In my last post I showed that using buffered solutions instead of Di-water we could obtained similar results with SC256 as we had with SC269. I used 20mM HEPES at pH7.5 with no salts and showed DDM diffusion through both “treated” and “untreated” SC256 samples. Additionally I showed that “treated” SC256 samples appeared to slow…

On Friday I posted results from a diffusion experiment in which I tested “treated” and “untreated” SC256 samples against the diffusion of a mixture of DDM and BSA. The DDM-BSA solution contained an initial DDM concentration of 1.0% and an initial BSA concentration of 2.5mg/mL; the solution also contained 20mM HEPES and was at a…

In an effort to conserve membrane samples I am working to run diffusion experiments with a mixture of BSA and DDM. This will only use 2 chips instead of 4. In our meeting on Tuesday it was mentioned that BSA can be detected using the TECAN at 280nm, while DDM is not detected at that…

I’ve been attempting to simulate protein sieving using the COMSOL model.  This first figure shows the comparison of the simulated separations to the actual results as determined by gel densitometry. The simulated separations tend to lag behind the experimental data for smaller proteins.  This is surprising since the simulation is faster than experimental results for…

After our meeting with Professor Dumont on Tuesday it was decided that we needed to try and perform the BSA/DDM seperation with a more porous membrane (to allow for eventual pressurization). SC256 was choosen and as an initial step I ran a simple small dye diffusion experiment to verify that the pores were open. As…

The last post I made about the BSA/DDM separations using “treated” and “untreated” SC269 samples explained a problem I was having in which the initial retentate drop was diffusing around the edge of the sample chip. It seems that SC269 is naturally more hydrophillic than SC267 therefore when “treated” it becomes so hydrophillic that the…

Yesterday I posted results of a diffusion experiment using rhodamine and fluoroscein that showed the pores in SC269 are open both before and after treatment in the UV-Ozone system. I set up another diffusion experiment to test “treated” and “untreated” SC269 samples with diffusion of BSA and DDM. As a reminder the focus of my…

We haven’t talked much about the optical properties of pnc-Si, but I thought it would be good to share some of the index and dispersion data I’ve collected using the ellipsometer.  Below are plots of index of refraction (n) and extinction coefficient (k) vesus energy.  The index is a measure of the optical density.  The…

This is a follow-up post to “Protein Assay Test.” I realized that I never posted the final stag of my experiments, in which I finally got BSA to go through the membranes. In “Protein Assay Test,” I described several experiments that I set up to see if I could get BSA to pass through a…

Yesterday I posted my results from a BSA diffusion experiment using “treated” and “untreated” SC269 samples. To ensure that the pores in SC269 are indeed open I took a step backwards and set up a diffusion experiment using small dye molecues; rhodamine and fluoroscein. Using Jess’ diffusion cell I set up a matrix to test…