The CY series represents a family of superior cyanine-based fluorophores covering visible to NIR spectra (λem 550-850 nm). Characterized by extended conjugation systems, these dyes deliver high molar extinction coefficients (>200,000 M⁻¹cm⁻¹), excellent quantum yields, and enhanced photostability. Engineered with reactive groups (NHS ester, maleimide), they demonstrate outstanding protein and nucleic acid conjugability. Their bright NIR performance enables multiplexed flow cytometry, in vivo optical imaging, and advanced immunoassay development. The structural modularity allows precise tuning of spectral properties for customized experimental designs.