20211217 adhesion test

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Participants present: Adam, Kristina, Endre and Thomas

Adhesion test

The goal of today is to retry the make cells (HeLa) adhere in the chip. For that we will use fibronectin again to coat the surfaces of a newly made chip, with a careful plasma treatment.

First try

We try to use the chip that we molded last week but the channel collapsed upon bonding with the glass (Adam). So we will remake one (making some PDMS) and cure it over lunch time.

Second try

We poured PDMS into a new master, then put it in the oven at 70 degrees °C over lunch to cure. However, the PDMS was not fully cured when we returned from our lunch-break. Miraculously, someone had previously made a fully cured PDMS-channel of 25 microns that we cut out and bonded onto the microscope slide to make a new microfluidic chip. This time the bonding was successful (Adam again). We filled the channel with a single drop of water in an effort to make the later injected fibronectin layer uniform. We then went to the bio-lab where we filled the channel with fibronectin (of unknown concentration; target concentration 2-10 mg cm^-2).

We detached the cells in a container using trypsin before incubating them. After taking the container out of the incubator, we used the usual passaging protocol to remove all the cells, without putting any back into the flask.

Moving on to the 420-lab, we injected the cells into the chip using a syringe and a tube. We attempted to fill the tube with water before injecting it into the chip to avoid airbubbles, but this was unsuccessful. Cells were injected into the chip at a flow of 5 uL/min, and we set up FlyCap to take microscope-images of cells near a trap in the chip every 5 minutes for 5 days.

Follow-up data

After a few minutes that the cells have been injected, some of the cells have been ''trapped'' and started to create a group of cells that could be found in several places on the surface of the fibronectin-covered surface of the chip. These groups of cells got to adhere to the surface later on but it is unknown how long it took before the cells have died out.