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In this work, we present a novel self-powered approach totally independent from any external energy source. We have developed a self-powered paper-based immunosensor that generates energy in the presence of the biomarker in the sample. In particular, the device - which has been labeled as Immuno-Battery - makes use of magnesium as anode and the widely employed HRP-labeled antibody as cathodic catalyst to detect C-reactive protein (CRP) presence in artificial samples. Feasibility of self-powered sensing is proved by submitting the immuno-battery to a resistive load. In this regime, the sensor provides operation voltages above 1.55 V and maximum power densities from 40 to 571 μW cm

This manuscript proves the reproducibility and robustness of cerium oxide nanoparticles, nanoceria, employed as a chemical reagent with oxidizing capacity (as an electron sink) at acidic pH. Unlike nanoceria multi-enzyme-mimetic capabilities at neutral or high pH, nanoceria can behave as a stoichiometric reagent at low pH where insoluble Ce4+ ions transform into soluble Ce3+ in the nanocrystal that finally dissolves. This behaviour can be interpreted as enzyme-like when nanoceria is in excess with respect to the substrate. Under these conditions, the Ce3+/Ce4+ ratio in the NPs can easily be estimated by titration with ferrocyanide. This procedure could become a rapid assessment tool for evaluating nanoceria capacity in liquid environments., N. Sabaté would like to acknowledge the financial support received from ERC Consolidator Grant (SUPERCELL – GA.648518). N. G. B and V. P. acknowledge financial support from the Spanish Ministerio de Ciencia, Innovación y Universidades (MCIU) (RTI2018-099965-B-I00, AEI/FEDER,UE) proyectos de I + D + i de programación conjunta internacional MCIN/AEI (CONCORD, PCI2019-103436) cofunded by the European Union and Generalitat de Catalunya (2017-SGR-1431). ICN2 is supported by the Severo Ochoa program from Spanish MINECO (SEV-2017-0706) and is funded by the CERCA Programme/Generalitat de Catalunya. Dmitry Galyamin thanks the doctoral program “Electroquímica. Ciència i Tecnologia” of the Universitat Autònoma de Barcelona (UAB).

An impedimetric sensor based on a three dimensional electrode array modified with concanavalin A (Con A) was used for label-free detection of bacterial endotoxin: lipopolysaccharide (LPS) from Escherichia coli. The transducer permits the detection of the surface charge changes due to interaction of immobilized Con A biorecognition element and LPS of E. coli in test solution. The deposition of Con A on the surface was carried out using the layer-by-layer method with polyethyleneimine (PEI) polycation as an initial layer. The sensor surface characterization by means of electrochemical impedance spectroscopy technique allowed registering variations in superficial resistance provoked by surface charge changes and is demonstrated as an effective method to monitor sensor parameters at each modification step as well as to follow Con A – LPS reaction. In order to prevent non-specific adsorption of LPS on PEI covered surface different blocking strategies were tested to achieve the specific response between Con A and LPS. Results obtained in this work clearly show that blocking with bovine serum albumin (BSA) is not sufficient to prevent non-specific interactions of PEI and to ensure the selective biorecognition of LPS by Con A. To achieve more efficient PEI blocking a new method was proposed based on consecutive deposition of Con A-glycogen-Con A layers. Sensors modified with PEI-(Con A-Gly)2-Con A multilayers are shown to be highly sensitive, selective and reproducible. Presented biosensor is able to detect bacterial LPS in a very short detection time (20 min) with 2 μg mL−1 limit of detection, which is much lower than reported for other biosensors with Con A., The authors acknowledge financial support from the Spanish Ministry of Economy and Competitiveness (project CTQ2014-54553-C3-1-R and S.B.O. fellowship of FPI-MICINN program BES-2015-071250) co-funded by the European Regional Development Fund (Feder) and from the Government of Russian Federation (Grant 074-U01).

The production of green hydrogen in water electrolyzers is limited by the oxygen evolution reaction (OER). State-of-the-art electrocatalysts are based on Ir. Ru electrocatalysts are a suitable alternative provided their performance is improved. Here we show that low-Ru-content pyrochlores (R2MnRuO7, R = Y, Tb and Dy) display high activity and durability for the OER in acidic media. Y2MnRuO7 is the most stable catalyst, displaying 1.5 V at 10 mA cm−2 for 40 h, or 5000 cycles up to 1.7 V. Computational and experimental results show that the high performance is owed to Ru sites embedded in RuMnOx surface layers. A water electrolyser with Y2MnRuO7 (with only 0.2 mgRu cm−2) reaches 1 A cm−2 at 1.75 V, remaining stable at 200 mA cm−2 for more than 24 h. These results encourage further investigation on Ru catalysts in which a partial replacement of Ru by inexpensive cations can enhance the OER performance.