2 research outputs found
Electrochemical Patterning and Detection of DNA Arrays on a Two-Electrode Platform
We
report a novel method of DNA array formation that is electrochemically
formed and addressed with a two-electrode platform. Electrochemical
activation of a copper catalyst, patterned with one electrode, enables
precise placement of multiple sequences of DNA onto a second electrode
surface. The two-electrode patterning and detection platform allows
for both spatial resolution of the patterned DNA array and optimization
of detection through DNA-mediated charge transport with electrocatalysis.
This two-electrode platform has been used to form arrays that enable
differentiation between well-matched and mismatched sequences, the
detection of TATA-binding protein, and sequence-selective DNA hybridization
Artificial Metalloproteins Containing Co<sub>4</sub>O<sub>4</sub> Cubane Active Sites
Artificial
metalloproteins (ArMs) containing Co<sub>4</sub>O<sub>4</sub> cubane
active sites were constructed via biotināstreptavidin
technology. Stabilized by hydrogen bonds (H-bonds), terminal and cofacial
Co<sup>III</sup>āOH<sub>2</sub> moieties are observed crystallographically
in a series of immobilized cubane sites. Solution electrochemistry
provided correlations of oxidation potential and pH. For variants
containing Ser and Phe adjacent to the metallocofactor, 1e<sup>ā</sup>/1H<sup>+</sup> chemistry predominates until pH 8, above which the
oxidation becomes pH-independent. Installation of Tyr proximal to
the Co<sub>4</sub>O<sub>4</sub> active site provided a single H-bond
to one of a set of cofacial Co<sup>III</sup>āOH<sub>2</sub> groups. With this variant, multi-e<sup>ā</sup>/multi-H<sup>+</sup> chemistry is observed, along with a change in mechanism at
pH 9.5 that is consistent with Tyr deprotonation. With structural
similarities to both the oxygen-evolving complex of photosystem II
(H-bonded Tyr) and to thin film water oxidation catalysts (Co<sub>4</sub>O<sub>4</sub> core), these findings bridge synthetic and biological
systems for water oxidation, highlighting the importance of secondary
sphere interactions in mediating multi-e<sup>ā</sup>/multi-H<sup>+</sup> reactivity