DOTA-tris(acid)-amido-dPEG®₁₁-Maleimide

DOTA-tris(acid)-amido-dPEG®11-maleimide, product number QBD-11167, links a thiol-reactive maleimide group with the popular, macrocyclic, bifunctional chelator 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) through a medium-length (37 atoms, 43.5 Å), single molecular weight, discrete PEG (dPEG®) linker. The DOTA moiety is designed to chelate trivalent radioisotopes of lanthanides and certain rare earth elements like yttrium. The maleimide group reacts chemoselectively with thiols at pH 6.5 – 7.5 in a click chemistry-like reaction. Because the four acetate groups on the macrocycle are unprotected, this DOTA compound should be conjugated to the target molecule at the end of the synthetic process when no further reactions will be carried out. DOTA products are commonly used in radiopharmacy in imaging, diagnostic, and therapeutic applications.

The medium-length, amphiphilic, flexible dPEG® linker between the DOTA and the TFP ester moieties increases the hydrodynamic volume and water solubility of conjugate molecules. The increased hydrodynamic volume can reduce a conjugate molecule’s renal clearance, thereby increasing serum half-life and reducing the dosage of the conjugate required for efficacy. Moreover, dPEG® is non-immunogenic, and the increased hydrodynamic volume helps reduce the immunogenicity of conjugated molecules.