MAL-dPEG®8-acid, product number 10275, is a crosslinker that joins sulfhydryl groups to free amines through a single molecular weight polyethylene glycol (PEG) chain of discrete length. The maleimidopropyl moiety reacts with sulfhydryl groups via a Michael addition reaction. The propionic acid terminus of the molecule reacts directly with free amines using EDC or another carbodiimide to form amide bonds. Alternatively, activation of the propionic acid group with N-hydroxysuccinimide (NHS), 2,3,5,6-tetrafluorophenol (TFP), or some other acylating agent permits amide bond formation under mild, controlled conditions.

Crosslinking with dPEG® Products

Chemical couplings between free amines and free thiols are among the most popular, most useful crosslinking reactions in bioconjugate chemistry.[1],[2] These syntheses require heterobifunctional reagents that bridge the two groups.

Traditional crosslinkers are hydrophobic molecules. However, Quanta BioDesign’s crosslinking products are water-soluble, amphiphilic, single molecular weight PEG compounds with discrete chain lengths, hence the dPEG® tradename under which we sell them.

Almost inevitably, the conjugation of conventional hydrophobic crosslinking reagents to biomolecules triggers problems such as aggregation and precipitation of the conjugates. Conversely, these problems do not occur with our water-soluble, non-immunogenic dPEG® crosslinkers. For more information about our dPEG® products, please see our “What is dPEG®?” page. Also, click here for answers to our most frequently asked questions.

How to Use MAL-dPEG®8-acid

The reaction of the maleimide end of MAL-dPEG®8-acid, product number 10275, with a sulfhydryl proceeds optimally at pH 6.5 – 7.5. Use the lowest reasonable pH within this range. Above pH 7.5, free amines compete with free thiols at the maleimide reaction site, which can cause confusing results. Moreover, at higher pH values, the maleimide ring may open to form unreactive maleamic acid.[3] For details about maleimide-thiol reaction chemistry, please click here.

After the maleimide end of the molecule reacts with a sulfhydryl, the terminal propionic acid group may be left unreacted for charge modification or the conjugate or activated with an acylating agent such as NHS or TFP. The active ester then reacts with free amines to complete the crosslink.

Uses of MAL-dPEG®8-acid

MAL-dPEG®8-acid, product number 10275, has been published in numerous patents and a few papers. The more notable published works involve the development of antibody-drug conjugates (ADCs). Other possible uses for this product include

  • crosslinking proteins to hydrogels;
  • development of imaging applications;
  • development of immunoassays; and,
  • surface coating of nanoparticles.

What can you do with this product?

Commercial Scale Production Is Available for MAL-dPEG®8-acid

If you need bulk product in a larger package size than our standard sizes, please contact us for a quote. Our commercial capabilities permit us to manufacture this product at any scale that you need.

Related Products

This product is one of several MAL-dPEG®-acid products with varying lengths of dPEG® spacers. Quanta BioDesign also offers a complete line of crosslinking products. The list of these products is here.

Act Now

Stop using conventional click chemistry crosslinkers! You can do better. MAL-dPEG®8-acid provides your conjugates with water solubility, improved hydrodynamic volume, no background noise (which means better signal), and no protein precipitation caused by aggregation. Why would you not use something better?

For cleaner, better crosslinking, click the “Add to Cart” button now and purchase MAL-dPEG®8-acid. You will not regret it. Click “Add to Cart” now.

Application References:

[1] Hermanson, G. T. Chapter 6, Heterobifunctional Crosslinkers. In Bioconjugate Techniques, 3rd ed.; Academic Press: New York, NY, 2013; pp 299–340, specifically page 300. Many scientists engaged in bioconjugation work consider Greg Hermanson’s book to be the definitive reference on the subject. Click here now to read a review of Greg’s book and to purchase it.

[2] Hermanson, G. T. Chapter 18, PEGylation and Synthetic Polymer Modification. In Bioconjugate Techniques, 3rd ed.; Academic Press: New York, NY, 2013; pp 787–838, specifically page 794.

[3] Hermanson, G. T. Chapter 6, op. cit., page 304.




Additional information

Weight .5 oz
Dimensions .75 × .75 × 2 in