Abstract
Cell sorting is important to biology research and the manufacture of cell-based therapeutics.
State-of-the-art techniques: Fluorescence and Magnetic-activated cell sorting (FACS/MACS) and
density-gradient centrifugation each have limitations in their throughput, efficiency, and technical
applications. The antibody labels required for FACS or MACS are an intermediate whose cytotoxicity
inhibits the safety compliance of cell-based pharmaceutical products.
This work’s objective is to advance the design of an alternative technique based upon
Dielectrophoresis (DEP). DEP does not require labelling, rather differences in the inherent
electrophysiology of the cells. This work used a 3D-electrode geometry (3D-DEP) achieving cell
capture of 93 % at 10,000 cells/s, and 55 % at 328,000 cells/s. These efficiencies are greater than
FACS, and throughputs greater than FACS or MACS making DEP sorting the most time-efficient
method.
To promote adoption of DEP cell sorting in the pharmaceutical industry, a novel drug delivery
platform, derived from enucleated cells, was analysed using DEP. DEP separation of the enucleated
cells was demonstrated from their parental stem cells. This is impossible with label-activated
techniques as the desired product and parental cells possess identical surface markers.
DEP analysis was performed on research cell lines to understand the electrophysiological changes of
cells after chemical fixation or tuberculosis infection, to establish DEP sorting in biosafety level 3
labs. Analysis was conducted but the limited range of cells raised further questions over the
differences between morphologies.
Electroosmotic flow (ACEOF) was explored for the concentration of unknown bodies, with
applications in spectrometry, and as an alternative to time-consuming ultracentrifugation of
nanoparticles. The first combined ACEOF and DEP device was produced to concentrate particles for
later DEP electrodes, improving DEP efficiency. When the 3D-DEP approach was then applied to
ACEOF, up to 62 % of latex microparticles were extracted. This could be the basis of an alternative
electrokinetic-based filtration system.