Recent advance of biological molecular imaging based on lanthanide-doped upconversion-luminescent nanomaterials

Nanomaterials

Volumn 4, Issue 1, 2014, Pages 129-154

  Min, Yuanzeng ^a   Li, Jinming ^a   Liu, Fang ^a   Padmanabhan, Parasuraman ^b   Yeow, Edwin K L ^a   Xing, Bengang ^a  

^a Nanyang Technological University   (Singapore)

^b NANYANG TECHNOLOGICAL UNIVERSITY   (Singapore)

Author keywords

Luminescent nanomaterials; Molecular imaging; Upconversion nanoparticles

Indexed keywords

EID: 84907518356     PISSN: None     EISSN: 20794991     Source Type: Journal    
DOI: 10.3390/nano4010129     Document Type: Review

References (117)

1. Achilefu, S. Introduction to concepts and strategies for molecular imaging. Chem. Rev. 2010, 110, 2575–2578.
2. He, X.; Gao, J.; Gambhir, S.S.; Cheng, Z. Near-infrared fluorescent nanoprobes for cancer molecular imaging: Status and challenges. Trends Mol. Med. 2010, 12, 574–583.
3. Hildebrandt, I.J.; Gambhir, S.S. Molecular imaging applications for immunology. Clin. Immunol. 2004, 2, 210–224.
4. Weissleder, R.; Pittet, M.J. Imaging in the era of molecular oncology. Nature 2008, 452, 580–589.
5. Jiang, T.T.; Xing, B.G; Rao, J.H. Recent development of biological reporter technology for detecting gene expression. Biotech. Genet. Eng. Rev. 2008, 25, 41–75.
6. Massoud, T.F.; Gambhir, S.S. Molecular imaging in living subjects: Seeing fundamental biological processes in a new light. Genes Dev. 2003, 17, 545–580.
7. Willmann, J.K.; van Bruggen, N.; Dinkelborg, L.M.; Gambhir, S.S. Molecular imaging in drug development. Nat. Rev. Drug Discov. 2008, 7, 591–607.
8. Mullard, A. Molecular imaging as a de-risking tool: Coming into focus? Nat. Rev. Drug Discov. 2013, 12, 251–252.
9. Hastings, J.W. Chemistries and colors of bioluminescent reactions: A review. Gene 1996, 173, 5–11.
10. Leoning, A.M.; Wu, A.M.; Gambhir, S.S. Red-shifted Renilla reniformis luciferase variants for imaging in living subjects. Nat. Methods 2007, 4, 641–643.
11. Contag, C.H.; Bachmann, M.H. Advances in in vivo bioluminescence imaging of gene expression. Annu. Rev. Biomed. Eng. 2002, 4, 235–260.
12. Ray, P.; Gambhir, S.S. Noninvasive imaging of molecular events with bioluminescent reporter genes in living subjects. Methods Mol. Biol. 2007, 411, 131–144.
13. Wehrman, T.S.; von Degenfeld, G.; Krutzik, P.O.; Nolan, G.P.; Blau, H.M. Luminescent imaging of beta-galactosidase activity in living subjects using sequential reporter-enzyme luminescence. Nature methods 2006, 3, 295–301.
14. Tung, C.H.; Zeng, Q.; Shah, K.; Kim, D.E.; Schellingerhout, D.; Weissleder, R. In vivo imaging of beta-galactosidase activity using far red fluorescent switch. Cancer Res. 2004, 6, 1579–1583.
15. Shah, K.; Tung, C.H.; Breakefield, X.O.; Weissleder, R. In vivo imaging of S-TRAIL-mediated tumor regression and apoptosis. Mol. Ther. 2005, 11, 926–931.
16. Zhou, W.; Valley, M.P.; Shultz, J.; Hawkins, E.M.; Bernad, L.; Good, T.; Good, D.; Riss, T.L.; Klaubert, D.H.; Wood, K.V. New bioluminogenic substrates for monoamine oxidase assays. J. Am. Chem. Soc. 2006, 128, 3122–3123.
17. Rao, J.; Dragulescu-Andrasi, A.; Yao, H. Fluorescent imaging in vivo: Recent advances. Curr. Opin. Biotech. 2007, 18, 17–25.
18. Licha, K.; Olbrich, C. Optical imaging in drug discovery and diagnostic applications. Adv. Drug Deliv. Rev. 2005, 57, 1087–1108.
19. Stefflova, K.; Chen, J.; Zheng, G. Using molecular beacons for cancer imaging and treatment. Front Biosci. 2007, 12, 4709–4721.
20. Escobedo, J.O.; Rusin, O.; Lim, S.; Strongin, R.M. NIR dyes for bioimaging applications. Curr. Opin. Chem. Biol. 2010, 184, 64–71.
21. Shao, Q.; Yang, Y.M.; Xing, B.G. Chemistry of Optical Imaging Probes. In Molecular Imaging Probes for Cancer Research; World Science: British Columbia, Canada, 2010.
22. Rothman, D.M.; Shults, M.D.; Imperiali, B. Chemical approaches for investigating phosphorylation in signal transduction networks. Trends Cell Biol. 2005, 15, 502–510.
23. Lawrence, D.S. The preparation and in vivo applications of caged peptides and proteins. Curr. Opin. Chem. Biol. 2005, 9, 570–575.
24. Erathodiyil, N.; Ying, J.Y. Functionalization of inorganic nanoparticles for bioimaging applications. Acc. Chem. Res. 2011, 44, 925–935.
25. Gao, J.H.; Chen, X.Y.; Cheng, Z. Near-infrared quantum dots as optical probes for tumor imaging. Curr. Top. Med. Chem. 2010, 10, 1147–1157.
26. Cai, W.B.; Chen, X.Y. Nanoplatforms for targeted molecular imaging in living subjects. Small 2007, 3, 1840–1854.
27. Biju, V. Chemical modifications and bioconjugate reactions of nanomaterials for sensing, imaging, drug delivery and therapy. Chem. Soc. Rev. 2014, 43, 744–764.
28. Michalet, X.; Pinaud, F.F.; Bentolila, L.A.; Tsay, J.M.; Doose, S.; Li, J.; Sundaresan, G.; Wu, A.; Gambhir, S.S.; Weiss, S. Quantum dots for live cells, in vivo imaging, and diagnostics. Science 2005, 307, 538–544.
29. Probst, C.E.; Zrazhevskiy, P.; Bagalkot, V.; Gao, X.H. Quantum dots as a platform for nanoparticle drug delivery vehicle design. Adv. Drug Deliv. Rev. 2013, 65, 703–718.
30. Biju, V.; Itoh, T.; Ishikawa, M. Delivering quantum dots to cells: Bioconjugated quantum dots for targeted and nonspecific extracellular and intracellular imaging. Chem. Soc. Rev. 2010, 39, 3031–3056.
31. Chi, X.; Huang, D.; Zhao, Z.; Zhou, Z.; Yin, Z.; Gao, J. Nanoprobes for in vitro diagnostics of cancer and infectious diseases. Biomaterials 2012, 33, 189–206.
32. Jayakumar, M.K.; Idris, N.M.; Zhang, Y. Remote activation of biomolecules in deep tissues using near-infrared-to-UV upconversion nanotransducers. Proc. Natl. Acad. Sci. USA 2012, 109, 8483–8488.
33. 4 nanoparticles. J. Am. Chem. Soc. 2008, 130, 5642–5643.
34. Wang, F.; Liu, X. Recent advances in the chemistry of lanthanide-doped upconversion nanocrystals. Chem. Soc. Rev. 2009, 38, 976–989.
35. Haase, H.; Schafer, H. Upconverting nanoparticles. Angew. Chem. Int. Ed. 2011, 50, 5808–5829.
36. Mader, H.S.; Kele, P.; Saleh, S.M.; Wolfbeis, O.S. Upconverting luminescent nanoparticles for use in bioconjugation and bioimaging. Curr. Opin. Chem. Biol. 2010, 14, 582–596.
37. Feng, W.; Sun, L.D.; Zhang, Y.W.; Yan, C.H. Synthesis and assembly of rare earth nanostructures directed by the principle of coordination chemistry in solution-based process. Coordin. Chem. Rev. 2010, 254, 1038–1053.
38. Cheng, L.; Wang, C.; Liu, Z. Upconversion nanoparticles and their composite nanostructures for biomedical imaging and cancer therapy. Nanoscale 2013, 5, 23–37.
39. Gu, Z.; Yan, L.; Tian, G.; Li, S.; Chai, Z.; Zhao, Y. Recent advances in design and fabrication of upconversion nanoparticles and their safe theranostic applications. Adv. Mater. 2013, 25, 3758–3779.
40. Liu, Y.; Tu, D.; Zhu, H.; Chen, X. Lanthanide-doped luminescent nanoprobes: Controlled synthesis, optical spectroscopy, and bioapplications. Chem. Soc. Rev. 2013, 42, 6924–6958.
41. Wang, F.; Banerjee, D.; Liu, Y.; Chen, X.; Liu, X. Upconversion nanoparticles in biological labeling, imaging, and therapy. Analyst 2010, 135, 1839–1854.
42. Cheng, L.; Yang, K.; Li, Y.; Chen, J.; Wang, C.; Shao, M.; Lee, S.T.; Liu, Z. Facile preparation of multifunctional upconversion nanoprobes for multimodal imaging and dual-targeted photothermal therapy. Angew. Chem. Int. Ed. 2011, 50, 7385–7390.
43. Zhou, J.; Liu, Z.; Li, F. Upconversion nanophosphors for small-animal imaging. Chem. Soc. Rev. 2012, 41, 1323–1349.
44. 4:Yb,Tm nanocrystals with efficient up-conversion fluorescence. Adv. Funct. Mater. 2006, 16, 2324–2329.
45. Wang, F.; Han, Y.; Lim, C.S.; Lu, Y.; Wang, J.; Xu, J.; Chen, H.; Zhang, C.; Hong, M.; Liu, X. Simultaneous phase and size control of upconversion nanocrystals through lanthanide doping. Nature 2010, 463, 1061–1065.
46. Mai, H.X.; Zhang, Y.W.; Si, R.; Yan, Z.G.; Sun, L.D.; You, L.P.; Yan, C.H. High-quality sodium rare-earth fluoride nanocrystals: Controlled synthesis and optical properties. J. Am. Chem. Soc. 2006, 128, 6426–6436.
47. 3 triangular nanoplates from a single-source precursor. J. Am. Chem. Soc. 2005, 127, 3260–3261.
48. 4:Yb,Er core and core/shell-structured nanocrystals. J. Phys. Chem. C 2007, 111, 13721–13729.
49. 4:Yb,Er nanocrystals from a unique delayed nucleation pathway monitored with upconversion spectroscopy. J. Phys. Chem. C 2007, 111, 13730–13739.
50. Wang, X.; Zhuang, J.; Peng, Q.; Li, Y. A general strategy for nanocrystal synthesis. Nature 2005, 437, 121–124.
51. Wang, L.; Li, P.; Zhuang, J.; Bai, F.; Feng, J.; Yan, X.; Li, Y. Carboxylic acid enriched nanospheres of semiconductor nanorods for cell imaging. Angew. Chem. Int. Ed. 2008, 47, 1054–1057.
52. 4 upconversion fluorescent nanocrystals. Mater. Lett. 2009, 63, 325–327.
53. 4:Yb,Er nanocrystals. Nanotechnology 2007, 18, 275609–275617.
54. 4:Yb/Er upconversion nanoparticles for in vivo imaging and drug delivery. Adv. Mater. 2012, 24, 1226–1231.
55. 3 nanoparticles. Nano. Lett. 2002, 2, 733–737.
56. 2 nanocrystals. J. Phys. Chem. B 2002, 106, 1909–1912.
57. 3+ nanocrystals. J. Appl. Phys. 2004, 96, 661–667.
58. 3+ nanocrystals. Opt. Mater. 2008, 30, 1284–1288.
59. 3+ co-doped upconversion nanophosphors. Mater. Lett. 2010, 64, 688–691.
60. 3+) doped upconversion nanophosphors. Appl. Phys. Lett. 2007, 90, 073104.
61. Ma, P.; Xiao, H.; Li, X.; Li, C.; Dai, Y.; Cheng, Z.; Jing, X.; Lin, J. Rational design of multifunctional upconversion nanocrystals/polymer nanocomposites for cisplatin(IV) delivery and biomedical imaging. Adv. Mater. 2013, 25, 4898–4905.
62. Yang, Y.; Shao, Q.; Deng, R.; Wang, C.; Teng, X.; Cheng, K.; Cheng, Z.; Huang, L.; Liu, Z.; Liu, X.; et al. In vitro and in vivo uncaging and bioluminescence imaging by using photocaged upconversion nanoparticles. Angew. Chem. Int. Ed. 2012, 51, 3125–3129.
63. Liu, J.N.; Bu, W.; Pan, L.M.; Zhang, S.; Chen, F.; Zhou, L.; Zhao, K.L.; Peng, W.; Shi, J. Simultaneous nuclear imaging and intranuclear drug delivery by nuclear-targeted multifunctional upconversion nanoprobes. Biomaterials 2012, 33, 7282–7290.
64. Xiong, L.; Yang, T.; Yang, Y.; Xu, C.; Li, F. Long-term in vivo biodistribution imaging and toxicity of polyacrylic acid-coated upconversion nanophosphors. Biomaterials 2010, 31, 7078–7085.
65. Rantanen, T.; Jarvenpaa, M.L.; Vuojola, J.; Kuningas, K.; Soukka, T. Fluorescence-quenching-based enzyme-activity assay by using photon upconversion. Angew. Chem. Int. Ed. 2008, 47, 3811–3813.
66. 3+ nanoparticles. Chem. Mater. 2009, 21, 717–723.
67. Bogdan, N.; Vetrone, F.; Ozin, G.A.; Capobianco, J.A. Synthesis of ligand-free colloidally stable water dispersible brightly luminescent lanthanide-doped upconverting nanoparticles. Nano. Lett. 2011, 11, 835–840.
68. 4:Yb,Er upconversion nanophosphors and their application to in vivo imaging of Caenorhabditis elegans. J. Mater. Chem. 2011, 21, 2632–2638.
69. Zhou, H.P.; Xu, C.H.; Sun, W.; Yan, C.H. Clean and flexible modification strategy for carboxyl/aldehyde-functionalized upconversion nanoparticles and their optical applications. Adv. Funct. Mater. 2009, 19, 3892–3900.
70. Chen, Z.; Chen, H.; Hu, H.; Yu, M.; Li, F.; Zhang, Q.; Zhou, Z.; Yi, T.; Huang, C. Versatile synthesis strategy for carboxylic acid-functionalized upconverting nanophosphors as biological labels. J. Am. Chem. Soc. 2008, 130, 3023–3029.
71. Wang, L.Y.; Yan, R.X.; Hao, Z.Y.; Wang, L.; Zeng, J.H.; Bao, J.; Wang, X.; Peng, Q.; Li, Y.D. Fluorescence resonant energy transfer biosensor based on upconversion-luminescent nanoparticles. Angew. Chem. Int. Edit. 2005, 44, 6054–6057.
72. Bao, Y.; Luu, Q.A.N.; Lin, C.K.; Schloss, J.M.; May, P.S.; Jiang, C.Y. Layer-by-layer assembly of freestanding thin films with homogeneously distributed upconversion nanocrystals. J. Mater. Chem. 2010, 20, 8356–8361.
73. Yang, Y.M.; Velmurugan, B.; Liu, X.; Xing, B. NIR photoresponsive crosslinked upconverting nanocarriers toward selective intracellular drug release. Small 2013, 9, 2937–2944.
74. Yang, Y.M.; Liu, F.; Liu, X.G.; Xing, B.G. NIR light controlled photorelease of siRNA and its targeted intracellular delivery based on upconversion nanoparticles. Nanoscale 2013, 5, 231–238.
75. Cao, T.; Yang, Y.; Gao, Y.; Zhou, J.; Li, Z.; Li, F. High-quality water-soluble and surface-functionalized upconversion nanocrystals as luminescent probes for bioimaging. Biomaterials 2011, 32, 2959–2968.
76. 3 nanoparticles as fluorescent labels. Anal. Chem. 2005, 77, 6864–6873.
77. Peer, D.; Karp, J.M.; Hong, S.; FaroKHzad, O.C.; Margalit, R.; Langer, R. Nanocarriers as an emerging platform for cancer therapy. Nat. Nanotechnol. 2007, 2, 751–760.
78. 3+ doped fluoride nanophosphors. Nano Lett. 2008, 8, 3834–3838.
79. Xing, H.Y.; Zheng, X.P.; Ren, Q.G.; Bu, W.B.; Ge, W.Q.; Xiao, Q.F.; Zhang, S.J.; Wei, C.Y.; Qu, H.Y.; Wang, Z.; et al. Computed tomography imaging-guided radiotherapy by targeting upconversion nanocubes with significant imaging and radiosensitization enhancements. Sci. Rep.-UK 2013, 3, 1–9.
80. Lim, S.F.; Riehn, R.; Ryu, W.S.; Khanarian, N.; Tung, C.K.; Tank, D.; Austin, R.H. In vivo and scanning electron microscopy imaging of up-converting nanophosphors in Caenorhabditis elegans. Nano Lett. 2006, 6, 169–174.
81. 3:Yb,Er in early development of zebrafish embryos. Theranostics 2013, 3, 258–266.
82. Mitsunaga, M.; Ogawa, M.; Kosaka, N.; Rosenblum, L.T.; Choyke, P.L.; Kobayashi, H. Cancer cell-selective in vivo near infrared photoimmunotherapy targeting specific membrane molecules. Nat. Med. 2011, 17, 1685–1691.
83. Chatterjee, D.K.; Rufaihah, A.J.; Zhang, Y. Upconversion fluorescence imaging of cells and small animals using lanthanide doped nanocrystals. Biomaterials 2008, 29, 937–943.
84. Zhou, J.; Sun, Y.; Du, X.; Xiong, L.; Hu, H.; Li, F. Dual-modality in vivo imaging using rare-earth nanocrystals with near-infrared to near-infrared (NIR-to-NIR) upconversion luminescence and magnetic resonance properties. Biomaterials 2010, 31, 3287–3295.
85. 4-based upconversion nanophosphors for trimodality imaging of NIR-to-NIR upconversion luminescence, X-ray computed tomography and magnetic resonance. Biomaterials 2012, 33, 5394–5405.
86. 3+ nanoprobe for CT and NIR-to-NIR fluorescent bimodal imaging. Biomaterials 2012, 33, 5384–5393.
87. 4 upconversion nanocrystals for sensitive bioimaging in vivo. J. Am. Chem. Soc. 2011, 133, 17122–17125.
88. 4-based upconversion nanophosphors for high-contrast bioimaging in different animal species. Biomaterials 2012, 33, 3733–3742.
89. Wang, C.; Cheng, L.; Xu, H.; Liu, Z. Towards whole-body imaging at the single cell level using ultra-sensitive stem cell labeling with oligo-arginine modified upconversion nanoparticles. Biomaterials 2012, 33, 4872–4881.
90. Chari, R.V. Targeted cancer therapy: Conferring specificity to cytotoxic drugs. Acc. Chem. Res. 2008, 41, 98–107.
91. Xiong, L.Q.; Chen, Z.G.; Yu, M.X.; Li, F.Y.; Liu, C.; Huang, C.H. Synthesis, characterization, and in vivo targeted imaging of amine-functionalized rare-earth up-converting nanophosphors. Biomaterials 2009, 30, 5592–5600.
92. Xiong, L.; Chen, Z.; Tian, Q.; Cao, T.; Xu, C.; Li, F. High contrast upconversion luminescence targeted imaging in vivo using peptide-labeled nanophosphors. Anal. Chem. 2009, 81, 8687–8694.
93. Danhier, F.; Le Breton, A.; Préat, V. RGD-based strategies to target alpha(v) beta(3) integrin in cancer therapy and diagnosis. Mol. Pharm. 2012, 9, 2961–2973.
94. Li, Y.; Jing, C.; Zhang, L.; Long, Y.T. Resonance scattering particles as biological nanosensors in vitro and in vivo. Chem. Soc. Rev. 2012, 41, 632–642.
95. Cai, W.; Chen, X. Anti-angiogenic cancer therapy based on integrin alphavbeta3 antagonism. Anticancer Agents Med. Chem. 2006, 6, 407–428.
96. Meyer, A.; Auernheimer, J.; Modlinger, A.; Kessler, H. Targeting RGD recognizing integrins: Drug development, biomaterial research, tumor imaging and targeting. Curr. Pharm. Des. 2006, 12, 2723–2747.
97. Yu, X.F.; Sun, Z.; Li, M.; Xiang, Y.; Wang, Q.Q.; Tang, F.; Wu, Y.; Cao, Z.; Li, W. Neurotoxin-conjugated upconversion nanoprobes for direct visualization of tumors under near-infrared irradiation. Biomaterials 2010, 31, 8724–8731.
98. Shao, Q.; Xing, B. Photoactive molecules for applications in molecular imaging and cell biology. Chem. Soc. Rev. 2010, 39, 2835–2846.
99. Mayer, G.; Heckel, A. Biologically active molecules with a “light switch”. Angew. Chem. Int. Ed. 2006, 45, 4900–4921.
100. Lee, H.; Larson, D.R.; Lawrence, D.S. Illuminating the chemistry of life: Design, synthesis, and applications of “caged” and related photoresponsive compounds. ACS Chem. Biol. 2009, 4, 409–427.
101. Young, D.D.; Deiters, A. Photochemical control of biological processes. Org. Biomol. Chem. 2007, 5, 999–1005.
102. Min, Y.; Li, J.; Liu, F.; Yeow, E.K.; Xing, B. Near-infrared light-mediated photoactivation of a platinum antitumor prodrug and simultaneous cellular apoptosis imaging by upconversion-luminescent nanoparticles. Angew. Chem. Int. Ed. 2014, 53, 1012–1016.
103. Cheng, L.; Yang, K.; Li, Y.; Zeng, X.; Shao, M.; Lee, S.T.; Liu, Z. Multifunctional nanoparticles for upconversion luminescence/MR multimodal imaging and magnetically targeted photothermal therapy. Biomaterials 2012, 33, 2215–2222.
104. 4 upconversion nanocrystals via an OA/ionic liquid two-phase system for in vivo dual-modality imaging. Adv. Funct. Mater. 2011, 21, 4470–4477.
105. Sun, Y.; Yu, M.; Liang, S.; Zhang, Y.; Li, C.; Mou, T.; Yang, W.; Zhang, X.; Li, B.; Huang, C.; et al. Fluorine-18 labeled rare-earth nanoparticles for positron emission tomography (PET) imaging of sentinel lymph node. Biomaterials 2011, 32, 2999–3007.
106. 153 Sm,Yb,Tm nanoparticles and their application in dual-modality upconversion luminescence and SPECT bioimaging. Biomaterials 2013, 34, 774–783.
107. 4 nanophosphors for multimodality PET/MR/UCL imaging. Biomaterials 2011, 32, 1148–1156.
108. Xing, H.; Bu, W.; Zhang, S.; Zheng, X.; Li, M.; Chen, F.; He, Q.; Zhou, L.; Peng, W.; Hua, Y.; et al. Multifunctional nanoprobes for upconversion fluorescence, MR and CT trimodal imaging. Biomaterials 2012, 33, 1079–1089.
109. 3+ nanocrystals under excitation at 1490 nm. ACS Nano 2011, 5, 4981–4986.
110. Idris, N.M.; Gnanasammandhan, M.K.; Zhang, J.; Ho, P.C.; Mahendran, R.; Zhang, Y. In vivo photodynamic therapy using upconversion nanoparticles as remote-controlled nanotransducers. Nat. Med. 2012, 18, 1580–1585.
111. Wang, C.; Tao, H.Q.; Cheng, L.; Liu, Z. Near-infrared light induced in vivo photodynamic therapy of cancer based on upconversion nanoparticles. Biomaterials 2011, 32, 6145–6154.
112. Cui, S.; Yin, D.; Chen, Y.; Di, Y.; Chen, H.; Ma, Y.; Achilefu, S.; Gu, Y. In vivo targeted deep-tissue photodynamic therapy based on near-infrared light triggered upconversion nanoconstructure. ACS Nano 2013, 7, 676–688.
113. 4 upconversion nanoparticles for in vitro and deeper in vivo bioimaging without overheating irradiation. ACS Nano 2011, 5, 3744–3757.
114. 3+-sensitized upconversion nanophosphors: Efficient in vivo bioimaging probes with minimized heating effect. ACS Nano 2013, 7, 7200–7206.
115. Zou, W.; Visser, C.; Maduro, J.A.; Pshenichnikov, M.S.; Hummelen, J.C. Broadband dye-sensitized upconversion of near-infrared light. Nat. Photon. 2012, 6, 560–564.
116. Shen, J.; Chen, G.; Vu, A.-M.; Fan, W.; Bilsel, O.S.; Chang, C.-C.; Han, G. Engineering the upconversion nanoparticle excitation wavelength: Cascade sensitization of tri-doped upconversion colloidal nanoparticles at 800 nm. Adv. Opt. Mater. 2013, 1, 644–650.
117. 3+-sensitized core-shell nanoparticles. J. Am. Chem. Soc. 2013, 135, 12608–12611.