Abstract

The spatial resolution of fluorescence molecular imaging is a critical issue for the success of the technique in biomedical applications. One important method for increasing the imaging resolution is to utilize multi-photon emissions. In this study, we thoroughly investigate the potential of the multi-photon upconversion emissions from rare-earth-doped upconverting nanoparticles for the improvement in spatial resolution of diffuse optical imaging. It is found that the imaging resolution is increased by a factor of 1.45 through employing two-photon upconversion emission compared with using the linear emission, and can be further elevated by a factor of 1.23 by using three-photon upconversion emission. In addition, we demonstrate that the pulsed excitation approach holds the promise of overcoming the low quantum yield associated with the high-order upconversion emissions.

© 2014 Optical Society of America

Full Article  |  PDF Article

References

  • View by:
  • |
  • |
  • |

  1. R. Weissleder and U. Mahmood, “Molecular imaging,” Radiology 219, 316–333 (2001).
    [CrossRef] [PubMed]
  2. C. Xu, W. Zipfel, J. B. Shear, R. M. Williams, and W. W. Webb, “Multiphoton fluorescence excitation: new spectral windows for biological nonlinear microscopy,” Proc. Natl. Acad. Sci. USA 93, 10763–10768 (1996).
    [CrossRef] [PubMed]
  3. Z. Li and Y. Zhang, “An efficient and user-friendly method for the synthesis of hexagonal-phase NaYF4:Yb, Er/Tm nanocrystals with controllable shape and upconversion fluorescence,” Nanotechnology 19, 345606 (2008).
    [CrossRef]
  4. F. Auzel, “Upconversion and anti-stokes processes with f and d ions in solids,” Chem. Rev. 104, 139–173 (2004).
    [CrossRef] [PubMed]
  5. M. Yu, F. Li, Z. Chen, H. Hu, C. Zhan, H. Yang, and C. Huang, “Laser scanning up-conversion luminescence microscopy for imaging cells labeled with rare-earth nanophosphors,” Anal. Chem. 81, 930–935 (2009).
    [CrossRef] [PubMed]
  6. J. Pichaandi, J.-C. Boyer, K. R. Delaney, and F. C. J. M. van Veggel, “Two-photon upconversion laser (scanning and wide-field) microscopy using Ln3+-doped NaYF4 upconverting nanocrystals: A critical evaluation of their performance and potential in bioimaging,” J. Phys. Chem. C 115, 19054–19064 (2011).
    [CrossRef]
  7. G. Chen, J. Shen, T. Y. Ohulchanskyy, N. J. Patel, A. Kutikov, Z. Li, J. Song, R. K. Pandey, H. Ågren, P. N. Prasad, and G. Han, “(α-NaYbF4:Tm3+)/CaF2 core/shell nanoparticles with efficient near-infrared to near-infrared up-conversion for high-contrast deep tissue bioimaging,” ACS Nano 6, 8280–8287 (2012).
    [CrossRef] [PubMed]
  8. Q. Liu, Y. Sun, T. Yang, W. Feng, C. Li, and F. Li, “Sub-10 nm hexagonal lanthanide-doped NaLuF4 upconversion nanocrystals for sensitive bioimaging in vivo,” J. Am. Chem. Soc. 133, 17122–17125 (2011).
    [CrossRef] [PubMed]
  9. J. Zhou, Z. Liu, and F. Li, “Upconversion nanophosphors for small-animal imaging,” Chem. Soc. Rev. 41, 1323–1349 (2012).
    [CrossRef]
  10. G. Chen, H. Qiu, P. N. Prasad, and X. Chen, “Upconversion nanoparticles: Design, nanochemistry, and applications in theranostics,” Chem. Rev. DOI: (2014).
    [CrossRef]
  11. H. Päkkilä, M. Ylihärsilä, S. Lahtinen, L. Hattara, N. Salminen, R. Arppe, M. Lastusaari, P. Saviranta, and T. Soukka, “Quantitative multianalyte microarray immunoassay utilizing upconverting phosphor technology,” Anal. Chem. 84, 8628–8634 (2012).
    [CrossRef] [PubMed]
  12. F. Wang, D. Banerjee, Y. Liu, X. Chen, and X. Liu, “Upconversion nanoparticles in biological labeling, imaging, and therapy,” Analyst 135, 1839–1854 (2010).
    [CrossRef] [PubMed]
  13. C. T. Xu, N. Svensson, J. Axelsson, P. Svenmarker, G. Somesfalean, G. Chen, H. Liang, H. Liu, Z. Zhang, and S. Andersson-Engels, “Autofluorescence insensitive imaging using upconverting nanocrystals in scattering media,” Appl. Phys. Lett. 93, 171103 (2008).
    [CrossRef]
  14. M. Nyk, R. Kumar, T. Y. Ohulchanskyy, E. J. Bergey, and P. N. Prasad, “High contrast in vitro and in vivo photoluminescence bioimaging using near infrared to near infrared up-conversion in Tm3+ and Yb3+ doped fluoride nanophosphors,” Nano Lett. 8, 3834–3838 (2008).
    [CrossRef] [PubMed]
  15. C. T. Xu, J. Axelsson, and S. Andersson-Engels, “Fluorescence diffuse optical tomography using upconverting nanoparticles,” Appl. Phys. Lett. 94, 251107 (2009).
    [CrossRef]
  16. H. Liu, C. T. Xu, D. Lindgren, H. Xie, D. Thomas, C. Gundlach, and S. Andersson-Engels, “Balancing power density based quantum yield characterization of upconverting nanoparticles for arbitrary excitation intensities,” Nanoscale 5, 4770–4775 (2013).
    [CrossRef] [PubMed]
  17. P. Svenmarker, C. T. Xu, and S. Andersson-Engels, “Use of nonlinear upconverting nanoparticles provides increased spatial resolution in fluorescence diffuse imaging,” Opt. Lett. 35, 2789–2791 (2010).
    [CrossRef] [PubMed]
  18. C. T. Xu, P. Svenmarker, H. Liu, X. Wu, M. E. Messing, L. R. Wallenberg, and S. Andersson-Engels, “High-resolution fluorescence diffuse optical tomography developed with nonlinear upconverting nanoparticles,” ACS Nano 6, 4788–4795 (2012).
    [CrossRef] [PubMed]
  19. H. Qiu, C. Yang, W. Shao, J. Damasco, X. Wang, H. Ågren, P. N. Prasad, and G. Chen, “Enhanced upconversion luminescence in Yb3+/Tm3+-codoped fluoride active core/active shell/inert shell nanoparticles through directed energy migration,” Nanomaterials 4, 55–68 (2014).
    [CrossRef]
  20. L. Caillat, B. Hajj, V. Shynkar, L. Michely, D. Chauvat, J. Zyss, and F. Pellé, “Multiphoton upconversion in rare earth doped nanocrystals for sub-diffractive microscopy,” Appl. Phys. Lett. 102, 143114 (2013).
    [CrossRef]
  21. H.-S. Qian and Y. Zhang, “Synthesis of hexagonal-phase core-shell NaYF4 nanocrystals with tunable upconversion fluorescence,” Langmuir 24, 12123–12125 (2008).
    [CrossRef] [PubMed]
  22. M. K. G. Jayakumar, N. M. Idris, and Y. Zhang, “Remote activation of biomolecules in deep tissues using near-infrared-to-uv upconversion nanotransducers,” Proc. Natl. Acad. Sci. USA 109, 8483–8488 (2012).
    [CrossRef] [PubMed]
  23. G. Chen, C. Yang, and P. N. Prasad, “Nanophotonics and nanochemistry: Controlling the excitation dynamics for frequency up- and down-conversion in lanthanide-doped nanoparticles,” Acc. Chem. Res. 46, 1474–1486 (2013).
    [CrossRef] [PubMed]
  24. W. Zou, C. Visser, J. A. Maduro, M. S. Pshenichnikov, and J. C. Hummelen, “Broadband dye-sensitized upconversion of near-infrared light,” Nat. Photonics 6, 560–564 (2012).
    [CrossRef]
  25. A. Priyam, N. M. Idris, and Y. Zhang, “Gold nanoshell coated NaYF4 nanoparticles for simultaneously enhanced upconversion fluorescence and darkfield imaging,” J. Mater. Chem. 22, 960–965 (2012).
    [CrossRef]
  26. J. Shen, G. Chen, T. Y. Ohulchanskyy, S. J. Kesseli, S. Buchholz, Z. Li, P. N. Prasad, and G. Han, “Tunable near infrared to ultraviolet upconversion luminescence enhancement in (α-NaYbF4:Tm3+)/CaF2 core/shell nanoparticles for in situ real-time recorded biocompatible photoactivation,” Small 9, 3213–3217 (2013).
    [PubMed]
  27. G. Chen, T. Y. Ohulchanskyy, R. Kumar, H. Ågren, and P. N. Prasad, “Ultrasmall monodisperse NaYF4:Yb3+/Tm3+ nanocrystals with enhanced near-infrared to near-infrared upconversion photoluminescence,” ACS Nano 4, 3163–3168 (2010).
    [CrossRef] [PubMed]
  28. H. Liu, C. T. Xu, G. Dumlupinar, O. B. Jensen, P. E. Andersen, and S. Andersson-Engels, “Deep tissue optical imaging of upconverting nanoparticles enabled by exploiting higher intrinsic quantum yield through using millisecond single pulse excitation with high peak power,” Nanoscale 5, 10034–10040 (2013).
    [CrossRef] [PubMed]
  29. C. T. Xu, Q. Zhan, H. Liu, G. Somesfalean, J. Qian, S. He, and S. Andersson-Engels, “Upconverting nanoparticles for pre-clinical diffuse optical imaging, microscopy and sensing: Current trends and future challenges,” Laser Photonics Rev. 7, 663–697 (2013).
    [CrossRef]

2014 (1)

H. Qiu, C. Yang, W. Shao, J. Damasco, X. Wang, H. Ågren, P. N. Prasad, and G. Chen, “Enhanced upconversion luminescence in Yb3+/Tm3+-codoped fluoride active core/active shell/inert shell nanoparticles through directed energy migration,” Nanomaterials 4, 55–68 (2014).
[CrossRef]

2013 (6)

L. Caillat, B. Hajj, V. Shynkar, L. Michely, D. Chauvat, J. Zyss, and F. Pellé, “Multiphoton upconversion in rare earth doped nanocrystals for sub-diffractive microscopy,” Appl. Phys. Lett. 102, 143114 (2013).
[CrossRef]

H. Liu, C. T. Xu, D. Lindgren, H. Xie, D. Thomas, C. Gundlach, and S. Andersson-Engels, “Balancing power density based quantum yield characterization of upconverting nanoparticles for arbitrary excitation intensities,” Nanoscale 5, 4770–4775 (2013).
[CrossRef] [PubMed]

G. Chen, C. Yang, and P. N. Prasad, “Nanophotonics and nanochemistry: Controlling the excitation dynamics for frequency up- and down-conversion in lanthanide-doped nanoparticles,” Acc. Chem. Res. 46, 1474–1486 (2013).
[CrossRef] [PubMed]

J. Shen, G. Chen, T. Y. Ohulchanskyy, S. J. Kesseli, S. Buchholz, Z. Li, P. N. Prasad, and G. Han, “Tunable near infrared to ultraviolet upconversion luminescence enhancement in (α-NaYbF4:Tm3+)/CaF2 core/shell nanoparticles for in situ real-time recorded biocompatible photoactivation,” Small 9, 3213–3217 (2013).
[PubMed]

H. Liu, C. T. Xu, G. Dumlupinar, O. B. Jensen, P. E. Andersen, and S. Andersson-Engels, “Deep tissue optical imaging of upconverting nanoparticles enabled by exploiting higher intrinsic quantum yield through using millisecond single pulse excitation with high peak power,” Nanoscale 5, 10034–10040 (2013).
[CrossRef] [PubMed]

C. T. Xu, Q. Zhan, H. Liu, G. Somesfalean, J. Qian, S. He, and S. Andersson-Engels, “Upconverting nanoparticles for pre-clinical diffuse optical imaging, microscopy and sensing: Current trends and future challenges,” Laser Photonics Rev. 7, 663–697 (2013).
[CrossRef]

2012 (7)

W. Zou, C. Visser, J. A. Maduro, M. S. Pshenichnikov, and J. C. Hummelen, “Broadband dye-sensitized upconversion of near-infrared light,” Nat. Photonics 6, 560–564 (2012).
[CrossRef]

A. Priyam, N. M. Idris, and Y. Zhang, “Gold nanoshell coated NaYF4 nanoparticles for simultaneously enhanced upconversion fluorescence and darkfield imaging,” J. Mater. Chem. 22, 960–965 (2012).
[CrossRef]

M. K. G. Jayakumar, N. M. Idris, and Y. Zhang, “Remote activation of biomolecules in deep tissues using near-infrared-to-uv upconversion nanotransducers,” Proc. Natl. Acad. Sci. USA 109, 8483–8488 (2012).
[CrossRef] [PubMed]

C. T. Xu, P. Svenmarker, H. Liu, X. Wu, M. E. Messing, L. R. Wallenberg, and S. Andersson-Engels, “High-resolution fluorescence diffuse optical tomography developed with nonlinear upconverting nanoparticles,” ACS Nano 6, 4788–4795 (2012).
[CrossRef] [PubMed]

J. Zhou, Z. Liu, and F. Li, “Upconversion nanophosphors for small-animal imaging,” Chem. Soc. Rev. 41, 1323–1349 (2012).
[CrossRef]

H. Päkkilä, M. Ylihärsilä, S. Lahtinen, L. Hattara, N. Salminen, R. Arppe, M. Lastusaari, P. Saviranta, and T. Soukka, “Quantitative multianalyte microarray immunoassay utilizing upconverting phosphor technology,” Anal. Chem. 84, 8628–8634 (2012).
[CrossRef] [PubMed]

G. Chen, J. Shen, T. Y. Ohulchanskyy, N. J. Patel, A. Kutikov, Z. Li, J. Song, R. K. Pandey, H. Ågren, P. N. Prasad, and G. Han, “(α-NaYbF4:Tm3+)/CaF2 core/shell nanoparticles with efficient near-infrared to near-infrared up-conversion for high-contrast deep tissue bioimaging,” ACS Nano 6, 8280–8287 (2012).
[CrossRef] [PubMed]

2011 (2)

Q. Liu, Y. Sun, T. Yang, W. Feng, C. Li, and F. Li, “Sub-10 nm hexagonal lanthanide-doped NaLuF4 upconversion nanocrystals for sensitive bioimaging in vivo,” J. Am. Chem. Soc. 133, 17122–17125 (2011).
[CrossRef] [PubMed]

J. Pichaandi, J.-C. Boyer, K. R. Delaney, and F. C. J. M. van Veggel, “Two-photon upconversion laser (scanning and wide-field) microscopy using Ln3+-doped NaYF4 upconverting nanocrystals: A critical evaluation of their performance and potential in bioimaging,” J. Phys. Chem. C 115, 19054–19064 (2011).
[CrossRef]

2010 (3)

F. Wang, D. Banerjee, Y. Liu, X. Chen, and X. Liu, “Upconversion nanoparticles in biological labeling, imaging, and therapy,” Analyst 135, 1839–1854 (2010).
[CrossRef] [PubMed]

P. Svenmarker, C. T. Xu, and S. Andersson-Engels, “Use of nonlinear upconverting nanoparticles provides increased spatial resolution in fluorescence diffuse imaging,” Opt. Lett. 35, 2789–2791 (2010).
[CrossRef] [PubMed]

G. Chen, T. Y. Ohulchanskyy, R. Kumar, H. Ågren, and P. N. Prasad, “Ultrasmall monodisperse NaYF4:Yb3+/Tm3+ nanocrystals with enhanced near-infrared to near-infrared upconversion photoluminescence,” ACS Nano 4, 3163–3168 (2010).
[CrossRef] [PubMed]

2009 (2)

C. T. Xu, J. Axelsson, and S. Andersson-Engels, “Fluorescence diffuse optical tomography using upconverting nanoparticles,” Appl. Phys. Lett. 94, 251107 (2009).
[CrossRef]

M. Yu, F. Li, Z. Chen, H. Hu, C. Zhan, H. Yang, and C. Huang, “Laser scanning up-conversion luminescence microscopy for imaging cells labeled with rare-earth nanophosphors,” Anal. Chem. 81, 930–935 (2009).
[CrossRef] [PubMed]

2008 (4)

Z. Li and Y. Zhang, “An efficient and user-friendly method for the synthesis of hexagonal-phase NaYF4:Yb, Er/Tm nanocrystals with controllable shape and upconversion fluorescence,” Nanotechnology 19, 345606 (2008).
[CrossRef]

C. T. Xu, N. Svensson, J. Axelsson, P. Svenmarker, G. Somesfalean, G. Chen, H. Liang, H. Liu, Z. Zhang, and S. Andersson-Engels, “Autofluorescence insensitive imaging using upconverting nanocrystals in scattering media,” Appl. Phys. Lett. 93, 171103 (2008).
[CrossRef]

M. Nyk, R. Kumar, T. Y. Ohulchanskyy, E. J. Bergey, and P. N. Prasad, “High contrast in vitro and in vivo photoluminescence bioimaging using near infrared to near infrared up-conversion in Tm3+ and Yb3+ doped fluoride nanophosphors,” Nano Lett. 8, 3834–3838 (2008).
[CrossRef] [PubMed]

H.-S. Qian and Y. Zhang, “Synthesis of hexagonal-phase core-shell NaYF4 nanocrystals with tunable upconversion fluorescence,” Langmuir 24, 12123–12125 (2008).
[CrossRef] [PubMed]

2004 (1)

F. Auzel, “Upconversion and anti-stokes processes with f and d ions in solids,” Chem. Rev. 104, 139–173 (2004).
[CrossRef] [PubMed]

2001 (1)

R. Weissleder and U. Mahmood, “Molecular imaging,” Radiology 219, 316–333 (2001).
[CrossRef] [PubMed]

1996 (1)

C. Xu, W. Zipfel, J. B. Shear, R. M. Williams, and W. W. Webb, “Multiphoton fluorescence excitation: new spectral windows for biological nonlinear microscopy,” Proc. Natl. Acad. Sci. USA 93, 10763–10768 (1996).
[CrossRef] [PubMed]

Ågren, H.

H. Qiu, C. Yang, W. Shao, J. Damasco, X. Wang, H. Ågren, P. N. Prasad, and G. Chen, “Enhanced upconversion luminescence in Yb3+/Tm3+-codoped fluoride active core/active shell/inert shell nanoparticles through directed energy migration,” Nanomaterials 4, 55–68 (2014).
[CrossRef]

G. Chen, J. Shen, T. Y. Ohulchanskyy, N. J. Patel, A. Kutikov, Z. Li, J. Song, R. K. Pandey, H. Ågren, P. N. Prasad, and G. Han, “(α-NaYbF4:Tm3+)/CaF2 core/shell nanoparticles with efficient near-infrared to near-infrared up-conversion for high-contrast deep tissue bioimaging,” ACS Nano 6, 8280–8287 (2012).
[CrossRef] [PubMed]

G. Chen, T. Y. Ohulchanskyy, R. Kumar, H. Ågren, and P. N. Prasad, “Ultrasmall monodisperse NaYF4:Yb3+/Tm3+ nanocrystals with enhanced near-infrared to near-infrared upconversion photoluminescence,” ACS Nano 4, 3163–3168 (2010).
[CrossRef] [PubMed]

Andersen, P. E.

H. Liu, C. T. Xu, G. Dumlupinar, O. B. Jensen, P. E. Andersen, and S. Andersson-Engels, “Deep tissue optical imaging of upconverting nanoparticles enabled by exploiting higher intrinsic quantum yield through using millisecond single pulse excitation with high peak power,” Nanoscale 5, 10034–10040 (2013).
[CrossRef] [PubMed]

Andersson-Engels, S.

H. Liu, C. T. Xu, G. Dumlupinar, O. B. Jensen, P. E. Andersen, and S. Andersson-Engels, “Deep tissue optical imaging of upconverting nanoparticles enabled by exploiting higher intrinsic quantum yield through using millisecond single pulse excitation with high peak power,” Nanoscale 5, 10034–10040 (2013).
[CrossRef] [PubMed]

H. Liu, C. T. Xu, D. Lindgren, H. Xie, D. Thomas, C. Gundlach, and S. Andersson-Engels, “Balancing power density based quantum yield characterization of upconverting nanoparticles for arbitrary excitation intensities,” Nanoscale 5, 4770–4775 (2013).
[CrossRef] [PubMed]

C. T. Xu, Q. Zhan, H. Liu, G. Somesfalean, J. Qian, S. He, and S. Andersson-Engels, “Upconverting nanoparticles for pre-clinical diffuse optical imaging, microscopy and sensing: Current trends and future challenges,” Laser Photonics Rev. 7, 663–697 (2013).
[CrossRef]

C. T. Xu, P. Svenmarker, H. Liu, X. Wu, M. E. Messing, L. R. Wallenberg, and S. Andersson-Engels, “High-resolution fluorescence diffuse optical tomography developed with nonlinear upconverting nanoparticles,” ACS Nano 6, 4788–4795 (2012).
[CrossRef] [PubMed]

P. Svenmarker, C. T. Xu, and S. Andersson-Engels, “Use of nonlinear upconverting nanoparticles provides increased spatial resolution in fluorescence diffuse imaging,” Opt. Lett. 35, 2789–2791 (2010).
[CrossRef] [PubMed]

C. T. Xu, J. Axelsson, and S. Andersson-Engels, “Fluorescence diffuse optical tomography using upconverting nanoparticles,” Appl. Phys. Lett. 94, 251107 (2009).
[CrossRef]

C. T. Xu, N. Svensson, J. Axelsson, P. Svenmarker, G. Somesfalean, G. Chen, H. Liang, H. Liu, Z. Zhang, and S. Andersson-Engels, “Autofluorescence insensitive imaging using upconverting nanocrystals in scattering media,” Appl. Phys. Lett. 93, 171103 (2008).
[CrossRef]

Arppe, R.

H. Päkkilä, M. Ylihärsilä, S. Lahtinen, L. Hattara, N. Salminen, R. Arppe, M. Lastusaari, P. Saviranta, and T. Soukka, “Quantitative multianalyte microarray immunoassay utilizing upconverting phosphor technology,” Anal. Chem. 84, 8628–8634 (2012).
[CrossRef] [PubMed]

Auzel, F.

F. Auzel, “Upconversion and anti-stokes processes with f and d ions in solids,” Chem. Rev. 104, 139–173 (2004).
[CrossRef] [PubMed]

Axelsson, J.

C. T. Xu, J. Axelsson, and S. Andersson-Engels, “Fluorescence diffuse optical tomography using upconverting nanoparticles,” Appl. Phys. Lett. 94, 251107 (2009).
[CrossRef]

C. T. Xu, N. Svensson, J. Axelsson, P. Svenmarker, G. Somesfalean, G. Chen, H. Liang, H. Liu, Z. Zhang, and S. Andersson-Engels, “Autofluorescence insensitive imaging using upconverting nanocrystals in scattering media,” Appl. Phys. Lett. 93, 171103 (2008).
[CrossRef]

Banerjee, D.

F. Wang, D. Banerjee, Y. Liu, X. Chen, and X. Liu, “Upconversion nanoparticles in biological labeling, imaging, and therapy,” Analyst 135, 1839–1854 (2010).
[CrossRef] [PubMed]

Bergey, E. J.

M. Nyk, R. Kumar, T. Y. Ohulchanskyy, E. J. Bergey, and P. N. Prasad, “High contrast in vitro and in vivo photoluminescence bioimaging using near infrared to near infrared up-conversion in Tm3+ and Yb3+ doped fluoride nanophosphors,” Nano Lett. 8, 3834–3838 (2008).
[CrossRef] [PubMed]

Boyer, J.-C.

J. Pichaandi, J.-C. Boyer, K. R. Delaney, and F. C. J. M. van Veggel, “Two-photon upconversion laser (scanning and wide-field) microscopy using Ln3+-doped NaYF4 upconverting nanocrystals: A critical evaluation of their performance and potential in bioimaging,” J. Phys. Chem. C 115, 19054–19064 (2011).
[CrossRef]

Buchholz, S.

J. Shen, G. Chen, T. Y. Ohulchanskyy, S. J. Kesseli, S. Buchholz, Z. Li, P. N. Prasad, and G. Han, “Tunable near infrared to ultraviolet upconversion luminescence enhancement in (α-NaYbF4:Tm3+)/CaF2 core/shell nanoparticles for in situ real-time recorded biocompatible photoactivation,” Small 9, 3213–3217 (2013).
[PubMed]

Caillat, L.

L. Caillat, B. Hajj, V. Shynkar, L. Michely, D. Chauvat, J. Zyss, and F. Pellé, “Multiphoton upconversion in rare earth doped nanocrystals for sub-diffractive microscopy,” Appl. Phys. Lett. 102, 143114 (2013).
[CrossRef]

Chauvat, D.

L. Caillat, B. Hajj, V. Shynkar, L. Michely, D. Chauvat, J. Zyss, and F. Pellé, “Multiphoton upconversion in rare earth doped nanocrystals for sub-diffractive microscopy,” Appl. Phys. Lett. 102, 143114 (2013).
[CrossRef]

Chen, G.

H. Qiu, C. Yang, W. Shao, J. Damasco, X. Wang, H. Ågren, P. N. Prasad, and G. Chen, “Enhanced upconversion luminescence in Yb3+/Tm3+-codoped fluoride active core/active shell/inert shell nanoparticles through directed energy migration,” Nanomaterials 4, 55–68 (2014).
[CrossRef]

G. Chen, C. Yang, and P. N. Prasad, “Nanophotonics and nanochemistry: Controlling the excitation dynamics for frequency up- and down-conversion in lanthanide-doped nanoparticles,” Acc. Chem. Res. 46, 1474–1486 (2013).
[CrossRef] [PubMed]

J. Shen, G. Chen, T. Y. Ohulchanskyy, S. J. Kesseli, S. Buchholz, Z. Li, P. N. Prasad, and G. Han, “Tunable near infrared to ultraviolet upconversion luminescence enhancement in (α-NaYbF4:Tm3+)/CaF2 core/shell nanoparticles for in situ real-time recorded biocompatible photoactivation,” Small 9, 3213–3217 (2013).
[PubMed]

G. Chen, J. Shen, T. Y. Ohulchanskyy, N. J. Patel, A. Kutikov, Z. Li, J. Song, R. K. Pandey, H. Ågren, P. N. Prasad, and G. Han, “(α-NaYbF4:Tm3+)/CaF2 core/shell nanoparticles with efficient near-infrared to near-infrared up-conversion for high-contrast deep tissue bioimaging,” ACS Nano 6, 8280–8287 (2012).
[CrossRef] [PubMed]

G. Chen, T. Y. Ohulchanskyy, R. Kumar, H. Ågren, and P. N. Prasad, “Ultrasmall monodisperse NaYF4:Yb3+/Tm3+ nanocrystals with enhanced near-infrared to near-infrared upconversion photoluminescence,” ACS Nano 4, 3163–3168 (2010).
[CrossRef] [PubMed]

C. T. Xu, N. Svensson, J. Axelsson, P. Svenmarker, G. Somesfalean, G. Chen, H. Liang, H. Liu, Z. Zhang, and S. Andersson-Engels, “Autofluorescence insensitive imaging using upconverting nanocrystals in scattering media,” Appl. Phys. Lett. 93, 171103 (2008).
[CrossRef]

G. Chen, H. Qiu, P. N. Prasad, and X. Chen, “Upconversion nanoparticles: Design, nanochemistry, and applications in theranostics,” Chem. Rev. DOI: (2014).
[CrossRef]

Chen, X.

F. Wang, D. Banerjee, Y. Liu, X. Chen, and X. Liu, “Upconversion nanoparticles in biological labeling, imaging, and therapy,” Analyst 135, 1839–1854 (2010).
[CrossRef] [PubMed]

G. Chen, H. Qiu, P. N. Prasad, and X. Chen, “Upconversion nanoparticles: Design, nanochemistry, and applications in theranostics,” Chem. Rev. DOI: (2014).
[CrossRef]

Chen, Z.

M. Yu, F. Li, Z. Chen, H. Hu, C. Zhan, H. Yang, and C. Huang, “Laser scanning up-conversion luminescence microscopy for imaging cells labeled with rare-earth nanophosphors,” Anal. Chem. 81, 930–935 (2009).
[CrossRef] [PubMed]

Damasco, J.

H. Qiu, C. Yang, W. Shao, J. Damasco, X. Wang, H. Ågren, P. N. Prasad, and G. Chen, “Enhanced upconversion luminescence in Yb3+/Tm3+-codoped fluoride active core/active shell/inert shell nanoparticles through directed energy migration,” Nanomaterials 4, 55–68 (2014).
[CrossRef]

Delaney, K. R.

J. Pichaandi, J.-C. Boyer, K. R. Delaney, and F. C. J. M. van Veggel, “Two-photon upconversion laser (scanning and wide-field) microscopy using Ln3+-doped NaYF4 upconverting nanocrystals: A critical evaluation of their performance and potential in bioimaging,” J. Phys. Chem. C 115, 19054–19064 (2011).
[CrossRef]

Dumlupinar, G.

H. Liu, C. T. Xu, G. Dumlupinar, O. B. Jensen, P. E. Andersen, and S. Andersson-Engels, “Deep tissue optical imaging of upconverting nanoparticles enabled by exploiting higher intrinsic quantum yield through using millisecond single pulse excitation with high peak power,” Nanoscale 5, 10034–10040 (2013).
[CrossRef] [PubMed]

Feng, W.

Q. Liu, Y. Sun, T. Yang, W. Feng, C. Li, and F. Li, “Sub-10 nm hexagonal lanthanide-doped NaLuF4 upconversion nanocrystals for sensitive bioimaging in vivo,” J. Am. Chem. Soc. 133, 17122–17125 (2011).
[CrossRef] [PubMed]

Gundlach, C.

H. Liu, C. T. Xu, D. Lindgren, H. Xie, D. Thomas, C. Gundlach, and S. Andersson-Engels, “Balancing power density based quantum yield characterization of upconverting nanoparticles for arbitrary excitation intensities,” Nanoscale 5, 4770–4775 (2013).
[CrossRef] [PubMed]

Hajj, B.

L. Caillat, B. Hajj, V. Shynkar, L. Michely, D. Chauvat, J. Zyss, and F. Pellé, “Multiphoton upconversion in rare earth doped nanocrystals for sub-diffractive microscopy,” Appl. Phys. Lett. 102, 143114 (2013).
[CrossRef]

Han, G.

J. Shen, G. Chen, T. Y. Ohulchanskyy, S. J. Kesseli, S. Buchholz, Z. Li, P. N. Prasad, and G. Han, “Tunable near infrared to ultraviolet upconversion luminescence enhancement in (α-NaYbF4:Tm3+)/CaF2 core/shell nanoparticles for in situ real-time recorded biocompatible photoactivation,” Small 9, 3213–3217 (2013).
[PubMed]

G. Chen, J. Shen, T. Y. Ohulchanskyy, N. J. Patel, A. Kutikov, Z. Li, J. Song, R. K. Pandey, H. Ågren, P. N. Prasad, and G. Han, “(α-NaYbF4:Tm3+)/CaF2 core/shell nanoparticles with efficient near-infrared to near-infrared up-conversion for high-contrast deep tissue bioimaging,” ACS Nano 6, 8280–8287 (2012).
[CrossRef] [PubMed]

Hattara, L.

H. Päkkilä, M. Ylihärsilä, S. Lahtinen, L. Hattara, N. Salminen, R. Arppe, M. Lastusaari, P. Saviranta, and T. Soukka, “Quantitative multianalyte microarray immunoassay utilizing upconverting phosphor technology,” Anal. Chem. 84, 8628–8634 (2012).
[CrossRef] [PubMed]

He, S.

C. T. Xu, Q. Zhan, H. Liu, G. Somesfalean, J. Qian, S. He, and S. Andersson-Engels, “Upconverting nanoparticles for pre-clinical diffuse optical imaging, microscopy and sensing: Current trends and future challenges,” Laser Photonics Rev. 7, 663–697 (2013).
[CrossRef]

Hu, H.

M. Yu, F. Li, Z. Chen, H. Hu, C. Zhan, H. Yang, and C. Huang, “Laser scanning up-conversion luminescence microscopy for imaging cells labeled with rare-earth nanophosphors,” Anal. Chem. 81, 930–935 (2009).
[CrossRef] [PubMed]

Huang, C.

M. Yu, F. Li, Z. Chen, H. Hu, C. Zhan, H. Yang, and C. Huang, “Laser scanning up-conversion luminescence microscopy for imaging cells labeled with rare-earth nanophosphors,” Anal. Chem. 81, 930–935 (2009).
[CrossRef] [PubMed]

Hummelen, J. C.

W. Zou, C. Visser, J. A. Maduro, M. S. Pshenichnikov, and J. C. Hummelen, “Broadband dye-sensitized upconversion of near-infrared light,” Nat. Photonics 6, 560–564 (2012).
[CrossRef]

Idris, N. M.

A. Priyam, N. M. Idris, and Y. Zhang, “Gold nanoshell coated NaYF4 nanoparticles for simultaneously enhanced upconversion fluorescence and darkfield imaging,” J. Mater. Chem. 22, 960–965 (2012).
[CrossRef]

M. K. G. Jayakumar, N. M. Idris, and Y. Zhang, “Remote activation of biomolecules in deep tissues using near-infrared-to-uv upconversion nanotransducers,” Proc. Natl. Acad. Sci. USA 109, 8483–8488 (2012).
[CrossRef] [PubMed]

Jayakumar, M. K. G.

M. K. G. Jayakumar, N. M. Idris, and Y. Zhang, “Remote activation of biomolecules in deep tissues using near-infrared-to-uv upconversion nanotransducers,” Proc. Natl. Acad. Sci. USA 109, 8483–8488 (2012).
[CrossRef] [PubMed]

Jensen, O. B.

H. Liu, C. T. Xu, G. Dumlupinar, O. B. Jensen, P. E. Andersen, and S. Andersson-Engels, “Deep tissue optical imaging of upconverting nanoparticles enabled by exploiting higher intrinsic quantum yield through using millisecond single pulse excitation with high peak power,” Nanoscale 5, 10034–10040 (2013).
[CrossRef] [PubMed]

Kesseli, S. J.

J. Shen, G. Chen, T. Y. Ohulchanskyy, S. J. Kesseli, S. Buchholz, Z. Li, P. N. Prasad, and G. Han, “Tunable near infrared to ultraviolet upconversion luminescence enhancement in (α-NaYbF4:Tm3+)/CaF2 core/shell nanoparticles for in situ real-time recorded biocompatible photoactivation,” Small 9, 3213–3217 (2013).
[PubMed]

Kumar, R.

G. Chen, T. Y. Ohulchanskyy, R. Kumar, H. Ågren, and P. N. Prasad, “Ultrasmall monodisperse NaYF4:Yb3+/Tm3+ nanocrystals with enhanced near-infrared to near-infrared upconversion photoluminescence,” ACS Nano 4, 3163–3168 (2010).
[CrossRef] [PubMed]

M. Nyk, R. Kumar, T. Y. Ohulchanskyy, E. J. Bergey, and P. N. Prasad, “High contrast in vitro and in vivo photoluminescence bioimaging using near infrared to near infrared up-conversion in Tm3+ and Yb3+ doped fluoride nanophosphors,” Nano Lett. 8, 3834–3838 (2008).
[CrossRef] [PubMed]

Kutikov, A.

G. Chen, J. Shen, T. Y. Ohulchanskyy, N. J. Patel, A. Kutikov, Z. Li, J. Song, R. K. Pandey, H. Ågren, P. N. Prasad, and G. Han, “(α-NaYbF4:Tm3+)/CaF2 core/shell nanoparticles with efficient near-infrared to near-infrared up-conversion for high-contrast deep tissue bioimaging,” ACS Nano 6, 8280–8287 (2012).
[CrossRef] [PubMed]

Lahtinen, S.

H. Päkkilä, M. Ylihärsilä, S. Lahtinen, L. Hattara, N. Salminen, R. Arppe, M. Lastusaari, P. Saviranta, and T. Soukka, “Quantitative multianalyte microarray immunoassay utilizing upconverting phosphor technology,” Anal. Chem. 84, 8628–8634 (2012).
[CrossRef] [PubMed]

Lastusaari, M.

H. Päkkilä, M. Ylihärsilä, S. Lahtinen, L. Hattara, N. Salminen, R. Arppe, M. Lastusaari, P. Saviranta, and T. Soukka, “Quantitative multianalyte microarray immunoassay utilizing upconverting phosphor technology,” Anal. Chem. 84, 8628–8634 (2012).
[CrossRef] [PubMed]

Li, C.

Q. Liu, Y. Sun, T. Yang, W. Feng, C. Li, and F. Li, “Sub-10 nm hexagonal lanthanide-doped NaLuF4 upconversion nanocrystals for sensitive bioimaging in vivo,” J. Am. Chem. Soc. 133, 17122–17125 (2011).
[CrossRef] [PubMed]

Li, F.

J. Zhou, Z. Liu, and F. Li, “Upconversion nanophosphors for small-animal imaging,” Chem. Soc. Rev. 41, 1323–1349 (2012).
[CrossRef]

Q. Liu, Y. Sun, T. Yang, W. Feng, C. Li, and F. Li, “Sub-10 nm hexagonal lanthanide-doped NaLuF4 upconversion nanocrystals for sensitive bioimaging in vivo,” J. Am. Chem. Soc. 133, 17122–17125 (2011).
[CrossRef] [PubMed]

M. Yu, F. Li, Z. Chen, H. Hu, C. Zhan, H. Yang, and C. Huang, “Laser scanning up-conversion luminescence microscopy for imaging cells labeled with rare-earth nanophosphors,” Anal. Chem. 81, 930–935 (2009).
[CrossRef] [PubMed]

Li, Z.

J. Shen, G. Chen, T. Y. Ohulchanskyy, S. J. Kesseli, S. Buchholz, Z. Li, P. N. Prasad, and G. Han, “Tunable near infrared to ultraviolet upconversion luminescence enhancement in (α-NaYbF4:Tm3+)/CaF2 core/shell nanoparticles for in situ real-time recorded biocompatible photoactivation,” Small 9, 3213–3217 (2013).
[PubMed]

G. Chen, J. Shen, T. Y. Ohulchanskyy, N. J. Patel, A. Kutikov, Z. Li, J. Song, R. K. Pandey, H. Ågren, P. N. Prasad, and G. Han, “(α-NaYbF4:Tm3+)/CaF2 core/shell nanoparticles with efficient near-infrared to near-infrared up-conversion for high-contrast deep tissue bioimaging,” ACS Nano 6, 8280–8287 (2012).
[CrossRef] [PubMed]

Z. Li and Y. Zhang, “An efficient and user-friendly method for the synthesis of hexagonal-phase NaYF4:Yb, Er/Tm nanocrystals with controllable shape and upconversion fluorescence,” Nanotechnology 19, 345606 (2008).
[CrossRef]

Liang, H.

C. T. Xu, N. Svensson, J. Axelsson, P. Svenmarker, G. Somesfalean, G. Chen, H. Liang, H. Liu, Z. Zhang, and S. Andersson-Engels, “Autofluorescence insensitive imaging using upconverting nanocrystals in scattering media,” Appl. Phys. Lett. 93, 171103 (2008).
[CrossRef]

Lindgren, D.

H. Liu, C. T. Xu, D. Lindgren, H. Xie, D. Thomas, C. Gundlach, and S. Andersson-Engels, “Balancing power density based quantum yield characterization of upconverting nanoparticles for arbitrary excitation intensities,” Nanoscale 5, 4770–4775 (2013).
[CrossRef] [PubMed]

Liu, H.

H. Liu, C. T. Xu, D. Lindgren, H. Xie, D. Thomas, C. Gundlach, and S. Andersson-Engels, “Balancing power density based quantum yield characterization of upconverting nanoparticles for arbitrary excitation intensities,” Nanoscale 5, 4770–4775 (2013).
[CrossRef] [PubMed]

H. Liu, C. T. Xu, G. Dumlupinar, O. B. Jensen, P. E. Andersen, and S. Andersson-Engels, “Deep tissue optical imaging of upconverting nanoparticles enabled by exploiting higher intrinsic quantum yield through using millisecond single pulse excitation with high peak power,” Nanoscale 5, 10034–10040 (2013).
[CrossRef] [PubMed]

C. T. Xu, Q. Zhan, H. Liu, G. Somesfalean, J. Qian, S. He, and S. Andersson-Engels, “Upconverting nanoparticles for pre-clinical diffuse optical imaging, microscopy and sensing: Current trends and future challenges,” Laser Photonics Rev. 7, 663–697 (2013).
[CrossRef]

C. T. Xu, P. Svenmarker, H. Liu, X. Wu, M. E. Messing, L. R. Wallenberg, and S. Andersson-Engels, “High-resolution fluorescence diffuse optical tomography developed with nonlinear upconverting nanoparticles,” ACS Nano 6, 4788–4795 (2012).
[CrossRef] [PubMed]

C. T. Xu, N. Svensson, J. Axelsson, P. Svenmarker, G. Somesfalean, G. Chen, H. Liang, H. Liu, Z. Zhang, and S. Andersson-Engels, “Autofluorescence insensitive imaging using upconverting nanocrystals in scattering media,” Appl. Phys. Lett. 93, 171103 (2008).
[CrossRef]

Liu, Q.

Q. Liu, Y. Sun, T. Yang, W. Feng, C. Li, and F. Li, “Sub-10 nm hexagonal lanthanide-doped NaLuF4 upconversion nanocrystals for sensitive bioimaging in vivo,” J. Am. Chem. Soc. 133, 17122–17125 (2011).
[CrossRef] [PubMed]

Liu, X.

F. Wang, D. Banerjee, Y. Liu, X. Chen, and X. Liu, “Upconversion nanoparticles in biological labeling, imaging, and therapy,” Analyst 135, 1839–1854 (2010).
[CrossRef] [PubMed]

Liu, Y.

F. Wang, D. Banerjee, Y. Liu, X. Chen, and X. Liu, “Upconversion nanoparticles in biological labeling, imaging, and therapy,” Analyst 135, 1839–1854 (2010).
[CrossRef] [PubMed]

Liu, Z.

J. Zhou, Z. Liu, and F. Li, “Upconversion nanophosphors for small-animal imaging,” Chem. Soc. Rev. 41, 1323–1349 (2012).
[CrossRef]

Maduro, J. A.

W. Zou, C. Visser, J. A. Maduro, M. S. Pshenichnikov, and J. C. Hummelen, “Broadband dye-sensitized upconversion of near-infrared light,” Nat. Photonics 6, 560–564 (2012).
[CrossRef]

Mahmood, U.

R. Weissleder and U. Mahmood, “Molecular imaging,” Radiology 219, 316–333 (2001).
[CrossRef] [PubMed]

Messing, M. E.

C. T. Xu, P. Svenmarker, H. Liu, X. Wu, M. E. Messing, L. R. Wallenberg, and S. Andersson-Engels, “High-resolution fluorescence diffuse optical tomography developed with nonlinear upconverting nanoparticles,” ACS Nano 6, 4788–4795 (2012).
[CrossRef] [PubMed]

Michely, L.

L. Caillat, B. Hajj, V. Shynkar, L. Michely, D. Chauvat, J. Zyss, and F. Pellé, “Multiphoton upconversion in rare earth doped nanocrystals for sub-diffractive microscopy,” Appl. Phys. Lett. 102, 143114 (2013).
[CrossRef]

Nyk, M.

M. Nyk, R. Kumar, T. Y. Ohulchanskyy, E. J. Bergey, and P. N. Prasad, “High contrast in vitro and in vivo photoluminescence bioimaging using near infrared to near infrared up-conversion in Tm3+ and Yb3+ doped fluoride nanophosphors,” Nano Lett. 8, 3834–3838 (2008).
[CrossRef] [PubMed]

Ohulchanskyy, T. Y.

J. Shen, G. Chen, T. Y. Ohulchanskyy, S. J. Kesseli, S. Buchholz, Z. Li, P. N. Prasad, and G. Han, “Tunable near infrared to ultraviolet upconversion luminescence enhancement in (α-NaYbF4:Tm3+)/CaF2 core/shell nanoparticles for in situ real-time recorded biocompatible photoactivation,” Small 9, 3213–3217 (2013).
[PubMed]

G. Chen, J. Shen, T. Y. Ohulchanskyy, N. J. Patel, A. Kutikov, Z. Li, J. Song, R. K. Pandey, H. Ågren, P. N. Prasad, and G. Han, “(α-NaYbF4:Tm3+)/CaF2 core/shell nanoparticles with efficient near-infrared to near-infrared up-conversion for high-contrast deep tissue bioimaging,” ACS Nano 6, 8280–8287 (2012).
[CrossRef] [PubMed]

G. Chen, T. Y. Ohulchanskyy, R. Kumar, H. Ågren, and P. N. Prasad, “Ultrasmall monodisperse NaYF4:Yb3+/Tm3+ nanocrystals with enhanced near-infrared to near-infrared upconversion photoluminescence,” ACS Nano 4, 3163–3168 (2010).
[CrossRef] [PubMed]

M. Nyk, R. Kumar, T. Y. Ohulchanskyy, E. J. Bergey, and P. N. Prasad, “High contrast in vitro and in vivo photoluminescence bioimaging using near infrared to near infrared up-conversion in Tm3+ and Yb3+ doped fluoride nanophosphors,” Nano Lett. 8, 3834–3838 (2008).
[CrossRef] [PubMed]

Päkkilä, H.

H. Päkkilä, M. Ylihärsilä, S. Lahtinen, L. Hattara, N. Salminen, R. Arppe, M. Lastusaari, P. Saviranta, and T. Soukka, “Quantitative multianalyte microarray immunoassay utilizing upconverting phosphor technology,” Anal. Chem. 84, 8628–8634 (2012).
[CrossRef] [PubMed]

Pandey, R. K.

G. Chen, J. Shen, T. Y. Ohulchanskyy, N. J. Patel, A. Kutikov, Z. Li, J. Song, R. K. Pandey, H. Ågren, P. N. Prasad, and G. Han, “(α-NaYbF4:Tm3+)/CaF2 core/shell nanoparticles with efficient near-infrared to near-infrared up-conversion for high-contrast deep tissue bioimaging,” ACS Nano 6, 8280–8287 (2012).
[CrossRef] [PubMed]

Patel, N. J.

G. Chen, J. Shen, T. Y. Ohulchanskyy, N. J. Patel, A. Kutikov, Z. Li, J. Song, R. K. Pandey, H. Ågren, P. N. Prasad, and G. Han, “(α-NaYbF4:Tm3+)/CaF2 core/shell nanoparticles with efficient near-infrared to near-infrared up-conversion for high-contrast deep tissue bioimaging,” ACS Nano 6, 8280–8287 (2012).
[CrossRef] [PubMed]

Pellé, F.

L. Caillat, B. Hajj, V. Shynkar, L. Michely, D. Chauvat, J. Zyss, and F. Pellé, “Multiphoton upconversion in rare earth doped nanocrystals for sub-diffractive microscopy,” Appl. Phys. Lett. 102, 143114 (2013).
[CrossRef]

Pichaandi, J.

J. Pichaandi, J.-C. Boyer, K. R. Delaney, and F. C. J. M. van Veggel, “Two-photon upconversion laser (scanning and wide-field) microscopy using Ln3+-doped NaYF4 upconverting nanocrystals: A critical evaluation of their performance and potential in bioimaging,” J. Phys. Chem. C 115, 19054–19064 (2011).
[CrossRef]

Prasad, P. N.

H. Qiu, C. Yang, W. Shao, J. Damasco, X. Wang, H. Ågren, P. N. Prasad, and G. Chen, “Enhanced upconversion luminescence in Yb3+/Tm3+-codoped fluoride active core/active shell/inert shell nanoparticles through directed energy migration,” Nanomaterials 4, 55–68 (2014).
[CrossRef]

J. Shen, G. Chen, T. Y. Ohulchanskyy, S. J. Kesseli, S. Buchholz, Z. Li, P. N. Prasad, and G. Han, “Tunable near infrared to ultraviolet upconversion luminescence enhancement in (α-NaYbF4:Tm3+)/CaF2 core/shell nanoparticles for in situ real-time recorded biocompatible photoactivation,” Small 9, 3213–3217 (2013).
[PubMed]

G. Chen, C. Yang, and P. N. Prasad, “Nanophotonics and nanochemistry: Controlling the excitation dynamics for frequency up- and down-conversion in lanthanide-doped nanoparticles,” Acc. Chem. Res. 46, 1474–1486 (2013).
[CrossRef] [PubMed]

G. Chen, J. Shen, T. Y. Ohulchanskyy, N. J. Patel, A. Kutikov, Z. Li, J. Song, R. K. Pandey, H. Ågren, P. N. Prasad, and G. Han, “(α-NaYbF4:Tm3+)/CaF2 core/shell nanoparticles with efficient near-infrared to near-infrared up-conversion for high-contrast deep tissue bioimaging,” ACS Nano 6, 8280–8287 (2012).
[CrossRef] [PubMed]

G. Chen, T. Y. Ohulchanskyy, R. Kumar, H. Ågren, and P. N. Prasad, “Ultrasmall monodisperse NaYF4:Yb3+/Tm3+ nanocrystals with enhanced near-infrared to near-infrared upconversion photoluminescence,” ACS Nano 4, 3163–3168 (2010).
[CrossRef] [PubMed]

M. Nyk, R. Kumar, T. Y. Ohulchanskyy, E. J. Bergey, and P. N. Prasad, “High contrast in vitro and in vivo photoluminescence bioimaging using near infrared to near infrared up-conversion in Tm3+ and Yb3+ doped fluoride nanophosphors,” Nano Lett. 8, 3834–3838 (2008).
[CrossRef] [PubMed]

G. Chen, H. Qiu, P. N. Prasad, and X. Chen, “Upconversion nanoparticles: Design, nanochemistry, and applications in theranostics,” Chem. Rev. DOI: (2014).
[CrossRef]

Priyam, A.

A. Priyam, N. M. Idris, and Y. Zhang, “Gold nanoshell coated NaYF4 nanoparticles for simultaneously enhanced upconversion fluorescence and darkfield imaging,” J. Mater. Chem. 22, 960–965 (2012).
[CrossRef]

Pshenichnikov, M. S.

W. Zou, C. Visser, J. A. Maduro, M. S. Pshenichnikov, and J. C. Hummelen, “Broadband dye-sensitized upconversion of near-infrared light,” Nat. Photonics 6, 560–564 (2012).
[CrossRef]

Qian, H.-S.

H.-S. Qian and Y. Zhang, “Synthesis of hexagonal-phase core-shell NaYF4 nanocrystals with tunable upconversion fluorescence,” Langmuir 24, 12123–12125 (2008).
[CrossRef] [PubMed]

Qian, J.

C. T. Xu, Q. Zhan, H. Liu, G. Somesfalean, J. Qian, S. He, and S. Andersson-Engels, “Upconverting nanoparticles for pre-clinical diffuse optical imaging, microscopy and sensing: Current trends and future challenges,” Laser Photonics Rev. 7, 663–697 (2013).
[CrossRef]

Qiu, H.

H. Qiu, C. Yang, W. Shao, J. Damasco, X. Wang, H. Ågren, P. N. Prasad, and G. Chen, “Enhanced upconversion luminescence in Yb3+/Tm3+-codoped fluoride active core/active shell/inert shell nanoparticles through directed energy migration,” Nanomaterials 4, 55–68 (2014).
[CrossRef]

G. Chen, H. Qiu, P. N. Prasad, and X. Chen, “Upconversion nanoparticles: Design, nanochemistry, and applications in theranostics,” Chem. Rev. DOI: (2014).
[CrossRef]

Salminen, N.

H. Päkkilä, M. Ylihärsilä, S. Lahtinen, L. Hattara, N. Salminen, R. Arppe, M. Lastusaari, P. Saviranta, and T. Soukka, “Quantitative multianalyte microarray immunoassay utilizing upconverting phosphor technology,” Anal. Chem. 84, 8628–8634 (2012).
[CrossRef] [PubMed]

Saviranta, P.

H. Päkkilä, M. Ylihärsilä, S. Lahtinen, L. Hattara, N. Salminen, R. Arppe, M. Lastusaari, P. Saviranta, and T. Soukka, “Quantitative multianalyte microarray immunoassay utilizing upconverting phosphor technology,” Anal. Chem. 84, 8628–8634 (2012).
[CrossRef] [PubMed]

Shao, W.

H. Qiu, C. Yang, W. Shao, J. Damasco, X. Wang, H. Ågren, P. N. Prasad, and G. Chen, “Enhanced upconversion luminescence in Yb3+/Tm3+-codoped fluoride active core/active shell/inert shell nanoparticles through directed energy migration,” Nanomaterials 4, 55–68 (2014).
[CrossRef]

Shear, J. B.

C. Xu, W. Zipfel, J. B. Shear, R. M. Williams, and W. W. Webb, “Multiphoton fluorescence excitation: new spectral windows for biological nonlinear microscopy,” Proc. Natl. Acad. Sci. USA 93, 10763–10768 (1996).
[CrossRef] [PubMed]

Shen, J.

J. Shen, G. Chen, T. Y. Ohulchanskyy, S. J. Kesseli, S. Buchholz, Z. Li, P. N. Prasad, and G. Han, “Tunable near infrared to ultraviolet upconversion luminescence enhancement in (α-NaYbF4:Tm3+)/CaF2 core/shell nanoparticles for in situ real-time recorded biocompatible photoactivation,” Small 9, 3213–3217 (2013).
[PubMed]

G. Chen, J. Shen, T. Y. Ohulchanskyy, N. J. Patel, A. Kutikov, Z. Li, J. Song, R. K. Pandey, H. Ågren, P. N. Prasad, and G. Han, “(α-NaYbF4:Tm3+)/CaF2 core/shell nanoparticles with efficient near-infrared to near-infrared up-conversion for high-contrast deep tissue bioimaging,” ACS Nano 6, 8280–8287 (2012).
[CrossRef] [PubMed]

Shynkar, V.

L. Caillat, B. Hajj, V. Shynkar, L. Michely, D. Chauvat, J. Zyss, and F. Pellé, “Multiphoton upconversion in rare earth doped nanocrystals for sub-diffractive microscopy,” Appl. Phys. Lett. 102, 143114 (2013).
[CrossRef]

Somesfalean, G.

C. T. Xu, Q. Zhan, H. Liu, G. Somesfalean, J. Qian, S. He, and S. Andersson-Engels, “Upconverting nanoparticles for pre-clinical diffuse optical imaging, microscopy and sensing: Current trends and future challenges,” Laser Photonics Rev. 7, 663–697 (2013).
[CrossRef]

C. T. Xu, N. Svensson, J. Axelsson, P. Svenmarker, G. Somesfalean, G. Chen, H. Liang, H. Liu, Z. Zhang, and S. Andersson-Engels, “Autofluorescence insensitive imaging using upconverting nanocrystals in scattering media,” Appl. Phys. Lett. 93, 171103 (2008).
[CrossRef]

Song, J.

G. Chen, J. Shen, T. Y. Ohulchanskyy, N. J. Patel, A. Kutikov, Z. Li, J. Song, R. K. Pandey, H. Ågren, P. N. Prasad, and G. Han, “(α-NaYbF4:Tm3+)/CaF2 core/shell nanoparticles with efficient near-infrared to near-infrared up-conversion for high-contrast deep tissue bioimaging,” ACS Nano 6, 8280–8287 (2012).
[CrossRef] [PubMed]

Soukka, T.

H. Päkkilä, M. Ylihärsilä, S. Lahtinen, L. Hattara, N. Salminen, R. Arppe, M. Lastusaari, P. Saviranta, and T. Soukka, “Quantitative multianalyte microarray immunoassay utilizing upconverting phosphor technology,” Anal. Chem. 84, 8628–8634 (2012).
[CrossRef] [PubMed]

Sun, Y.

Q. Liu, Y. Sun, T. Yang, W. Feng, C. Li, and F. Li, “Sub-10 nm hexagonal lanthanide-doped NaLuF4 upconversion nanocrystals for sensitive bioimaging in vivo,” J. Am. Chem. Soc. 133, 17122–17125 (2011).
[CrossRef] [PubMed]

Svenmarker, P.

C. T. Xu, P. Svenmarker, H. Liu, X. Wu, M. E. Messing, L. R. Wallenberg, and S. Andersson-Engels, “High-resolution fluorescence diffuse optical tomography developed with nonlinear upconverting nanoparticles,” ACS Nano 6, 4788–4795 (2012).
[CrossRef] [PubMed]

P. Svenmarker, C. T. Xu, and S. Andersson-Engels, “Use of nonlinear upconverting nanoparticles provides increased spatial resolution in fluorescence diffuse imaging,” Opt. Lett. 35, 2789–2791 (2010).
[CrossRef] [PubMed]

C. T. Xu, N. Svensson, J. Axelsson, P. Svenmarker, G. Somesfalean, G. Chen, H. Liang, H. Liu, Z. Zhang, and S. Andersson-Engels, “Autofluorescence insensitive imaging using upconverting nanocrystals in scattering media,” Appl. Phys. Lett. 93, 171103 (2008).
[CrossRef]

Svensson, N.

C. T. Xu, N. Svensson, J. Axelsson, P. Svenmarker, G. Somesfalean, G. Chen, H. Liang, H. Liu, Z. Zhang, and S. Andersson-Engels, “Autofluorescence insensitive imaging using upconverting nanocrystals in scattering media,” Appl. Phys. Lett. 93, 171103 (2008).
[CrossRef]

Thomas, D.

H. Liu, C. T. Xu, D. Lindgren, H. Xie, D. Thomas, C. Gundlach, and S. Andersson-Engels, “Balancing power density based quantum yield characterization of upconverting nanoparticles for arbitrary excitation intensities,” Nanoscale 5, 4770–4775 (2013).
[CrossRef] [PubMed]

van Veggel, F. C. J. M.

J. Pichaandi, J.-C. Boyer, K. R. Delaney, and F. C. J. M. van Veggel, “Two-photon upconversion laser (scanning and wide-field) microscopy using Ln3+-doped NaYF4 upconverting nanocrystals: A critical evaluation of their performance and potential in bioimaging,” J. Phys. Chem. C 115, 19054–19064 (2011).
[CrossRef]

Visser, C.

W. Zou, C. Visser, J. A. Maduro, M. S. Pshenichnikov, and J. C. Hummelen, “Broadband dye-sensitized upconversion of near-infrared light,” Nat. Photonics 6, 560–564 (2012).
[CrossRef]

Wallenberg, L. R.

C. T. Xu, P. Svenmarker, H. Liu, X. Wu, M. E. Messing, L. R. Wallenberg, and S. Andersson-Engels, “High-resolution fluorescence diffuse optical tomography developed with nonlinear upconverting nanoparticles,” ACS Nano 6, 4788–4795 (2012).
[CrossRef] [PubMed]

Wang, F.

F. Wang, D. Banerjee, Y. Liu, X. Chen, and X. Liu, “Upconversion nanoparticles in biological labeling, imaging, and therapy,” Analyst 135, 1839–1854 (2010).
[CrossRef] [PubMed]

Wang, X.

H. Qiu, C. Yang, W. Shao, J. Damasco, X. Wang, H. Ågren, P. N. Prasad, and G. Chen, “Enhanced upconversion luminescence in Yb3+/Tm3+-codoped fluoride active core/active shell/inert shell nanoparticles through directed energy migration,” Nanomaterials 4, 55–68 (2014).
[CrossRef]

Webb, W. W.

C. Xu, W. Zipfel, J. B. Shear, R. M. Williams, and W. W. Webb, “Multiphoton fluorescence excitation: new spectral windows for biological nonlinear microscopy,” Proc. Natl. Acad. Sci. USA 93, 10763–10768 (1996).
[CrossRef] [PubMed]

Weissleder, R.

R. Weissleder and U. Mahmood, “Molecular imaging,” Radiology 219, 316–333 (2001).
[CrossRef] [PubMed]

Williams, R. M.

C. Xu, W. Zipfel, J. B. Shear, R. M. Williams, and W. W. Webb, “Multiphoton fluorescence excitation: new spectral windows for biological nonlinear microscopy,” Proc. Natl. Acad. Sci. USA 93, 10763–10768 (1996).
[CrossRef] [PubMed]

Wu, X.

C. T. Xu, P. Svenmarker, H. Liu, X. Wu, M. E. Messing, L. R. Wallenberg, and S. Andersson-Engels, “High-resolution fluorescence diffuse optical tomography developed with nonlinear upconverting nanoparticles,” ACS Nano 6, 4788–4795 (2012).
[CrossRef] [PubMed]

Xie, H.

H. Liu, C. T. Xu, D. Lindgren, H. Xie, D. Thomas, C. Gundlach, and S. Andersson-Engels, “Balancing power density based quantum yield characterization of upconverting nanoparticles for arbitrary excitation intensities,” Nanoscale 5, 4770–4775 (2013).
[CrossRef] [PubMed]

Xu, C.

C. Xu, W. Zipfel, J. B. Shear, R. M. Williams, and W. W. Webb, “Multiphoton fluorescence excitation: new spectral windows for biological nonlinear microscopy,” Proc. Natl. Acad. Sci. USA 93, 10763–10768 (1996).
[CrossRef] [PubMed]

Xu, C. T.

H. Liu, C. T. Xu, D. Lindgren, H. Xie, D. Thomas, C. Gundlach, and S. Andersson-Engels, “Balancing power density based quantum yield characterization of upconverting nanoparticles for arbitrary excitation intensities,” Nanoscale 5, 4770–4775 (2013).
[CrossRef] [PubMed]

H. Liu, C. T. Xu, G. Dumlupinar, O. B. Jensen, P. E. Andersen, and S. Andersson-Engels, “Deep tissue optical imaging of upconverting nanoparticles enabled by exploiting higher intrinsic quantum yield through using millisecond single pulse excitation with high peak power,” Nanoscale 5, 10034–10040 (2013).
[CrossRef] [PubMed]

C. T. Xu, Q. Zhan, H. Liu, G. Somesfalean, J. Qian, S. He, and S. Andersson-Engels, “Upconverting nanoparticles for pre-clinical diffuse optical imaging, microscopy and sensing: Current trends and future challenges,” Laser Photonics Rev. 7, 663–697 (2013).
[CrossRef]

C. T. Xu, P. Svenmarker, H. Liu, X. Wu, M. E. Messing, L. R. Wallenberg, and S. Andersson-Engels, “High-resolution fluorescence diffuse optical tomography developed with nonlinear upconverting nanoparticles,” ACS Nano 6, 4788–4795 (2012).
[CrossRef] [PubMed]

P. Svenmarker, C. T. Xu, and S. Andersson-Engels, “Use of nonlinear upconverting nanoparticles provides increased spatial resolution in fluorescence diffuse imaging,” Opt. Lett. 35, 2789–2791 (2010).
[CrossRef] [PubMed]

C. T. Xu, J. Axelsson, and S. Andersson-Engels, “Fluorescence diffuse optical tomography using upconverting nanoparticles,” Appl. Phys. Lett. 94, 251107 (2009).
[CrossRef]

C. T. Xu, N. Svensson, J. Axelsson, P. Svenmarker, G. Somesfalean, G. Chen, H. Liang, H. Liu, Z. Zhang, and S. Andersson-Engels, “Autofluorescence insensitive imaging using upconverting nanocrystals in scattering media,” Appl. Phys. Lett. 93, 171103 (2008).
[CrossRef]

Yang, C.

H. Qiu, C. Yang, W. Shao, J. Damasco, X. Wang, H. Ågren, P. N. Prasad, and G. Chen, “Enhanced upconversion luminescence in Yb3+/Tm3+-codoped fluoride active core/active shell/inert shell nanoparticles through directed energy migration,” Nanomaterials 4, 55–68 (2014).
[CrossRef]

G. Chen, C. Yang, and P. N. Prasad, “Nanophotonics and nanochemistry: Controlling the excitation dynamics for frequency up- and down-conversion in lanthanide-doped nanoparticles,” Acc. Chem. Res. 46, 1474–1486 (2013).
[CrossRef] [PubMed]

Yang, H.

M. Yu, F. Li, Z. Chen, H. Hu, C. Zhan, H. Yang, and C. Huang, “Laser scanning up-conversion luminescence microscopy for imaging cells labeled with rare-earth nanophosphors,” Anal. Chem. 81, 930–935 (2009).
[CrossRef] [PubMed]

Yang, T.

Q. Liu, Y. Sun, T. Yang, W. Feng, C. Li, and F. Li, “Sub-10 nm hexagonal lanthanide-doped NaLuF4 upconversion nanocrystals for sensitive bioimaging in vivo,” J. Am. Chem. Soc. 133, 17122–17125 (2011).
[CrossRef] [PubMed]

Ylihärsilä, M.

H. Päkkilä, M. Ylihärsilä, S. Lahtinen, L. Hattara, N. Salminen, R. Arppe, M. Lastusaari, P. Saviranta, and T. Soukka, “Quantitative multianalyte microarray immunoassay utilizing upconverting phosphor technology,” Anal. Chem. 84, 8628–8634 (2012).
[CrossRef] [PubMed]

Yu, M.

M. Yu, F. Li, Z. Chen, H. Hu, C. Zhan, H. Yang, and C. Huang, “Laser scanning up-conversion luminescence microscopy for imaging cells labeled with rare-earth nanophosphors,” Anal. Chem. 81, 930–935 (2009).
[CrossRef] [PubMed]

Zhan, C.

M. Yu, F. Li, Z. Chen, H. Hu, C. Zhan, H. Yang, and C. Huang, “Laser scanning up-conversion luminescence microscopy for imaging cells labeled with rare-earth nanophosphors,” Anal. Chem. 81, 930–935 (2009).
[CrossRef] [PubMed]

Zhan, Q.

C. T. Xu, Q. Zhan, H. Liu, G. Somesfalean, J. Qian, S. He, and S. Andersson-Engels, “Upconverting nanoparticles for pre-clinical diffuse optical imaging, microscopy and sensing: Current trends and future challenges,” Laser Photonics Rev. 7, 663–697 (2013).
[CrossRef]

Zhang, Y.

M. K. G. Jayakumar, N. M. Idris, and Y. Zhang, “Remote activation of biomolecules in deep tissues using near-infrared-to-uv upconversion nanotransducers,” Proc. Natl. Acad. Sci. USA 109, 8483–8488 (2012).
[CrossRef] [PubMed]

A. Priyam, N. M. Idris, and Y. Zhang, “Gold nanoshell coated NaYF4 nanoparticles for simultaneously enhanced upconversion fluorescence and darkfield imaging,” J. Mater. Chem. 22, 960–965 (2012).
[CrossRef]

H.-S. Qian and Y. Zhang, “Synthesis of hexagonal-phase core-shell NaYF4 nanocrystals with tunable upconversion fluorescence,” Langmuir 24, 12123–12125 (2008).
[CrossRef] [PubMed]

Z. Li and Y. Zhang, “An efficient and user-friendly method for the synthesis of hexagonal-phase NaYF4:Yb, Er/Tm nanocrystals with controllable shape and upconversion fluorescence,” Nanotechnology 19, 345606 (2008).
[CrossRef]

Zhang, Z.

C. T. Xu, N. Svensson, J. Axelsson, P. Svenmarker, G. Somesfalean, G. Chen, H. Liang, H. Liu, Z. Zhang, and S. Andersson-Engels, “Autofluorescence insensitive imaging using upconverting nanocrystals in scattering media,” Appl. Phys. Lett. 93, 171103 (2008).
[CrossRef]

Zhou, J.

J. Zhou, Z. Liu, and F. Li, “Upconversion nanophosphors for small-animal imaging,” Chem. Soc. Rev. 41, 1323–1349 (2012).
[CrossRef]

Zipfel, W.

C. Xu, W. Zipfel, J. B. Shear, R. M. Williams, and W. W. Webb, “Multiphoton fluorescence excitation: new spectral windows for biological nonlinear microscopy,” Proc. Natl. Acad. Sci. USA 93, 10763–10768 (1996).
[CrossRef] [PubMed]

Zou, W.

W. Zou, C. Visser, J. A. Maduro, M. S. Pshenichnikov, and J. C. Hummelen, “Broadband dye-sensitized upconversion of near-infrared light,” Nat. Photonics 6, 560–564 (2012).
[CrossRef]

Zyss, J.

L. Caillat, B. Hajj, V. Shynkar, L. Michely, D. Chauvat, J. Zyss, and F. Pellé, “Multiphoton upconversion in rare earth doped nanocrystals for sub-diffractive microscopy,” Appl. Phys. Lett. 102, 143114 (2013).
[CrossRef]

Acc. Chem. Res. (1)

G. Chen, C. Yang, and P. N. Prasad, “Nanophotonics and nanochemistry: Controlling the excitation dynamics for frequency up- and down-conversion in lanthanide-doped nanoparticles,” Acc. Chem. Res. 46, 1474–1486 (2013).
[CrossRef] [PubMed]

ACS Nano (3)

C. T. Xu, P. Svenmarker, H. Liu, X. Wu, M. E. Messing, L. R. Wallenberg, and S. Andersson-Engels, “High-resolution fluorescence diffuse optical tomography developed with nonlinear upconverting nanoparticles,” ACS Nano 6, 4788–4795 (2012).
[CrossRef] [PubMed]

G. Chen, T. Y. Ohulchanskyy, R. Kumar, H. Ågren, and P. N. Prasad, “Ultrasmall monodisperse NaYF4:Yb3+/Tm3+ nanocrystals with enhanced near-infrared to near-infrared upconversion photoluminescence,” ACS Nano 4, 3163–3168 (2010).
[CrossRef] [PubMed]

G. Chen, J. Shen, T. Y. Ohulchanskyy, N. J. Patel, A. Kutikov, Z. Li, J. Song, R. K. Pandey, H. Ågren, P. N. Prasad, and G. Han, “(α-NaYbF4:Tm3+)/CaF2 core/shell nanoparticles with efficient near-infrared to near-infrared up-conversion for high-contrast deep tissue bioimaging,” ACS Nano 6, 8280–8287 (2012).
[CrossRef] [PubMed]

Anal. Chem. (2)

M. Yu, F. Li, Z. Chen, H. Hu, C. Zhan, H. Yang, and C. Huang, “Laser scanning up-conversion luminescence microscopy for imaging cells labeled with rare-earth nanophosphors,” Anal. Chem. 81, 930–935 (2009).
[CrossRef] [PubMed]

H. Päkkilä, M. Ylihärsilä, S. Lahtinen, L. Hattara, N. Salminen, R. Arppe, M. Lastusaari, P. Saviranta, and T. Soukka, “Quantitative multianalyte microarray immunoassay utilizing upconverting phosphor technology,” Anal. Chem. 84, 8628–8634 (2012).
[CrossRef] [PubMed]

Analyst (1)

F. Wang, D. Banerjee, Y. Liu, X. Chen, and X. Liu, “Upconversion nanoparticles in biological labeling, imaging, and therapy,” Analyst 135, 1839–1854 (2010).
[CrossRef] [PubMed]

Appl. Phys. Lett. (3)

C. T. Xu, N. Svensson, J. Axelsson, P. Svenmarker, G. Somesfalean, G. Chen, H. Liang, H. Liu, Z. Zhang, and S. Andersson-Engels, “Autofluorescence insensitive imaging using upconverting nanocrystals in scattering media,” Appl. Phys. Lett. 93, 171103 (2008).
[CrossRef]

C. T. Xu, J. Axelsson, and S. Andersson-Engels, “Fluorescence diffuse optical tomography using upconverting nanoparticles,” Appl. Phys. Lett. 94, 251107 (2009).
[CrossRef]

L. Caillat, B. Hajj, V. Shynkar, L. Michely, D. Chauvat, J. Zyss, and F. Pellé, “Multiphoton upconversion in rare earth doped nanocrystals for sub-diffractive microscopy,” Appl. Phys. Lett. 102, 143114 (2013).
[CrossRef]

Chem. Rev. (1)

F. Auzel, “Upconversion and anti-stokes processes with f and d ions in solids,” Chem. Rev. 104, 139–173 (2004).
[CrossRef] [PubMed]

Chem. Soc. Rev. (1)

J. Zhou, Z. Liu, and F. Li, “Upconversion nanophosphors for small-animal imaging,” Chem. Soc. Rev. 41, 1323–1349 (2012).
[CrossRef]

J. Am. Chem. Soc. (1)

Q. Liu, Y. Sun, T. Yang, W. Feng, C. Li, and F. Li, “Sub-10 nm hexagonal lanthanide-doped NaLuF4 upconversion nanocrystals for sensitive bioimaging in vivo,” J. Am. Chem. Soc. 133, 17122–17125 (2011).
[CrossRef] [PubMed]

J. Mater. Chem. (1)

A. Priyam, N. M. Idris, and Y. Zhang, “Gold nanoshell coated NaYF4 nanoparticles for simultaneously enhanced upconversion fluorescence and darkfield imaging,” J. Mater. Chem. 22, 960–965 (2012).
[CrossRef]

J. Phys. Chem. C (1)

J. Pichaandi, J.-C. Boyer, K. R. Delaney, and F. C. J. M. van Veggel, “Two-photon upconversion laser (scanning and wide-field) microscopy using Ln3+-doped NaYF4 upconverting nanocrystals: A critical evaluation of their performance and potential in bioimaging,” J. Phys. Chem. C 115, 19054–19064 (2011).
[CrossRef]

Langmuir (1)

H.-S. Qian and Y. Zhang, “Synthesis of hexagonal-phase core-shell NaYF4 nanocrystals with tunable upconversion fluorescence,” Langmuir 24, 12123–12125 (2008).
[CrossRef] [PubMed]

Laser Photonics Rev. (1)

C. T. Xu, Q. Zhan, H. Liu, G. Somesfalean, J. Qian, S. He, and S. Andersson-Engels, “Upconverting nanoparticles for pre-clinical diffuse optical imaging, microscopy and sensing: Current trends and future challenges,” Laser Photonics Rev. 7, 663–697 (2013).
[CrossRef]

Nano Lett. (1)

M. Nyk, R. Kumar, T. Y. Ohulchanskyy, E. J. Bergey, and P. N. Prasad, “High contrast in vitro and in vivo photoluminescence bioimaging using near infrared to near infrared up-conversion in Tm3+ and Yb3+ doped fluoride nanophosphors,” Nano Lett. 8, 3834–3838 (2008).
[CrossRef] [PubMed]

Nanomaterials (1)

H. Qiu, C. Yang, W. Shao, J. Damasco, X. Wang, H. Ågren, P. N. Prasad, and G. Chen, “Enhanced upconversion luminescence in Yb3+/Tm3+-codoped fluoride active core/active shell/inert shell nanoparticles through directed energy migration,” Nanomaterials 4, 55–68 (2014).
[CrossRef]

Nanoscale (2)

H. Liu, C. T. Xu, G. Dumlupinar, O. B. Jensen, P. E. Andersen, and S. Andersson-Engels, “Deep tissue optical imaging of upconverting nanoparticles enabled by exploiting higher intrinsic quantum yield through using millisecond single pulse excitation with high peak power,” Nanoscale 5, 10034–10040 (2013).
[CrossRef] [PubMed]

H. Liu, C. T. Xu, D. Lindgren, H. Xie, D. Thomas, C. Gundlach, and S. Andersson-Engels, “Balancing power density based quantum yield characterization of upconverting nanoparticles for arbitrary excitation intensities,” Nanoscale 5, 4770–4775 (2013).
[CrossRef] [PubMed]

Nanotechnology (1)

Z. Li and Y. Zhang, “An efficient and user-friendly method for the synthesis of hexagonal-phase NaYF4:Yb, Er/Tm nanocrystals with controllable shape and upconversion fluorescence,” Nanotechnology 19, 345606 (2008).
[CrossRef]

Nat. Photonics (1)

W. Zou, C. Visser, J. A. Maduro, M. S. Pshenichnikov, and J. C. Hummelen, “Broadband dye-sensitized upconversion of near-infrared light,” Nat. Photonics 6, 560–564 (2012).
[CrossRef]

Opt. Lett. (1)

Proc. Natl. Acad. Sci. USA (2)

M. K. G. Jayakumar, N. M. Idris, and Y. Zhang, “Remote activation of biomolecules in deep tissues using near-infrared-to-uv upconversion nanotransducers,” Proc. Natl. Acad. Sci. USA 109, 8483–8488 (2012).
[CrossRef] [PubMed]

C. Xu, W. Zipfel, J. B. Shear, R. M. Williams, and W. W. Webb, “Multiphoton fluorescence excitation: new spectral windows for biological nonlinear microscopy,” Proc. Natl. Acad. Sci. USA 93, 10763–10768 (1996).
[CrossRef] [PubMed]

Radiology (1)

R. Weissleder and U. Mahmood, “Molecular imaging,” Radiology 219, 316–333 (2001).
[CrossRef] [PubMed]

Small (1)

J. Shen, G. Chen, T. Y. Ohulchanskyy, S. J. Kesseli, S. Buchholz, Z. Li, P. N. Prasad, and G. Han, “Tunable near infrared to ultraviolet upconversion luminescence enhancement in (α-NaYbF4:Tm3+)/CaF2 core/shell nanoparticles for in situ real-time recorded biocompatible photoactivation,” Small 9, 3213–3217 (2013).
[PubMed]

Other (1)

G. Chen, H. Qiu, P. N. Prasad, and X. Chen, “Upconversion nanoparticles: Design, nanochemistry, and applications in theranostics,” Chem. Rev. DOI: (2014).
[CrossRef]

Cited By

OSA participates in CrossRef's Cited-By Linking service. Citing articles from OSA journals and other participating publishers are listed here.

Alert me when this article is cited.


Figures (5)

Fig. 1
Fig. 1

Schematic description of the geometry used in the photon-migration simulations and optical imaging experiments.

Fig. 2
Fig. 2

COMSOL simulation of light propagation modeling the resolution using the scanning imaging method for multi-photon upconversion emissions. (a) FWHMs of the excitation-emission profiles at various fluorescent-inclusion depths. (b) Ratio of the FWHMs between multi-photon upconversion emissions of different orders.

Fig. 3
Fig. 3

(a) The upconversion spectrum of core–shell NaYF4:Yb3+,Tm3+@NaYF4 nanoparticles under excitation of a CW 975 nm laser diode at a power density of 0.5 W/cm2. The spectrum was measured with a standard Ocean Optics QE65000 scientific-grade spectrometer and no extra calibration was performed. Inset: schematic energy level diagrams of Yb3+ and Tm3+ ions and the proposed upconversion pathways of the NIR and red emissions following the excitation at 975 nm. (b) The power dependency of the NIR and red upconversion emissions under CW excitation at 975 nm.

Fig. 4
Fig. 4

(a) Excitation-emission profiles and (b) the cross-sections through y = 10 mm of the NIR and red upconversion emissions from core–shell NaYF4:Yb3+,Tm3+@NaYF4 nanoparticles. The FWHMs for the cross-sections through y = 10 mm are 4.4 mm and 3.6 mm for the NIR and red upconversion emission, respectively.

Fig. 5
Fig. 5

The enhancement of the three-photon upconversion emission band by using pulsed excitation at various average excitation intensities. The pulsed laser source had a 10 Hz repetition rate and a 10 ms pulse width.

Equations (2)

Equations on this page are rendered with MathJax. Learn more.

( μ a x D x ( r ) 2 ) Φ x ( r ) = S ( r ) ,
( μ a m D m ( r ) 2 ) Φ m ( r ) = n ( r ) ξ ( β ) [ Φ x ( r ) ] β ,

Metrics