Electrochemical contributions: Rudolf Brdička (1906–1970)

Abstract

Rudolf Brdička (Figure 1) was a Czech physical chemist and electrochemist, particularly known for his research on biomedical applications of polarography.

Brdička was a pupil and later a collaborator of Prof. Jaroslav Heyrovský (the inventor of the polarographic method and recipient of the Nobel Prize in 1959). Following his studies on polarography performed with Heyrovský, Brdička devoted all his scientific career to the use of polarography for different electroanalytical applications. Since at that time polarography was used for electrochemical analysis of small organic redox molecules and particularly for the detection of various inorganic cations and their complexes, Brdička studied the electrochemistry of cobalt cations (Co³⁺). While the Co³⁺ polarographic wave was following the expected redox behavior similar to other polarographic metal ion reactions, surprisingly very unusual polarographic waves were observed in the presence of some proteins. The observed phenomenon was explained as a catalytic redox process that involves complex formation between Co³⁺ cations with thiol (-SH) groups in the protein backbone. The polarographic waves were named Brdička waves. The exact mechanism, which involves two catalytic processes proceeding at different potentials, was elucidated in detail later (B. Raspor, J. Electroanal. Chem. 2001, 503, 159–162). It was shown that the electrochemical process includes the redox process of the thiol-complex of Co³⁺ and then catalytic reduction of H⁺ cations and H₂ evolution at more negative potentials, thus resulting in double polarographic waves. The observed waves were used as a very sensitive indication of proteins (note that it was a catalytic process) and the waves were specific to different kinds of proteins (note that they were dependent on the presence of thiol groups in the proteins). The Brdička waves were used in the analysis of protein-biomarkers of cancer and other health problems over several decades (Figure 2).

Presently, the polarographic analysis is not used and the Brdička waves have only historic interest. Notably, the Brdička waves originate from the redox processes of thiol groups in the peripheral lysine residues, thus is not related to the redox transformations of enzyme active centers, which are important for various biosensor and bioelectronic applications.

The author declares no conflict of interest.