CF® dye with BCN reacts with azide to form 1,2,3-triazole by copper free 1,3-dipolar Huisgen cycloaddition. This copper-free bioorthogonal reaction allows staining the surface of live cells or cell extracts when there are concerns about native protein function loss with copper. CF® dyes are Biotium's line of next-generation fluorescent dyes with advantages in brightness, photostability, and conjugate specificity compared to other fluorescent dyes. • Green fluorescent CF®488A dye has excitation/emission at 490/515 nm. • Red fluorescent CF®568 dye has excitation/emission at 562/583 nm. • Deep-red fluorescent CF®594 dye has excitation/emission at 593/614 nm. • Far-red fluorescent CF®640R dye has excitation/emission at 642/662 nm. • Far-red/near-IR fluorescent CF®770R dye has excitation/emission at 680/701 nm. • Blue fluorescent CF®405S dye has excitation/emission at 404/431 nm. • Blue fluorescent CF®405M dye has excitation/emission at 408/452 nm. • CF®500-BCN has excitation/emission at 500/510 nm, and is designed for intracellular copper-free reaction with azide. • CF®650-BCN has excitation/emission at 650/670 nm, and is designed for intracellular copper-free reaction with azide. • Far-red/near-IR fluorescent CF®680 dye has excitation/emission at 681/698 nm. • Far-red fluorescent CF®647 dye has excitation/emission at 650/665 nm. • 405 nm-excitable green fluorescent CF®440 dye has excitation/emission at 440/515 nm.