BSA-Au Update
5nm BSA-Au appears to be 12.7nm.
10nm BSA-Au is 18nm.
Dilution dependent size change of 5nm BSA-Au.
One theory for the size change was that residual BSA was combining with the Au peak and for some reason dilution of the BSA was causing a migration of the peak. This doesn’t necessarily make much sense as the Au is being diluted by the same factor each time. I tried washing the BSA-Au more to minimize the amount of unconjugated BSA, but this sample still seems to be increasing in size with dilution (data in progress). As the solution becomes more dilute, this may cause the BSA to desorb, but we’d expect a reduction in size of the BSA-Au. It is still possible that the increase in size may be because of an artifact. The model doesn’t take into account a “core-shell” model that may have different absorbance characteristics.
I tried to stabilize the Au with .005% Tween, but the particles immediately aggregated when introduced to PBS.