How do you raise an antibody against a molecule too small to be immunogenic?
Where these antibodies are used
Detecting a drug, a metabolite, a residue or a toxin in a real sample — food, feed, water, urine, serum, an industrial process stream. In every one of these, the analyte arrives surrounded by molecules that look almost identical to it: the parent drug alongside its metabolites, one aminoglycoside among a family of them, one mycotoxin in a class of structural cousins.
An immunoassay is only as good as that discrimination. Sensitivity is comparatively easy to buy; specificity against a close analogue is what determines whether the assay survives contact with real samples.
How we do it
Three steps, and the second is the one that matters.
- Hapten design and conjugation. Which part of the molecule is presented to the immune system, and which part is buried by the linker, decides what the resulting antibodies can see. Getting this wrong produces antibodies specific to the linker, or to a face of the molecule shared by every analogue you needed to exclude. This choice is made before immunization and cannot be repaired afterwards.
- Competitive selection against real cross-reactants. After immunization we pan the library in the presence of the soluble cross-reactive substances that occur in your actual samples, absorbing the binders that cannot discriminate. Clones that survive have been forced to distinguish your analyte from its look-alikes as a condition of being selected at all.
- Confirmation by competition ELISA with free analyte, which is also the format most small-molecule immunoassays end up running.
Steering selection away from structurally similar molecules is where this platform earns its place. It is the hardest part of any small-molecule immunoassay, and it is a selection capability rather than a screening one.
- Small-molecule-specific clones with sequences
- Competition-ELISA specificity data, including against the analogues you named
- Recombinant material, so assay performance does not drift with the lot
Documented hapten antibodies from our work include 8-OHdG and antibiotics. We describe the programmes we have run rather than claiming a class we have not; if your analyte is far from anything we have done, we will tell you that when you send it.
What to send us for a feasibility view
The structure of the analyte, the structures of the molecules it must be distinguished from, the matrix, and the sensitivity the assay needs. That is enough for a scientist to tell you whether hapten design has a plausible route — and, occasionally, that it does not, which is cheaper to hear now.
Need to detect a small molecule among its look-alikes?
Send the structure and the cross-reactants that matter. A PhD scientist reads it and replies within two business days. No NDA needed to start.
Talk to a scientist →Frequently asked questions
Can you make an antibody that distinguishes a drug from its metabolite?
That is the central question of most hapten campaigns and the answer depends on where the two structures differ. If the difference is at a position we can present to the immune system while burying the shared face with the linker, the odds are good. Send both structures and we will say which situation you are in.
Do you do the hapten synthesis?
We design the hapten and conjugation strategy. Synthesis is arranged as part of scope or supplied by you, depending on what your chemistry team already has.
Rabbit or mouse for haptens?
Rabbit, in our hands. Rabbits recognise a broader epitope repertoire including small molecules, and rabbit monoclonals typically reach affinities where mouse monoclonals sit at nanomolar — which matters directly for the sensitivity of a competitive assay.
Can the antibody be used in a lateral-flow device?
Yes, and if that is the intended format say so at the start. Lateral flow imposes constraints on affinity and on conjugation chemistry that are easier to select for than to retrofit.
Do we own the clones?
Yes, sequences included, with no downstream royalties in standard scope — which matters for a reagent going into a commercial test kit.