Cell Patterning in Microfluidic Devices Combined with Micro-Contact Printing

Angel M. Olivera-Torres Author

08/03/2020 Added

29 Plays

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Surface chemistry and fluid mechanics come together to deposit live-cells onto treated surfaces for extracellular matrix manipulation.

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[00:00:01.135]Hello everyone my name is Angel
[00:00:03.505]Olivera-Torres, and today I'm going to
[00:00:05.765]talk to you about Cell Patterning in
[00:00:07.855]Microfluidic Devices Combined with
[00:00:10.145]Micro-contact Printing. Being able to
[00:00:12.335]manipulate the cell environment is at the
[00:00:14.905]forefront of discovering new biological
[00:00:17.545]phenomena that occur at the cell-cell
[00:00:20.235]and cell-substrate interface. Several
[00:00:22.678]strategies have been assembled to help
[00:00:25.238]biophysical cues on singular cells with
[00:00:28.318]high spatial and temporal resolution.
[00:00:30.968]Microfluidic devices with microcontact
[00:00:33.998]printing and InkJet bioprinting are
[00:00:36.658]commonly used for cell assembly and
[00:00:39.408]patterning functional surfaces in the
[00:00:41.938]study of cell-cell and cell substrate
[00:00:44.198]interactions. However, most studies focus
[00:00:46.988]on single cell variable manipulation due
[00:00:50.988]to the difficulty in production of large
[00:00:54.008]area cell arrays. So what I'm showing you
[00:00:56.588]here is a lithography of some
[00:00:58.558]microprinting and here is an InkJet 3D
[00:01:03.118]printing of the same process. The aim of
[00:01:06.938]our project however, uses a microfluidic
[00:01:10.088]device that uses a lot of tools for the
[00:01:13.221]design and assembly of a large array of
[00:01:15.921]cell patterns and on elastomeric surfaces
[00:01:19.181]with superhydrophilic and superhydrophobic
[00:01:22.231]contrast surfaces. So in this case, we'll
[00:01:25.871]have a relaxed surface, in this case
[00:01:28.490]PDMS, strain it, apply the microfluidic
[00:01:32.490]device, and create an array of
[00:01:34.910]microdroplets that self assemble upon
[00:01:37.960]relaxation of the device. We have
[00:01:40.920]demonstrated the ability to create
[00:01:43.210]patterned cell arrays on a
[00:01:45.280]superhydrophilic/superhydrophobic
[00:01:48.050]elastomeric surface via airborne
[00:01:50.640]microfluidic device with controlled
[00:01:53.170]microdroplet size and density. We treated
[00:01:56.200]the elastomeric surface with
[00:01:58.020]bio-compatible Poly-D-Lysine for proper
[00:02:01.730]wettability microdroplet organization and
[00:02:05.580]distribution, as well as enhanced focal
[00:02:08.490]adhesion formation, leading to a higher
[00:02:10.990]cell viability and proliferation as seen
[00:02:14.990]through fluorescence imaging.
[00:02:17.410]In these images what I am showing you is
[00:02:20.330]the oxidizing process which is the PDMS
[00:02:25.410]substrate, which is inert, to cells or
[00:02:28.730]any kind of biological material, and then
[00:02:32.460]we oxidize with plasma to create a range
[00:02:35.860]geometric shapes of our desire onto that.
[00:02:40.460]surface. Then we assemble the microfluidic
[00:02:43.880]device which consists of a syringe,
[00:02:46.630]a nozzle, and a bio-compatible cell
[00:02:49.720]solution within this syringe, and then
[00:02:53.360]our substrate will stand right in front of
[00:02:56.550]that microfluidic device and be sprayed
[00:03:00.120]for about a minute to 45 seconds upon
[00:03:03.260]stretching.
[00:03:04.980]Down here we can see this device,
[00:03:08.110]the stretch chamber, onto which the PDMS
[00:03:11.380]is loaded, stretched, and then sprayed as
[00:03:14.800]I've shown you here above.
[00:03:18.080]In the middle image is a 2D, motorized,
[00:03:21.680]assembled, stage on which the stretch
[00:03:29.390]chamber is loaded, and then the spray
[00:03:33.050]is able to spray at a fixed distance
[00:03:35.960]exactly 90 degrees or perpendicular to
[00:03:38.580]the surface. After spraying we can check
[00:03:42.580]under a small camera the arrangement of
[00:03:46.880]the microdroplets onto that PDMS surface
[00:03:51.120]and as shown on this image if those arrays
[00:03:53.930]if done properly are very well contrasted
[00:03:57.930]on this very superhydrophilic/
[00:04:00.450]superhydrophobic surface. Now, we've
[00:04:05.710]established a very good relationship
[00:04:07.960]between the wettability contrast onto
[00:04:11.530]these patterns, as well as very good cell
[00:04:15.100]viability done on the substrates, and
[00:04:20.608]as you can see on the results over here,
[00:04:24.098]we've gone through extensive trial and
[00:04:26.486]error, to figure out what is the correct
[00:04:29.896]droplet size distribution as well as what
[00:04:32.966]are the correct pressures that allow the
[00:04:36.686]cells to become airborne but do not
[00:04:40.026]rupture and die through the shear stress
[00:04:42.867]that is experienced upon contact with
[00:04:45.707]the substrate. Now over here, we can see
[00:04:49.887]that the contact angle is approximately
[00:04:53.527]7.86-8.36 degrees relative to the
[00:04:59.737]surface. Over here to the right, is the
[00:05:04.607]superhydrophilic/superhydrophobic contrast
[00:05:08.607]and this is just fluorescence imaging
[00:05:11.577]showing that contrast where it's green
[00:05:14.387]it's superhydrophilic and where it's
[00:05:16.977]black it's superhydrophobic.
[00:05:20.247]The image next to that on the right is
[00:05:23.327]showing an array of cell colonies that
[00:05:27.327]have been deposited upon this substrate
[00:05:31.327]thanks to our microfluidic device. Now
[00:05:35.327]down here, all the way at the bottom, is
[00:05:39.327]a almost confluent cell array with
[00:05:43.327]micro-colonies, I'm sorry, micro-colonies,
[00:05:50.967]that have been assembled on this substrate
[00:05:54.347]that have grown to confluency and we've
[00:05:57.107]been able to control their cell
[00:05:59.147]environment as well as their shape and,
[00:06:02.207]and distribution. Now, with the work that
[00:06:05.997]we've done so far we've established a
[00:06:08.687]pretty good relationship between the
[00:06:11.287]contrast, the cell resolution, and the
[00:06:14.777]wettability contrast of these patterns,
[00:06:18.777]and future work is to combine this spray
[00:06:23.887]this microfluidic device along with other
[00:06:27.287]similar projects. For example, combining
[00:06:31.287]the cell assembly with hydrogrel matrix
[00:06:34.027]for 3D scaffolding. So spraying with the
[00:06:38.027]microfluidic device on a 3D matrix that
[00:06:42.027]is activated through photoinitiation,
[00:06:46.027]and encapsulate the cells so they can grow
[00:06:49.097]in a more comprehensive scaffold. More
[00:06:54.027]bio-mimetic of biological systems.
[00:06:58.027]We also want to produce cell patterned
[00:07:00.737]arrays of decreasing size leading to the
[00:07:03.937]isolation of individual cells in
[00:07:06.527]superhydrophilic composite regions
[00:07:09.277]and study the expression of mechano-
[00:07:11.297]sensing molecules at the cell-cell
[00:07:13.537]junction under a straining load. Design
[00:07:17.537]different patterned arrays that provide
[00:07:20.407]uniform distribution for straining force
[00:07:24.357]to cell patterned array showing
[00:07:26.747]advancement from conventional mechanical
[00:07:29.677]simulation methods, and we also want to
[00:07:31.647]provide a framework that can be applied to
[00:07:34.677]other cellular arrays such as cell
[00:07:37.007]migration and stem cell differentiation
[00:07:39.547]and proliferation in cell patterned array.
[00:07:43.547]That is all I have for you today,
[00:07:45.707]and I appreciate you tuning in and
[00:07:48.337]listening to our presentation today.

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Comments

1 Comments

Excellent job Angel! I like the design of your experiment. I wonder if the trial-and-error portion of your experiment can take advantage of statistical approaches such as principal component analysis. Best Francisco

Francisco Munoz-Arriola
02/22/21 12:10 pm

Cell Patterning in Microfluidic Devices Combined with Micro-Contact Printing

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