Spectroscopic and Binding Properties of Near-Infrared Tricarbocyanine Dyes to Double-Stranded DNA

Abstract

The noncovalent binding and spectroscopic properties of several near-infrared tricarbocyanine dyes with respect to sonicated calf-thymus DNA are reported. The dyes investigated were diethylthiatricarbocyanine iodide (DTTCI), diethyloxatricarbocyanine iodide (DOTCI), and 1,1',3,3,3',3'-hexamethylindotricarbocyanine iodide (HITCI), which are cationic and possess absorption maxima at 772, 695, and 750 nm, respectively, in DMSO. In buffered aqueous solutions, these dyes demonstrated extensive ground-state aggregation in aqueous solvents when compared to DMSO. In the presence of double-stranded DNA (dsDNA), the fluorescence emission spectra revealed enhancement ratios of bound-to-free dye ranging from 4.5 for DOTCI to 128 for DTTCI. Spectrophotometric titrations and Scatchard analyses of the dye-dsDNA complexes yielded nonlinear plots, suggestive of possible multiple binding sites on the DNA. Viscometric titrations of the complexes showed increased solution viscosities for DTTCI, consistent with an unraveling and lengthening of the dsDNA upon complexation. Fluorescence lifetime data of the dye-dsDNA complexes showed longer lifetimes exhibited by these dyes in the presence of the dsDNA compared with those in solutions with no DNA.

Preliminary Structure–activity Relationship Study of Heptamethine Indocyanine Dyes for Tumor-Targeted Imaging

“…Through comparison of selectivity of 9, 10, 11 in which structures comprise benzo ring between R 3 and R 4 , we found that these compounds lost the property of tumor targeting. It indicates that the formation of benzo ring between R 3 and R 4 in indole ring is disadvantage to retain the tumor selectivity.…”

Fluorimetric studies and noncovalent labeling of protein with the near‐infrared dye HITCI for analysis by CE‐LIF

“…In the presence of double-stranded DNA, the emission spectrum revealed a fluorescence enhancement of 4 to 5 times over that seen for HITCI alone, compared to 128-fold enhancement for DTTCI, another cationic tricarbocyanine dye. Scatchard analysis revealed the presence of two binding sites for HITCI, with provisional binding constants of 4.27610 4 M -1 and 2.89610 3 M -1 reported, the former ascribed to stronger, intercalating dye molecules and the latter to weaker exterior binding molecules [13].…”

Advances in the study of luminescence probes for proteins

“…Cyanine dyes are widely used as fluorescent probes for biomacromolecules, and their representative structures [92][93][94][95][96][97] are shown in Fig. 10.…”