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Carboxyfluorescein-dPEG®₂₄-amido-dPEG®₂₄-DSPE (QBD-11385)



Carboxyfluorescein-dPEG®24-amido-dPEG®24-DSPE, product number QBD-11385, consists of the lipid 1,2-Distearoyl-SN-glycero-3-phosphoethanolamine (DSPE) conjugated to a long (152 atoms, 180.0 Å), single molecular weight, discrete polyethylene glycol (dPEG®) spacer that has been functionalized with 5(6)-carboxyfluorescein. The dPEG® spacer consists of two dPEG®24 linkers joined by an amide bond, making the spacer effectively a dPEG®48 product with a molecular weight of slightly more than 2,000 Daltons (i.e., equivalent to a PEG2000). The product is designed for use in liposomes and micelles where a fluorescent dye label is needed. The carboxyfluorescein dye has an absorbance maximum (λex) of 497 nm and an emission maximum (λem) of 524 nm, with an extinction coefficient of 63303 M-1 cm-1 at 497 nm, and an A280 correction factor of 0.18.

Liposomes and micelles are often coated with traditional, polymeric PEG2000 (a polymer PEG having an average molecular weight of 2,000 Daltons) at a density of about 5 – 8 mole%. A polymer PEG2000 consists of an intractable mixture of different chain lengths and molecular weights of PEG, making analysis difficult. Unlike a traditional, non-uniform (that is, dispersed) PEG2000, QBD-11385, carboxyfluorescein-dPEG®24-amido-dPEG®24-DSPE is a single, uniform product. Carboxyfluorescein-dPEG®24-amido-dPEG®24-DSPE is designed to provide a convenient dye label for liposomes, micelles, and other lipid nanoparticles. This allows labeled liposomes and micelles to be tracked over time.


Unit Size5 mg, 10 mg
Molecular Weight3363.04; single compound
Chemical formulaC₁₆₄H₂₉₄N₃O₆₄P
Purity> 97%
SpacersdPEG® Spacer is 152 atoms and 180.0 Å
Typical solubility properties (for additional information contact Customer Support)Methylene Chloride, Methanol, Acetonitrile, DMSO, or Chloroform
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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