DISSERTATION

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