title: Specific excitonic interactions in the aggregates of hyaluronic acid and cyanine dyes with different lengths of methine group.
abstract: The absorption and circular dichroism (CD) spectra of three types of cyanine dyes with different lengths of methine group (3,3'-diethylthiadicarbocyanine iodide, DTDC; 3,3'-diethylthiacarbocyanine iodide, DTC; and 3,3'-diethylthiacyanine iodide, DTTHC) in an aqueous solution were compared with and without hyaluronic acid (HA), which has a helical structure. DTDC forms chiral H- and J-aggregates, whereas DTC and DTTHC are unable to form any aggregates. DTDC also forms H- and J-aggregates in the presence of sodium polyacrylate (PA) with a random-coil structure; however, the PA-DTDC aggregates exhibit no chirality. These results suggest that the chirality of HA-DTDC aggregates is induced by the helical structure of HA. In 2.4 vol% and 10 vol% methanol, HA-DTDC aggregates displayed different patterns of temperature dependence, whereas no aggregation was observed in 30 vol% methanol. The solubility of DTDC in a mixed solvent of water and methanol is generally improved by the addition of methanol, which prevents the aggregation of DTDC.
authors.affiliation: Graduate School of Energy Science, Kyoto University, Yoshida-Honmachi, Sakyo-Ku, Kyoto 606-8501, Japan. tobata.haruko.86w@st.kyoto-u.ac.jp sagawa.takashi.6n@kyoto-u.ac.jp.
authors.forename: H
authors.initials: H
authors.lastname: Tobata
authors.forename: T
authors.initials: T
authors.lastname: Sagawa
mesh_terms: D002232:Carbocyanines / Q000737:chemistry*; D002942:Circular Dichroism; D004396:Coloring Agents / Q000737:chemistry*; D006820:Hyaluronic Acid / Q000737:chemistry*; D015394:Molecular Structure; D013056:Spectrophotometry, Ultraviolet; D013696:Temperature
chemical_list: D002232:Carbocyanines; D004396:Coloring Agents; D006820:Hyaluronic Acid