Non-ionic detergents like Tween 20 or Tween 80 (1% m/v) can do the job.

You will use PBST exactly once to prepare the coating solution for your ELISA :)

The purpose of blocking is to inactivate adherent groups on the surface to prevent non-specific interactions with the antibodies. This reduces the background signal.

Thank you so much Robert Adolf Brinzer and Wolfgang Schechinger for your responses. I understand the purpose of blocking at all, I was just curious in difference between protein based and protein free approach. To set my question directly - How non-protein solutions block adherent plastic surface in comparison with BSA or skim milk mixture?

Thank you and good luck with your science!

Hello Maroš Huličiak

Protein-free blocking buffer does not contain protein. It usually contains polymers such as polyethylene glycol, polyvinyl alcohol, and polyvinylpyrrolidone. The absence of protein from protein-free blocking buffer eliminates problems associated with traditional protein-based blockers, such as cross-reactivity and interference from glycosylated proteins.

Also, protein-free blocking buffer is compatible with antibodies and avidin/biotin-based systems and results in high signal to background ratios. Besides, this type of buffer will eliminate any concern associated with regulatory compliance issues where use of animal source components is restricted.

Best.

Malcolm Nobre How does Blocking does not influence the target antigen along with the surface antigens?