BCN-PEG4-acid | CAS 1881221-47-1

BCN-PEG4-acid is a BCN (bicyclononyne) functionalized, PEG4-based carboxylic acid click chemistry reagent designed for strain-promoted cycloaddition with tetrazines. The reagent combines a compact, highly reactive BCN cyclooctyne motif with a short hydrophilic PEG spacer and a terminal acid handle that supports conjugation to biomolecules, polymers, and surfaces. BCN-PEG4-acid is widely used in chemical biology and molecular imaging workflows where stable, catalyst-free labeling and tunable linker length are advantageous for building tetrazine-reactive probe architectures.

1. Tetrazine Probe Conjugation

BCN-PEG4-acid is commonly used to generate BCN-labeled intermediates that can be coupled to tetrazine-bearing probes for fast, bioorthogonal labeling in complex experimental environments. The PEG4 spacer helps reduce steric congestion and improves accessibility of the cyclooctyne moiety when conjugated to proteins, peptides, or nanoparticles, supporting robust probe assembly for downstream imaging, flow-based assays, and analytical characterization. The terminal carboxylic acid functionality also enables convenient coupling to amines or surface chemistries during reagent preparation, making BCN-PEG4-acid a practical building block for constructing modular tetrazine-reactive reagent sets.

2. Surface And Material Functionalization

BCN-PEG4-acid is frequently applied in biomaterials science to functionalize polymeric and solid supports that will later be exposed to tetrazine-tagged ligands, affinity reagents, or imaging components. The carboxylic acid handle supports attachment to engineered surfaces and linker strategies used in microfabricated platforms, coatings, and hydrogel systems, while the BCN group provides a strain-promoted handle for subsequent click coupling under mild conditions. This approach is particularly useful for creating spatially addressable or batch-assembled materials where controlled incorporation of reactive sites is needed for reproducible probe immobilization and surface chemistry optimization.

3. Protein Labeling Workflows

BCN-PEG4-acid is used in chemical biology laboratories as a linker reagent to introduce BCN functionality onto proteins and protein-derived reagents prior to tetrazine-mediated conjugation. The PEG4 spacer is beneficial when labeling bulky targets or multi-domain constructs, helping maintain target recognition and improving the effective availability of the BCN moiety for rapid coupling to tetrazine partners. Researchers commonly employ BCN-PEG4-acid in workflows that require orthogonal, catalyst-free assembly of multi-component labeling reagents, such as preparing protein conjugates for microscopy, binding studies, and multiplexed analytical panels.

4. Nanoparticle And Polymer Conjugates

BCN-PEG4-acid is well suited for preparing BCN-functional nanoparticles and polymer conjugates that serve as carriers for tetrazine-reactive imaging or targeting modules. The PEG4-based design supports colloidal stability and can reduce nonspecific interactions when incorporated into polymer shells or surface layers, which is valuable for constructing well-defined conjugate architectures. The carboxylic acid group provides a practical handle for integrating BCN functionality into polymer backbones or surface linkers, enabling consistent downstream click assembly with tetrazine-bearing dyes, affinity ligands, or reporter components used in molecular imaging reagent development and analytical tool creation.