High-Throughput Synthesis
and Electrochemical Screening
of a Library of Modified Electrodes for NADH Oxidation
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Abstract
We report the combinatorial preparation and high-throughput
screening
of a library of modified electrodes designed to catalyze the oxidation
of NADH. Sixty glassy carbon electrodes were covalently modified with
ruthenium(II) or zinc(II) complexes bearing the redox active 1,10-phenanthroline-5,6-dione
(phendione) ligand by electrochemical functionalization using one
of four different linkers, followed by attachment of one of five different
phendione metal complexes using combinatorial solid-phase synthesis
methodology. This gave a library with three replicates of each of
20 different electrode modifications. This library was electrochemically
screened in high-throughput (HTP) mode using cyclic voltammetry. The
members of the library were evaluated with regard to the surface coverage,
midpeak potential, and voltammetric peak separation for the phendione
ligand, and their catalytic activity toward NADH oxidation. The surface
coverage was found to depend on the length and flexibility of the
linker and the geometry of the metal complex. The choices of linker
and metal complex were also found to have significant impact on the
kinetics of the reaction between the 1,10-phenanthroline-5,6-dione
ligand and NADH. The rate constants for the reaction were obtained
by analyzing the catalytic currents as a function of NADH concentration
and scan rate, and the influence of the surface molecular architecture
on the kinetics was evaluated