Lecture 10: 31/10 Flashcards
What is the most useful thing about uCP?
Helps us understand cell geometry (shape and size) and how its changed by its environment
It creates a precisely patterned regions for cells to attach, and controls size and geometry
What are examples of insights we can get from mircocontact printing?
- apoptosis increases and proliferation decreases on small patterns
- cortactin density is highest in adherent vertices
- Cell collections generally have largest stresses at the edge
Do cells have to spread on large surfaces to survive?
Yes, large surfaces allow cells to proliferate. Area influences cell survival
On small patterns apoptosis increases, proliferation decreases
What is the general challenge with uCP?
Generating the structure so that it does not fold
Challenges creating structure:
1. high resolution
2. well-ordered
3. consistent patterns
What are examples of natural templates used as masters?
Cotton candy and granulated sugar
(sugars and other water-soluble materials are continent for PDMS molding, as you can cure the PDMS, and then wash out the sugar)
How are colloidal crystals used to make patterns?
- Well-ordered crystal arrays create hexagonally spaced raised stamp points
- Offers non-binary stamp due to curved edge (can be pro or con)
- This is an example of bottom-up patterning
- place colloidal crystals on glass
- add pdms cast
- peel pdms
- pour expoxy resin, remove pdms
- coat with metal
What is an example of a bottom-up approach for patterning?
- Block copolymer which self-assemble at the nano-scale
- Feature size and density is regulated by the chemistry and physics of the copolymer rather than the deposition technique
- Limited to lines and dots with no control over geometry
What limits 3D printing?
- Larger size of printer resolution
- Molding off of 3D printed masters can cause chemical incompatibilities
How can contractility be measured using deformed pattern area?
- stress is highest at vertices, cell is pulling hardest at the corners (thus this is where the pattern is altered)
- can calculate total contractile work by looking at the change in area
How much work do benign or metastatic cells do? How does this help cancer diagnostics?
Pattern deformations reveal metastatic breast cancer cells work harder than benign cancer cells.
Smaller samples used, smaller experiments, which leads to more insight at a lower overall cost
How can we use AFM to measure rupture strength of DNA? How can we use the rupture strength of DNA to measure binding affinities?
- DNA is pulled by AFM
- However, if we can characterize the rupture strengths of DNA we wouldn’t need AFM we would just need calibrated DNA sensors with known rupture strengths
- This would allow us to know the binding affinities of fluorophores etc. thru miniaturization
- DNA is pre-defined and consistent
- this allows us to do many more force measurements at once
How can droplets be used to create rxns?
Two immiscible fluids (water and oil) create droplets which can be used for independent reactions for extremely cheap and high throughput
each droplet is a separate femtoliter microreactor
If electron movement is the electronics parameter, what is the mechanics parameter to minimize?
stress or strain
(put in known force -> displacement, put in known displacement -> force)
What are the types of stimulus used in microfluidic applications in cell mechanics?
a. shear stress
b. interstitial flow
c. stretching
d. stiffness gradient
e. confinement
f. force measurements
How can be mircofluidic shear be used in mechanosensing?
- Answering how much does the shear stress influence cells (aka how to cells respond)
- Faster, better approach to use microfluidics
- FLNa can impact a cells mechanosensing, as you apply increasing amount of microfluidic shear stress, we can look at how much the cell contractility changes for different amounts of FLNa
- more shear stress, larger contractility (A7 cells with FLNa contract in response to shear)
