Description

DBCO-dPEG®4-TFP ester, product number QBD-11362, is a heterobifunctional, bioorthogonal crosslinker designed to join azides and amines across a short (16 atoms, 17.9 Å), flexible, hydrophilic, single molecular weight, discrete PEG (dPEG®) spacer. The tetrafluorophenyl (TFP) ester reacts specifically with free amines to form amide bonds; the optimum reaction pH is 7.5 – 8.0. The dibenzylcyclooctyne (DBCO) moiety selectively forms triazole linkages with azides via a click chemistry reaction known as strain-promoted azide-alkyne cycloaddition (SPAAC), also known as copper-free click chemistry. The amphiphilic dPEG® linker increases conjugates’ hydrodynamic volumes, and it can be used to create space in sterically crowded supramolecular constructs.

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.

Description

Hydroxy-dPEG®4-TFP ester, product number QBD-11341, is a short (16 atoms, 17.9 Å), hydroxy-terminated, single molecular weight, discrete polyethylene glycol (dPEG®) compound functionalized with a 2,3,5,6-tetrafluorophenyl (TFP) ester for conjugation to primary and secondary amines. This product can be used for modification of amine-functionalized surfaces (e.g., silica, glass), modification of proteins and peptides at accessible amine sites on the molecules, the construction of discrete PEG dendrimers, and many other applications. The free hydroxy end of the dPEG® spacer can be functionalized for further reactions or left unmodified to increase hydrophilicity or modify the charge of conjugate molecules and surfaces.

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.

Description

Bromoacetamido-dPEG®4-amido-DBCO, product number QBD-11221, combines a thiol-reactive bromoacetyl group with dibenzylcyclooctyne (DBCO, also known as DIBAC), a copper-free click chemistry reactive group. The two reactive groups link via a short (16 atoms, 17.9 Å), flexible, single molecular weight, discrete polyethylene glycol (dPEG®) linker. The bromoacetyl group reacts chemoselectively with thiols at pH ≥ 8.0. This differs from the maleimide group, which reacts chemoselectively with sulfhydryls within the range of pH 6.5 – 7.5. The DBCO moiety is a strained cyclooctyne ring flanked by two benzyl rings on either side. DBCO was designed for strain promoted azide-alkyne cycloaddition (SPAAC), also known as copper-free click chemistry.

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.

Description

Bromoacetamido-dPEG®4-TFP ester, product number QBD-11200, is a short (18 atoms, 20.4 Å), single molecular weight, discrete PEG (dPEG®) crosslinker functionalized with a thiol-reactive bromoacetate group on one end and an amine-reactive 2,3,5,6-tetrafluorophenyl (TFP) ester on the other.

The short, flexible, non-immunogenic dPEG® crosslinker increases the hydrodynamic volumes of conjugates in aqueous media, thereby increasing water solubility. The increased hydrodynamic volume can reduce or eliminate conjugate molecules’ renal clearance and shield conjugates from opsonization.

The bromoacetate moiety is an alternative to the maleimide group, reacting chemoselectively with free thiols at pH ≥8.0. It is useful for situations where the conjugate molecule needs to be kept at a high pH (≥8.0), above the range where maleimides can be used effectively, or in constructs where maleimide groups are unstable.

TFP esters are an alternate reactive group to N-hydroxysuccinimidyl (NHS) esters and react with amines at an optimal pH range of 7.5 – 8.0, higher than the optimal range for NHS esters (pH 7.0 – 7.5). TFP esters are more hydrolytically stable than NHS esters, and they are more reactive toward amines in their optimal pH range than NHS esters are within the pH range 7.0 – 7.5.

Specifications

Documents

References

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

Fmoc-N-amido-dPEG®4-TFP ester, product number QBD-11000 contains an Fmoc-protected amine on one end of a short (16 atoms), single molecular weight, discrete-chain-length polyethylene glycol (dPEG®) spacer and the tetrafluorophenyl (TFP) ester of a propionic acid group on the other end. This product is ready for the direct introduction of a water-soluble, amphiphilic spacer into a peptide chain. The Fmoc protecting group on the N-terminus of the molecule cleaves easily with standard peptide chemistry.

Fmoc-N-amido-dPEG®4-TFP ester permits our customers to insert a short dPEG® spacer into a peptide chain using standard Fmoc chemistry without the need to activate the acid terminus for conjugation. The product works equally well in solid-phase and solution-phase synthetic processes. In aqueous solutions, TFP esters are more hydrolytically stable than NHS esters and have an optimum pH range of 7.5 – 8.0 for conjugation. The dPEG® linker attaches at the N-terminal end of the peptide chain or on the free amine side chain of amino acids such as lysine. Additional peptide synthesis can be carried out to extend the peptide further, creating a peptide with a flexible, hydrophilic linker or spacer in the middle or joining two different peptides across the dPEG® bridge. In addition, the dPEG® chain can provide spacing in a synthetic construct where steric hindrance is a problem. Amphiphilic, non-immunogenic dPEG® increases the hydrodynamic volume and improves the water solubility of the conjugate while remaining soluble in organic solvents. The Fmoc protecting group is removed easily with a solution of piperidine in N,N-dimethylformamide (DMF).

Specifications

Documents

References

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

Fmoc-N-amido-dPEG®4-NHS ester, product number QBD-10994 contains an Fmoc-protected amine on one end of a short (16 atoms), single molecular weight, discrete-chain-length polyethylene glycol (dPEG®) spacer and the N-hydroxysuccinimidyl (NHS) ester of a propionic acid group on the other end. This product is ready for the direct introduction of a water-soluble, amphiphilic spacer into a peptide chain. The Fmoc protecting group on the N-terminus of the molecule cleaves easily with standard peptide chemistry.

Fmoc-N-amido-dPEG®4-NHS ester permits our customers to insert a short dPEG® spacer into a peptide chain using standard Fmoc chemistry without the need to activate the acid terminus for conjugation. The product works equally well in solid-phase and solution-phase synthetic processes. The dPEG® linker attaches at the N-terminal end of the peptide chain or on the free amine side chain of amino acids such as lysine. Additional peptide synthesis can be carried out to extend the peptide further, creating a peptide with a flexible, hydrophilic linker or spacer in the middle. Also, the dPEG® chain can provide spacing in a synthetic construct where steric hindrance is a problem. Amphiphilic, non-immunogenic dPEG® increases the hydrodynamic volume and improves the water solubility of the conjugate while remaining soluble in organic solvents. The Fmoc protecting group is removed easily with a solution of piperidine in N,N-dimethylformamide (DMF).

Specifications

Documents

References

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.

Design of a modular tetrameric scaffold for the synthesis of membrane-localized D-peptide inhibitors of HIV-1 entry. J. Nicholas Francis, Joseph S Redman, Debra M Eckert, and Michael S. Kay. Bioconjugate Chemistry, 2012, 23 (6), pp 1252-1258, May 1, 2012. DOI: 10.1021/bc300076f.

Multivalent Benzamidine Molecules for Plasmin Inhibition: Effect of Valency and Linker Length. Tanmaye Nallan Chakravarthula, Dr. Ziqian Zeng, Prof. Nathan J. Alves. ChemMedChem, Volume 17, Issue 22, (2022), 09/16/2022, https://doi.org/10.1002/cmdc.202200364.

Description

Lipoamido-dPEG®4-acid, product number QBD-10806, is a single molecular weight, discrete PEG (dPEG®) surface modification reagent for metal surfaces, especially gold and silver. The hydrophilic dPEG®4 spacer is 24 atoms (27.5 Å) long. The lipoamide moiety rapidly forms stable dative bonds with gold or silver. Using a carbodiimide such as EDC and an acylating agent such N-hydroxysuccinimide (NHS), the propionic acid group will react with free amines to form amide bonds. The water-soluble, non-immunogenic dPEG® spacer adds hydrodynamic volume to conjugates made with this product. For circulating nanoparticles, the increased hydrodynamic volume reduces or eliminates opsonization and facilitates a longer circulation time in vivo.

Lipoic acid, also known as thioctic acid and alpha-lipoic acid (ALA), is an organosulfur compound used by cells as an essential cofactor for several enzymes in aerobic respiration. The sulfur atoms at positions C6 and C8 form a disulfide bond in a five (5)-membered ring. Like other thiol products, lipoic acid readily forms dative bonds with gold, silver, and other metals. Because two dative bonds form for each molecule of lipoic acid, the thiol-metal dative bond is more stable than dative bonds formed with compounds containing one free thiol atom. Lipoic acid exists typically in an oxidized (closed ring) state. It is readily reduced to an open ring state called dihydrolipoic acid (DHLA) using tris(2-carboxyethyl)phosphine (TCEP) or other reducing agents.

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), pp. 188-190, 458-497, 924-935.

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.

Site-Specific Conjugation of Antibody on Gold Nanoparticle Surface for One-Step Diagnosis of Prostate Specific Antigen with Dynamic Light Scattering. Nur Mustafaoglu, Tanyel Kiziltepe, and Basar Bilgicer. Nanoscale. 2017, pp 1-32. May 18, 2017. DOI: 10.1039/C7NR03096G.

Gastrointestinal Bioavailability of 2.0 nm Diameter Gold Nanoparticles. Candice A. Smith, Carrie A. Simpson, Ganghyeok Kim, Carly J. Carter, and Daniel L. Feldheim. ACS Nano. 2013, 7 (5) pp 3991–3996. April 21, 2013. DOI: 10.1021/nn305930e.

Compact Biocompatible Quantum Dots Functionalized for Cellular Imaging. Wenhao Liu, Mark Howarth, Andrew B. Greytak, Yi Zheng, Daniel G. Nocera, Alice Y. Ting, and Moungi G. Bawendi. J. Am. Chem. Soc. 2008, 130 (4) pp 1274–1284. January 5, 2008. DOI: 10.1021/ja076069p.

Description

Lipoamido-dPEG®4-TFP ester, product number QBD-10641, is a single molecular weight, discrete PEG (dPEG®) modifier of gold and silver surfaces, for example, on nanoparticles. The lipoic acid moiety on one end of the 24-atoms-long dPEG® spacer forms dative bonds with metals like gold and silver. The TFP ester reacts with free amines to form free amines, optimally in the pH range 7.5 – 8.0. The distance from the disulfide bond in the lipoic acid ring to the carbonyl carbon adjacent to the 2,3,5,6-tetrafluorophenol (TFP) ester, the distance is 24 atoms (28.0 Å). Applications for this product include creating self-assembled monolayers (SAMs) on metal surfaces and crosslinking and immobilizing peptides and proteins to the surfaces of metal nanoparticles.

Lipoic acid, also known as alpha-lipoic acid, α-lipoic acid, and thioctic acid, consists of a five-membered ring containing a disulfide attached to a pentanoic acid group. As a naturally occurring antioxidant, lipoic acid functions as a cofactor in several enzyme systems. It is a bidentate thiol ligand that forms two stable dative bonds per lipoic acid group with gold, silver, and other metals. These dative bonds form with oxidized lipoic acid or reduced dihydrolipoic acid (DHLA). Because it forms two dative bonds on metal surfaces, lipoic acid is more stable than PEGylation reagents containing a single thiol. This increased stability prevents lipoic-acid-functionalized dPEG® products from being oxidized off the metal surface. The lipoic acid group forms dative bonds with metals with or without reduction to DHLA. If reduction to DHLA is preferred, Tris(2-carboxyethyl)phosphine (TCEP) will rapidly reduce lipoic acid to DHLA.

TFP esters react more readily with amines and possess better hydrolytic stability than N-hydroxysuccinimide (NHS). The superiority of PEG-TFP esters over NHS esters is documented in the scientific literature.

When using this product, it is typical to conjugate the carboxyl end of the dPEG® to an amine to form an amide bond before forming a dative bond between a metal surface and the lipoic acid moiety of Lipoamido-dPEG®4-TFP ester. The TFP ester reacts optimally at pH 7.5 – 8.0, but it will also react with amines at pH values above and below this range.
Lipoamido-dPEG®4-TFP ester has limited solubility in water or aqueous buffer. We recommend using dry (over 3 Å molecular sieves) water-miscible solvents such as N, N-dimethylacetamide (DMAC) or acetonitrile to form a stock solution that can be added to aqueous buffer to carry out the reaction.

Specifications

Documents

References

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

DBCO-dPEG®4-MAL, product number QBD-10592, is a short, single molecular weight, discrete polyethylene glycol (dPEG®) crosslinking reagent. The dibenzylcyclooctyne (DBCO) moiety permits strain-promoted azide-alkyne cycloaddition (SPAAC), also known as “”copper-free click chemistry.”” The maleimidopropyl (MAL) functional group forms a thiol-ether linkage with sulfhydryl groups. The short, single molecular weight dPEG® spacer is hydrophilic and non-immunogenic. DBCO-dPEG®4-MAL provides the benefits of PEG (increased water solubility, non-immunogenicity) without the analytical headaches of PEG dispersity.

The copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) discovered by K. Barry Sharpless and coworkers is one of the best-known click chemistry reactions, but its in vivo usability is limited by copper toxicity. Carolyn Bertozzi and coworkers developed SPAAC as a way to avoid copper’s toxic effects on living cells using a highly strained cyclooctyne. Developments since the initial publication show that reagents based on DBCO provide excellent, highly selective reactivity with azides, forming a triazole product.

Maleimide groups are widely popular for their ability to react rapidly with sulfhydryl groups via a Michael addition to form thioether bonds.

Vector Laboratories’ dPEG® products clearly differ from traditional polymeric polyethylene glycol (PEG). Traditional PEG is a dispersed polymer product with a Poisson distribution of chain lengths and molecular weights. The intractable mixture of chain lengths and molecular weights in traditional PEG products creates significant analytical challenges. In contrast, Vector Laboratories’ dPEG® products are single molecular weight compounds with discrete chain lengths. Using Vector Laboratories’ products greatly simplifies the analysis of dPEG®-conjugated compounds.

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.

Description

Azido-dPEG®4-TFP ester, product number QBD-10567, is a crosslinking compound designed for copper(I)-catalyzed, ruthenium catalyzed, and strain promoted click chemistry (CuAAC, RuAAC, and SPAAC, respectively). The two ends of the molecule are separated by a short (16 atoms), single molecular weight, discrete polyethylene glycol (dPEG®) spacer. The spacer imparts water solubility to QBD-10567 and increases the hydrodynamic volume of the conjugate molecule. The azide group provides the click chemistry functionality, while the 2,3,5,6-tetrafluorophenyl (TFP) ester reacts primary and secondary amines. The single molecular weight and discrete chain length of the spacer simplifies analysis of the product and of its conjugates.

TFP esters are an alternative to the widely popular N-hydroxysuccinimidyl (NHS) esters. TFP esters are more hydrolytically stable than NHS esters, and their optimal reaction pH range (7.5 – 8.0) is somewhat higher than NHS esters (7.0 – 7.5). Moreover, TFP esters in their optimal pH range are more reactive toward free amines than NHS esters.

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.