Hello
I also emailed to Candor bioscience regrading stabilizer performance for metal conjugated antibodies.
This is what they said "It could be possible that some labeled antibodies aggregate especially after multiple temperature cycles. Proclin 300 is normally stable but we don’t know if metal could have a catalytic effect on proclin which leads to a premature degradation........ If you suppose that aggregation could be a problem it could be useful to add
[b]Tween 20 (e.g. 0.05-0.2%)[/b] that should be able to reduce such aggregation. But we have not tried out this with metal-labeled antibodies but with antibodies labeled with fluorescence-dyes. When we know the reason fort he high background and bad performance of your antibodies (e.g. aggregation or degradation or bacterial growth) then it should be possible to improve the antibody stabilizer especially for the metal-labeled antibodies. "
I did some experiment to see whats going on with some antibodies
I had anti-eomes antibody conjugated to 162Dy at different time points : 1 week old, 6-month old and 14 month old. the first 2 antibodies work well except the 14-month old one causing significant signal shift and messing up with other channels
So I used BD comp bead and stain with just these antibodies separately. one looks the best but with the third one there is considerable background suggesting that those are aggregates.
And when I use linear scale there is a considerable difference between first 2 working antibodies and third non-working antibody as is seen in the figure below. I believe those are many aggregates with varying numbers of antibodies per aggregate.
I also ran these three antibodies on western blot to see if there is a degradation and also included stabilizer alone and pure antibody
It reveals at least there is no degradation. All there antibodies seem similar but the older antibodies show bigger band size. Supposedly all antibodies plus stabilizer must have the same protein concentration. (I store the antibodies at 0.5 mg/ml concentration in stabilizer.)
the third antibody (and also the second one, although very weak) has a band more than 250kDa in size.
to my experience making a master mix of antibodies and using an antibody having those aggregates in that mix causes aggregation of other antibodies and leads to signal shift and increase nonspecific signals in some channels. And when we use all the antibodies except the faulty one it helps to get rid off those signals.
My question is :
- How good is the current antibody stabilizer for long term storage of metal conjugated antibodies ?
- Do you think adding tween, as suggested by company, would have any adverse effect on metal conjugated antibodies ? Is it safe to add it ?
Thanks
Muharrem