DBCO-PEG5-NHS ester | CAS 2144395-59-3

DBCO-PEG5-NHS ester is a cyclooctyne (DBCO)-functionalized polyethylene glycol NHS ester designed for strain-promoted copper-free click bioconjugation and efficient amide coupling to primary amines. The reagent combines an NHS-activated handle for robust attachment to amine-containing biomolecules or surfaces with a DBCO cyclooctyne moiety that can be reacted with azide-bearing partners in subsequent click steps. Its PEG5 spacer improves solubility and reduces steric constraints, making it a common choice for preparing azide-reactive conjugates used in labeling, imaging, and modular biomaterials workflows.

1. Protein And Peptide Labeling

DBCO-PEG5-NHS ester is widely used to functionalize proteins, peptides, and protein domains by reacting the NHS ester with accessible lysine residues or N-terminal amines, yielding DBCO-bearing bioconjugates that can later undergo strain-promoted azide–alkyne cycloaddition. This workflow is especially valuable when researchers need a stable, modular labeling intermediate that can be coupled to azide-functional dyes, affinity tags, or imaging handles under copper-free conditions. The PEG5 spacer helps maintain conjugate solubility and promotes more uniform accessibility of the DBCO group during downstream click conjugation, which is important for consistent labeling across different protein formats.

2. Antibody Conjugation Workflows

DBCO-PEG5-NHS ester supports antibody and antibody-fragment derivatization for building azide-reactive immunoconjugation tools used in molecular imaging and assay development. By installing DBCO groups onto amine-rich antibody surfaces through NHS ester chemistry, the reagent enables subsequent coupling to azide-functional reporters or multivalent constructs without requiring copper catalysts. The PEG spacer can mitigate steric shielding near the antibody surface, helping preserve reactivity of the cyclooctyne handle for efficient azide click coupling during probe assembly. This approach is commonly adopted in research settings where modularity and orthogonal reactivity are required to generate consistent conjugate libraries.

3. Surface and Bead Functionalization

DBCO-PEG5-NHS ester is frequently employed to create azide-reactive surfaces, resins, and bead-based platforms by coupling the NHS ester to amine-bearing coatings, linkers, or functionalized polymers. The resulting DBCO-presenting materials can then be used to capture or pattern azide-tagged biomolecules, enabling modular immobilization strategies for biosensing, enrichment, and workflow automation in chemical biology and materials laboratories. PEG5 spacing is particularly useful on heterogeneous surfaces, where it can improve accessibility of the DBCO moiety and reduce nonspecific steric effects that otherwise limit click coupling efficiency. This makes the reagent a practical choice for preparing reusable conjugation-ready solid supports.

4. Nucleic Acid and Biomolecule Conjugates

DBCO-PEG5-NHS ester is used to generate DBCO-functional biomolecule conjugates for downstream click assembly with azide-functional nucleic acid components, oligonucleotide tags, or other azide-bearing molecular partners. While nucleic acids are not typically NHS-reactive without introducing amine-containing modifications, the reagent is commonly applied to amine-functional carriers or to conjugation intermediates that bridge nucleic acids to imaging or analytical reporters. The PEG5 linker contributes to improved handling and dispersion of conjugates, which is beneficial when preparing multicomponent labeling reagents or constructing modular probe architectures that rely on azide–DBCO click compatibility. This use case aligns with common molecular biology and chemical biology workflows that prioritize orthogonal coupling steps and reproducible conjugate construction.