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 9689c5aa-6556-4b3c-b5d1-1e693715ba07's line of next-generation fluorescent dyes with advantages in brightness, photostability, and conjugate specificity compared to other fluorescent dyes. Blue fluorescent CF®405M dye has excitation/emission at 408/452 nm.