Preface: Micro/Nanodevices for Electrochemical Bioanalysis

Medical and healthcare technology is advancing at a rapid pace, but the world is constantly threatened by new infectious diseases. In addition, progressive diseases such as cancer and neurodegenerative diseases are increasing worldwide, requiring accurate diagnosis of disease progression and drug response. Detection of biomarkers using electrochemical techniques is promising in terms of its high sensitivity, selectivity, fast temporal response, low-cost instrumentation, and compatibility with other bioanalytical techniques such as DNA amplification, immunosorbent assays, and microfluidic systems. Many electrochemical sensors have been developed to date, and commercialization is also progressing. However, there is still a growing need for devices that can measure in real-time with greater sensitivity to meet the demands of the medical and healthcare applications. This special issue “Micro/Nanodevices for electrochemical bioanalysis” aims to overlook recent advancements in micro/nano electrochemical devices, with a particular focus on the analysis of biological samples, such as nucleic acids, proteins, metabolites, and cells. The collection begins with an article by Yusuke Kanno et al. reviewing strategies for electrochemical detection of pathogenic nucleic acids. There are a vast number of developments in electrochemical detections of nucleic acids, but they have effectively collected the techniques for on-site testing of pathogenic nucleic acids with a focus on 2019 and beyond so that readers can follow the latest advances in the field. The second article, by Kyoko Sugiyama et al., presents a new means of immobilizing glucose oxidase on an electrode using the layer-by-layer technique. As also mentioned in Kanno's review, electrode functionalization methods are very important for the development of sensitive molecular recognition sites on electrochemical sensors. The method provided by Sugiyama et al. can be a versatile means for the immobilization of enzymes and it is promising for the application of other enzyme reaction-specific sensors. Finally, Ino et al. present porous membrane electrodes as an emerging platform for bioanalysis. The review ranges from general fabrication techniques of porous membrane electrodes to their applications in biosensors and cell analysis. Although porous membranes have initially been developed as separators and desalination materials, they showcased the unique aspects of porous membrane electrodes as a promising substrate for biosensing. Consequently, miniaturization of electrochemical devices to the micro- and nanoscale is a mainstream way to achieve highly sensitive electrochemical sensors. However, in order to overcome the specific difficulties of working with biological samples, such as biodegradation, the presence of foreign substances, biocompatibility requirements, and solution limitations, it is necessary to continuously investigate the facile and effective ways of electrode modifications and functionalization techniques. This collection covers these aspects and we hope that it will provide some inspiration to the readers. Finally, we would like to express our thanks to the editorial team of Electrochemical Science Advances for their kind and dedicated support. The authors declare no conflicts of interest.