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_________________________________________________________________ Aims of the Work<br />
This thesis focuses on the development of a new strategy for the gold surface modification by<br />
thiolated molecules that will enable for a controlled immobilization of molecules, regardless of<br />
their charge in a fast manner. The main envisaged application of the proposed strategy is in the<br />
production of DNA chips as means for overcoming limitations in the development of point-ofcare<br />
devices.<br />
The initial part of this work focuses on understanding the processes occurring at the interface<br />
during surface modification, taking into consideration the interdependence of physico-chemical<br />
properties of the investigated molecules, electrode polarization and the surrounding solution,<br />
with the goal of finding strategies to improve the kinetics and the reproducibility of immobilization<br />
of both intrinsically charged molecules, such as DNA, and uncharged molecules, such<br />
as alkylthiols. The influence of potential pulses on the surface modification is explored as a<br />
new strategy to obtain high-quality DNA sensing platforms, and the advantages of this approach<br />
over the standard passive approach are investigated. Moreover, this work focuses on<br />
implementing the developed strategy into the fabrication of a DNA array for multiple probe<br />
detection. The potential pulse-assisted cleaning of Au modified surfaces is also investigated<br />
with the aim to regenerate the Au surfaces within a very short time, while not causing any<br />
damage to the electrode surface. The last part of the thesis focuses on the implementation of the<br />
newly established surface modification strategy into the development of a new DNA sensing<br />
platform based on the signal amplification via enzyme-conjugated intercalating compound as a<br />
hybridization indicator. Challenges related to the use of intercalators are mainly reflected in the<br />
need to prevent non-specific adsorption to obtain a desired contrast between ss- and dsDNA.<br />
Therefore, the ability of the developed surface modification strategy to create high-quality DNA<br />
sensing surfaces for this application is evaluated.<br />
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