Abstract:
This thesis describes the development of two different methods to produce an optimal
platform for immobilizing biological matter (cells and proteins). Firstly, transparent
indium tin oxide (ITO) microelectrodes were fabricated and used to immobilize
suspended NIH 3T3 fibroblast cells by positive dielectrophoresis (DEP). The ITO
electrodes facilitated microscopic observation of immobilized cells as compared to
metallized electrodes. DEP was used to capture arrays of individual cells and small cell
clusters within a microfluidic network. The extent of cellular immobilization (no-cell,
single-cell, or multiple-cell capture) directly correlated with the applied voltage and
inversely with the flow velocity. Specific conditions yielding predominantly single-cell
capture were identified. The viability of immobilized cells was confirmed using
fluorescence microscopy.
In the second method, silicon microtechnology was used to make silicon microarray
sector slides for facilitating high accuracy protein interactions and identifications.
Photolithography and anisotropic chemical etching was used for creating pyramid-like
array structures in each sector, to increase the sector surface area and hence the
concentration of the reactant. The silicon microarrays were coated with different
dielectric films to investigate if they improve the presence and relative abundance of
specific variants of key signaling molecules. The microarray structures were also
modified with a chemical surface coating: 3-metcaptopropyltrimethoxysilane (MPTMS).
Competitive binding assays were then used to test the protein binding accuracy and
sensitivity of the silicon based microarrays. Native silicon and dielectric layer
microarrays produced poor protein molecule capture during Reverse Phase Antibody
process. The presence of MPTMS was found to improve the extent of protein
immobilization, thereby improving characterization of immobilized proteins on
microarray structures.
