Narrow pore EO theory In narrow pores that have a significant Debye length, we need to use the same corrections on surface potential in streaming potential theory that we used in electroosmosis theory (click on link above for EO theory). In essence, the equation for streaming potential (E) becomes: where , P is the applied…
I had some extra samples from last week and had been wanting to try SEM on cells, so I went for it this week. Specifically, I was hoping to get images of vacuoles in cells over free-standing pnc-Si. I followed a rather complicated protocol full of dangerous chemicals to fix the cells and then dehydrate…
I’ve been working recently with amyloid-beta (AB) provided to me by some people in Brad Nilsson’s lab. These experiments are related to the HMM diffusion experiments for our collaboration with Harold Smith. Basically, AB fibrils are very long (microns) and we are looking for ways to either prevent their aggregation from smaller peptides/oligos, or to…
During my previous derivations of electroosmotic theory, I described the electroosmotic velocity using the classical Helmholtz-Smoluchowski equation: where ε is the permittivity, E the electric field, ζ the zeta potential, and η the viscosity. This equations basically says the velocity of electroosmosis is dependent on the electric field across the material and the zeta potential….
One of the other suggestions from Angela Glading at lab meeting a while ago was to quantify the vacuoles on different culture areas. So, I selected images from 3 different experiments (all at day14 of growth) and counted the number of cells which expressed vacuoles on different areas. I then used my mask code in…
My last post dealing with this project was the first to definitively demonstrate HMM diffusion through pnc-Si. Unfortunately, there wasn’t a difference between the HMM filtrate signal for intact and digested (+RNAse) samples. As a reminder, HMM is a large protein multimer held together, partly, with RNA. We hope to show that HMM can not…
In order to verify our measurement technique for the determination of Young’s modulus of pnc-Si, I decided to look at a PECVD silicon nitride membrane SiMPore is using for cell culture applications. The membrane window is 1 mm x 1 mm with 3 um holes. The Young’s modulus of silicon nitride thin films has been…
In my initial report on the Young’s modulus of pnc-Si, I used the generalized pressure-displacement equation to fit my experimental data to extract a Young’s modulus of around 100 GPa (Polysilicon is ~150 GPa). Unfortunately, there was quite a bit of variability in the residual stress in these experiments. I believe this variability was due…
My last post was the first experiment I performed with rat lung epithelial cells on transwells. It seemed like there was vacuolization but it was delayed compared to endothelial cells (and only happened on 1 of 2 pnc-Si transwells). Here, I did a repeat with a lower seeding density (25000 cells/cm2) and with SC613. The…
A couple weeks ago when I presented at lab meeting, Angela Glading suggested that I look at epithelial cell vacuolization on transwells. This was in order to determine if vacuole formation was endothelial cell-specific. If I’m remembering correctly, the rationale was that the vacuole-less fibroblasts I showed were not contact-inhibited cells and thus not a…