title: Phospholipid-bound molecular rotors: synthesis and characterization.
abstract: Molecular rotors are fluorescent molecules with a viscosity-sensitive quantum yield that are often used to measure viscosity changes in cell membranes and liposomes. However, commercially available molecular rotors, such as DCVJ (1) do not localize in cell membranes but rapidly migrate into the cytoplasm leading to unreliable measurements of cell membrane viscosity. To overcome this problem, we synthesized molecular rotors covalently attached to a phospholipid scaffold. Attaching the rotor group to the hydrophobic end of phosphatidylcholine (PC) did not affect the rotor's viscosity sensitivity and allowed adequate integration into artificial bilayers as well as complete localization in the plasma membrane of an endothelial cell line. Moreover, these new rotors enabled the monitoring of phospholipid transition temperature. However, attachment of the rotor groups to the hydrophilic head of the phospholipid led to a partial loss of viscosity sensitivity. The improved sensitivity and exclusive localization in the cell plasma membrane exhibited by the phospholipid-bound molecular rotors suggest that these probes can be used for the study of membrane microviscosity.
authors.affiliation: Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093-0412, USA.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Haidekker
authors.forename: Thomas
authors.initials: T
authors.lastname: Brady
authors.forename: Ke
authors.initials: K
authors.lastname: Wen
authors.forename: Cliff
authors.initials: C
authors.lastname: Okada
authors.forename: Hazel Y
authors.initials: HY
authors.lastname: Stevens
authors.forename: Jeniffer M
authors.initials: JM
authors.lastname: Snell
authors.forename: John A
authors.initials: JA
authors.lastname: Frangos
authors.forename: Emmanuel A
authors.initials: EA
authors.lastname: Theodorakis
mesh_terms: D002460:Cell Line; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D004396:Coloring Agents; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism; D005456:Fluorescent Dyes / Q000138:chemical synthesis* / Q000737:chemistry*; D006801:Humans; D007202:Indicators and Reagents; D008051:Lipid Bilayers; D008081:Liposomes; D008958:Models, Molecular; D008968:Molecular Conformation; D009570:Nitriles / Q000737:chemistry; D010743:Phospholipids / Q000138:chemical synthesis* / Q000737:chemistry*; D011807:Quinolizines / Q000737:chemistry; D013055:Spectrophotometry, Infrared
chemical_list: D004396:Coloring Agents; D005456:Fluorescent Dyes; D007202:Indicators and Reagents; D008051:Lipid Bilayers; D008081:Liposomes; D009570:Nitriles; D010743:Phospholipids; D011807:Quinolizines; C061441:9-(dicyanovinyl)julolidine