The use of nanowires, nano and micro needles in biomedical applications has
markedly increased in the past years, mainly due to attractive properties such as
biocompatibility and simple fabrication. Specifically, these structures have shown
promise in applications including cell separation, tumor cell capture, intracellular
delivery, cell therapy, cancer treatment and as cell growth scaffolds.
The work proposed here aims to study two platforms for different applications:
a vertical magnetic nanowire array for mesenchymal stem cell differentiation and a
micro needle platform for intracellular delivery.
First, a thorough evaluation of the cytotoxicity of nanowires was done in order
to understand how a biological system interacts with high aspect ratio structures.
Nanowires were fabricated through pulsed electrodeposition and characterized by
electron microscopy, vibrating sample magnetometry and energy dispersive X-ray
spectroscopy. Studies of biocompatibility, cell death, cell membrane integrity,
nanowire internalization and intracellular dissolution were all performed in order
to characterize the cell response. Results showed a variable biocompatibility
depending on nanowire concentration and incubation time, with cell death resulting
from an apoptotic pathway arising after internalization.
A vertical array of nanowires was then used as a scaffold for the differentiation
of human mesenchymal stem cells. Using fluorescence and electron microscopy, the
interactions between the dense array of nanowires and the cells were analyzed, as
well as the biocompatibility of the array and its effects on cell differentiation. A
magnetic field was additionally applied on the substrate to observe a possible
differentiation. Stem cells grown on this scaffold showed a cytoskeleton and focal
adhesion reorganization, and later expressed the osteogenic marker osteopontin.
The application of a magnetic field counteracted this outcome.
Lastly, a micro needle platform was fabricated through lithography and
electrodeposition, characterized using the previously mentioned techniques and
then evaluated as a vector for intracellular delivery. Fluorescence and electron
microscopy imaging were first performed to assess the biocompatibility, cell
spreading and the interface of the cells and the needles. Intracellular delivery of a
fluorescent dye was achieved via inductive heating of the needles, with the results
showing a dependency of delivery and cell survivability on the exposure time.
|Date of Award||Dec 2017|
|Original language||English (US)|
- Biological, Environmental Science and Engineering
|Supervisor||Jurgen Kosel (Supervisor) & Timothy Ravasi (Supervisor)|
- Cell Culture
- Magnetic Nanowires
- mesenchymal stem cells