MAL-dPEG®₂₄-amido-dPEG®₂₄-TFP ester




MAL-dPEG®24-amido-dPEG®24-TFP ester, product number 11303, is a monodisperse, crosslinking PEGylation reagent that joins sulfhydryl groups to amines through a single molecular weight, discrete PEG (dPEG®) chain. At pH 6.5 – 7.5, the maleimido group reacts specifically with sulfhydryl (thiol) groups to form a thioether bond. The 2,3,5,6-tetrafluorophenyl (TFP) ester reacts with free amines to form amide bonds. Compared with N-hydroxysuccinimide (NHS) esters, TFP esters are more reactive and hydrolytically stable in aqueous buffer. The water-soluble, nonimmunogenic dPEG® spacer increases the hydrophilicity and hydrodynamic volume of conjugates made with this product.

Crosslinking Reactions with PEGylation Reagents

One of the most popular, most useful crosslinking reactions in bioconjugate chemistry[1],[2] is the conjugation of free amines to free thiols. These reactions require heterobifunctional reagents that bridge the two groups. Typical crosslinkers are short and hydrophobic. Quanta BioDesign’s dPEG® crosslinking products are water-soluble, amphiphilic, single molecular weight PEG compounds with discrete chain lengths.

Conventional hydrophobic crosslinking reagents frequently trigger aggregation and precipitation of the conjugates made from them. Moreover, these hydrophobic crosslinkers may contribute to non-specific binding problems in some assays. These problems do not happen with our water-soluble, non-immunogenic dPEG® crosslinkers.

Traditional PEGylation reagents are made from dispersed polymers. These polymeric reagents are intractably complex mixtures of different PEG chain lengths and molecular weights. This complexity creates difficulties in the analysis of conjugates. Quanta BioDesign’s dPEG® products have no dispersity (Ð = 1). Each dPEG® product consists of a discrete chain of PEG with a single molecular weight. The uniform nature of our dPEG® products eliminates one of the most vexing analytical difficulties faced by users of traditional polymer PEG products.

Learn more about dPEG® products!

What is dPEG®?

Frequently Asked Questions (about dPEG® products)

Why Use a TFP ester?

TFP esters are more stable in aqueous buffers than NHS esters. Moreover, TFP esters have higher reactivity with free amines compared to NHS esters.[3] NHS esters hydrolyze readily in water or aqueous buffer. As the pH increases, the hydrolysis rate of the NHS ester increases.[4] In 2017, a study by J. Wang, et al., on the performance of fluorophenyl esters concluded, “With regards to PEGylation, the TFP ester performed better than NHS ester.”[5] In-house research at Quanta BioDesign confirms the superior performance of TFP esters over NHS esters.

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TFP Esters Have More Hydrolytic Stability and Greater Reactivity Than NHS Esters

How Do I Use MAL-dPEG®24-amido-dPEG®24-TFP ester?

TFP esters react under the same conditions as NHS esters. However, the optimal pH range for TFP esters (7.5 – 8.0) is slightly higher than for NHS esters (7.0 – 7.5).5 Amide bond formation between the TFP-activated propionic acid group of MAL-dPEG®24-amido-dPEG®24-TFP ester and a free amine will be slightly slower at a suboptimal pH compared to the reaction rate within the optimum pH range.

The maleimide end of MAL-dPEG®24-amido-dPEG®24-TFP ester, product number 11303, reacts optimally with a sulfhydryl at pH 6.5 – 7.5. Conduct the conjugation at the lowest reasonable pH within this range. Above pH 7.5, free amines compete with free thiols at the maleimide reaction site, which may confound the data. Moreover, at higher pH values, the maleimide ring may open to form unreactive maleamic acid.[6]

Learn more about the maleimide-thiol reaction!

Maleimide Reaction Chemistry.

What Applications Use MAL-dPEG®24-amido-dPEG®24-TFP ester?

MAL-dPEG®24-amido-dPEG®24-TFP ester, product number 11303, can be used the same way and in the same applications as the equivalent NHS esters. Possible uses for this product include the following:

  • Increasing the water solubility and hydrodynamic volume of biomolecules;
  • Constructing antibody-drug conjugates (ADCs);
  • Tethering antibodies to atomic force microscopy (AFM) probes;
  • Coating nanoparticle surfaces;
  • Building supramolecular constructs; and,
  • Conjugating the TFP ester end of the molecule to a liposomal surface and then attaching a small molecule drug, peptide, or antibody to the maleimide group for targeted delivery of a diagnostic or therapeutic package.

How can you use this product in your next product development project?

Do You Offer Commercial Scale Quantities of MAL-dPEG®24-amido-dPEG®24-TFP ester?

Yes, we do. 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.

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Hydrophobic crosslinkers create more problems than they solve. Traditional disperse polymer PEG crosslinkers add unnecessary analytical complexity to conjugates that incorporate them.

So, stop using inferior products!

Start using single molecular weight dPEG® crosslinkers and discover the dPEG® difference. To get started, please click the “Add to Cart” button now to order MAL-dPEG®24-amido-dPEG®24-TFP ester, product number 11303.

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 3, The Reactions of Bioconjugation. In Bioconjugate Techniques; Academic Press: New York, NY, 2013; pp 229–258, specifically page 239.

[4] Ibid, page 234.

[5] Wang, J.; Zhang, R.-Y.; Wang, Y.-C.; Chen, X.-Z.; Yin, X.-G.; Du, J.-J.; Lei, Z.; Xin, L.-M.; Gao, X.-F.; Liu, Z.; et al. Polyfluorophenyl Ester-Terminated Homobifunctional Cross-Linkers for Protein Conjugation. Synlett 2017, 28 (15), 1934–1938.

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

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