title: Design of fluorescent nanocapsules as ratiometric nanothermometers.
abstract: We have developed a novel design of optical nanothermometers that can measure the surrounding temperature in the range of 20-85 °C. The nanothermometers comprise two organic fluorophores encapsulated in a crosslinked polymethacrylate nanoshell. The role of the nanocapsule shell around the fluorophores is to form a well-defined and stable microenvironment to prevent other factors besides temperature from affecting the dyes' fluorescence. The two fluorophores feature different temperature-dependent emission profiles; a fluorophore with relatively insensitive fluorescence (rhodamine 640) serves as a reference whereas a sensitive fluorophore (indocyanine green) serves as a sensor. The sensitivity of the nanothermometers depends on the type of nanocapsule-forming lipid and is affected by the phase transition temperature. Both the fluorescence intensity and the fluorescence lifetime can be utilized to measure the temperature.
authors.affiliation: Department of Radiology, Washington University in St. Louis School of Medicine, St. Louis, MO 63110 (USA), Fax: (+1) 314-747-5191.
authors.forename: Natalia G
authors.initials: NG
authors.lastname: Zhegalova
authors.forename: Sergey A
authors.initials: SA
authors.lastname: Dergunov
authors.forename: Steven T
authors.initials: ST
authors.lastname: Wang
authors.forename: Eugene
authors.initials: E
authors.lastname: Pinkhassik
authors.forename: Mikhail Y
authors.initials: MY
authors.lastname: Berezin
mesh_terms: D005456:Fluorescent Dyes / Q000737:chemistry*; D007208:Indocyanine Green / Q000737:chemistry*; D008055:Lipids / Q000737:chemistry; D008081:Liposomes / Q000737:chemistry; D053769:Nanocapsules / Q000737:chemistry*; D044367:Phase Transition; D010713:Phosphatidylcholines / Q000737:chemistry; D011109:Polymethacrylic Acids / Q000737:chemistry*; D012235:Rhodamines / Q000737:chemistry*; D013696:Temperature; D013821:Thermometers
chemical_list: D005456:Fluorescent Dyes; D008055:Lipids; D008081:Liposomes; D053769:Nanocapsules; D010713:Phosphatidylcholines; D011109:Polymethacrylic Acids; D012235:Rhodamines; C030613:polymethacrylic acid; C002448:1,2-linoleoylphosphatidylcholine; D007208:Indocyanine Green
keywords: fluorescence lifetime; indocyanine green; nanocapsules; thermometers; vesicles