Electrochemistry of certain Fe complexes in solution and on the surface of electrode

Jakub Věžník^1,2, Jakub Sopoušek^2,3, Martin Konhefr^1, Libuše Trnková^1, Karel Lacina^2

^1 Department of Chemistry, Faculty of Science, Masaryk University, Kamenice 5, Brno, Czech
Republic

^2 Central European Institute of Technology, Masaryk University, Kamenice 5, Brno, Czech Republic

^3 Department of Biochemistry, Faculty of Science, Masaryk University, Kamenice 5, Brno, Czech
Republic

jveznik@mail.muni.cz

^

Aminoferrocene is a simple derivative of ferrocene with one amino group attached directly to one of
its two cyclopentadienyl rings of ferrocene. The proximity (and conjugation) of the amino group
means that the basicity of the group is greatly influenced by the oxidation state of the Fe ion and
vice versa, the redox potential of Fe ion is changed upon protonation of the amine.^[1] This alone
leads to quite interesting electrochemical results, but we tried to leverage this behaviour by
modifying the original molecule with labile imine bond, that could be broken upon oxidation of Fe
ion in the molecule. We probed four imino derivatives (two with boronic acid in the ortho position
and two para derivatives) for their electrochemical behaviour and tested them on cell viability to
judge whether these could be used as ROS (reactive oxygen species) sensitive prodrugs. ^[2]

This contribution would also like to address how the surface of the electrode can sometimes
complicate electrochemical measurements, but also how the sensitivity to surface changes can be
employed in impedance based biosensing. Poly-L-lysine served as a base for modification of
electrodes and through several simple steps electrodes can be provided with antigen which can then
later bind our target analyte (usually antibody).^[3] Proteins, which are the most common target
analyte, are very diverse class of molecules, despite being made from the same building blocks.
While most proteins found in blood are of negative charge, notably antibodies (natural or
manufactured) often possess a slight positive charge to promote binding to negatively charged cell
structures and proteins. Depending on measuring conditions this charge can lead to erroneous
results, where the capture of analyte is unnoticed by the negatively charged ferrocyanide probe,
which is routinely used in immunosensing due to its stability and availability.^[4]


[1]  J. Věžník, M. Konhefr, L. Trnková, P. Skládal, K. Lacina, Electrochim. Acta 2019, 318,
534–541.

[2]  J. Věžník, M. Konhefr, Z. Fohlerová, K. Lacina, Journal of Inorganic Biochemistry 2021, 224,
111561.

[3]  J. Sopoušek, J. Věžník, P. Skládal, K. Lacina, ACS Appl. Mater. Interfaces 2020, 12,
14620–14628.

[4]  J. Sopoušek, J. Věžník, J. Houser, P. Skládal, K. Lacina, Electrochimica Acta 2021, 388,
138616.