Developing biosensors for advanced medical diagnostics
Within the SAMBA project, imaging and spectroscopy were utilised to investigate electric properties of a variety of mutants of the blue copper proteins azurin and plastocyanin, assembled on gold electrode surfaces. Proximal probe analyses, characterised by the ability to manipulate matter at the nanometre scale, were carried out with high resolution under a variety of controllable environmental conditions. The topological structure of the self-assembled protein adlayers was examined by fluid-phase Atomic force microscopy (AFM), Scanning tunnelling microscopy (STM) and electrochemistry. A significant perturbation of the diffusive pseudo-azurin voltammetric signal was observed when nitrite reductase was added in micromolar concentrations. This contains a redox-active blue copper centre along with a non-blue enzyme-active copper centre, which can be covalently tethered to modified gold-electrode surfaces in configurations where direct electron transfer is possible. Based on this natural biological partner of pseudo-azurin, the coupling of electron transfer with substrate catalytic turnover can be utilised in the development of an efficient sensor for nitrite. Collaborative links are being sought with industrial partners in order to translate the accumulated knowledge into a robust commercial application.
