title: Tunable Narrow Band Emissions from Dye-Sensitized Core/Shell/Shell Nanocrystals in the Second Near-Infrared Biological Window.
abstract: We introduce a hybrid organic-inorganic system consisting of epitaxial NaYF4:Yb3+/X3+@NaYbF4@NaYF4:Nd3+(X = null, Er, Ho, Tm, or Pr) core/shell/shell (CSS) nanocrystal with organic dye, indocyanine green (ICG) on the nanocrystal surface. This system is able to produce a set of narrow band emissions with a large Stokes-shift (>200 nm) in the second biological window of optical transparency (NIR-II, 1000-1700 nm), by directional energy transfer from light-harvesting surface ICG, via lanthanide ions in the shells, to the emitter X3+in the core. Surface ICG not only increases the NIR-II emission intensity of inorganic CSS nanocrystals by ∼4-fold but also provides a broadly excitable spectral range (700-860 nm) that facilitates their use in bioapplications. We show that the NIR-II emission from ICG-sensitized Er3+-doped CSS nanocrystals allows clear observation of a sharp image through 9 mm thick chicken breast tissue, and emission signal detection through 22 mm thick tissue yielding a better imaging profile than from typically used Yb/Tm-codoped upconverting nanocrystals imaged in the NIR-I region (700-950 nm). Our result on in vivo imaging suggests that these ICG-sensitized CSS nanocrystals are suitable for deep optical imaging in the NIR-II region.
authors.affiliation: Institute for Lasers, Photonics, and Biophotonics and Department of Chemistry, University at Buffalo, State University of New York , Buffalo, New York 14260, United States.|School of Chemistry and Chemical Engineering, Harbin Institute of Technology , Harbin, Heilongjiang 150001, People's Republic of China.
authors.forename: Wei
authors.initials: W
authors.lastname: Shao
authors.affiliation: Institute for Lasers, Photonics, and Biophotonics and Department of Chemistry, University at Buffalo, State University of New York , Buffalo, New York 14260, United States.|School of Chemistry and Chemical Engineering, Harbin Institute of Technology , Harbin, Heilongjiang 150001, People's Republic of China.
authors.forename: Guanying
authors.initials: G
authors.lastname: Chen
authors.affiliation: Institute for Lasers, Photonics, and Biophotonics and Department of Chemistry, University at Buffalo, State University of New York , Buffalo, New York 14260, United States.
authors.forename: Andrey
authors.initials: A
authors.lastname: Kuzmin
authors.affiliation: Institute for Lasers, Photonics, and Biophotonics and Department of Chemistry, University at Buffalo, State University of New York , Buffalo, New York 14260, United States.
authors.forename: Hilliard L
authors.initials: HL
authors.lastname: Kutscher
authors.affiliation: Institute for Lasers, Photonics, and Biophotonics and Department of Chemistry, University at Buffalo, State University of New York , Buffalo, New York 14260, United States.
authors.forename: Artem
authors.initials: A
authors.lastname: Pliss
authors.affiliation: Institute for Lasers, Photonics, and Biophotonics and Department of Chemistry, University at Buffalo, State University of New York , Buffalo, New York 14260, United States.|College of Optoelectronic Engineering, Shenzhen University , Shenzhen, Guangdong 518060, People's Republic of China.
authors.forename: Tymish Y
authors.initials: TY
authors.lastname: Ohulchanskyy
authors.affiliation: Institute for Lasers, Photonics, and Biophotonics and Department of Chemistry, University at Buffalo, State University of New York , Buffalo, New York 14260, United States.
authors.forename: Paras N
authors.initials: PN
authors.lastname: Prasad