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m-dPEG®₄₈-CO(CH₂)₃-acid (QBD-10142)



m-dPEG®48-CO(CH2)3-acid, product number QBD-10142, is a long, methyl-capped, discrete chain length polyethylene glycol (dPEG®) spacer. The reactive end of the molecule terminates in a propionic acid group. This product is the precursor to QBD-10143, m-dPEG®48-NH-CO(CH2)3CO-TFP ester. Also, m-dPEG®48-CO(CH2)3-acid is part of a broad line of amine-reactive m-dPEG® spacers. The dPEG® spacer lengths range from 2 to 49 ethylene glycol units and have either carboxylic acid or active esters of those acids as functional groups.

The terminal propionic acid moiety can be coupled directly to free amines using EDC or another carbodiimide. Alternatively, converting the reactive end into an active ester permits the conjugation of the transformed product to free amines. N-hydroxysuccinimide (NHS), 2,3,5,6-tetrafluorophenol (TFP), and 2,3,4,5,6-pentafluorophenol (PFP) typically are used for this purpose.

m-dPEG®48-CO(CH2)3-acid reacts with amine-functionalized surfaces (carbon nanotubes, nanoparticles made of silica or various metals, quantum dots, and similar types of products) or free amines on biomolecules. When used to coat surfaces or modify biomolecules, m-dPEG®48-CO(CH2)3-acid reduces or eliminates non-specific binding and increases water solubility. Crucially, the elimination of non-specific binding may increase the signal-to-noise ratio in imaging applications and assays where this is a consideration. Please note that modifying the surface amines of biomolecules with this uncharged, methyl-capped dPEG® spacer may alter the overall charge of the resulting conjugates.


Unit Size 100 mg, 1000 mg
Molecular Weight 2259.70; single compound
Chemical formula C₁₀₂H₂₀₃NO₅₁
Purity > 95%
Spacers dPEG® Spacer is 151 atoms and 178.5 Å
Shipping Ambient
Typical solubility properties (for additional information contact Customer Support) Methylene chloride, Acetonitrile, DMAC, DMSO or water.
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.


  1. 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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