Physicochemical properties of new cyanine dye derivatives in DNA conjugates

Cyanine dyes are one of the most commonly used classes of fluorescent probes. All Cy5 fluoresce at ~ 660 nm, while Cy7 emit in the near-infrared range (700–900 nm), making them particularly suitable for biomedical applications due to reduced tissue autofluorescence in this spectral region. The fluorescence intensity of cyanine dyes typically increases upon conjugation with biomolecules such as nucleic acids. Furthermore, their fluorescence can be significantly modulated through duplex formation between dye-modified single-stranded DNA and its complementary sequence. In this study, we investigated physicochemical properties of a series of Cy5 and Cy7 derivatives with substituents of varying lengths at distinct molecular positions in both single-and double-stranded DNA conjugates.