Single Chain Fvs (scFvs) are recombinant antibody fragments, which commonly consist of a full variable (epitope-binding) region of an immunoglobulin heavy chain covalently linked to the corresponding variable region of an immunoglobulin light chain. These regions are usually expressed as a single continuous sequence, which may or may not be separated by a short linking amino acid sequence.

One of the main advantages of the scFv fragment is that it is essentially a minimal version of an IgG molecule. However, despite its reduced size, the fragment still retains the full activity, specificity, and stability of a full immunoglobulin molecule. When used on ELISA, immuno-bead or biochip surfaces the reduced size of the scFv fragment allows for a more densely packed coating of the fragment’s binding regions (CDRs) thus giving higher potential assay sensitivities. Additionally, due to the removal of the entire immunoglobulin Fc region, there is reduced likelihood of observing interference from secondary antibodies or from the well-known.