N-(Azido-PEG3)-N-Boc-PEG4-acid | CAS 2112731-95-8

N-(Azido-PEG3)-N-Boc-PEG4-acid is a PEG-based azide-containing click chemistry reagent designed for bioorthogonal conjugation workflows. The molecule combines an azide handle with extended polyethylene glycol spacers that improve solubility and reduce nonspecific interactions during labeling and surface functionalization. Its protected amine functionality (Boc) and terminal carboxylic acid make it well-suited for building modular, water-compatible conjugates used in chemical biology, probe development, and biomaterials assembly.

1. Biomolecule Labeling

N-(Azido-PEG3)-N-Boc-PEG4-acid is widely used as a click-ready linker for introducing an azide functional group onto biomolecules and biomolecule-derived constructs. Researchers commonly incorporate the terminal carboxylic acid for coupling to amine- or hydrazide-bearing targets, then use the azide for subsequent strain-promoted or copper-catalyzed azide–alkyne cycloaddition with complementary partners. The PEG3/PEG4 spacing helps maintain conjugate accessibility, which is particularly valuable when labeling proteins, peptides, nucleic-acid reagents, or polymer-modified biomolecules where steric crowding can limit effective coupling. This reagent is also frequently selected for generating homogeneous labeling reagents that retain aqueous compatibility for downstream imaging and analytical workflows.

2. Surface And Material Functionalization

N-(Azido-PEG3)-N-Boc-PEG4-acid supports azide installation on material surfaces and polymeric scaffolds used in biomaterials research. The carboxylic acid enables attachment strategies to substrates that can present reactive amines or activated linkers, while the PEG spacers provide a hydrated, antifouling-like environment that can improve reagent dispersion and reduce nonspecific adsorption. Once immobilized, the azide handle serves as a modular attachment point for post-functionalization with cyclooctyne or alkyne-bearing molecules, allowing iterative assembly of coatings, biosensing interfaces, and cell-interaction materials. This makes the reagent a practical building block for creating clickable material platforms used in mechanistic studies, materials characterization, and probe immobilization.

3. Molecular Imaging Probe Building

N-(Azido-PEG3)-N-Boc-PEG4-acid is commonly used in the preparation of imaging and detection probes that require a stable, water-compatible azide functionality for later conjugation. Its PEG architecture supports solubility and helps preserve probe performance during multi-step reagent assembly, including attachment to targeting motifs or scaffold components prior to final click coupling. The terminal acid facilitates integration into probe-building schemes where a linker must be introduced before radiolabeling, fluorescent tagging, or affinity handle installation. By providing a defined azide-bearing spacer, the reagent helps maintain controlled distances between probe components, which can be important for minimizing quenching, improving labeling reproducibility, and enabling consistent probe architecture across batches.

4. Diagnostic Reagent Conjugates

N-(Azido-PEG3)-N-Boc-PEG4-acid is used to generate click-compatible conjugates for diagnostic reagent development and assay reagent construction. The azide group allows efficient coupling to alkyne-bearing detection moieties, affinity ligands, or signal-generating tags under bioconjugation conditions that are compatible with complex reagent formulations. The PEG spacers help manage conjugate behavior in aqueous assay buffers, supporting consistent reagent handling and reducing aggregation that can complicate assay readouts. In typical workflows, the carboxylic acid is employed to connect the azide-bearing linker to assay components, enabling modular swapping of detection chemistries while keeping the conjugation interface standardized for scalable reagent preparation.