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MAL-dPEG®₈-NHS ester (QBD-10274)



MAL-dPEG®8-NHS ester, product number QBD-10274, is a crosslinker that joins a sulfhydryl to a free amine through a hydrophilic bridge. The sulfhydryl groups react with a maleimide group via a Michael addition reaction. The amines form amide bonds with the crosslinker by nucleophilic substitution of the N-hydroxysuccinimidyl (NHS) ester of a carboxylic acid group. The maleimide and NHS functional groups on the crosslinking compound sit at either end of a discrete-length polyethylene glycol chain (dPEG®).

Reactions that join free amines with free thiols are among the most popular, most useful crosslinking reactions in bioconjugate chemistry. These reactions require heterobifunctional reagents that bridge the two groups. Traditional crosslinkers are hydrophobic molecules. Vector Laboratories’ dPEG® crosslinking products are water-soluble, amphiphilic, single molecular weight PEG compounds with discrete chain lengths.

The conjugation of conventional hydrophobic crosslinking reagents to biomolecules almost inevitably triggers problems such as aggregation and precipitation of the conjugates. These problems do not occur with our water-soluble, non-immunogenic dPEG® crosslinkers.

Because NHS esters hydrolyze readily in water or aqueous buffer, the NHS ester end of the molecule must conjugate to a target molecule before conjugating the maleimide end of the molecule. At pH 7.0 – 7.5, NHS esters react optimally with free amines. However, NHS esters can react with free amines with pH as low as 6.5. As the pH increases, the hydrolysis rate of the NHS ester increases. Indeed, at pH 8 and 25°C, the half-life of an NHS ester in aqueous media is one hour, while at pH 8.6 and 4°C, the half-life falls to ten (10) minutes.[3] Thus, we strongly discourage storing MAL-dPEG®8-NHS ester, product number QBD-10274, in water or aqueous buffer. Instead, we recommend that customers make new solutions of the product as needed, use them immediately, and discard unused solutions after use.

The reaction of the maleimide end of MAL-dPEG®8-NHS ester 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.

The use of MAL-dPEG®8-NHS ester has been published in numerous scientific papers and patents. The following list highlights some of the more important uses of this product:
development of molecular pincers;
development of fluorescent immunosensors for pathogenic bacteria;
crosslinking proteins to hydrogels;
development of antibody-drug conjugates (ADCs)
development of a detection methodology for single-stranded oligonucleotides;
crosslinking HIV-1 envelope proteins;
development of imaging applications;
development of immunoassays; and,
surface coating of nanoparticles.


Unit Size100 mg, 1000 mg
Molecular Weight689.71; single compound
Chemical formulaC₃₀H₄₇ N₃O₁₅
Purity> 98%
SpacersdPEG® Spacer is 34 atoms and 39.2 Å
Typical solubility properties (for additional information contact Customer Support)Methylene chloride, Acetonitrile, DMAC or DMSO.
Storage and handling-20°C; Always let come to room temperature before opening; be careful to limit exposure to moisture and restore under an inert atmosphere; stock solutions can be prepared with dry solvent and kept for several days (freeze when not in use). dPEG® pegylation compounds are generally hygroscopic and should be treated as such. This will be less noticeable with liquids, but the solids will become tacky and difficult to manipulate, if care is not taken to minimize air exposure.


Greg T. Hermanson, Bioconjugate Techniques, 2nd Edition, Elsevier Inc., Burlington, MA 01803, April, 2008 (ISBN-13: 978-0-12-370501-3; ISBN-10: 0-12-370501-0); See pp. 276-335 for general description and use of heterobifunctional crosslinkers, as well as his specific discussion with protocols of our MAL-dPEG®x-NHS esters on pp. 718-722.

Greg T. Hermanson, Bioconjugate Techniques, 3rd Edition, Elsevier, Waltham, MA 02451, 2013, ISBN 978-0-12-382239-0; See Chapter 18, Discrete PEG Reagents, pp. 787-821, for a full overview of the dPEG® products.

Enhanced Systemic Anti-Angiogenic siVEGF Delivery using PEGylated Oligo-D-Arginine. Jee Young Chung, Qurrat Ul Ain, Hyun-Lin Lee, So-Mi Kim, and Yong-Hee Kim. Molecular Pharmaceutics. 2017, pp 1-36. July 13, 2017. DOI: 10.1021/acs.molpharmaceut.7b00282.

Molecular Pincers: Antibody-Based Homogeneous Protein Sensors. Ewa Heyduk, Benjamin Dummit, Yie-Hwa Chang, and Tomasz Heyduk. Analytical Chemistry. 2008, 80 (13) pp 5152-5159. May 21, 2008. DOI: 10.1021/ac8004154.

Reprogramming cardiomyocyte mechanosensing by crosstalk between integrins and hyaluronic acid receptors. Anant Chopra, Victor Lin, Amanda McCollough, Sarah Atzet, Glenn D. Prestwich, Andrew S. Wechsler, Maria E. Murray, Shaina A. Oake, J. Yasha Kresh, Paul A. Janmey. Journal of Biomechanics. 2012, 45 (5), pp 824-831. October 4, 2011. DOI:10.1016/j.jbiomech.2011.11.023.

Intercellular and extracellular adhesion signals control cardiac myocyte structural and functional remodeling: mechanosensing mediated by cadherin and hyaluronan receptors. Anant Chopra. Doctoral Dissertation, Drexel University: Philadelphia, PA, May 2012.

Fluorescent homogeneous immunosensors for detecting pathogenic bacteria. Ewa Heyduk, Tomasz Heyduk. Analytical Biochemistry. 2010, 396 (2) pp 298–303. September 24, 2009. DOI:10.1016/j.ab.2009.09.039.

Photounbinding of Calmodulin from a Family of CaM Binding Peptides. Klaus G. Neumu ller, Kareem Elsayad, Johannes M. Reisecker, M. Neal Waxham, Katrin G. Heinze. PLoS ONE. 2010, 5 (11) pp e14050. November 18, 2010. DOI: 10.1371/journal.pone.0014050.

Chemical cross-linking of HIV-1 Env for direct TLR7/8 ligand conjugation compromises recognition of conserved antigenic determinants. Yu Feng, Mattias N.E. Forsell, Barbara Flynn, William Adams, Karin Loré, Robert Seder, Richard T. Wyatt, Gunilla B. Karlsson Hedestam. Virology. 2013, 446 (1-2) pp 56-65. August 15, 2013. DOI: 10.1016/j.virol.2013.07.028.

Peptide ligands that use a novel binding site to target both TGF-B receptors. Lingyin Li, Brendan P. Orner, Tao Huang,b Andrew P. Hinck and Laura L. Kiessling. Molecular BioSystems. 2010. 6 (12) pp 2341-2576. September 3, 2010. DOI: 10.1039/c0mb00115e.

Detection Methodology Based on Target Molecule-Induced Sequence-Specific Binding to a Single-Stranded Oligonucleotide. Agnieszka Lass-Napiorkowska, Ewa Heyduk, Ling Tian, and Tomasz Heyduk. Analytical Chemistry. 2012, 84 (7), pp 3382–3389. March 7, 2012. DOI: 10.1021/ac3001034.

Imaging of Hsp70-positive tumors with cmHsp70.1 antibody-conjugated gold nanoparticles. Mathias K Gehrmann, Melanie A Kimm, Stefan Stangl, Thomas E Schmid, Peter B Noel, Ernst J Runneny, and Gabriele Multhoff. International Journal of Nanomedicine. 2015, 10, pp 5687-5700. September 8, 2015. DOI: 10.2147/IJN.S87174.

Design and synthesis of tesirine, a clinical antibody-drug conjugate pyrrolobenzodiazepine dimer payload. Arnaud Charles Tiberghien, Jean-Noel Levy, Luke A. Masterson, Neki V. Patel, Lauren R. Adams, Simon Corbett, David G. Williams, John A. Hartley, and Philip W. Howard. ACS Medicinal Chemistry Letters. 2016, May 24, 2016. DOI: 10.1021/acsmedchemlett.6b00062.

Mapping of Molecular Structure of the Nanoscale Surface in Bio-nanoparticles. Luciana M Herda, Delyan R Hristov, Maria Cristina Lo Giudice, Ester Polo, and Kenneth A Dawson. Journal of the American Chemical Society. 2017. 139(1), 111-114. DOI: 10.1021/jacs.6b12297.

Applicable patents and legal notices are available at legal notices.

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