DBCO-PEG4-acid | CAS 1537170-85-6

DBCO-PEG4-acid is a DBCO (dibenzocyclooctyne) functionalized PEG4 carboxylic acid designed for strain-promoted azide–alkyne cycloaddition (SPAAC) click chemistry under copper-free conditions. The PEG4 spacer improves solubility and reduces steric constraints, while the terminal acid enables straightforward conjugation to biomolecules, surfaces, and polymeric scaffolds via standard coupling chemistries. This reagent is widely used as a modular handle for attaching DBCO-bearing linkers to targeting ligands, biomaterials, and imaging or assay platforms where robust, bioorthogonal labeling is required.

1. Bioconjugation To Biomolecules

DBCO-PEG4-acid is commonly employed to generate azide-reactive bioconjugates by first converting the carboxylic acid into an activated ester or coupling handle, then attaching it to proteins, peptides, antibodies, or affinity reagents. The PEG4 chain helps maintain accessibility of the DBCO moiety for efficient SPAAC labeling after conjugation, supporting workflows where a DBCO-functional intermediate is prepared and later reacted with azide-tagged partners. This approach is frequently used in chemical biology for building multi-component probes, including reagent sets for labeling, pull-downs, and modular assembly of complex biomolecular constructs.

2. Surface And Material Functionalization

DBCO-PEG4-acid is well suited for immobilizing click-reactive functionality onto material surfaces such as glass, polymer films, and nanoparticle platforms through carboxyl-directed surface coupling strategies. Once tethered, the DBCO group provides a copper-free route to attach azide-bearing biomolecules, capture ligands, or reporter tags, enabling straightforward fabrication of functional coatings and assay-ready materials. The PEG4 spacer can improve ligand presentation and reduce nonspecific steric effects, which is especially valuable when immobilized DBCO sites must remain accessible for downstream azide conjugation steps.

3. Molecular Imaging Probe Assembly

DBCO-PEG4-acid is frequently used in the preparation of imaging reagents and fluorescent or luminescent labeling tools where a DBCO-bearing scaffold is reacted with azide-functional reporters. The PEG4-acid design supports incorporation into probe architectures that require controlled spacing between the reactive click handle and the imaging moiety, helping maintain signal compatibility and reducing aggregation tendencies during labeling. In molecular imaging and diagnostic reagent development, DBCO-PEG4-acid is often selected as a practical intermediate for assembling multi-label probes, including multivalent constructs that benefit from flexible linker length.

4. Polymer And Nanoparticle Labeling

DBCO-PEG4-acid is applied to functionalize polymer backbones and nanoparticle surfaces with SPAAC-compatible DBCO groups, enabling subsequent conjugation to azide-terminated polymers, targeting peptides, or other reactive components. The PEG4 spacer can enhance dispersion and accessibility of the DBCO sites, which is important for maintaining consistent labeling density across heterogeneous materials. This reagent is commonly integrated into industrial and research workflows for producing click-assembled polymer conjugates, surface-modified nanocarriers, and modular material systems used in advanced materials science and bioanalytical assay development.