Activated Alkynes in Metal‐free Bioconjugation

Bioconjugation is a chemical strategy to form a covalent linkage between two molecules, at least one of which is a biomolecule. Bioconjugation has been a booming research topic along with the development of organic chemistry. The advancement of bioconjugation has greatly promoted many fields like analysis, medicine, and material science. In the past several years, various synthetic methodologies have been employed for bioconjugation chemistry, mainly containing two aspects: one is the conjugation based on the modification of extrinsic functional groups on the biomolecules, followed by covalent linking with expected reporters or targeting units. Another strategy is the direct conjugation of some functional units to the native groups in the biomolecule without any previous modification. Both of them have advantages and insufficiencies in some aspects, which depend on their specific application areas. In the past two decades, alkyne-related polymer chemistry has been a constant research interest for Tang and coworkers, which has also inspired the research progress in bioconjugation. In this chapter, the progress of metal-free bioconjugation based on activated alkynes is summarized and some representative works are displayed for further elaborations. The screening of activated alkynes to improve reactivity and general applicability for bioconjugation is also discussed; we hope the noted activated alkynes will inspire the applications of modern bioconjugation.