Special Issue for Electrochemical Immunosensors – State of the Art

Abstract

There is a huge demand for fast, reliable and low-cost analytical systems for the detection and quantification of proteins with relevance in medicine, environmental pollutant monitoring, food safety, detection of foodborne pathogens and bioterrorism. Indeed, the development of biosensors fulfilling the requirements of adequate sensitivity and selectivity as well as convenience of use and cost is one of the grand scientific, engineering, and educational challenges of the 21st century. In this context, electrochemical immunosensors are considered particularly attractive analytical tools as a consequence of their inherent high sensitivity, simplicity of the operational procedure, easy availability and affordable cost of the required equipment together with possibility of miniaturization and suitability for in-field applications. Electrochemical immunosensors seek to exploit the great potentiality of immunoreactions in conjunction with electroanalytical techniques in a broad context facing a wide variety of analytical problems in medicine, biomedical research, drug discovery, environment, food, process industries, security and defense. The main goal is to provide a selective and fast response to the presence of a specific compound in a complex mixture of components, without perturbing the system. Interestingly, immunosensing using electroanalytical techniques is playing a more and more important role in protein analysis. Moreover, the growing research in advanced nanomaterials has impressively impacted also this field, by providing a great variety of novel, versatile and rationally designed nanostructured supports for transduction, signal generation and amplification. In parallel with these major advances in nanotechnology, the wide variety of immunoreagents available (commercial or produced by genetic recombination on demand conjugated with a variety of tags according to the required needs) and the versatility of design and modification offered by electrochemical substrates have also played major roles in the outstanding capabilities demonstrated by these electrochemical biosensors. The plethora of sophisticated approaches developed has exceeded even the experts' expectations in terms of functionality and resiliency. Due to the high demand of the world market and human interest for having devices able to provide the concentration of species in different complex samples, in a simple and fast way, a hard competition on this field has occurred among the researchers in recent years. In addition, the excellent and solid academic and practical multidisciplinary formation in sensors biotechnology, surface chemistry, advanced nanomaterials, and electrochemical transduction and characterization methods for immunodetection of these researchers amply justifies the unimaginable progress reached in such a short time and the fact that people working in this area do not dare to put limits on this field. The present Special Issue, which compiles 9 full papers, 2 short communications and 8 dedicated review articles, was authored by leading experts and pioneers in electrochemical immunosensors. These articles shed useful insights into the latest advances, current trends and future prospects in this exciting field. In particular, the selected contributions described the development of electrochemical immunosensing scaffolds to detect pollutants (polybrominated diphenyllethers, mycotoxins), clinical biomarkers (interleukin-8, estrogen and progesterone receptors), drugs (brombuterol), rotavirus and microbes and revise nicely the use of screen-printed electrodes, common and uncommon nanostructures, polymeric films, 3D-printing microfluidics and proximity ligation assays in the development of electrochemical immunosensors. Compiled contributions give also expert and updated overviews of this topic in multiplexed approaches, control of electron transfer, advantages compared with aptasensors and latest applications in real clinical practice. Therefore, one can envision further exciting applications of electrochemical immune-platforms for making ‘house-calls' in biomedical diagnostics and cancer theranostics, as inspectors for environmental monitoring, even in harsh working conditions, as well as alarm devices for food safety. The unique combination and integration of nanotechnology, micro and nanofluidics with immunoreactions and electrochemical analytical methodologies is expected to produce major advances in this area and open up new opportunities not only from the scientific point of view but even from a market perspective preparing point-of-care devices and in-situ alarm systems. Given the rapid development, interest and progress made in this field, the examples compiled in this Special Issue are just a small sample of those expected to come in this amazing field which future growth and success will rely on the abilities of the researchers to continue innovating and collaborating to address the existing challenges and opportunities. In the near future, advances in fundamental knowledge of new nanomaterials along with a focus on practical applications in real-world systems will drive electrochemical immunosensors to breakthroughs in many fields of social and economical relevance. As a logical consequence of the incessant flow of impressive ideas and innovations it looks like this field has the horsepower to keep on advancing for the foreseeable future.