Dynamic light scattering => baseline

[Martin Picard]

Hi !
Sorry for a naive question from a biologist. I am making proteoliposomes within which a fluorescent probe, pyranine (lex = 455 nm, lem = 509 nm), has been trapped. I try to quality control my preparations using DLS (Dynapro, Proteinsolutions) and my concern is that whatever the measurement, if pyranin is present, the baseline is systematically above 2 ... Hence the autocorelation curve is aberrant and I can not obtain any reasonable information on my liposomes.I obtain decent results as soon as pyranin is absent. The laser wavelength is 8336 A ...
Does anyone have an idea what is going on ?

Thanks

Martin

 

[Andy Resnick]

Can you titrate the pyranine? I'm just wondering if the problem is background fluorescence or not- if the baseline is always the same level regardless of the amount of pyranine present, it would argue that the problem is not pyranine but something else.