Measurement of analyte concentrations and gradients near 2D cell cultures and analogs using electrochemical microelectrode arrays: fast transients and physiological applications
This PhD research relates to the design,
fabrication, characterization, and optimization of on-chip electrochemical
microelectrode arrays (MEAs) for measurement of transient concentrations and
gradients, focusing on fast transients and physiological applications. In
particular, this work presents the determination of kinetic mechanisms taking
place at an active interface (either physiological or non-physiological) in
contact with a liquid phase using the MEA device to simultaneously estimate the
concentration and gradient of the analyte of interest at the surface of the
active interface. The design approach of the MEA device and the corresponding
measurement methodology to acquire reliable concentration information is
discussed. The ability of the MEA device to measure fast (i.e., in sub-second
time scale) transient gradients is demonstrated experimentally using a
controllable diffusion-reaction system which mimics the consumption of hydrogen
peroxide by a 2D cell culture. The proposed MEA device and measurement
methodology meet effectively most of the requirements for physiological applications
and as a demonstration of this, two physiological applications are presented.
In one application, the MEA device was tailored to measure the hydrogen
peroxide uptake rate of human astrocytes and glioblastoma multiforme cells in
2D cell culture as a function of hydrogen peroxide concentration at the cell
surface; the results allowed to quantitatively determine the uptake kinetics
mechanisms which are well-described by linear and Michaelis-Menten expressions,
in agreement with the literature. In the other application, further
customization of the MEA device was realized to study the glucose uptake
kinetics of human bronchial epithelial and small cell lung cancer cells, these
latter with and without DDX5 gene knockdown; the results allowed to distinguish
mechanistic differences in the glucose uptake kinetics among the three cell
lines. These results were complemented with measurements of glycolytic and
respiration rates to obtain a bigger picture of the glucose metabolism of the
three cell lines. Finally, additional applications, both physiological and
non-physiological, are proposed for the developed MEA device.
Funding
NSF Nanobiosensing Program Grant #1403582
Colciencias Call #529
Colombia-Purdue Institute for Advanced Scientific Research