Studies on solvatochromic properties of aminophenylstyryl-quinolinum dye, LDS 798, and its application in studying submicron lipid based structure

The styryl group of dyes has been used in cellular studies for over 20 years because of their solvatochromic and/or electrochromic properties. Here we report characterization of solubility and solvatochromic properties of a near infra-red styryl dye, styryl 11 or LDS 798. We have extended our studies to small unilamellar vesicles and lipid based nanoparticles and found that solvatochromic properties of this dye used in tandem with fluorescence correlation spectroscopy can be used to efficiently determine the diffusion coefficient and hence the size of the submicron lipid based particles. This technique has the potential to provide essential information about liposomal and vesicular structures and their movement in vitro and in situ.

Graphical AbstractApplication of solvatochromic dye LDS 798 in measuring the diffusion coefficient of liposomes by FCS. The MCS trace (left) clearly shows the change in fluorescence signal of LDS 798 after addition of liposomes.Research Highlights►LDS 798, a NIR dye, is used to label liposomes for single molecule based studies. ►LDS 798 has a moderate partition coefficient indicating it is soluble in water. ►LDS 798 has solvatochromic fluorescence properties like similar dyes. ►Last two properties of LDS 798 result in easy and effective liposome labeling.