DISSERTATION

_____________________________________________________________ Results and Discussion
3.3.2 Formation of compact thiol SAMs within minutes
Data analysis was done based on discussions with Dr. Felipe Conzuelo and Dr. Arturo Estrada-
Vargas. Parts of this section were published in ref. 89 : “D. Jambrec, F. Conzuelo, A. Estrada-
Vargas, W. Schuhmann, ChemElectroChem 2016, 3, 1484-1489.” written by the author. Figure
adapted from ref. 89 .
A typical approach for a DNA sensor buildup is a two-step immobilization strategy, in which
initially a probe DNA is grafted on the surface and subsequently the electrode is covered by a
thiol SAM. Thiol passivation forces the grafted DNA to lift up and to obtain a more favorable
orientation for the hybridization process concomitantly removing unspecifically bound DNA
strands. Additionally, the blocking ability of the passivation step in the DNA sensor preparation
plays an important role in the efficiency of an envisaged DNA sensing scheme. It prevents
unspecific adsorption of undesired molecules employed in the detection scheme and determines
the signal of the negative control. Therefore, controlling of the blocking ability of the modified
surface is crucial for construction of very sensitive and reproducible DNA sensors.
3.3 Importance of controlling the surface 67