| 1. |
- Liu, Jing, et al.
(författare)
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Deep, high contrast microscopic cell imaging using three-photon luminescence of beta-(NaYF4:Er3+/NaYF4) nanoprobe excited by 1480-nm CW laser of only 1.5-mW
- 2015
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Ingår i: Biomedical Optics Express. - 2156-7085. ; 6:5, s. 1857-1866
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Tidskriftsartikel (refereegranskat)abstract
- It is challenging to achieve deep microscopic imaging for the strong scattering in biotissue. An efficient three-photon luminescence can effectively increase the penetration depth. Here we report that beta-NaYF4: Er3+/NaYF4 UCNPs were excited by a 1480-nm CW-laser and emitted 543/653-nm light through a three-photon process. With the merit of the hexagonal crystal phase, sub-milliwatt laser power was utilized to excite the UCNP-probed cells to minimize the heating effect. The polymer-coated UCNPs were shown to be harmless to cells. The deep, high contrast in vitro microscopic imaging was implemented through an artificial phantom. Imaging depth of 800 mu m was achieved using only 1.5 mW excitation and a 0.7 NA objective. The green/red emission intensities ratio after penetrating the phantom was studied, indicating that longer emission wavelength is preferred for deep multiphoton microscopy. The proposed and demonstrated beta-UCNPs would have great potential in three-photon microscopy. (C) 2015 Optical Society of America
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| 2. |
- Liu, Jing, et al.
(författare)
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Sub-5-nm lanthanide-doped ZrO2@NaYF4 nanodots as efficient upconverting probes for rapid scanning microscopy and aptamer-mediated bioimaging
- 2015
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Ingår i: Optical Materials Express. - 2159-3930 .- 2159-3930. ; 5:8, s. 1759-1771
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Tidskriftsartikel (refereegranskat)abstract
- Upconversion nanoparticles (UCNPs) is a class of promising probes widely used in protein molecules imaging due to the no photobleaching and non-blinking emission. However, it is still remained challenging to synthesize a type of ultra-small but bright UCNPs. In this paper, a new class of efficient sub-5-nm upconversion nanodots (UCNDs) was elaborately designed and experimentally demonstrated. The proposed uniform UCNDs comprise two parts: a 3.5-nm Ln(3+)-doped ZrO2 core and 0.5-nm NaYF4 shell. The emission intensity of the proposed UCNDs was measured to be more than 10 times brighter than that of the conventional 10-nm NaYF4 UCNPs. Under 300 kW.cm(-2) irradiance excitation, the 15 mol% Er3+-doped UCNDs exhibit an 18-fold enhanced intensity and one fifth emission lifetime compared to the 0.5 mol% Er3+-doped ones. Using the biocompatible UCNDs, the aptamer-mediated proteins-targeted imaging was performed and demonstrated high efficiency. These ultra-small, efficient UCNDs would have great potentials in rapid scanning and cellular imaging.
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| 3. |
- Wang, Baoju, et al.
(författare)
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Visible-to-visible four-photon ultrahigh resolution microscopic imaging with 730-nm diode laser excited nanocrystals
- 2016
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Ingår i: Optics Express. - : Optical Society of America. - 1094-4087. ; 24:2, s. A302-A311
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Tidskriftsartikel (refereegranskat)abstract
- Further development of multiphoton microscopic imaging is confronted with a number of limitations, including high-cost, high complexity and relatively low spatial resolution due to the long excitation wavelength. To overcome these problems, for the first time, we propose visible-to-visible four-photon ultrahigh resolution microscopic imaging by using a common cost-effective 730-nm laser diode to excite the prepared Nd3+-sensitized upconversion nanoparticles (Nd3+-UCNPs). An ordinary multiphoton scanning microscope system was built using a visible CW diode laser and the lateral imaging resolution as high as 161-nm was achieved via the four-photon upconversion process. The demonstrated large saturation excitation power for Nd3+-UCNPs would be more practical and facilitate the four-photon imaging in the application. A sample with fine structure was imaged to demonstrate the advantages of visible-to-visible four-photon ultrahigh resolution microscopic imaging with 730-nm diode laser excited nanocrystals. Combining the uniqueness of UCNPs, the proposed visible-to-visible four-photon imaging would be highly promising and attractive in the field of multiphoton imaging.
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| 4. |
- Wen, Xuanyuan, et al.
(författare)
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Designed Er3+-singly doped NaYF4 with double excitation bands for simultaneous deep macroscopic and microscopic upconverting bioimaging
- 2016
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Ingår i: Biomedical Optics Express. - : OSA - The Optical Society. - 2156-7085. ; 7:6, s. 2174-2185
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Tidskriftsartikel (refereegranskat)abstract
- Simultaneous deep macroscopic imaging and microscopic imaging is in urgent demand, but is challenging to achieve experimentally due to the lack of proper fluorescent probes. Herein, we have designed and successfully synthesized simplex Er3+-doped upconversion nanoparticles (UCNPs) with double excitation bands for simultaneous deep macroscopic and microscopic imaging. The material structure and the excitation wavelength of Er3+-singly doped UCNPs were further optimized to enhance the upconversion emission efficiency. After optimization, we found that NaYF4:30% Er3+@NaYF4:2% Er3+ could simultaneously achieve efficient two-photon excitation (2PE) macroscopic tissue imaging and three-photon excitation (3PE) deep microscopic when excited by 808 nm continuous wave (CW) and 1480 nm CW lasers, respectively. In vitro cell imaging and in vivo imaging have also been implemented to demonstrate the feasibility and potential of the proposed simplex Er3+-doped UCNPs as bioprobe.
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| 5. |
- Wu, Ruitao, et al.
(författare)
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Optical depletion mechanism of upconverting luminescence and its potential for multi-photon STED-like microscopy
- 2015
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Ingår i: Optics Express. - : Optical Society of America. - 1094-4087. ; 23:25, s. 32401-32412
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Tidskriftsartikel (refereegranskat)abstract
- Simulated emission depletion (STED) microscopy is very powerful, but still suffers from small tissue penetration depth, photobleaching of fluorescent probes and complicated imaging systems. Here, we propose an optical luminescence depletion mechanism employing upconverting nanoparticles (UCNPs) and explore its potential for multi-photon STED-like microscopy. With the addition of Yb3+ ions in NaYF4:Er3+ UCNPs, the two-photon green emission of Er3+ under 795-nm excitation was successfully depleted by 1140-nm laser through the synergetic effect of the excited state absorption and the interionic energy transfer. This STED-like depletion mechanism was systematically investigated using steady-state rate equations, evidenced by the surprising emerging of 478-nm emission. The green emission depletion efficiency was about 30%, limited by the current laser source. Our work indicates that NaYF4:Yb3+/Er3+ UCNPs will be potential probes for multi-photon super-resolution microscopy with many advantages, including long-wavelength-induced large penetration, non-photobleaching and non-photoblinking properties, cost-effective and simplified imaging systems.
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