BSA does not diffuse through SC269
As I mentioned in the meeting this morning the SC267 samples have run out so I have begun testing SC269 for use in my experiments. This post pertains to a BSA diffusion experiment that I set up yesterday and allowed to run overnight. I took two SC269 samples; “treated” the first for 20min at 150C in the UV-Ozone system (after clean) and left the second “untreated”. 6uL of 5mg/mL BSA was placed on the top-side of each of the two samples with 60uL of DI-water on the backside. The samples were assembled in Jess’ diffusion cell and allowed to sit overnight. When I checked the cell this morning I noticed that the retentate solution of the “treated” sample appeared to have moved around the edge of the chip and made contact with the filtrate solution.
In the above assay image the well on the left in the SC269 bracket is the “untreated” sample while the right well is the “treated” sample. As can be seen the 5mg/mL BSA solution did make its way around the edge of the chip in the case of the “treated” sample, probably a result of the diffusion cell being bumped.
The absorbance analysis showed that in the case of the “untreated” SC269 sample very little if any BSA diffused across the membrane; the final filtrate concentration of BSA was ~0.005mg/mL (essentially zero). On the other hand the contaminated “treated” SC269 sample had a final filtrate concentration of ~0.41mg/mL.
With this initial test done I took a step back and set up a diiffusion experiement with small dye; rhodamine and fluoroscein using both “treated” and “untreated” SC269 samples. Pending these results the next step is to run a matrix testing “treated” and “untreated” SC269 samples with DDM and BSA diffusion.
You’ll need to show that the detergent does make it through SC269. This suggests that SC269 had more intrinsic surface charge than SC267, since untreated SC267 did allow BSA diffusion (right?). Backing up such conjectures with contact angles would help us believe.