Fluorescence Dye 488-I with Streptavidin conjugate. Fluorescence Dye 488-I conjugates are significantly brighter than fluorescein conjugates and much more photostable. Additionally, the fluorescence of Fluorescence Dye 488-I is not affected by pH between 4-10. Compared to Alexa Fluor 488, "Fluorescence Dye 488-I of single isomer has much hihger purity, bringing better performance consistancy from batch to batch.