormones in saliva samples from different volunteers providing results comparable to those obtained using amperometric transduction with a commercial potentiostat and with ELISA methodologies involving the same immunoreagents for each target hormone. [ABSTRACT FROM AUTHOR]