I’ve recently been exploring hydraulic permeability using the pressure cell. As you may recall, the majority of our permeability measurements have been done in the centrifuge (EQ format or closed bucket). The pressure cell allows for a more accurate measurement of permeability because it is not affected by changing water levels or variable driving pressures….
I’ve updated by 3D separations figure by using actual DLS sizes rather than the dimensions roughly obtained from crystal structures. I have run into a snag with reporting the data however – use sizes by intensity or sizes by number. The difference is due to the fact that the raw DLS data is from intensity,…
In the previous post, I discussed how we could evaluate the flux of molecules through the membrane and alluded that this method could be used similarly to our effective diffusion coefficient manner of evaluating membrane impact. Here are results of the full comparison. Standard setup: 15nm membrane, 1 hour time point, 1mm fluid wells, 5%…
In this post I take a look at the flux of molecules through the 1-D membrane simulations. I will then use this flux to compare to systems lacking a membrane. First off, how to find the flux. Inside the membrane, the Flux = -Dm dc/dx. Unfortunately this is extremely hard to calculate because of the…
To identify how much of an effect the membrane has on particular simulations, we originally came up with the idea of using a phenomenological effective diffusion to view the membrane impact (see this post). Here is the most up to date version of the figure, which was slotted for use in the simulated diffusion paper:…
Because of the disagreement between the experimental and simulation comparison in this post, I decided to take a look at the Sterlitech membranes using SEM. Barrett gave me a hand with all the images, and we tried to look at the edge for thickness and the pores for density/overlapping pores. In this first image, the…
Another one of the questions I’ve been trying to answer with regard to endothelial cell vacuoles is whether membrane mechanics or permeability drive vacuole expression. I’ve thought of several experimental designs to test this that haven’t worked (i.e., using very small volumes on the apical side to minimize permeability, using PDMS plugs to block the…
Last week, I annealed a few amorphous 15 nm TEM grids in the RTP. We have always speculated that the stress from the bulk silicon was a necessary condition to induce pore formation and I wanted to confirm this. I picked six different temperatures: 600, 700, 750, 800, 900, and 1000 C. They were annealed…
One of the ongoing efforts with endothelial cell culture on pnc-Si is to confirm that the holes in these cells are actually vacuoles. In my last post, I tried to do this with FITC-Dextran and TMRIA with indefinite results. I ordered some 5-6-carboxytetramethylrhodamine (TAMRA, C-300 from Invitrogen) to do this test again. This rhodamine dye…
Tom recently designed a wafer with 1cm2 chips containing a 2×2 array of 1mm2 square membrane windows that fit on 384-well plates. I wanted one of these chips to get a preliminary data image for my R21 application. Instead, I saw something much cooler. I plated bEnd3 cells on the pnc-Si side of this chip…