Bromo-PEG4-azide（Cat No.:I015793）is a heterobifunctional polyethylene glycol linker designed for versatile bioconjugation and chemical modification. It features a terminal bromide group that undergoes nucleophilic substitution with thiols, amines, or other reactive nucleophiles, and an azide group compatible with copper-catalyzed or strain-promoted click chemistry with alkynes. The PEG4 spacer provides hydrophilicity, flexibility, and minimized steric hindrance, ensuring excellent solubility and accessibility in diverse environments. This dual-functional reagent is widely employed in chemical biology, proteomics, drug delivery, and materials science, enabling modular assembly and controlled molecular design for advanced research applications.