Okay this one is a pretty easy question, but I'm curious how other labs are storing their ThT salt. I get varying information from companies. We have been storing ours at RT in cabinet (bottle is amber). I'm thinking that some issues I have been having lately maybe related to condition of the ThT salt. In addition to, I am also curious about the oxidation of ThT. I'm monitoring the fibrillization process of amyloids under oxidative conditions, but I know that ThT is susceptible to oxidation. Fortunately the concentrations of the oxidant are very low and ctrl experiments have thus far have not shown any interferences. However, if ThT being susceptible to oxidation is a commonly know fact what ctrl experiment should I do to convince both myself and the review beyond a reasonable doubt that the ThT with be fine in my experiments?
If long term storage is an issue, Thioflavin T can be recrystallized from acetonitile: ethanol 3:1 if you suspect there may be a problem http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3286464/
If you suspect the Thioflavin T is oxidized in solution try running a control sample of Amyloid without ThT along with ThT in the same solution and a sample with amyloid and ThT. Then add ThT to the fibers. Thje increase in fluoresence between the two samples should approximately match
We use Thioflavin S, not Thioflavin T, but also store ours at RT in an amber bottle (with foil around just in case). I suppose you could re-crystallize it as mentioned above, or perhaps store it under inert gas (argon, nitrogen, etc). When we make solutions of ThS, we use it immediately and discard any extra. I don't think I'd trust an old aliquot since it can degrade/become oxidized.
You can have a control with only ThioT and oxidant and monitor that with time. However, there can be an issue as such dyes bind to their target in a certain state...oxidation might affect the binding and hence may yield spurious results. One way of getting around is to have a control peptide/protein that is aggregating. The other other possibility is to use some cellulose as a control.An alternate method would be to measure the kinetics with other dyes like DCVJ, BSB etc. Good luck amyloiding!!!!
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