10 and 15nm Cutoff Sepcons Both Allow Cytochrome C to Pass, but not BSA
In a previous post, we showed that both Cytochrome C and BSA at concentrations of ~1mg/mL through 20nm cutoff Sepcons with about the same filtrate concentration (~60% of the feed concentration). Yesterday (1/14/13) we repeated these experiments with 10 and 15nm cutoff Sepcons and demonstrated pretty clearly that either 10 or 15nm Sepcons can be used to separate the two molecules. Further, 20nm cutoff Sepcons allow both species to pass.
It should be noted that the volume of filtrate was fairly low for 15nm cutoff separations, and very low for 10nm separations. For 10nm, I found one pass at 1500 rpm for 5 minutes wasn’t enough – it took 10 minutes at 2000rpm to get approximately 20uL of filtrate. For 15nm, 5 minutes at 1500 was sufficient to get ~25uL of filtrate.
As soon as we get the peg-lyated membranes we will replicate these experiments with the new chips. We will also be investigating how hydraulic permeability changes once the membranes have been peg-lyated.