Adsorption Quantification IV
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 an experiment. In this manner we could use it to test both sides of these membranes to benchmark their “stickyness.”
Today I came up with a method to test a single side, without the hassle (and possible error) associated with breaking apart a centrifugal device. I punched out pieces of the Millipore cellulose and PES membranes and drew around the edges of these pieces with vacuum grease. The vacuum grease stopped the protein solution from traveling over the edge and coming in contact with the underside of the membrane. I rinsed well as before and solubized adsorbed protein with sample buffer. Here are the results.
The single side tests of both cellulose and PES membranes are indeed less sticky than the entire membrane. Surprisingly it looks like PES is less sticky than teflon, although there is a bit of uncertainty associated with the teflon gel. I think we’re getting really close to the whole story here, and it might be interesting to see if we can do a surface treatment (maybe silanization) and drop pnc-Si down to this level too.