Can small molecules performing heterogeneous sandwich immunoassay? - (Aug/05/2013 )

my experiment design to perform sandwich immunoassay, but analyte specimen was small molecule around 250 da

so i think it will be impossible to perform in double sandwich immunoassay (mono, polyclonal antibody)

it will be possible to perform in heterogeneous sandwich immunoassay such as

1. Anti BSA antibdy

2. BSA (66 kDa) conjugates with analytes specimen (250 Da)

3. Anti spcimen antibody

Thank you ~~

You're right about not being able to do a traditional sandwich assay.  What you outlined will likely work but it won't give you as accurate quantitation as if you performed a competition or inhibition assay.  Coat your specific anti-specimen antibody on the plate, block, then incubate with free specimen and specimen conjugated to a detection molecule such as HRP (I'm assuming that if you can conjugate your specimen to BSA then you could conjugate it to HRP....).  A competition assay such as this is the most common way small molecules are assayed in an immunoassay format.

Thank you..Enthusiast, i already did competitive assay, but i want to perform another method such as heterogeneous sandwich immunoassay, thank you for suggestion i will reconsider for accurate quantitation