DISSERTATION

_____________________________________________________________ Results and Discussion
3.3.3 Reproducible recycling of Au modified surfaces within seconds
Parts of this section are in the manuscript that is in preparation: “Fully potential-controlled
preparation of DNA chips” with coauthors: D. Jambrec, Y. U. Kayran and W. Schuhmann.
Electrochemical SAM desorption has a wide range of applications including cleaning of gold
electrodes to allow reusability of the surface (i.e. sensor recycling) 18 or modifying surface
wettability and fabrication of mixed SAM layers 96,97 . The interest for electrochemical
desorption of SAMs in this thesis is the development of a very fast and efficient desorption
approach that allows cleaning of individual electrodes on a chip prior to their modification with
appropriate DNA strands. Since DNA and alkylthiols that are used for surface modification
have different anchoring molecules, where alkylthiols form only a single Au-S bond and the
DNA forms six bonds Au-S from three disulfides within the anchoring site (see Section 3.4.1),
we tested the efficiency of the developed potential pulse-assisted desorption approach on both
types of molecules.
Figure 3.41. Removal of DNA from the electrode surface (2 mm gold electrode). a) EIS
and b) CV were used for the characterization of the surface at each step. DNA
immobilization: incubation for 2 min in 1 µM DNA solution (10 mM PB, 450 mM K2SO4).
Potential pulse-desorption: 0.9/-0.9 V vs. Ag/AgCl/3 M KCl, 10 ms pulse duration, 30 s.
Measurements were performed in 10 mM PB, 20 mM K2SO4 containing 5 mM of
K3[Fe(CN)6] and K4[Fe(CN)6]; CV at 100 mV/s scan rate.
3.3 Importance of controlling the surface 81