Overview: This collaborative research program will explore neural stem cell (NSC) biomechanics during
differentiation. An interdisciplinary approach will be implemented, coupling stem cell biology and materials engineering with graphene physics. In the course of the project the mechanical forces applied by
NSC at different stages of their evolution will be measured with highest resolution and correlated to
downstream effects. In order to achieve required resolution of the force measurements, we propose a new
method. Large area graphene films will be deposited on (to overlay conformally) the surface of interest
and provide the local strain via a special correlation technique: two graphene Raman lines, ωG and ω2D,
will be collected in a confocal scanning microscopy, mapping the whole surface, including where NCS
growth and development happens. Then the strain will be extracted from the specific correlation
transformation of ωG and ω2D channels. We have identified the following major research objectives:
Objective 1: Investigate methods for integrating 2D graphene layers with NSC compatible substrata.
Objective 2: Develop methods to optimize Raman signal from graphene layers integrated with living cells.
Objective 3: Using Raman spectroscopy enabled strain field analysis, elucidate the mechanical forces
exhibited by NSCs during growth cone morphogenesis, and further correlate growth cone biomechanics
to downstream effects on neuronal differentiation.
Intellectual Merit: During neuronal differentiation, NSCs extend neuritis, which are known to interrogate
the growth surface. These neuritis are capable of both applying forces to the surface and sensing specific
features on the surface. These surface based cues have been implicated in downstream signaling processes,
specifically those that lead to differentiation. Studying these forces, however, is a challenging task, as
current methods rely on microscopy techniques that use point “targets” for imaging to track material
deformation. These methods, while inherently useful, do not fully represent the continuum field of forces
that cells may exhibit, at required sub-micron resolution, nor are they useful with non-ideal surfaces.
To study the biomechanics of NSC differentiation, we will develop a new, non-invasive, continuum forcestrain field measurement technique based on direct conversion of local Raman spectra into biomechanical
data. This method, already used for graphene inorganic samples, will be explored, adjusted and applied to
the surfaces of interest: polyacrylamide films, polystyrene/silica colloidal crystals and hydrogels, glass
slides, all uncoated (as a control surface) and coated with graphene. This range of substrates will allow us
to investigate the role of surface roughness/topography, stiffness and biocompatibility during growth cone
development and synaptic targeting in vitro. We will use known chemical mediators of cell adhesion and
differentiation, in the form of extracellular matrix proteins, to examine in parallel the chemical influences
on cell mechanics.
Broader Impacts: Our program will address critical challenges that must be overcome to advance the
understanding of dynamic cell division processes that ultimately lead to neuronal differentiation. In the
near term, the proposed research is expected to advance the frontiers of multiple disciplines in the areas
of neuronal cell biology and health care.
Integration of research and education is a high priority, and this interdisciplinary research program will
provide an excellent opportunity for graduate and undergraduate student training, both from a research
perspective, as well as during dissemination of their results to the greater scientific and public community.
Two graduate students, will be recruited to work in this collaborative project, and will be required to TA at
least one semester during their education to enhance their experience. The PIs have a long history of
successful outreach in Pennsylvania and across the nation, involving multiple venues at Lehigh: at local
K-12 schools (Palisades High School, Moravian Academy), a school children development National
facility (the DaVinci Discovery Center), a senior citizens enrichment program (SAGE), lectures in the
Lehigh Summer Microscopy School, STEM enhancement programs via local Community Colleges
(NCCC, LCTI and LCCC) and local Kutztown University, an outreach summer camp (OptoCamp), and
REU and GAAN programs. For industrial outreach to 100+ companies in PA and beyond the Lehigh
Liaison programs will be used.
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