Page 48 - ASME_NEMB_2016_Program

Technical Program TRACK 4

TRACK 4 NANO-PHENOMENA IN LIVING SYSTEMS they interact with the vesicle so as to provide novel designs of drug delivery
applications. Results have revealed that the RNTs are capable to trigger
local disturbance around the vesicle and therefore promote the vesicle
MONDAY, FEBRUARY, 22 translocation toward the RNTs. By investigating the translocation time and
driving forces required for RNTs to enter inside of the vesicle under various
rotation frequencies as well as the interaction energy between coated RNTs
4-1 and the vesicle, we have tuned the coating pattern of the ligands on the
PHYSICAL PROCESSES AND MECHANICS surface of RNTs to open a specified channel in the vesicle for promoting the
drug delivery. Our findings can provide useful guidelines for the molecular
design of patterned RNTs for controllable bio/inorganic interfaces and help
Bexar/Travis 9:30am - 11:00am establish qualitative rules for the organization and optimization of ligands on
the surface of desired drug delivery carriers.
On the other hand, cell-to-cell communications via the tunneling nanotubes
Session Organizer: Sulin Zhang, Penn State Univ, University Park, or gap junction channels are vital for the development and maintenance of
PA, United States multicellular organisms. Instead of these intrinsic communication pathways,
how to design artificial communication channels between cells remains a
9:30am Fluctuations in in-vitro experiments of cells on sub- challenging but interesting problem. Here we perform dissipative particle dy-
strates namics simulations to analyze the interaction between rotational nanotubes
(RNTs) and vesicles so as to provide a novel design mechanism for cell-to-
cell communication. Simulation results have demonstrated that the RNTs are
Keynote. NEMB2016-5950 capable of generating local disturbance and promote vesicle translocation
toward the RNTs. Through ligand pattern designing on the RNTs, we can
Vikram Deshpande, Cambridge Univ, Cambridge Cb21pz, United find a suitable nanotube candidate with a specific ligand coating pattern for
Kingdom forming the RNT-vesicle network. The results also show that a RNT can act
as a bridged channel between vesicles which facilitates substance transfer.
Complex bio-chemical processes attempt to maintain constant time-av- Our findings provide useful guidelines for the molecular design of patterned
eraged concentrations of a range of proteins within cells in a process RNTs for creating a synthetic channel between cells.
commonly referred to as cellular homeostasis. These chemical processes
typically cause fluctuations of the state of cells that depends on the ex- 10:20am Biophysical insights into the architecture of the nucle-
tra-cellular environment. We present a statistical mechanics view to model ar envelope
these fluctuations. First the probability of observing a cell in a particular state
is estimated in terms of the free-energy of that state using the basic idea
of Gibbs entropy. Next a model is presented to estimate this free-energy. Technical Presentation. NEMB2016-6076
The model includes stress-fiber reorganisation and the associated contrac-
tility by considering the energetics of the actin/myosin functional units that Mehdi Torbati, University of Houston, Houston, TX, United States,
constitute the stress-fibers. This model then used to elucidate the range of Tanmay Lele, University of Florida, Gainesville, FL, United States,
states over which the cell can fluctuate in a particular environment and the Ashutosh Agrawal, University of Houston, Houston, TX, United
probability of observing each of those states. Finally predictions are present- States
ed for a range of experimentally observed phenomena using this approach.
This includes: (i) the spreading of cells as a function of the stiffness and the The nuclear envelope is a barrier that surrounds the nucleus and consists of
substrate; (ii) durotaxis whereby cells tends to migrate guided by rigidity the inner nuclear membrane (INM) and the outer nuclear membrane (ONM).
gradients on substrates and (iii) differentiation of stem cells guided by the These two bilayers are uniformly spaced and fuse at the sites of nuclear
stiffness of substrates. pore complexes (NPC). How the spacing between the two bilayers and the
distance between nuclear pores are maintained, are however, not yet un-
10:00am Coarse-Grained Modeling of Cell Responses to Active derstood. Furthermore, the mechanism of pore formation and distribution of
Rotational Nanoparticle NPCs in nuclear envelope has not yet been investigated.

Technical Presentation. NEMB2016-5931 In this paper we study the effects of different mechanisms, including distrib-
uted loads on the membrane due to LINC complexes, protein-induced spon-
Xianqiao Wang, Liuyang Zhang, University of Georgia, Athens, taneous curvature, and the interplay between equilibrium in-plane tension
and transmembrane pressure, on the architecture of the nuclear envelope.
GA, United States Among all these possible mechanisms, our study reveals that the resting
tension of the membrane and the distributed load acting over the ONM due
Recent years have witnessed the explosive growth of interest in nanopar- to cytoskeleton are the main mechanical factors responsible for mainte-
ticles (NPs) with a wealth of biomedical applications since they are widely nance of the nuclear envelope architecture. Our data also suggests a simple
used as carriers to translocate drug molecules and useful materials into cell mechanism for formation of new pores regulated by the interplay between
interiors. A number of simulation suggested that the membrane translocation the resting tension and the external pressure of ~10-100 Pa on the ONM.
of anisotropic NPs is often accompanied by spontaneous and continuous
rotation of the NPs. Take the spontaneous rotation for example, the ligand 10:40am Mechanical stress directs metastatic-like dispersion
coated NPs with anisotropic patterns rotated to preferred orientation while
penetrating through the membrane. Similar behavior was observed for the and malignant transformation in cancerous microtissues
translocation of graphene sheets across the membrane. In the endocyto-
sis process of anisotropic NPs, the anisotropic NPs generally undergo a Technical Presentation. NEMB2016-6018
transient rotation during the wrapping process to minimize the free energy.
Different from the limited effect of spontaneous rotation of anisotropic NPs, Sulin Zhang, Penn State Univ, University Park, PA, United States,
the promoting effect of continuous NP rotation is ascribed to the enhanced Yao Zhang, Pennsylvania State University, University Park, PA, Unit-
membrane monolayer protrusion as well as exerts a shearing force to rup- ed States
ture the membrane. However, the fundamental mechanism of how a vesicle
48 responds to the active RNP remains poorly understood. Metastasis, the spread of cancer cells from the primary tumor to invade
On one hand, here we perform dissipative particle dynamics simulations to distant tissues and organs, is the leading cause of cancer mortality. Yet the
analyze the rotation frequencies, size, and coating patterns of the RNTs as
biophysical mechanisms regulating cancer metastasis have remained poorly