Enzymatic selfpowered biosensing devices

Self-powered biosensors have been the focus of intense research due to the wide range of potential applications concerning real-time personal healthcare monitoring and disease diagnostics. The increased demand for autonomous biosensors along with the progress achieved in enzymatic fuel cells (EFCs) as power sources, hold great potential for developing new devices. Firstly, focus is given to the concepts underlying the fundamental operation of EFCs, covering both direct electron transfer and mediated electron transfer systems. As an essential step to achieve the required EFC power density performances in real applications, enzyme immobilization is critically discussed in terms of strategies to immobilize and stabilize enzymes at the electrodes of the EFCs. Highlight is then given to the progress obtained in EFCs-based biosensors. Since these devices harvest electrical power from biological systems, their unique advantages favored progress in terms of biomedical applications of self-powered biosensors. Therefore, the most recent advances in implantable, wearable and point-of-care autonomous biosensors incorporating EFCs is summarized and discussed. Key technological challenges are still present, but these devices are on track to achieve the foreseen realization of the full diagnostic potential of enzymatic fuel cells-based biosensors.One of the authors (F.T.C.M.) gratefully acknowledges Fundação para a Ciência e Tecnologia for financial support (postdoc grant reference No. SFRH/BPD/97891/2013, entitled “Biomedical devices for easier and quicker screening procedures of Alzheimer disease”). The authors from BioMark are grateful to the project IBEROS (Instituto de Bioingeniería en Red para el Envejecimiento Saludable), POCTEP/0245‐BEROS‐1‐E, PROGRAMA INTERREG 2014–2020, funded through FEDER within the cooperation region of Galicia/Spain and North of Portugal. The authors from BioMark are grateful to the project Cancer (NORTE‐01‐0145‐FEDER‐000029), entitled “Advancing cancer research: from basic knowledge to application,” funded by Norte 2020 – Programa Operacional Regional do Norte. The authors from the Centre of Biological Engineering (CEB) gratefully acknowledge the support of the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UID/BIO/04469 unit, COMPETE 2020 (POCI‐01‐0145‐FEDER‐006684), and the project entitled “MultiBiorefinery‐multi‐purpose strategies for broadband agro‐forest and fisheries by‐products valorization: a step forward for a truly integrated biorefinery” (POCI‐01‐0145‐FEDER‐016403). The authors also acknowledge financial support from the BioTecNorte operation (NORTE‐01‐0145‐FEDER‐000004), funded by the European Regional Development Fund under the scope of Norte2020 – Programa Operacional Regional do Norte.info:eu-repo/semantics/publishedVersio

Nucleic Acid Aptamers Against Biotoxins: A New Paradigm Toward the Treatment and Diagnostic Approach

Nucleic acid aptamers are short single-stranded DNA or RNA oligonucleotides that can bind to their targets with very high affinity and specificity, and are generally selected by a process referred to as systematic evolution of ligands by exponential enrichment. Conventional antibody-based therapeutic and diagnostic approach currently employed against biotoxins pose major limitations such as the requirement of a live animal for the in vivo enrichment of the antibody species, decreased stability, high production cost, and side effects. Aptamer technology is a viable alternative that can be used to combat these problems. Fully sequestered in vitro, aptamers eliminate the need for a living host. Furthermore, one of the key advantages of using aptamers instead of antibodies is that they can be selected against very weakly immunogenic and cytotoxic substances. In this review, we focus on nucleic acid aptamers developed against various biotoxins of plant, microorganism, or animal origin and show how these can be used in diagnostics (e.g., biosensors) and therapy