endo-BCN-PEG3-acid | CAS 1807501-82-1

endo-BCN-PEG3-acid is a strained-alkyne (BCN) click chemistry reagent functionalized with a short PEG3 linker and terminated with a carboxylic acid for convenient conjugation and downstream coupling. As a cyclooctyne-based bioorthogonal handle, it is commonly used in strain-promoted azide–alkyne cycloaddition (SPAAC) workflows where azide-bearing biomolecules or materials need to be selectively functionalized without copper catalysis. The PEG3 spacer supports aqueous compatibility and helps present the BCN moiety for efficient labeling in complex biological or materials environments, making endo-BCN-PEG3-acid a practical reagent for probe and surface construction.

1. Azide Biomolecule Labeling

endo-BCN-PEG3-acid is widely used to functionalize azide-tagged peptides, proteins, antibodies, and nucleic-acid derivatives in labeling and screening workflows that benefit from copper-free click chemistry. The carboxylic acid enables additional coupling steps (for example, attachment to activated ester or carbodiimide-activated partners) when a single BCN-bearing intermediate is not sufficient. Researchers often select this reagent to incorporate a clickable strained-alkyne handle into bioconjugates while maintaining compatibility with aqueous buffers and multi-step conjugation strategies.

2. Targeted Imaging Probe Conjugation

endo-BCN-PEG3-acid supports the assembly of molecular imaging and detection reagents by providing a BCN group that can be clicked onto azide-functional imaging scaffolds, affinity ligands, or reporter constructs. The PEG3 linker helps reduce steric constraints between the imaging moiety and the reactive BCN, which is particularly useful when building modular probe architectures for optical or fluorescence-based assays and other imaging readouts. The terminal acid further allows integration into probe pipelines that require standardized attachment chemistry prior to or after SPAAC labeling.

3. Surface And Material Functionalization

endo-BCN-PEG3-acid is used to introduce SPAAC-reactive BCN functionality onto polymer surfaces, hydrogel components, and other material platforms that carry azide groups or are designed for subsequent azide incorporation. The PEG3 spacer improves presentation of the strained-alkyne at interfaces, which can be important for consistent labeling density and for minimizing nonspecific interactions in complex media. The carboxylic acid handle also supports material-to-material coupling schemes, enabling BCN-bearing coatings, capture surfaces, and modular material building blocks for research-grade assay development.

4. Multistep Bioconjugate Building Blocks

endo-BCN-PEG3-acid is commonly employed as a versatile intermediate in multistep bioconjugation workflows where a BCN handle must be introduced early and further derivatized later. The combination of a click-reactive BCN group with a PEG3 spacer and a terminal acid supports sequential assembly strategies, such as installing BCN onto one module and then using the acid for orthogonal coupling to a second functional element. This makes the reagent a practical choice for constructing complex conjugates used in chemical biology toolkits, including standardized linkers for libraries of azide-bearing targets and reporter modules.