N3-PEG-CH2CH2COOH

Alpha-(azido)-omega-(carboxy) poly(ethylene glycol) (N3-PEG-COOH) is a heterobifunctional precision PEG derivative with a defined chain length. The two ends bear azide and carboxyl groups, respectively. Discrete chain lengths with different degrees of polymerization are available. The azide can undergo copper-catalyzed click reactions with terminal alkynes or copper-free click conjugation with strained alkynes such as DBCO and BCN. The carboxyl group can be activated for amide coupling with primary-amine-containing molecules, retaining a handle for subsequent ligand or carrier attachment. The two end groups can be coupled sequentially using compatible reactions and appropriate protection strategies, enabling surface immobilization, functional-molecule bridging, and directional spacer synthesis.

Customization available.