Biotin-PEG3-Bromide is a short PEG linker incorporating both a biotin group and a bromide. The bromide, being a halogen, is readily substituted by nucleophiles such as alcohols or amines. Additionally, bromide can participate in various cross-coupling reactions, such as the Suzuki reaction. Biotin is applicable in affinity-based applications, like pull-down assays or attachment to streptavidin proteins.