Permeability and Convection/Diffusion

Permeability data first:
Wafer 310
r = 4.3 units from center
n = 3
2.0 mg/mL cytochrome C in 1x PBS
mean permeability = 27-33 uL/(min-cm2-psi)
*** corrected to account for (2) 115x2014um slits
[The range is due to variations in measurement and total accounting for initial uL]
Wrapping with parafilm resulted in only a mean of 13uL of 1000 initial uL unaccounted for after 2 hour spin. Likely due to loss to tube walls.

In another experiment, I ran 2 w310 samples at 1500rpm (~5psi) for 1 hour. Total protein passage was approx 1.36x greater than 2 samples run at 1000rpm for 1 hour. Fluid transport was not much greater than fluid loss, therefore not reportable. Mean r = 2.5. Limited sample size and variation in pore sizes could account for why the difference was not ideally 1.5x. Also possible that cytoC is not a good tracer for water and has non-linear transport effects at greater pressures/speeds.

Protein Transport.
In the above experiment of n=3. Transport of protein was not significantly greater than would be expected by convection alone. Protein transport ranged from 0.09-0.12mg where expectations were 0.10-0.12mg of 1.0mg based on fluid convection.

In the two n=2 experiments, protein transport was also near expectations for convection.

Conclusion – If diffusive transport was significant, it was offset by protein hindrance in small pores during convection. Will re-try similar experiments with a different wafer.

Side Note – Wafer 319 had pin holes in the four samples I pulled (1 to 4,-1) . All four samples either failed or equilibrated due to the pin holes at 1000rpm after 5 mins.