Massive integration of biosensors into design of Internet-of-Things (IoT) is vital for progress of healthcare. However, the integration of biosensors is challenging due to limited availability of battery-less biosensor designs. In this work, a combination of nanomaterials for wireless sensing of biological redox reactions is described. The design exploits silver nanoparticles (AgNPs) as part of the RFID tag antenna. We demonstrate that a redox enzyme, particularly, horseradish peroxidase (HRP), can convert AgNPs into AgCl in the presence of its substrate, hydrogen peroxide. This strongly changes the impedance of the tag. The presented example exploits gold nanoparticle (AuNP)-assisted electron transfer (ET) between AgNPs and HRP. We show that AuNP is a vital intermediate for establishing rapid ET between the enzyme and AgNPs. As an example, battery-less biosensor-RFID tag designs for H2O2 and glucose are demonstrated. Similar battery-less sensors can be constructed to sense redox reactions catalysed by other oxidoreductase enzymes, their combinations, bacteria or other biological and even non-biological catalysts. In this work, a fast and general route for converting a high number of redox reaction based sensors into battery-less sensor-RFID tags is described.

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In this study we have introduced a new sensitive and selective biosensor for the determination of cytochrome C (Cyt C) as a biomarker for cell apoptosis.

Studies of direct electron transfer (DET) between enzymes and electrodes, among other reasons, are aimed at designing the simplest and most efficient biosensor designs. This direction might become especially valuable for the widespread integration of biosensors in Internet-of-Things (IoT) networks. In this Minireview, the simplicity of the design of wireless biosensors based on DET is discussed. It can be concluded that DET allows construction of wireless biosensors, which require no or only a few semiconductor elements. Hopefully, some of these demonstrations will translate into competitive and useful devices strongly promoting biosensing in IoT networks.[a] Prof.