m-dPEG®₂₅-acid

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 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^®₂₅-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^®₂₅-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.

Quanta BioDesign, Ltd., makes and sells single molecular weight PEG linkers and spacers with discrete chain lengths under the trade name dPEG^®. Our products are distinctly different from traditional PEG products because they are single molecular weight compounds with defined chain lengths rather than disperse polymers. However, dPEG^® products confer all of the benefits of traditional PEG products without the intractable mixture of different chain lengths and molecular weights of PEG found in traditional PEG products. To learn more about dPEG^® products, please read our “What is dPEG^®?” page. Please also visit our Frequently Asked Questions page to get answers to the questions we answer most often.