Chiral stacking of cyanine or porphyrin as cationic fluorescent dyes in the presence of anionic polysaccharide of hyaluronic acid
Haruko Tobata, Koyuki Nagashima, Yutaka Okazaki, Takashi Sagawa
SN Applied Sciences
Cyanine dye or porphyrin are part of an important family of fluorophores, which have been widely used for photosensitization and optical recording materials. We compared herein the aggregation behaviors of two types of cationic dyes of cyanine or porphyrin in the presence of hyaluronic acid, which contains D-glucuronic acid as anionic helical polysaccharide. UV–Vis absorption and photoluminescence spectra of those aqueous solutions revealed that fluorescent dyes of cyanine form H- and J-aggregates in the presence of hyaluronic acid. In particular, photoluminescent quenching through the H- and J-aggregates was observed in the mixture of anionic hyaluronic acid and the cationic cyanine dyes. On the contrary, increment of the intensities of the emission was confirmed in the mixture of porphyrin-hyaluronic acid through the effective interaction between the cationic porphyrin and anionic hyaluronic acid, which was confirmed by remarkable split-Cotton effects of induced circular dichroism in the visible region, though the UV-Vis spectra of porphyrin with hyaluronic acid did not show any sign of aggregation of porphyrin itself. Further addition of hyaluronic acid resulted in the decrease of the extent of the induced circular dichroism, though photoluminescent intensity was kept without quenching. It was also confirmed that the light scattering could be detected only when the remarkable split-Cotton effects were observed. Therefore, cationic porphyrin and anionic hyaluronic acid form complex and the complex might assemble to show the light scattering, though the single molecule of porphyrin was surrounded by polysaccharides and isolated without dye-aggregation.
Fluorescence, Photoluminescence, Chemical stability, Circular dichroism, Materials