Tetrazine Click Reagents

Tetrazine click reagents are bioorthogonal labeling molecules that react rapidly with strained alkenes, such as transcyclooctene (TCO) through the IEDDA (inverse electron-demand Diels-Alder) reaction. This copper-free click chemistry proceeds efficiently under physiological conditions, forming a stable covalent linkage while releasing nitrogen gas as the only byproduct. Due to their exceptional reaction kinetics, specificity, and compatibility with living systems, tetrazine reagents are among the most widely used click chemistry tools for labeling proteins, nucleic acids, cells, and other biomolecules in applications including imaging, bioconjugation, diagnostics, and targeted drug delivery.