Page 37 - ASME_NEMB_2016_Program

TRACK 3 TRACK 3 Technical Program

electrical resistances originated from the length difference between the graphene nanopetals. Guided cell movement was also observed along the
diameter of the circle and the length of any parallel chord of the bottom fibers. Terminating the graphene petals with hydrogen and oxygen did not
circular chamber. Marotta et al., reported a direct EF stimulation device with affect the attachment frequency of the cells. This attachment is most likely
a 6-well plate, but the EF was not uniform and the cells were exposed to caused by the ridges on nanopetal, which cells use as mechanical anchors.
electrolysis products. Further understanding the mechanisms of this interaction and improvising
this method can be very useful to design novel tissue engineering and re-
To address this challenge, we designed a three-dimensional (3D) polymeric generative medicine strategies.
insert to apply a uniform EF at the bottom of common tissue cultureware
such as a multi-well plate well or a petri dish. By using 3D computer aided 5:20pm Understanding the Effects of Variable Biaxial Stretch
design approach to equalize the electric resistance throughout the device, on NIH/3T3 Fibroblasts
a uniform EF with a coefficient of variance (CV) of 1.2 % can be created with
high stimulation area percentage of at least 69.5%, two fold increase com- Technical Presentation. NEMB2016-5998
pared to current reported electrical stimulation device, in a 35 mm petri dish
or a 6-well plate well. The design principle can be adjusted to easily scale
up the device for bigger petri dishes and increases the effective stimulation Hamed Ghazizadeh, North Carolina Agricultural and Technical
area percentage further. In particular NIH/3T3 mouse embryonic fibroblast State University, Greensboro, NC, United States, Soodeh B Ravari,
cells were used to validate the performance of the 3D designed Poly(methyl Dennis R LaJeunesse, University of North Carolina at Greensboro,
methacrylate) insert in a circular-shaped 6-well plate. Greensboro, NC, United States, Shyam Aravamudhan, North Car-
olina Agricultural and Technical State University, Greensboro, NC,
In principle, the inserts can be mass-produced by injection molding and United States
easily adapted by common laboratories without microfabrication capability
in the future. Taking the advantage of high stimulation area of our device, Introduction: Cells, especially those of fat and muscle, are constantly sub-
the cell yield is increased and large amount of cellular products can be re-
covered which is highly beneficial for downstream biochemical analysis. Our jected to mechanical stress during various physical activities. Understanding
the role of the physical activity and the resultant mechanical stresses are
polymeric inserts can be a general tool for cell-EF studies as well as electri- critical for various cellular activities in the body, such as controlling cell
cal pacing in tissue engineering and electrical stimulation for biotechnology growth, migration, differentiation, apoptosis, and wound repair. In order to
applications.
isolate the effects of different parameters, current studies have considered
applying regular (waveform) forces, which may not be able to mimic in vivo
5:00pm Cells Interact With Graphene Nanopetals Coated On conditions. In this study, we demonstrated the effects of 25%, 50%, and 75%
Carbon Fibers variability in amplitude of applied mechanical forces (5-10% strain) on cell
response by comparing it with the regular waveform forces to understand
Technical Presentation. NEMB2016-5979 whether it is possible to control cell functions through irregular mechanical
forces.
Soham Ghosh, Purdue University, Boulder, CO, United States,
Guoping Xiong, Timothy Fisher, Bumsoo Han, Purdue University, Methodology: We report on the cellular and mechanistic response of NI-
H/3T3 fibroblastic cells cultured on silicone flexible membranes subjected
West Lafayette, IN, United States to cyclic biaxial stretch using a custom-built stretching system, as previously
described (Karumbaiah et al. 2012). The membrane was plasma-treated
Interaction of biological cells with synthetic materials is an important re- and Collagen coated to increase cell adhesion. In this work, the viability
search area in tissue engineering and regenerative medicine. As a prom- and morphological changes at the cell surface were studied in response to
ising emerging biomaterial candidate, graphene and its derivatives show cycle-by-cycle variability in amplitude of the applied force. In order to better
wide range of mechanical, electrical and optical properties tunable to a high mimic in vivo, the cell responses were studied at 5%, 7.5% and 10% strain
precision. Specifically, 2D single-layer graphene (SLG), few-layer graphene (low stretching magnitudes) while keeping the frequency constantly at 0.05
(FLG) and 3D nanostructures have been the focus of much recent research s-1 and being stretched for 6 hours and 24 hours.
because of their unique properties. Implementing the capabilities of this
versatile material with biological cells and tissues may have potential to Results: The results indicate that cell proliferation increased slightly about
advance tissue engineering and regenerative medicine. However the inter- 5-15% while showing no significant change in cell viability (only 1-3% change).
action of cells with graphene based materials remains challenging. Limited However, proliferation decreased slightly for variable amplitude (up to 6%). In
success has been reported for cell culture in graphene environment specific both cases (regular and irregular waveforms), the spreading factor increased
to neural cells and stem cells. But generally large class of cell types do not significantly by about 25-50%, which indicates the role of actin filament
adhere or respond to graphene based material easily unless significant response to mechanical forces. Additionally, cells tended to migrate to the
chemical modifications are performed, which have their own limitations. As center and corners of the membrane due to the shear stress resulting from
an advancement to circumvent this technical limitation, we report the strong media movements.
interaction of biological cells with graphene nanopetals (GPs) grown on cy-
lindrical carbon fibers.
Conclusion: Overall, low stretching magnitudes and low frequencies, which
are closer to that of in vivo, have no considerable negative effects on the
Commercial carbon fiber tows (YSH-60) was used as the substrate to grow cells’ viability, while cell proliferation increased considerably which makes it
GPs through microwave plasma chemical vapor deposition (MPCVD). As the possible to control fibroblast’s proliferation rate through exposure time and
model system graphene nanopetals were grown on carbon fibers. As a re- strain percentage. Cells were also found to respond negatively to variable
sult, GPs grow approximately 500 to 800 nm out from the carbon fiber sur- cyclic forces. Lastly, the resultant shear stress in most of the biaxial systems
face, with a typical width of a single, unwrinkled 2D petal ranging from 100 is inevitable and could be the driving force for cell migration.
nm to 900 nm, and a petal thickness of a few nanometers, exhibiting distinct
surface roughness. On contrast, the bare carbon fiber surface is relatively
smooth with visible nanoscale grooves. The fibers (bare/ GP) were attached
on partially polymerized type 1 collagen gel. After complete polymerization, 3-5
cells were cultured on this platform. VASCULAR AND BONE ENGINEERING

Cells could be found attached on the GP coated fibers but did not attach on
bare fiber (control). Fibroblast, epithelial and endothelial cells show similar Hidalgo 4:00pm - 5:40pm 37
behavior. Time lapse imaging revealed that cells attach on the fibers by cre-
ating blebs and protrusion, the scale of which is compared to irregularities of Session Organizer: Hyunjoon Kong, University of Illinois At Urba-