– Biotin-PEG-Alk (MW 1000) is a biotinylated polyethylene glycol (PEG) derivative featuring alkyne functionality for click chemistry applications. Biotin acts as an enzyme co-factor for protein labeling, while PEG imparts hydrophilic, water-soluble, low-toxicity properties. The alkyne group (Alk) enables copper-catalyzed azide-alkyne cycloaddition (CuAAC) reactions with azido-modified molecules, enhancing targeting and binding with biotin receptors.