A few weeks ago, I posted discoloration results on carbonized membranes here.  It was 6 weeks yesterday since I started this experiment, so I decided to stop it (few, if any, cell applications require 6-weeks of culture).   These were SC141 chips in the flat (not transwell) format.  I also used DMEM with high NaHCO3 levels. …

I repeated the first degradation experiment (posted here) to confirm the results.  I also tracked discoloration of the samples this time.  As before, I used 1X PBS, but this time, the entire assay was performed in the 37C oven. Discoloration pictures: The PSi sample starts with a new rainbow coloration and then completely discolors to…

For the last two weeks, we have observed that membranes have been wrinkling post-oxide strip.  After some investigation, it was determined that the cause of wrinkling was from a cracked SiO2 target in the sputter system. I also saw a suppression of pore formation in the wrinkled films as compared to an unwrinkled membrane. The…

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…

Anant and I found a protocol in Biomaterials a few weeks ago that allows colorimetric determination of silicic acid.  It was used to track the degradation of PSi samples in Tris-HCl buffer. I optimized this protocol and got standard linear curves, as reported in the protocols section of the blog here.  Here, I report the…

I finally got some MATLAB code working which calculates permeability coefficients (P, in cm/s) from a non-sink, generalized equation.  This data is from (n=5) fluorescein (MW~370 Da) transport experiments in the Tecan (time vs. receiver well concentration (Cr) values).  In this first set of data, I used polycarbonate and polyester transwells, at room temperature, without…

This post shows that C-dots are pretty close to neutral.  Here I’ve looked at gold nanoparticles and albumin. 5nm Gold: The distribution is very spread out, but everything centers around -58 mV. 10nm Gold: This sample looks a little bimodal.  Peaks are at -33 and 0 mV. Albumin: Much better than the gold samples.  It…

I’ve tried to collect some information on the protein ladder that we’ve been using for separations.  Sizes have thus far been taken from crystal structures and loosely measured used JMol on the PDB site.  This is meant to just give us an idea of dimensions; hydrodynamic data would probably be better. pI and charge information…

I used 100kD Millipore Celllulose membranes to separate the 2 C-dot particles.  The results are similar to those I’ve obtained with pnc-Si; the 10nm particles pass while the 30nm ones do not. Cy5 10nm particles: Sulforhodamine 30nm particles: Here are the sieving ratios: Particle Ratio 10nm (abs) .60 10nm (fluor) .59 30nm (abs) .02 30nm…

This post outlines two sets of polymer membrane separations using 100kD PES and 30kD cellulose in diffusion mode.  The 100kD PES experiment is a repeat of the experiment found here; in the first trial of this work, there was no filtrate remaining on the backside.  This time there was filtrate remaining that I could test…