Tunable Narrow Band Emissions from Dye-Sensitized Core/Shell/Shell Nanocrystals in the Second Near-Infrared Biological Window.

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.

[1]  Wei Feng,et al.  Sub-10 nm hexagonal lanthanide-doped NaLuF4 upconversion nanocrystals for sensitive bioimaging in vivo. , 2011, Journal of the American Chemical Society.

[2]  Nathaniel L Rosi,et al.  Near-infrared luminescent lanthanide MOF barcodes. , 2009, Journal of the American Chemical Society.

[3]  François Légaré,et al.  Exploiting the biological windows: current perspectives on fluorescent bioprobes emitting above 1000 nm. , 2016, Nanoscale horizons.

[4]  Y. Liu,et al.  Ultrasensitive nanosensors based on upconversion nanoparticles for selective hypoxia imaging in vivo upon near-infrared excitation. , 2014, Journal of the American Chemical Society.

[5]  Vasilis Ntziachristos,et al.  Looking and listening to light: the evolution of whole-body photonic imaging , 2005, Nature Biotechnology.

[6]  Shuo Diao,et al.  Through-skull fluorescence imaging of the brain in a new near-infrared window , 2014, Nature Photonics.

[7]  Ralph Weissleder,et al.  Near-infrared fluorescence: application to in vivo molecular imaging. , 2010, Current opinion in chemical biology.

[8]  Shuo Diao,et al.  A small-molecule dye for NIR-II imaging. , 2016, Nature materials.

[9]  Paras N. Prasad,et al.  (α-NaYbF4:Tm(3+))/CaF2 core/shell nanoparticles with efficient near-infrared to near-infrared upconversion for high-contrast deep tissue bioimaging. , 2012, ACS nano.

[10]  M. C. Mancini,et al.  Bioimaging: second window for in vivo imaging. , 2009, Nature nanotechnology.

[11]  Ling-Dong Sun,et al.  Nd(3+)-sensitized upconversion nanophosphors: efficient in vivo bioimaging probes with minimized heating effect. , 2013, ACS nano.

[12]  Hai Zhu,et al.  Upconverting near-infrared light through energy management in core-shell-shell nanoparticles. , 2013, Angewandte Chemie.

[13]  A. N. Bashkatov,et al.  Optical properties of human skin, subcutaneous and mucous tissues in the wavelength range from 400 to 2000 nm , 2005 .

[14]  G. Dieke,et al.  The Spectra of the Doubly and Triply Ionized Rare Earths , 1963 .

[15]  Wing-Cheung Law,et al.  Core/shell NaGdF4:Nd(3+)/NaGdF4 nanocrystals with efficient near-infrared to near-infrared downconversion photoluminescence for bioimaging applications. , 2012, ACS nano.

[16]  J. C. Kraft,et al.  Interactions of Indocyanine Green and Lipid in Enhancing Near-Infrared Fluorescence Properties: The Basis for Near-Infrared Imaging in Vivo , 2014, Biochemistry.

[17]  Yan Wang,et al.  Energy-Cascaded Upconversion in an Organic Dye-Sensitized Core/Shell Fluoride Nanocrystal. , 2015, Nano letters.

[18]  Hongjie Dai,et al.  Ag2S quantum dot: a bright and biocompatible fluorescent nanoprobe in the second near-infrared window. , 2012, ACS nano.

[19]  Kevin Welsher,et al.  Deep-tissue anatomical imaging of mice using carbon nanotube fluorophores in the second near-infrared window , 2011, Proceedings of the National Academy of Sciences.

[20]  P. Prasad,et al.  Upconversion Nanoparticles: Design, Nanochemistry, and Applications in Theranostics , 2014, Chemical reviews.

[21]  Xiaoming Li,et al.  Epitaxial seeded growth of rare-earth nanocrystals with efficient 800 nm near-infrared to 1525 nm short-wavelength infrared downconversion photoluminescence for in vivo bioimaging. , 2014, Angewandte Chemie.

[22]  Qiang Sun,et al.  Mechanistic investigation of photon upconversion in Nd(3+)-sensitized core-shell nanoparticles. , 2013, Journal of the American Chemical Society.

[23]  B. Wall,et al.  Rare-earth-doped biological composites as in vivo shortwave infrared reporters , 2013, Nature Communications.

[24]  Zhengquan Li,et al.  An efficient and user-friendly method for the synthesis of hexagonal-phase NaYF4:Yb, Er/Tm nanocrystals with controllable shape and upconversion fluorescence , 2008, Nanotechnology.

[25]  Y. Nagasaki,et al.  Near-infrared (1550 nm) in vivo bioimaging based on rare-earth doped ceramic nanophosphors modified with PEG-b-poly(4-vinylbenzylphosphonate). , 2011, Nanoscale.

[26]  Guosong Hong,et al.  Multifunctional in vivo vascular imaging using near-infrared II fluorescence , 2012, Nature Medicine.