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DOTA-tris(acid)-amido-dPEG®₁₁-bromoacetamide (QBD-11152)



DOTA-tris(acid)-amido-dPEG®11-bromoacetamide, product number QBD-11152, combines the macrocycle 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) through a single molecular weight, discrete polyethylene glycol (dPEG®) linker to a thiol-reactive bromoacetyl group that couples to the dPEG® linker via an amide bond. The linker contains 38 atoms and is 43.9 Å long from the terminal amide adjacent to the DOTA moiety to the methylene group adjacent to the bromine atom. This product is useful in radioimaging and radiotherapeutic applications.

The bromoacetate moiety (present as the bromoacetamide in QBD-11152) reacts chemoselectively, but not chemospecifically, with free thiol groups to form stable thioether bonds. The rate and specificity of bromoacetate for free thiols depends upon the pH of the reaction and the relative availability (compared to thiols) of other groups with which the bromoacetate moiety can react (for example, surface-accessible amines).

DOTA is a highly popular bifunctional chelator used in a variety of diagnostic and therapeutic applications for the delivery of radionuclides, particularly lanthanide radionuclides and certain rare earth radioisotopes such as yttrium. DOTA is the preferred ligand for treatments using trivalent lanthanides because it binds the metal ions to form thermodynamically stable, kinetically inert complexes.

The flexible, medium-length, single molecular weight dPEG® linker between the DOTA and the bromoacetate groups serves many purposes. First, each ethylene glycol unit in the dPEG® chain acquires up to three molecules of water through hydrogen bonding. Consequently, the molecule gains water solubility. Second, in aqueous environments such as blood, dPEG® increases the hydrodynamic volume of dPEG® conjugates. With larger hydrodynamic volumes, conjugates are less susceptible to renal excretion, meaning that lower doses of the diagnostic or therapeutic agent are needed for efficacious performance of the conjugate. Third, dPEG® is non-immunogenic, and its large hydrodynamic volume helps reduce the immunogenicity of conjugated molecules.


Unit Size50 mg, 100 mg, 500 mg
Molecular Weight1280.056; single compound
Chemical formulaC₄₆H₈₁BrF₆N₆O₂₃
Purity> 95%
SpacersdPEG® Spacer is 38 atoms and 43.9 Å
Typical solubility properties (for additional information contact Customer Support)DCM, Methanol, DMF, DMSO, or DMAC
Storage and handling-20°C; Always let come to room temperature before opening; be careful to limit exposure to moisture and restore under an inert atmosphere; stock solutions can be prepared with dry solvent and kept for several days (freeze when not in use). dPEG® pegylation compounds are generally hygroscopic and should be treated as such. This will be less noticeable with liquids, but the solids will become tacky and difficult to manipulate, if care is not taken to minimize air exposure.


Greg T. Hermanson, Bioconjugate Techniques, 2nd Edition, Elsevier Inc., Burlington, MA 01803, April, 2008 (ISBN-13: 978-0-12-370501-3; ISBN-10: 0-12-370501-0). Specifically see pp. 726-729 in his Chapter 18 on discrete PEG compounds for pegylation applications.

Greg T. Hermanson, Bioconjugate Techniques, 3rd Edition, Elsevier, Waltham, MA 02451, 2013, ISBN 978-0-12-382239-0; See chapter 18, Discrete PEG Reagents, pp.787-821, for a full overview of the dPEG® products.

Applicable patents and legal notices are available at legal notices.

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