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@PHDTHESIS{Milos:892864,
author = {Milos, Frano},
title = {{T}hree-{D}imensional {P}olymeric {T}opographies for
{N}eural {I}nterfaces},
volume = {72},
school = {RWTH Aachen},
type = {Dissertation},
address = {Jülich},
publisher = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
reportid = {FZJ-2021-02403},
isbn = {978-3-95806-586-4},
series = {Schriften des Forschungszentrums Jülich. Reihe Information
/ Information},
pages = {154 S.},
year = {2021},
note = {RWTH Aachen, Diss., 2021},
abstract = {Optimal integration of artificial interfaces with neural
tissue is critical to develop novel neural regeneration
scaffolds and neuroprosthetic implants. The topography of
the implantable device can promote nerve repair as it
affects neuronal growth via contact guidance. Furthermore,
topography may be utilized to establish a stable and close
contact with neural tissue required to improve the
electrical neuron-device coupling. The goal of this thesis
is to investigate the effects of nano- and microtopographies
on the development and adhesion of embryonic cortical
neurons. Three different polymer surfaces with topographical
structures of varying dimensions were used – namely,
i)anisotropic poly(N-isopropylacrylamide) (PNIPAAm)
nanogels, ii) isotropic OrmoComp nanopillars, and iii)
isotropic poly(3-hexylthiophene-2,5-diyl) (P3HT)
micropillars. Anisotropic PNIPAAm nanogel arrays induced
perpendicular alignment of major neurites and accelerated
axon development, resulting in an $~80\%$ increase in axon
length compared to either unstructured nanogel substrates or
glass substrates. Despite being relatively soft compared to
glass substrates, unstructured nanogels did not induce
substantial changes in neuronal morphology, indicating that
neurons “perceive” unstructured nanogels as equivalent
to glass. Isotropic OrmoComp nanopillars aligned neurites
along topographically dictated angles (0°, 90°) with
higher pillars (400 nm) confining neurites to a greater
extent compared to lower pillars (100 nm). Furthermore,
higher nanopillars promoted growth cone elongation and axon
development resulting in $~40\%$ longer axons compared to
flat substrates. A larger surface area of the nanopillars
was correlated with higher density of point contact
adhesions in the growth cone and a reduction in actin
retrograde flow rates, indicating a stronger coupling
between the growth cone and the substrate which enables
accelerated and persistent neurite outgrowth. Furthermore,
F-actin accumulations and paxillin-rich adhesions were
observed in the neuronal soma at nanopillars, indicating
that neurons form a close contact with the nanoscale
topography. Isotropic P3HT micropillars represent a
relatively soft interface that enables neurons to achieve a
close and conformal contact mediated by membrane
rearrangements. Optical stimulation of embryonic neurons
growing on photosensitive P3HT substrates induced a
significant increase in neurite outgrowth compared to
control substrates without deleterious effects on neuronal
viability. The effects of photostimulation were further
enhanced by the microtopography, indicating that P3HT acts
as an active interface with possible applications in
$\textit{in vitro}$ neural regeneration scaffolds.
Furthermore, MEAs functionalized with P3HT micropillars
yielded a significant increase in the signal-to-noise ratio
(SNR) compared to flat MEAs, indicating that micropillars
improve the cell-electrode coupling. Optical stimulation of
spontaneous network activity on P3HT-functionalized MEAs
induced neuronal firing and increased the firing rate.
Although the process was not fully reproducible, optical
excitation of P3HT interfaces provides a promising strategy
for modulating network activity in a non-invasive manner.},
cin = {IBI-3},
cid = {I:(DE-Juel1)IBI-3-20200312},
pnm = {524 - Molecular and Cellular Information Processing
(POF4-524)},
pid = {G:(DE-HGF)POF4-524},
typ = {PUB:(DE-HGF)3 / PUB:(DE-HGF)11},
urn = {urn:nbn:de:0001-2021122104},
url = {https://juser.fz-juelich.de/record/892864},
}