In addition, the EdRox project was designed to explore specifically the possibilities of fluorescence detection to monitor the activity of redox enzymes. It is well-know that such methods offer unmatched detection sensitivity, an aspect that is key to the development of successful biosensor applications based on redox enzymes. The EdRox project was highly instrumental and successful in developing and validating this novel approach that we now call the FluRedox principle. First of all, ultimate sensitivity was achieved and demonstrated by monitoring the catalytic activity of a single redox enzyme. Secondly, pilot experiments were performed in collaboration with three SME's that established the viability of the FluRedox principle in a number of biosensor applications, demonstrating high sensitivity and versatility. Practical applications that were implemented are the testing of the efficacy of anti-biotics, the measurement of nitrogen-mineralization of soil, and the monitoring of oxygen in industrial cooling waters. Prior to, and partially in the course of this project, patent applications were filed by one of the EdRox partners. A spin-off, 'KeySense', will be activated as soon as the contacts with industry mentioned above, lead to commercial activities.
The interfacing of bio-molecules to nanostructures, electrode surfaces and/or optical components constitutes the new discipline of bioelectronics, based on electron transfer between a protein and an electrode, which can be monitored by amperometric techniques. The integration of bio-molecules with electronics has strong potential for applications in a variety of functional devices, ranging from biosensors to solar fuel cells.
Typically, a bio-electronic device consists of an assembly of redox-active proteins on a conducting electrode such that the electron transfer process can be transformed into a measurable output signal by electronic transduction. The EdRox project has shown that direct coupling of the protein to an electrode by surface assembly offers important advantages from a technological point of view in terms of efficiency, reactivity, specificity, selectivity and sensitivity. Important factors that were explored in this project were: optimization of electrical contact, biocompatibility of the interface, and control over alignment and orientation of the surface-assembled bio-molecules. EdRox was successful in improving protocols for immobilization and mono-layer formation of bio-molecules on electrode surfaces. Furthermore, it was shown to be advantageous to engineer a linker or an electron-relay unit between the electrode and the bio-molecules as a conduit for electrons, improving electrical contact.