This special red fluorescent dye DBCO-AF647 enables the possibility for copper-free click chemistry which is mostly used in reaction where cytotoxic copper catalyst is not an option. The click reaction takes place via strain-promoted Alkyne-Azide Chemistry (SPAAC) which does not need a Cu (I) catalysis or heating. Once attached to a biomolecule, fluorescence microscopy detection can be carried out just like with Cy5, or any other alternative dye.