PDMS, diffusion and pressurization update
I’m having trouble getting the PDMS to cure on the NC. When I first started these experiments in August, the PDMS seemed to cure on the NC without a problem. Now, when I remove the PDMS + NC from the oven, after heating for 2+ hours at the highest setting, I notice that the PDMS is still sticky, and not firm as it was in the past. I tried varying the ratio of elastomer base:curing agent(1:10; 1:5; 1:3), and that did not seem to help at all. A positive stamp of PDMS onto NC puts less PDMS onto the NC, but the PDMS still spreads too much to be reliable. The negative stamp (a sep-con taped onto the NC and held down with washers and vacuum grease), allows for a more uniform array, however is unreliable because the sep-cons shift during the experiment, allowing PDMS to seep under them.
To continue with an array format, I can try heating the NC with some kind of metal stamp. This might prevent proteins from spreading on the NC, which is what we want. A positive to trying a heat stamp, is that if it works, a uniform/reproduceable array can be made.
I ran another diffusion trial with BSA, Myosin and Myosin + BSA. The results that I’m getting are not as clear as when i did the experiment two weeks ago. I am not getting a distinct separation, like I did before. Now there is only a faint Ponceau stain for BSA even though I’m using the same membranes (W 677). I ran a control this time, to show that Myosin and BSA both show a stain with Ponceau S. A stain was apparent for the three protein samples.
Jess and I tried to set up a pressurized system with the Sep-con and submarine. I tried using an old wafer, W410, but the wafer could not withstand pressures great than 1PSI. I’ll look through all of the data on the wafers that we have now, to see if any can withstand the pressure I need. My goal is if we can get the pressurized system to work for one sepcon, maybe we can create a system to pressurize 100 sep-cons at a time, like a trans well plate. The ultimate goal of these experiments is to start with a small scale prototype and expand to a system that can process at least 100 solutions at a time. Currently we have 20,000 samples to process once I can get a prototype to work.
