Figure 2
From: Molecular imaging of rheumatoid arthritis: emerging markers, tools, and techniques
Probes can be composed of small molecules, peptides, proteins, antibodies, antibody fragments, nanobodies, and nanoparticles. A schematic overview of a conventional antibody, a heavy-chain antibody, Fab fragments, and a nanobody is given. CH, heavy chain constant domain; CL, light chain constant domain; Fab, antigen-binding domain; Fc, constant domain; MMR, macrophage mannose receptor; TNF-α, tumor necrosis factor-alpha; VH, heavy chain variable domain; VHH, heavy chain only antibody VL, light chain variable domain.