Big molecules in a small space : Macromolecules in Micro-confinement 陳陳陳 ([email protected]) 陳陳陳陳陳陳陳陳陳陳陳陳陳陳陳陳陳 Entropy
Jan 02, 2016
Big molecules in a small space : Macromolecules in Micro-confinement
陳彥龍 ([email protected])
中央研究院物理研究所和應用科學中心
Entropy
Polymers in Biology
Nuclei are stained blue with DAPIActin filaments are labeled red with phalloidin Microtubules are marked green by an antibody
Endothelial Cell
F-Actin
DNA
Diameter: 7nm Persistence length : ~10 m
3.4 nm
Persistence length : ~ 50 nm
Organ Printing
Mironov et al. (2003)
Boland et al. (2003)
Forgacs et al. (2000)
Organ printing and cell assembly
• Cells deposited into gel matrix fuse when they are in
proximity of each other
• Induce sufficient vascularization
• Embryonic tissues are viscoelastic
• Smallest features ~ O(mm)
• High throughput
• Low material cost
• High degree of parallelization
• High sensitivity
Advantages of microfluidic chips
Efficient device depends on controlled transport
Channel dimension ~ 10nm - 100 m
40m
Fluid plug reactor from Cheng group, RCAS
Microfluidic washing machine, Schwartz group
Confining Macromolecules
Theory and simulations help us understand dynamics of macromolecules
Physics of confined polymers
Expt
H H
Quasi-2D Quasi-1D K. Jo, D.C. Schwartz
Flow Direction
760 nm (w) x 160 nm (h)
1cm
How does macromolecule dynamics change as confinement becomes smaller ?
What do we do ?
Molecular Dynamics
- Model atoms and molecules using
Newton’s law of motion
Monte Carlo
- Statistically samples energy and configuration
space of systems
Cellular Automata
- Complex pattern formation from simple computer instructions
Large particle in a granular flow
Polymer configuration sampling
Sierpinksi gasket
-If alive, dead in next step
-If only 1 living neighbor, alive
Our Research
2 nm
3.4 nm
1 nm 10 nm 100 nm 1 m 10 m 100 m
persistence length p radius of
gyration
Rg
contour length L
Atomistic
Coarse graining
MicrochannelsNanochannels
Capture essential physics : Polymers, Solvent, Confinement
Flow timescale ~ minutes => coarse-grained model
Calculations are based on physics.
Without physics, simulations are just numbers.
Computer simulations allow us to perform extremely complex computation to imitate the real world and study
microscopic and macroscopic systems.
Theory and computation can make predictions before the experiment is (can be) done.
Calculations can guide/confirm experiments / resolve controversies / predict new phenomenon.