Near-infrared light-mediated rare-earth nanocrystals: recent advances in improving photon conversion and alleviating the thermal effect
Source abstract
Abstract
With the rapid development of nanotechnology, the unique rare-earth lanthanide-doped upconversion nanocrystals (UCNs), which can convert tissue-penetrable near-infrared (NIR) photonic irradiation into ultraviolet, visible, and NIR emissions, have a significant potential in bioimaging, diagnosis, and therapy, as well as in photovoltaic systems and optical data storage. Despite the promising achievements made in the past decade, critical challenges associated with low upconversion efficiencies and the overheating effect induced by NIR laser-irradiation still remain in the biomedical fields. In high demand are more well-defined material design and unique structural modifications that are capable of solving these technical concerns and promoting such promising NIR light-mediated upconversion nanocrystals for their further application in the medical sciences. Recent advances in upconversion nanomaterials have witnessed a tremendous development towards enhancing their photon conversion efficiency, which provides great opportunities in expanding the potential of the UCNs in bioimaging diagnosis and anticancer therapy. Hence, this review is mainly focused on summarizing the fundamental principles and strategies that improve upconversion luminescence and the approaches to reduce the local thermal effect on the basis of a rational design of UCNs. In addition, the future perspectives in the development of UCNs for biomedical applications are also proposed. Rare-earth elements and organic dyes are improving the safety and efficiency of innovative fluorescent probes designed to diagnose tumors and other disorders deep inside living tissue. Upconversion nanocrystals are microscopic particles that can release a broad range of infrared, visible, and ultraviolet light after activation by laser irradiation. Bengang Xing from Nanyang Technological University in Singapore and colleagues review how these nanomaterials may be engineered to achieve brighter luminescence while minimizing laser-related heating. Although researchers normally impregnate upconversion nanocrystals with small amounts of rare earths, new findings show that boosting rare earth levels with ions such as neodymium enables the tuning of laser excitations to biologically compatible frequencies, and emission outputs to specific colors. Adding organic molecules capable of broadband light adsorption to the nanocrystals offers opportunities for targeted, ultra-bright imaging and activation of biomolecules. With the rapid development of nanotechnology, the unique rare earth lanthanide-doped upconversion nanocrystals (UCNs), which can convert tissue-penetrable near-infrared (NIR) photonic irradiation into ultraviolet, visible and NIR emissions, have found significant potential in bioimaging, diagnosis, therapy, as well as photovoltaics and optical data storage. Despite the promising achievements made in the past decade, critical challenges associated with low upconversion efficiencies and overheating effect induced by NIR laser-irradiation remain in the biomedical fields. More well-defined material design and unique structural modification are highly demanded that are capable of solving these technical concerns and promoting such promising NIR light mediated upconversion nanocrystals for their further practice in medical sciences. Recent advances in upconversion nanomaterials have witnessed the tremendous development towards enhancing the photon converted efficiency, which provides great opportunities in expanding the UCNs potential in bioimaging diagnosis and anticancer therapy. Hence, this review is mainly focusing on summarizing the fundamental principles and strategies to improve the upconversion luminescence and the approaches to reduce the local thermal effect on the basis of rational design of UCNs. In addition, the future perspectives in the development of UCNs for biomedical applications are also proposed.
Source: openalex_inverted_index · Quality: baseline
Research context
OpenAlex topics: Luminescence Properties of Advanced Materials · Nanoplatforms for cancer theranostics · Luminescence and Fluorescent Materials
SciVX discovery tags are terminology-based. OpenAlex topics are source-provided classifications.
References (100+)
Show source-provided references
1. Rubin, E. H., Allen, J. D., Nowak, J. A. & Bates, S. E. Developing precision medicine in a global world. Clin. Cancer Res. 20, 1419–1427 (2014).10.1158/1078-0432.CCR-14-0091 ↗
2. Friedman, A. A., Letai, A., Fisher, D. E. & Flaherty, K. T. Precision medicine for cancer with next-generation functional diagnostics. Nat. Rev. Cancer 15, 747–756 (2015).10.1038/nrc4015 ↗
3. Arnedos, M. et al. Precision medicine for metastatic breast cancer--limitations and solutions. Nat. Rev. Clin. Oncol. 12, 693–704 (2015).10.1038/nrclinonc.2015.123 ↗
4. Hussain, T. & Nguyen, Q. T. Molecular imaging for cancer diagnosis and surgery. Adv. Drug Deliv. Rev. 66, 90–100 (2014).10.1016/j.addr.2013.09.007 ↗
5. Kircher, M. F., Hricak, H. & Larson, S. M. Molecular imaging for personalized cancer care. Mol. Oncol. 6, 182–195 (2012).10.1016/j.molonc.2012.02.005 ↗
6. Kuimova, M. K. et al. Imaging intracellular viscosity of a single cell during photoinduced cell death. Nat. Chem. 1, 69–73 (2009).10.1038/nchem.120 ↗
7. Weissleder, R., Schwaiger, M. C., Gambhir, S. S. & Hricak, H. Imaging approaches to optimize molecular therapies. Sci. Transl. Med. 8, 355ps316 (2016).10.1126/scitranslmed.aaf3936 ↗
8. Yang, Y. et al. Core-shell and co-doped nanoscale metal-organic particles (NMOPs) obtained via post-synthesis cation exchange for multimodal imaging and synergistic thermo-radiotherapy. NPG Asia Mater. 9, e344–e344 (2017).10.1038/am.2016.205 ↗
9. Willmann, J. K., van Bruggen, N., Dinkelborg, L. M. & Gambhir, S. S. Molecular imaging in drug development. Nat. Rev. Drug. Discov. 7, 591–607 (2008).10.1038/nrd2290 ↗
10. Kobayashi, H., Ogawa, M., Alford, R., Choyke, P. L. & Urano, Y. New strategies for fluorescent probe design in medical diagnostic imaging. Chem. Rev. 110, 2620–2640 (2010).10.1021/cr900263j ↗
11. Rao, J., Dragulescu-Andrasi, A. & Yao, H. Fluorescence imaging in vivo: recent advances. Curr. Opin. Biotechnol. 18, 17–25 (2007).10.1016/j.copbio.2007.01.003 ↗
12. Medintz, I. L., Uyeda, H. T., Goldman, E. R. & Mattoussi, H. Quantum dot bioconjugates for imaging, labelling and sensing. Nat. Mater. 4, 435–446 (2005).10.1038/nmat1390 ↗
13. Wegner, K. D. & Hildebrandt, N. Quantum dots: bright and versatile in vitro and in vivo fluorescence imaging biosensors. Chem. Soc. Rev. 44, 4792–4834 (2015).10.1039/C4CS00532E ↗
14. Gao, M., Yu, F., Lv, C., Choo, J. & Chen, L. Fluorescent chemical probes for accurate tumor diagnosis and targeting therapy. Chem. Soc. Rev. 46, 2237–2271 (2017).10.1039/C6CS00908E ↗
15. Chen, Z. J., Ren, W., Wright, Q. E. & Ai, H. W. Genetically encoded fluorescent probe for the selective detection of peroxynitrite. J. Am. Chem. Soc. 135, 14940–14943 (2013).10.1021/ja408011q ↗
16. Heil, K., Pearson, D. & Carell, T. Chemical investigation of light induced DNA bipyrimidine damage and repair. Chem. Soc. Rev. 40, 4271–4278 (2011).10.1039/C000407N ↗
17. Yang, Y., Mu, J. & Xing, B. Photoactivated drug delivery and bioimaging. Wiley Interdiscip. Rev. Nanomed. Nanobiotechnol. 9, e1408 (2017).10.1002/wnan.1408 ↗
18. Yang, Y., Aw, J. & Xing, B. Nanostructures for NIR light-controlled therapies. Nanoscale 9, 3698–3718 (2017).10.1039/C6NR09177F ↗
19. Hilderbrand, S. A. & Weissleder, R. Near-infrared fluorescence: application to in vivo molecular imaging. Curr. Opin. Chem. Biol. 14, 71–79 (2010).10.1016/j.cbpa.2009.09.029 ↗
20. Idris, N. M., Jayakumar, M. K., Bansal, A. & Zhang, Y. Upconversion nanoparticles as versatile light nanotransducers for photoactivation applications. Chem. Soc. Rev. 44, 1449–1478 (2015).10.1039/C4CS00158C ↗
21. Yang, D. et al. Current advances in lanthanide ion (Ln(3+))-based upconversion nanomaterials for drug delivery. Chem. Soc. Rev. 44, 1416–1448 (2015).10.1039/C4CS00155A ↗
22. Zheng, W. et al. Lanthanide-doped upconversion nano-bioprobes: electronic structures, optical properties, and biodetection. Chem. Soc. Rev. 44, 1379–1415 (2015).10.1039/C4CS00178H ↗
23. Chen, C., Li, C. & Shi, Z. Current advances in lanthanide-doped upconversion nanostructures for detection and bioapplication. Adv. Sci. 3, 1600029 (2016).10.1002/advs.201600029 ↗
24. Liu, G. Advances in the theoretical understanding of photon upconversion in rare-earth activated nanophosphors. Chem. Soc. Rev. 44, 1635–1652 (2015).10.1039/C4CS00187G ↗
25. Han, S., Deng, R., Xie, X. & Liu, X. Enhancing luminescence in lanthanide-doped upconversion nanoparticles. Angew. Chem. Int. Ed. 53, 11702–11715 (2014).10.1002/anie.201403408 ↗
26. Biju, V. Chemical modifications and bioconjugate reactions of nanomaterials for sensing, imaging, drug delivery and therapy. Chem. Soc. Rev. 43, 744–764 (2014).10.1039/C3CS60273G ↗
27. Chen, G., Qiu, H., Prasad, P. N. & Chen, X. Upconversion nanoparticles: design, nanochemistry, and applications in theranostics. Chem. Rev. 114, 5161–5214 (2014).10.1021/cr400425h ↗
28. Feng, W., Zhu, X. & Li, F. Recent advances in the optimization and functionalization of upconversion nanomaterials for in vivo bioapplications. NPG Asia Mater. 5, e75 (2013).10.1038/am.2013.63 ↗
29. Xing, H. et al. Multifunctional nanoprobes for upconversion fluorescence, MR and CT trimodal imaging. Biomaterials 33, 1079–1089 (2012).10.1016/j.biomaterials.2011.10.039 ↗
30. Shi, J. et al. A new near-infrared persistent luminescence nanoparticle as a multifunctional nanoplatform for multimodal imaging and cancer therapy. Biomaterials 152, 15–23 (2018).10.1016/j.biomaterials.2017.10.032 ↗
31. Sun, Y. et al. Fluorine-18 labeled rare-earth nanoparticles for positron emission tomography (PET) imaging of sentinel lymph node. Biomaterials 32, 2999–3007 (2011).10.1016/j.biomaterials.2011.01.011 ↗
32. Yang, Y. et al. Hydrothermal synthesis of NaLuF4:153Sm,Yb,Tm nanoparticles and their application in dual-modality upconversion luminescence and SPECT bioimaging. Biomaterials 34, 774–783 (2013).10.1016/j.biomaterials.2012.10.022 ↗
33. Zhou, J., Liu, Z. & Li, F. Upconversion nanophosphors for small-animal imaging. Chem. Soc. Rev. 41, 1323–1349 (2012).10.1039/C1CS15187H ↗
34. 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. 53, 1012–1016 (2014).10.1002/anie.201308834 ↗
35. Yang, Y. et al. In vitro and in vivo uncaging and bioluminescence imaging by using photocaged upconversion nanoparticles. Angew. Chem. Int. Ed. 51, 3125–3129 (2012).10.1002/anie.201107919 ↗
36. Ai, X. et al. Remote regulation of membrane channel activity by site-specific localization of lanthanide-doped upconversion nanocrystals. Angew. Chem. Int. Ed. 56, 3031–3035 (2017).10.1002/anie.201612142 ↗
37. Peng, J. et al. Real-time in vivo hepatotoxicity monitoring through chromophore-conjugated photon-upconverting nanoprobes. Angew. Chem. Int. Ed. 56, 4165–4169 (2017).10.1002/anie.201612020 ↗
38. Su, Q., Feng, W., Yang, D. & Li, F. Resonance energy transfer in upconversion nanoplatforms for selective biodetection. Acc. Chem. Res. 50, 32–40 (2017).10.1021/acs.accounts.6b00382 ↗
39. Chen, G., Agren, H., Ohulchanskyy, T. Y. & Prasad, P. N. Light upconverting core-shell nanostructures: nanophotonic control for emerging applications. Chem. Soc. Rev. 44, 1680–1713 (2015).10.1039/C4CS00170B ↗
40. Wang, Y. F. et al. Nd3+-Sensitized upconversion nanophosphors: efficient in vivo bioimaging probes with minimized heating effect. ACS Nano 7, 7200–7206 (2013).10.1021/nn402601d ↗
41. Shen, J. et al. Engineering the upconversion nanoparticle excitation wavelength: cascade sensitization of tri-doped upconversion colloidal nanoparticles at 800 nm. Adv. Opt. Mater. 1, 644–650 (2013).10.1002/adom.201300160 ↗
42. Haase, M. & Schafer, H. Upconverting nanoparticles. Angew. Chem. Int. Ed. 50, 5808–5829 (2011).10.1002/anie.201005159 ↗
43. Auzel, F. Upconversion and anti-stokes processes with f and d ions in solids. Chem. Rev. 104, 139–173 (2004).10.1021/cr020357g ↗
44. Dong, H., Sun, L. D. & Yan, C. H. Basic understanding of the lanthanide related upconversion emissions. Nanoscale 5, 5703–5714 (2013).10.1039/c3nr34069d ↗
45. Dong, A. et al. A generalized ligand-exchange strategy enabling sequential surface functionalization of colloidal nanocrystals. J. Am. Chem. Soc. 133, 998–1006 (2011).10.1021/ja108948z ↗
46. Duan, C., Liang, L., Li, L., Zhang, R. & Xu, Z. P. Recent progress in upconversion luminescence nanomaterials for biomedical applications. J. Mater. Chem. B 6, 192–209 (2018).10.1039/C7TB02527K ↗
47. Huang, L. et al. Expanding anti-stokes shifting in triplet-triplet annihilation upconversion for in vivo anticancer prodrug activation. Angew. Chem. Int. Ed. Engl. 56, 14400–14404 (2017).10.1002/anie.201704430 ↗
48. Huang, L. et al. Enhancing photodynamic therapy through resonance energy transfer constructed near-infrared photosensitized nanoparticles. Adv. Mater. 29 1604789 (2017).10.1002/adma.201604789 ↗
49. Bai, Y. et al. The effect of Li on the spectrum of Er3+ in Li-and Er-codoped ZnO nanocrystals. J. Phys. Chem. C. 112, 12259–12263 (2008).10.1021/jp803373e ↗
50. Luo, X. & Cao, W. Upconversion luminescence properties of Li+-doped ZnWO4: Yb, Er. J. Mater. Res. 23, 2078–2083 (2008).10.1557/JMR.2008.0275 ↗
51. Cao, B., Feng, Z., He, Y., Li, H. & Dong, B. Opposite effect of Li+ codoping on the upconversion emissions of Er3+-doped TiO2 powders. J. Sol.-Gel Sci. Technol. 54, 101–104 (2010).10.1007/s10971-010-2163-3 ↗
52. Liu, L. et al. Efficient two-color luminescence of Er3+/Yb3+/Li:+ ZrO2 nanocrystals. Opt. Mater. 33, (1234–1238 (2011).
53. Yin, W. et al. Enhanced red emission from GdF3: Yb3+, Er3+ upconversion nanocrystals by Li+ doping and their application for bioimaging. Chem. Eur. J. 18, 9239–9245 (2012).10.1002/chem.201201053 ↗
54. Hu, M. et al. Synergistically enhanced upconversion luminescence in Li+-doped core–shell-structured ultrasmall nanoprobes for dual-mode deep tissue fluorescence/CT imaging. J. Mater. Chem. B 5, 2662–2670 (2017).10.1039/C6TB02976K ↗
55. Liang, H. et al. Enhancement of upconversion luminescence of Y2O3: Er3+ nanocrystals by codoping Li+–Zn2+. J. Alloy. Compd. 509, 409–413 (2011).10.1016/j.jallcom.2010.09.044 ↗
56. Jiang, L., Xiao, S., Yang, X., Ding, J. & Dong, K. Enhancement of up-conversion luminescence in Zn2SiO4: Yb3+, Er3+ by co-doping with Li+ or Bi3+. Appl. Phys. B 107, 477–481 (2012).10.1007/s00340-012-4986-9 ↗
57. Niu, N. et al. Rapid microwave reflux process for the synthesis of pure hexagonal NaYF4: Yb3+, Ln3+, Bi3+(Ln3+ = Er3+, Tm3+, Ho3+) and its enhanced UC luminescence. J. Mater. Chem. 22, 21613–21623 (2012).10.1039/c2jm34653b ↗
58. Ramasamy, P., Chandra, P., Rhee, S. W. & Kim, J. Enhanced upconversion luminescence in NaGdF4: Yb, Er nanocrystals by Fe3+ doping and their application in bioimaging. Nanoscale 5, 8711–8717 (2013).10.1039/c3nr01608k ↗
59. Auzel, F. Upconversion and anti-stokes processes with f and d ions in solids. Chem. Rev. 104, 139–174 (2004).10.1021/cr020357g ↗
60. Zhao, J. et al. Single-nanocrystal sensitivity achieved by enhanced upconversion luminescence. Nat. Nanotechnol. 8, 729–734 (2013).10.1038/nnano.2013.171 ↗
61. Wang, J. et al. Enhancing multiphoton upconversion through energy clustering at sublattice level. Nat. Mater. 13, nmat3804 (2013).
62. Cao, B., He, Y., Feng, Z., Li, Y. & Dong, B. Optical temperature sensing behavior of enhanced green upconversion emissions from Er–Mo: Yb2Ti2O7 nanophosphor. Sens. Actuator B-Chem. 159, 8–11 (2011).10.1016/j.snb.2011.05.018 ↗
63. Dong, B. et al. Temperature sensing and in vivo imaging by molybdenum sensitized visible upconversion luminescence of rare-earth oxides. Adv. Mater. 24, 1987–1993 (2012).10.1002/adma.201200431 ↗
64. Li, Z., Dong, B., He, Y., Cao, B. & Feng, Z. Selective enhancement of green upconversion emissions of Er:3+ Yb3+Al5O12 nanocrystals by high excited state energy transfer with Yb3+–Mn2+ dimer sensitizing. J. Lumin. 132, 1646–1648 (2012).10.1016/j.jlumin.2012.02.034 ↗
65. Li, X. et al. Energy migration upconversion in manganese (II)- doped nanoparticles. Angew. Chem. Int. Ed. 127, 13510–13515 (2015).10.1002/ange.201507176 ↗
66. Lingeshwar Reddy, K. et al. Enhancement of luminescence intensity in red emitting NaYF4: Yb/Ho/Mn upconversion nanophosphors by variation of reaction parameters. J. Phys. Chem. C 121, 11783–11793 (2017).10.1021/acs.jpcc.7b01334 ↗
67. Zeng, J. H., Xie, T., Li, Z. H. & Li, Y. Monodispersed nanocrystalline fluoroperovskite up-conversion phosphors. Cryst. Growth Des. 7, 2774–2777 (2007).10.1021/cg070477n ↗
68. Xie, M.-Y. et al. Synthesis of Yb3+/Er3+ co-doped MnF2 nanocrystals with bright red up-converted fluorescence. Scr. Mater. 60, 190–193 (2009).10.1016/j.scriptamat.2008.10.010 ↗
69. Wang, J., Wang, F., Wang, C., Liu, Z. & Liu, X. Single-band upconversion emission in lanthanide-doped KMnF3 nanocrystals. Angew. Chem. Int. Ed. 50, 10369–10372 (2011).10.1002/anie.201104192 ↗
70. Zhang, Y., Lin, J. D., Vijayaragavan, V., Bhakoo, K. K. & Tan, T. T. Y. Tuning sub-10 nm single-phase NaMnF3 nanocrystals as ultrasensitive hosts for pure intense fluorescence and excellent T1 magnetic resonance imaging. Chem. Commun. 48, 10322–10324 (2012).10.1039/c2cc34858f ↗
71. Tian, G. et al. Mn2+ dopant-controlled synthesis of NaYF4: Yb/Er upconversion nanoparticles for in vivo imaging and drug delivery. Adv. Mater. 24, 1226–1231 (2012).10.1002/adma.201104741 ↗
72. Wang, F., Fan, X., Wang, M. & Zhang, Y. Multicolour PEI/NaGdF4: Ce3+, Ln3+ nanocrystals by single-wavelength excitation. Nanotechnology 18, 025701 (2006).10.1088/0957-4484/18/2/025701 ↗
73. Zhou, J. et al. Fluorine-18-labeled Gd3+/Yb3+/Er3+ co-doped NaYF4 nanophosphors for multimodality PET/MR/UCL imaging. Biomaterials 32, 1148–1156 (2011).10.1016/j.biomaterials.2010.09.071 ↗
74. Chen, Q. et al. Confining excitation energy in Er3+-sensitized upconversion nanocrystals through Tm3+-Mediated transient energy trapping. Angew. Chem. Int. Ed. 56, 7605–7609 (2017).10.1002/anie.201703012 ↗
75. Yi, G. & Chow, G. Water-soluble NaYF4: Yb,Er(Tm)/NaYF4/polymer core/shell/shell nanoparticles with significant enhancement of upconversion fluorescence. Chem. Mater. 19, 341–343 (2007).10.1021/cm062447y ↗
76. Mai, H., Zhang, Y., Sun, L. & Yan, C. Highly efficient multicolor up-conversion emissions and their mechanisms of monodisperse NaYF4: Yb, Er core and core/shell-structured nanocrystals. J. Phys. Chem. C. 111, 13721–13729 (2007).10.1021/jp073920d ↗
77. Schäfer, H., Ptacek, P., Zerzouf, O. & Haase, M. Synthesis and optical properties of KYF4/Yb, Er nanocrystals, and their surface modification with undoped KYF4. Adv. Funct. Mater. 18, 2913–2918 (2008).10.1002/adfm.200800368 ↗
78. Ansari, A. A., Yadav, R. & Rai, S. Enhanced luminescence efficiency of aqueous dispersible NaYF4: Yb/Er nanoparticles and the effect of surface coating. RSC Adv. 6, 22074–22082 (2016).10.1039/C6RA00265J ↗
79. Dong, C., Korinek, A., Blasiak, B., Tomanek, B. & van Veggel, F. C. Cation exchange: a facile method to make NaYF4: Yb, Tm-NaGdF4 core–shell nanoparticles with a thin, tunable, and uniform shell. Chem. Mater. 24, 1297–1305 (2012).10.1021/cm2036844 ↗
80. Lin, X. et al. Core-shell-shell upconversion nanoparticles with enhanced emission for wireless optogenetic inhibition. Nano. Lett. 18, 948–956 (2018).10.1021/acs.nanolett.7b04339 ↗
81. Vetrone, F., Naccache, R., Mahalingam, V., Morgan, C. G. & Capobianco, J. A. The active-core/active-shell approach: A strategy to enhance the upconversion luminescence in lanthanide-doped nanoparticles. Adv. Funct. Mater. 19, 2924–2929 (2009).10.1002/adfm.200900234 ↗
82. Qian, H.-S. & Zhang, Y. Synthesis of hexagonal-phase core-shell NaYF4 nanocrystals with tunable upconversion fluorescence. Langmuir 24, 12123–12125 (2008).10.1021/la802343f ↗
83. Ghosh, P. et al. Enhancement of upconversion emission of LaPO4: Er@ Yb core-shell nanoparticles/nanorods. J. Phys. Chem. C. 112, 9650–9658 (2008).10.1021/jp801978b ↗
84. Liu, Y. et al. A strategy to achieve efficient dual-mode luminescence of Eu3+ in lanthanides doped multifunctional NaGdF4 nanocrystals. Adv. Mater. 22, 3266–3271 (2010).10.1002/adma.201000128 ↗
85. Liu, X. et al. Breakthrough in concentration quenching threshold of upconversion luminescence via spatial separation of the emitter doping area for bio-applications. Chem. Commun. 47, 11957–11959 (2011).10.1039/c1cc14774a ↗
86. Yang, D. et al. Colloidal synthesis and remarkable enhancement of the upconversion luminescence of BaGdF5: Yb3+/Er3+ nanoparticles by active-shell modification. J. Mater. Chem. 21, 5923–5927 (2011).10.1039/c0jm04179c ↗
87. Chen, D. et al. Lanthanide dopant-induced formation of uniform sub-10 nm active-core/active-shell nanocrystals with near-infrared to near-infrared dual-modal luminescence. J. Mater. Chem. 22, 2632–2640 (2012).10.1039/C1JM14589D ↗
88. Zhang, Y. et al. Synthesis of ultra-small BaLuF5: Yb3+, Er3+@ BaLuF5: Yb3+ active-core–active-shell nanoparticles with enhanced up-conversion and down-conversion luminescence by a layer-by-layer strategy. J. Mater. Chem. C. 3, 2045–2053 (2015).10.1039/C4TC02541E ↗
89. Wang, F. et al. Tuning upconversion through energy migration in core-shell nanoparticles. Nat. Mater. 10, 968–973 (2011).10.1038/nmat3149 ↗
90. Chen, X. et al. Confining energy migration in upconversion nanoparticles towards deep ultraviolet lasing. Nat. Commun. 7, 10304 (2016).
91. Jin, L. M., Chen, X., Siu, C. K., Wang, F. & Yu, S. F. Enhancing multiphoton upconversion from NaYF4:Yb/Tm@NaYF4 core-shell nanoparticles via the use of laser cavity. ACS Nano 11, 843–849 (2017).10.1021/acsnano.6b07322 ↗
92. Barnes, W. L., Dereux, A. & Ebbesen, T. W. Surface plasmon subwavelength optics. Nature 424, 824–830 (2003).10.1038/nature01937 ↗
93. Zhang, H. et al. Plasmonic modulation of the upconversion fluorescence in NaYF4: Yb/Tm hexaplate nanocrystals using gold nanoparticles or nanoshells. Angew. Chem. Int. Ed. 49, 2865–2868 (2010).10.1002/anie.200905805 ↗
94. Feng, A. L. et al. Distance-dependent plasmon-enhanced fluorescence of upconversion nanoparticles using polyelectrolyte multilayers as tunable spacers. Sci. Rep. 5, 7779 (2015).
95. Saboktakin, M. et al. Metal-enhanced upconversion luminescence tunable through metal nanoparticle nanophosphor separation. ACS Nano 6, 8758–8766 (2012).10.1021/nn302466r ↗
96. Zhang, W., Ding, F. & Chou, S. Y. Large enhancement of upconversion luminescence of NaYF4:Yb3+/Er3+ nanocrystal by 3D plasmonic nano-antennas. Adv. Mater. 24, OP236–OP241 (2012).
97. Yin, Z. et al. Plasmon-enhanced upconversion luminescence on vertically aligned gold nanorod monolayer supercrystals. ACS Appl. Mater. Interfaces 8, 11667–11674 (2016).10.1021/acsami.5b12075 ↗
98. Niu, W. et al. 3-Dimensional photonic crystal surface enhanced upconversion emission for improved near-infrared photoresponse. Nanoscale 6, 817–824 (2014).10.1039/C3NR04884E ↗
99. Wang, X. et al. Dye-sensitized lanthanide-doped upconversion nanoparticles. Chem. Soc. Rev. 46, 4150–4167 (2017).10.1039/C7CS00053G ↗
100. Chen, G. et al. Energy-cascaded upconversion in an organic dye-sensitized core/shell fluoride nanocrystal. Nano. Lett. 15, 7400–7407 (2015).10.1021/acs.nanolett.5b02830 ↗