A mong the various types of nanomaterials that have been developed, nanostructured metal oxides (NMOs) have recently aroused much interest as immobilizing matrices for biosensor development ( Figure 1) [1][2][3][4][5][6][7][8][9]. Nanostructured oxides of metals such as zinc, iron, cerium, tin, zirconium, titanium, metal and magnesium have been found to exhibit interesting nanomorphological, functional biocompatible, non-toxic and catalytic properties. Th ese materials also exhibit enhanced electron-transfer kinetics and strong adsorption capability, providing suitable microenvironments for the immobilization of biomolecules and resulting in enhanced electron transfer and improved biosensing characteristics. Various morphologies of NMOs have been obtained using a variety of methods, including soft templating for the preparation of nanorods and nanofi bers [10], sol-gel methods for the production of three-dimensional (3D) ordered rough nanostructures [6,11], radiofrequency sputtering for rough nanostructures [4] and hydrothermal deposition for nanoparticles with controlled shape [12]. All of these NMOs have been reported to have potential applications in biosensors. Recently, the optical, electrical and magnetic properties of NMOs have been reported to be enhanced through the incorporation of nanoparticles of conducting or semiconducting materials such as carbon nanotubes, graphene, gold and silver, as well as quantum dots of various semiconductors, with advantages for improved biosensor characteristics [13][14][15][16]. It is expected that the judicious application of an NMO may lead to the fabrication of novel biosensing devices with enhanced signal amplifi cation and coding strategies for bioaffi nity assays and effi cient electrical communication with redox biomolecules/ enzymes that may address future diagnostic needs.Th e unique properties of NMOs off er excellent prospects for interfacing biological recognition events with electronic signal transduction and for designing a new generation of bioelectronics devices that may exhibit novel functions. Th e controlled preparation of an NMO is considered to play a signifi cant role in the development of biosensors. Eff orts are being made to explore the prospects and future challenges of NMOs for the development of biosensing devices and the evolution of new strategies for bioaffi nity assays and effi cient electrical communication. In this review, we focus on developments over the past fi ve years in NMO-based biosensors for clinical and non-clinical applications (Figure 2). Fundamentals of nanostructured metal oxides for biosensingAmong the various immobilizing matrices that have been developed, NMOs have exceptional optical and electrical properties due to electron and phonon confi nement, high surface-to-volume ratios, modifi ed surface work function, high surface reaction activity, high catalytic effi ciency and strong adsorption ability. For these reasons, NMOs have been utilized to increase the loading of biomolecules per Nanostructured metal oxide-based b...

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To manage the COVID-19 pandemic, development of rapid, selective, sensitive diagnostic systems for early stage β-coronavirus severe acute respiratory syndrome (SARS-CoV-2) virus protein detection is emerging as a necessary response to generate the bioinformatics needed for efficient smart diagnostics, optimization of therapy, and investigation of therapies of higher efficacy. The urgent need for such diagnostic systems is recommended by experts in order to achieve the mass and targeted SARS-CoV-2 detection required to manage the COVID-19 pandemic through the understanding of infection progression and timely therapy decisions. To achieve these tasks, there is a scope for developing smart sensors to rapidly and selectively detect SARS-CoV-2 protein at the picomolar level. COVID-19 infection, due to human-to-human transmission, demands diagnostics at the point-of-care (POC) without the need of experienced labor and sophisticated laboratories. Keeping the above-mentioned considerations, we propose to explore the compartmentalization approach by designing and developing nanoenabled miniaturized electrochemical biosensors to detect SARS-CoV-2 virus at the site of the epidemic as the best way to manage the pandemic. Such COVID-19 diagnostics approach based on a POC sensing technology can be interfaced with the Internet of things and artificial intelligence (AI) techniques (such as machine learning and deep learning for diagnostics) for investigating useful informatics via data storage, sharing, and analytics. Keeping COVID-19 management related challenges and aspects under consideration, our work in this review presents a collective approach involving electrochemical SARS-CoV-2 biosensing supported by AI to generate the bioinformatics needed for early stage COVID-19 diagnosis, correlation of viral load with pathogenesis, understanding of pandemic progression, therapy optimization, POC diagnostics, and diseases management in a personalized manner.

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