Final answer:
The purpose of PBS-T20 in the medical testing/ELISA lab is as a blocking solution to prevent non-specific binding, thereby reducing background noise that could lead to false-positive results.
Step-by-step explanation:
The purpose of PBS-T20 in the medical testing/ELISA lab is to function as a blocking solution, specifically to block non-specific protein binding sites on the microtiter plate wells. This is essential to reduce background noise, which corresponds to unspecific adsorption that could lead to false positives or ambiguous results. During ELISA, after the primary antibody is added and any unbound antibodies are washed away, a blocking solution like PBS-T20 is used to occupy any remaining protein-binding sites.
The solution contains PBS (Phosphate Buffered Saline) with a detergent such as Tween 20, which helps to prevent the non-specific binding of proteins to the plate, enhancing the specificity of the antibody-antigen interaction. This step is vital for ensuring that when the secondary antibody is added, it only binds to the primary antibody that is attached to the targeted antigen, rather than nonspecific sites on the well.