Hi Vera:

You can try to use your anti-biotin Ab directly, maybe it will work well. If you detect any background on your membrane, I suggest you prepare the anti biotin Ab in the same blocking solution.

Hello.

Which hybridization solution do you use?

How abundant is your target?

Have you tried to do without blocking?

To answer your questions:

1. ˝Will this protect my membrane from anti-biotin antibody non-specific binding?˝

Salmon sperm in pre-hyb solution is going to block nonspecific binding of your probe to nonspecific sequences in your RNA sample. This is going to reduce background noise. So the answer is: yes, it will.

2. ˝Have I to block with milk after probe hybridization and washes? In the last case, Will this disrupt the probe-RNA union?˝

You do not have to use additional blocking step.

good luck.

Hi Vera Garcia-Outeiral

For biotin labeled probes, you dont need anti-biotin antibodies, its easily detected with following kits from thermoscientific (see the link below). The kits is supplemented with blocking buffer/ wash buffer, hybridization buffer, and signal detection buffers.

https://www.thermofisher.com/order/catalog/product/89880

In my previous answer, I completely failed to observe you are writing about northern blot antibody! Northern blot is usually performed with a labeled probe (DNA or RNA). RNA probe is better and you can produce it by in vitro transcription.

Full agree with Ghanam.