FUNCTIONAL CONDUCTIVE NANOCARBONS AND DIAMOND

THIN FILMS FOR ULTRA-SENSITIVE BIOSENSING APPLICATIONS

Prof. Robert Bogdanowicz

Dept. Metrology and Optoelectronics, Electronics, Telecommunications and Informatics,

Gdansk University of Technology, Poland; e-mail: rbogdan@eti.pg.edu.pl

Abstract: The most common material for electrodes in electrochemical sensing systems is gold or other noble metals, as these can be applied though physical vapor deposition. However, they are optically opaque or highly absorptive, thus cannot be used as the optically functional working electrode. Among the most interesting novel, optically transparent candidate materials for electrochemical analyses are (i) boron-doped diamond (BDD), (ii) high surface area carbon nanowalls (B:CNW) and (iii) fluorine-doped tin oxide or tin-doped indium oxide.

The novel B:CNW and BDD biosensing surfaces are grown by the microwave plasma-assisted CVD. The effect of boron incorporation not only enhances the electrical and electrochemical properties but also influences the structure of CNW by changing it from the maze-like to a heterogeneous distribution of nearly straight walls [1] (Fig. 1A). B:CNW or BDD could be nanostructured to achieve microelectrodes (Fig. 1B). Both BDD and B:CNW electrochemical electrodes show outstanding electrochemical properties, such as high standard rate constant (k°), low peak-to-peak separation value (ΔE) for the oxidation and reduction processes of the [Fe(CN)₆]^3−/4− redox system, and low surface resistivity. For these reasons, B:CNW are successfully applied for the primary nucleic acid bases detection [1] or paracetamol determination [2], while BDD electrodes are used for the development of a rapid-response ultrasensitive biosensor for influenza virus detection [3] and for stress marker - Isatin determination [4]. Taking into consideration achieved properties, the studied electrodes could be applied in the point-of care (PoC) diagnostic systems, which are currently one of the fastest growing areas of the health care. Diamond based sensors are still underutilized in POCs, while they exhibit much higher sensitivity and the same or lower costs than currently used devices.