Modification and characterization of potential bioelectronic interfaces

In this dissertation, planar biocompatible dielectric and metal surfaces, modified with
self-assembling organic monolayers and functionalized gold nanoparticles are studied.
In the field of bioelectronics, adhesion and guiding of cells (especially neurons) on a
substrate is of great importance, and withal a hard challenge. Optimization and
engineering of properties of a carrier (biocompatible inorganic substrates) can
potentially improve the contact between cells and substrates, increase the survival rate
of cells and improve the signal transfer. Nowadays it is clear, that the cell interacts with
outer world via proteins, which, following the physical approach, interact with the
surface via electrostatic interaction. Unfortunately, in aqueous environment, proteins
responsible for the cell adhesion as well as most inorganic substrates bear a net negative
surface charge that leads to an electrostatic repulsion and, consequently, impairs
adhesion.
The use of functionalized organic molecules or inorganic nanoparticles allows
engineering the surface properties of various materials in order to facilitate the cell
adhesion. Therefore, in this dissertation, planar biocompatible dielectric and metal
surfaces modified subsequently with organic molecules, and functionalized gold
nanoparticles are characterized via an optimized surface potential analysis in
combination with other supporting techniques (e.g. ellipsometry, wetting angle and
SEM). Additionally, a setup for the deposition of molecular monolayers, including in-situ
cleaning and activation, accompanied by in-situ electronic analysis via capacitive and
microwave measurements is developed and tested. During this work, the deposition and
functionalization of AuNPs as well as a streaming potential/streaming current
experiment for the analysis of the surface potential of the substrates and layers were
improved and optimized.
Using especially the time- and pH-dependent analysis of the ?? potential, we can analyze
the various types of ‘simple’ (e.g. various biocompatible substrates, metallic layers,
graphene) and complex (e.g. molecular monolayers, functionalized gold nanoparticles)
interfaces and identify possible candidates for the modification of a given surface with
respect to their surface potential (e.g. organic molecules with different
functionalization). Finally, our extended analysis allows us to determine the stability of
a given surface and monitor the change of the surface potential due to the engineering
of a surface (e.g. via deposition of gold nanoparticles). In this dissertation, planar biocompatible dielectric and metal surfaces, modified with
self-assembling organic monolayers and functionalized gold nanoparticles are studied.
In the field of bioelectronics, adhesion and guiding of cells (especially neurons) on a
substrate is of great importance, and withal a hard challenge. Optimization and
engineering of properties of a carrier (biocompatible inorganic substrates) can
potentially improve the contact between cells and substrates, increase the survival rate
of cells and improve the signal transfer. Nowadays it is clear, that the cell interacts with
outer world via proteins, which, following the physical approach, interact with the
surface via electrostatic interaction. Unfortunately, in aqueous environment, proteins
responsible for the cell adhesion as well as most inorganic substrates bear a net negative
surface charge that leads to an electrostatic repulsion and, consequently, impairs
adhesion.
The use of functionalized organic molecules or inorganic nanoparticles allows
engineering the surface properties of various materials in order to facilitate the cell
adhesion. Therefore, in this dissertation, planar biocompatible dielectric and metal
surfaces modified subsequently with organic molecules, and functionalized gold
nanoparticles are characterized via an optimized surface potential analysis in
combination with other supporting techniques (e.g. ellipsometry, wetting angle and
SEM). Additionally, a setup for the deposition of molecular monolayers, including in-situ
cleaning and activation, accompanied by in-situ electronic analysis via capacitive and
microwave measurements is developed and tested. During this work, the deposition and
functionalization of AuNPs as well as a streaming potential/streaming current
experiment for the analysis of the surface potential of the substrates and layers were
improved and optimized.
Using especially the time- and pH-dependent analysis of the ?? potential, we can analyze
the various types of ‘simple’ (e.g. various biocompatible substrates, metallic layers,
graphene) and complex (e.g. molecular monolayers, functionalized gold nanoparticles)
interfaces and identify possible candidates for the modification of a given surface with
respect to their surface potential (e.g. organic molecules with different
functionalization). Finally, our extended analysis allows us to determine the stability of
a given surface and monitor the change of the surface potential due to the engineering
of a surface (e.g. via deposition of gold nanoparticles).