Single domain antibodies represent the smallest antibody that was proven of diagnostic and therapeutic usefulness. They are antibody fragments that engineered from single monomeric variable domains of either camelids’ heavy-chain antibody (VHH) or cartilaginous fishes’ IgNAR (VNAR). On the other hand, it is also possible to develop single domain antibodies from camelized human antibodies.
http://www.creative-biolabs.com/single-domain-antibody-library-service.html
