Hello, I am trying to coat half of a microfluidic channel with poly-d-lysine (PDL) while leaving another half intact. I wonder if anybody has tried to use laminar flow to coat this way? I worry that using flow may poorly affect the coating. Thanks for your advices.
I guess you are going to do cell culture using poly-d-lysine or poly-l-lysine. I am not sure which way are you going to coat on a glass slide. If you are selected wet-etching, just half of glass slide are dipping into the coating solution and wash with DI solution.
I recommend you to read the reference paper how to treat the glass slide. Follow their methods. If the surface does not maintain hydrophilic surface due to a chemical coating, it becomes a hurdle for flow control. Due to insufficient information, It is hard to provide detail solution.
Hi Mr. Kang,
Thanks for the answer. I usually use Poly-D-lysine to enhance cell attachment to the glass slide. In this particular occasion, I am trying to use laminar flow to coat half of a channel with PDL so that the adherent cells only stay in half of the channel instead of spreading everywhere. Please see attached a sketch of my idea.
I hope this makes my question clearer. Hope you can give me some advices.
Thanks a lot,
Long.
Hello Long, your approach will work but it may be hard to pull off technically due to the length of time it can take to stabilize the flow, and possible transients that could happen for a variety of reasons, as well as the challenge of not messing it up when you rinse the channel. I recommend not trying to use syringe pumps at any rate. If in your sketch above the PDL is "blue" and you have some non-PDL containing buffer as red - first fill the chip with the red buffer. Have reservoirs or pipette tips or whatever filled with the red solution at both inlets. Connect the two outlets to a common vacuum source (multiple ways to do this, but you can for example make a tee coming of a single vacuum line). Pull vacuum so that you are pulling the "red" buffer from both inlets. Then (maybe with a friend's help) add your PDL solution to the "blue" inlet, mixing with pipette, while pulling continuously with the vacuum. You will want to set it up so that the "blue" reservoir is emptied first. When the blue reservoir is almost emptied, refill it with "red" buffer and keep pulling vacuum. Do this a couple times until you are back to pulling "red" buffer through both inlets. One consideration is whether the viscosity of your "blue" PDL solution exceeds that of your "red" solution, your flow profile will not look exactly the way you sketched it; the higher viscosity one may take up more than half the width of the channel.
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