carbocyanines and pyranine

The potential biomedical utility of the photoinduced destabilization of liposomes depends in part on the use of green to near infrared light with its inherent therapeutic advantages. The polymerization of bilayers can be sensitized to green light by associating selected amphiphilic cyanine dyes, i.e. the cationic 1,1'-dioctadecyl-3,3,3', 3'-tetramethylindocarbocyanine (DiI), or the corresponding anionic disulfonated DiI (DiI-DS), with the lipid bilayer. The DiI sensitization of the polymerization of 1, 2-dioleoyl-sn-glycero-3-phosphoethanolamine/1,2-bis[10-(2', 4'-hexadienoyloxy)-decanoyl]-sn-glycero-3-phosphocholine liposomes caused liposome destabilization with release of encapsulated aqueous markers. In separate experiments, similar photosensitive liposomes were endocytosed by cultured HeLa cells. Exposure of the cells and liposomes to 550 nm light caused a net movement of the liposome-encapsulated 8-hydroxypyrene-1,3,6-trisulfonic acid (HPTS) from low pH compartment(s) to higher pH compartment(s). This suggests that photolysis of DiI-labelled liposomes results in delivery of the contents of the endocytosed liposomes to the cytoplasm. The release of HPTS into the cytoplasm appears to require the photoactivated fusion of the labelled liposomes with the endosomal membrane. These studies aid in the design of visible light sensitive liposomes for the delivery of liposome-encapsulated reagents to the cytoplasm.

Topics: Arylsulfonates; Carbocyanines; Color; Cytoplasm; Drug Carriers; Endocytosis; Endosomes; Fluorescent Dyes; HeLa Cells; Humans; Hydrogen-Ion Concentration; Light; Liposomes; Membrane Fusion; Naphthalenes; Phosphatidylcholines; Phosphatidylethanolamines; Photolysis; Pyridinium Compounds; Sulfonic Acids; Temperature; Ultraviolet Rays

An inexpensive adapter mounted in front of the objective lens of a fundus camera permits routine fluorescein angiography of the heavily pigmented iris. Angiograms of these patients whose iris pigment was dense enough that standard methods of iris angiography would disclose little or no information were performed with the use of the adapter. For use in the study of the iris vasculature in the research laboratory, three dyes with spectral characteristics different from those of fluorescein allow angiography of the iris at different wavelengths. Angiograms using these dyes were performed on the eye of a cynomolgus monkey. The angiograms were each taken as close as possible to the same time sequence and show dramatically different filling and staining patterns.

Topics: Animals; Arylsulfonates; Carbocyanines; Eye Color; Fluorescein; Fluorescein Angiography; Fluoresceins; Fluorescent Dyes; Humans; Iris Diseases; Macaca fascicularis; Rhodamines