Biotin-PEG-Alk (MW 2000) is a biotin-labeled polyethylene glycol (PEG) derivative featuring an alkyne group for click chemistry applications. This compound, efficiently binding to biotin targets due to the alkyne moiety that can react with azides, serves as a versatile tool in bioconjugation processes, including the labeling of proteins. The hydrophilic nature of PEG ensures solubility in aqueous environments and minimal toxicity, while the alkyne (an acyclic hydrocarbon that may be branched or unbranched) facilitates copper-catalyzed azide-alkyne cycloaddition (CuAAC), enhancing biotin-avidin interaction assays and molecular assembly.