w312
Number of Pores Histogram
Contributed Area Histogram
5nm BSA-Au is detected in the filtrate after 24 hours. 10nm BSA-Au is not. The 5nm registers around 10nm after conjugation and the 10nm is closer to 15nm.
This selected membrane is not very porous, although it does have pores (as high as 42nm) that would appear to allow the 10nm BSA-Au through.
My previous 2 posts on co-cultures presented images but I also tracked the TEER in these experiments. This post shows that data. The top 2 graphs are from the 1st co-culture experiment – the bottom graph is from the second experiment (where my PET controls died), as % Day 0: On PET, the coculture TEER…
Nakul and I noted last week that the UV-ozone system was not performing. We took pictures of control and treated samples (2x) to measure contact angles on Amorphous, pnc-Si, Oxide and Nitride TEM grids. Our results were pathetic – most samples had less than a 10 degree decrease in contact angle, staying near 60 degrees….
Last week I performed spins with SepCons from w310. I tracked permeability and tried to perform some separations with proteins. w310 had high air permeability (link), but from my diffusion data it looked looked like the cutoff was possibly between beta-galactosidase and phosphorylase b (link). Myosin definitely did not make it through these membranes, but…
Previously we have worried about the validity of our adsorption data considering we have used it to test both sides of anisotropic membranes that have cutoffs below the size of albumin. Today we came up with the idea that albumin can be used as a probe for adsorption, not as simply a model protein in…
In my last diffusion experiment, I used wafer SC 442. The results seemed to show that IgG was indeed diffusing through the membrane. As a follow up experiment, I am trying to show that I can pass IgG through more than just the one membrane. Furthermore, SC 505 has a much larger average pore size…
Originally, I created the following figure to visualize the relationship between sieving coefficient and molecular weight: (originally from this post) I can now take the protein dimensions that I obtained from crystal structures (posted here) and replot this figure: In this version of the figure the sigmoidal shape of the curve is even more obvious…
Can you also post the Malvern data for these particles in PBS?
Jess,
Were these done with ozone treated membranes, or just plain old out of the box ones? Are air bubbles still a concern? Shigeru usually does a plasma treatment + IPA. What format is this being done in? (Sorry I can’t keep track of them all!)
Dave,
This is the same benchtop diffusion format that use for the protein. I didn’t try Shigaru’s method for this first test because I want to be able to compare the results with my previous protein separations.
Perhaps these histograms are deceiving us. The argument that porosity doesn’t matter in diffusion must have its limits. For example by increasing pore size but decreasing number one could maintain the same porosity while lowering the pore density tremendously. Eventually the waiting game to wander along the surface and find the big pores will begin to matter, but at what values? In this case there are ~14 pores sufficient to pass a 20 nm particle in what ever size image gave you the histogram. Please calculate the porosity and pore density for pores above and below 20 nm. In other words what is the distance between large pores. We need to see if the time to find these pores vs. finding 5nm(= 10 nm) finding their pores might be significantly different and make a difference for this non-equilibrium experiment.