m-dPEG®₂₅-amido-dPEG®₂₄-acid

m-dPEG®25-amido-dPEG®24-acid, product number 11097, is a long, methyl-terminated, discrete length polyethylene glycol (dPEG®) spacer. A propionic acid group forms the reactive end of the molecule. An amide bond in the center of the dPEG® chain joins two PEG subunits. m-dPEG®25-amido-dPEG®24-acid is designed to modify surfaces containing available free amines. This product is a much longer version of m-dPEG®12-amido-dPEG®12-acid, product number 10148. Also, PN11097 is the precursor to m-dPEG®25-amido-dPEG®24-TFP ester, product number 11096.

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-amido-dPEG®24-acid, product number 11097, 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-amido-dPEG®24-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.

Many applications potentially, successfully could use m-dPEG®25-amido-dPEG®24-TFP ester to improve performance and function. Among those applications are:

cell surface engineering;
PK, BD, and immunogenicity profile improvements for biomolecules;
imaging applications to reduce non-specific binding and background;
dendrimer construction;
nanoparticle, quantum dot, and carbon nanotube surface coating; and,
prevention of protein aggregation.

m-dPEG®25-amido-dPEG®24-acid, product number 11097, is just one member of an extensive line of methyl-terminated dPEG® products. This line includes dPEG® spacers containing 2 to 49 ethylene glycol units. These products terminate with a carboxylic acid moiety. Activation of the carboxylic acid with NHS, TFP, or PFP is typically carried out before a subsequent reaction with free amines. Also, the carboxylic acid group may be coupled directly to free amines with a carbodiimide such as EDC. In addition to better hydrolytic stability, TFP esters have proven to be more reactive than NHS esters for amine-reactive products.

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