Description

m-dPEG®48-MAL, product number QBD-10932, is a sulfhydryl-reactive, single molecular weight, with a long (152 atoms, 178.6 Å), discrete-chain-length PEG (dPEG®). This product modifies surfaces and biomolecules with free thiol groups through the maleimide reactive group. The non-immunogenic, methyl-terminated dPEG® chain has no charge but adds water solubility and hydrodynamic volume to molecules to which it is conjugated.

The reaction of the maleimide end of m-dPEG®48-MAL, product number QBD-10932, with a sulfhydryl proceeds best 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 creates confusing results. Moreover, at higher pH values, the maleimide ring may open to form unreactive maleamic acid.

Possible uses for m-dPEG®48-MAL include the following:
Surface coating and passivation of thiolated nanoparticles;
Modification of cysteine residues on peptides, proteins, and other sulfhydryl-containing molecules to increase hydrophilicity and decrease immunogenicity;
Modification of cysteine residues on peptides, proteins, and other sulfhydryl-containing molecules to increase hydrodynamic volume and reduce or eliminate renal clearance of the modified compound;
Supramolecular construction (for example, of hydrogels); and,
As a probe of protein structure or enzymatic function.

Specifications

Documents

References

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). Specifically see pp. 726-729 in his Chapter 18 on discrete PEG compounds for pegylation applications.

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.

Complement Activation and Cell Uptake Responses Toward Polymer-Functionalized Protein Nanocapsules. Nicholas M. Molino, Kateryna Bilotkach, Deborah A. Fraser, Dongmei Ren, and Szu-Wen Wang. Biomacromolecules, 2012, 13 (4), pp 974–981. March 14, 2012. DOI: 10.1021/bm300083e.

Description

m-dPEG^®₄₈-amine, product number QBD-10918, is a non-immunogenic, water-soluble chemical modification reagent. The product contains a single molecular weight, discrete-length polyethylene glycol (dPEG^®) chain terminated on one end with a methyl group and on the other end with a reactive primary amine. The linker length is 146 atoms (173.1 Å). The amino group reacts with carboxylic acids (and their active esters), aldehydes, and ketones. Reacting the amino group with aldehydes or ketones forms a labile imine (Schiff base) that can be reduced to a secondary amine under mild conditions to provide greater stability to the conjugate. Reacting carboxylic acids or their active esters with m-dPEG®48-amine forms stable amide bonds. Uses for this product include passivating surfaces and coating biomolecules.

Biomolecules modified with m-dPEG^®₄₈-amine display enhanced water solubility, increased hydrodynamic volume, and reduced immunogenicity. This product reacts quickly with active esters of carboxylic acids (for example, NHS esters and TFP esters) to form amide bonds. Also, it forms amide bonds directly with carboxylic acids using the carbodiimide EDC.

m-dPEG^®₄₈-amine has been cited in the scientific literature and is potentially useful in numerous applications. Such applications include the following:
Passivating nanoparticle surfaces, including the surfaces of carbon nanotubes and graphene oxide;
Creating a non-immunogenic “stealth” coating for liposomes and micelles;
Increasing the hydrodynamic volume of small molecules, including peptides and antibody fragments; and,
Increasing the water solubility of hydrophobic molecules.

Specifications

Documents

References

Greg T. Hermanson, Bioconjugate Techniques, 2nd Edition, Elsevier Inc., Burlington, MA 01803, April, 2008 (ISBN-13: 978-0-12-370501-3; IBSN-10: 0-12-370501-0). Specifically see pp. 726-729 in his Chapter 18 on discrete PEG compounds for pegylation applications.

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.

A new reagent for stable thiol specific conjugation. Stephen Brocchini , George Badescu , Penny Bryant , Julia Swierkosz , Farzad Khayrzad , Estera Pawlisz , Monika Farys , Yuehua Cong , Norbert Rumpf , and Antony Godwin. Bioconjugate Chemistry. 2013. December 23, 2013. DOI: 10.1021/bc400245v.

Description

m-dPEG^®₄₈-NH-CO(CH₂)₃CO-TFP ester, product number QBD-10143, is a long (151 atoms, 178.5 Å), methyl-terminated, discrete-length polyethylene glycol (dPEG®) spacer. With a reactive end of 2,3,5,6-tetrafluorophenyl (TFP) ester, m-m-dPEG^®₄₈-NH-CO(CH₂)₃CO-TFP ester is designed to modify surfaces containing available free amines.

In aqueous media, free amines react optimally with TFP esters at pH 7.5 – 8.5. Compared to N-hydroxysuccinimidyl (NHS) esters, TFP esters are more hydrolytically stable in water and aqueous buffer. Nevertheless, in aqueous media, the rate at which the ester hydrolyzes to the carboxylic acid increases as the pH rises. Moreover, please note that reacting free amines on biomolecules with this uncharged, methyl-capped dPEG® spacer may alter the overall charge of the resulting conjugates.

Many applications potentially could use m-dPEG^®₄₈-NH-CO(CH₂)₃CO-TFP ester successfully. Among those applications are: cell surface engineering; PK, BD, and immunogenicity profile improvements for biomolecules; imaging applications, by reducing background and non-specific binding and consequently increasing the signal-to-noise ratio; dendrimer construction; nanoparticle, quantum dot, and carbon nanotube surface coating; and, prevention of protein aggregation.

Specifications

Documents

References

1. 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.

Description

m-dPEG®48-CO(CH2)3-acid, product number QBD-10142, is a long, methyl-capped, discrete chain length polyethylene glycol (dPEG®) spacer. The reactive end of the molecule terminates in a propionic acid group. This product is the precursor to QBD-10143, m-dPEG®48-NH-CO(CH2)3CO-TFP ester. Also, m-dPEG®48-CO(CH2)3-acid is part of a broad line of amine-reactive m-dPEG® spacers. The dPEG® spacer lengths range from 2 to 49 ethylene glycol units and have either carboxylic acid or active esters of those acids as functional groups.

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 the 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®48-CO(CH2)3-acid 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®48-CO(CH2)3-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.

Specifications

Documents

References

1. 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.