MAL-dPEG®₂₄-TFP ester




MAL-dPEG®24-TFP ester, product number 10554, is a crosslinking reagent with a polyethylene glycol (PEG) cross-bridge that joins free amines to free thiols (sulfhydryl groups). The sulfhydryl groups react with a maleimido group via a Michael addition reaction. The amines form amide bonds with the crosslinker by nucleophilic substitution of the 2,3,5,6-tetrafluorophenyl (TFP) ester of the terminal propionic acid group. The maleimido and TFP functional groups on the crosslinking compound sit at either end of a long, discrete-length chain of PEG (hence, dPEG®).

Crosslinking Reactions

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 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. 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. 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.

Nevertheless, our customers enjoy all the benefits of PEG, minus the headaches that PEG polymers cause. 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.

TFP Esters are Superior to NHS esters

TFP esters are more stable in aqueous buffers than N-hydroxysuccinimidyl (NHS) esters. Moreover, TFP esters have higher reactivity with free amines than 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.

How to Use MAL-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-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-TFP ester, product number 10554, 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] For details about maleimide-thiol reaction chemistry, please click here.

Uses of MAL-dPEG®24-TFP ester

MAL-dPEG®24-TFP ester, product number 10554, can be used the same way and in the same applications as the equivalent NHS esters. Possible uses for this product include the following:

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

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

Bulk Scale Synthesis of MAL-dPEG®24-TFP ester is Available

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.

Buy Now!

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-TFP ester, product number 10554.

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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