| 1. |
- Peng, Tingting, et al.
(författare)
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The Spectroscopic Properties and Microscopic Imaging of Thulium-Doped Upconversion Nanoparticles Excited at Different NIR-II Light
- 2021
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Ingår i: Biosensors. - : MDPI AG. - 2079-6374. ; 11:5
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Tidskriftsartikel (refereegranskat)abstract
- Lanthanide-doped upconversion nanoparticles (UCNPs) are promising bioimaging nanoprobes due to their excellent photostability. As one of the most commonly used lanthanide activators, Tm3+ ions have perfect ladder-type electron configuration and can be directly excited by bio-friendly near-infrared-II (NIR-II) wavelengths. Here, the emission characteristics of Tm3+-doped nanoparticles under laser excitations of different near-infrared-II wavelengths were systematically investigated. The 1064 nm, 1150 nm, and 1208 nm lasers are proposed to be three excitation strategies with different response spectra of Tm3+ ions. In particular, we found that 1150 nm laser excitation enables intense three-photon 475 nm emission, which is nearly 100 times stronger than that excited by 1064 nm excitation. We further optimized the luminescence brightness after investigating the luminescence quenching mechanism of bare NaYF4: Tm (1.75%) core. After growing an inert shell, a ten-fold increase of emission intensity was achieved. Combining the advantages of NIR-II wavelength and the higher-order nonlinear excitation, a promising facile excitation strategy was developed for the application of thulium-doped upconversion nanoparticles in nanoparticles imaging and cancer cell microscopic imaging.
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| 2. |
- Li, Nana, et al.
(författare)
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Yb3+-enhanced UCNP@SiO2 nanocomposites for consecutive imaging, photothermal-controlled drug delivery and cancer therapy
- 2016
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Ingår i: Optical Materials Express. - : Optical Society of America. - 2159-3930 .- 2159-3930. ; 6:4, s. 1161-1171
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Tidskriftsartikel (refereegranskat)abstract
- UCNP-based drug delivery systems commonly rely on stimulisensitive auxiliaries, lacking a straightforward manipulation strategy. Here we designed Yb3+-enhanced upconversion/ mesoporous silica nanocomposites (UCNP@SiO2) for consecutive cell imaging, photothermal drug delivery and cancer therapy. Core UCNPs (NaYbF4: 2% Er3+) were synthesized and coated with mesoporous silica, whose high-efficiency photothermal properties were verified in vitro. Then doxorubicin hydrochloride (DOX) was loaded on the UCNP@SiO2 and successfully triggered to release by a 975 nm laser of 150 mW or 300 mW. Before the therapy, we used a much lower laser power of 15 mW (which would cause little DOX release) for UCNP-probed fluorescence imaging of Hela cells and affirmed a favorable cell uptake of nanocomposites. Subsequently, cell viability assay and PI stain have demonstrated that the 300 mW laser could manipulate drug delivery of UCNP@SiO2-DOX and cause a severe loss of cell viability. The Yb3+-enhanced UCNP@SiO2 shows a great potential in simultaneous biomedical imaging and photothermal-triggered on-site drug delivery for chemotherapy of cancer. (C) 2016 Optical Society of America
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| 3. |
- Lv, Junliang, et al.
(författare)
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Absorption-dependent generation of singlet oxygen from gold bipyramids excited under low power density
- 2015
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Ingår i: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 5:100, s. 81897-81904
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Tidskriftsartikel (refereegranskat)abstract
- Metal nanoparticles (MNPs) can be used as a kind of new photodynamic therapy (PDT) agent because singlet oxygen (O-1(2)) can be generated through directly sensitizing MNPs. Gold nanorods, gold nanoshells and gold nanoechinus were confirmed to be efficient PDT agents in vivo. However, the major excitation spectra of O-1(2) from all of them are not in the optical biological window (650-900 nm). Herein, gold bipyramids (GBPs) with tunable absorption wavelength were prepared and used to explore O-1(2) generation capability. O-1(2) can be generated when GBPs were excited by continuous-wave light within a wide range of wavelengths (660-975 nm). The highest O-1(2) generation capabilities were obtained when they were excited at the wavelength of the absorption peak, which was quite different from those of other gold nanomaterials. It was also found that O-1(2) can be generated efficiently by a laser of very low power density (200 mW cm(-2)). The capability of GBPs for PDT has been demonstrated through the destruction of cancer cells. The synergistic effect of PDT and photothermal therapy for the destruction of cancer cells was also demonstrated.
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| 4. |
- Tan, Chunlin, et al.
(författare)
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Acid-assisted hydrothermal synthesis of red fluorescent carbon dots for sensitive detection of Fe(III)
- 2017
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Ingår i: RSC Advances. - : ROYAL SOC CHEMISTRY. - 2046-2069. ; 7:65, s. 40952-40956
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Tidskriftsartikel (refereegranskat)abstract
- Red-emitting carbon dots (C-dots) were synthesized from p-phenylenediamine (p-PD) aqueous solution with nitric acid (HNO3) assistance by hydrothermal reaction at 200 degrees C for 2 h. p-PD aqueous solution can be transferred to C-dots (or poly(p-PD)) with (or without) the addition of acid. Different acid systems, such as HNO3, H3PO4 and HF, can directly synthesize red-emitting C-dots, and the fluorescence can be enhanced by increasing the strength of acids. N-CDs, 3.46 nm-average-sized C-dots, prepared in dilute HNO3, have a quantum yield of 15.8% with unique, excitation-wavelength independent emission in the red region (600 and 680 nm) and a broad visible excitation band. Carboxyl, ester and hydroxyl groups on the C-dots surface directly lead to red emission. N-CDs have a certain selective specificity for Fe3+ detection and the linear range is 10-300 nmol L-1 with a limit of determination of 1.9 nmol L-1.
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| 5. |
- 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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| 6. |
- 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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| 7. |
- 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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| 8. |
- Xue, Qiu, et al.
(författare)
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Super-Resolution Imaging and Fluorescence Enhancement Based on Microsphere-Mediated Light Field Modulation
- 2023
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Ingår i: LASER & OPTOELECTRONICS PROGRESS. - : Shanghai Institute of Optics and Fine Mechanics. - 1006-4125. ; 60:10
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Tidskriftsartikel (refereegranskat)abstract
- Microspheres can modulate the light field and focus the incident beam into an extremely narrow area on the back of the microsphere, so that the incident beam's full width at half maxima is smaller than the optical diffraction limit, and the focused intensity is considerably higher than the incident one. In addition, the microspheres have high numerical aperture characteristics, which can improve the collection efficiency of detection signals. Based on these benefits, microspheres offer a novel concept and method for realizing optical super-resolution imaging and fluorescence enhancement. Super-resolution imaging and fluorescence enhancement technologies based on optical microspheres are simpler, more direct, and easier to implement than traditional technologies. Their imaging and enhancement effects are comparable to those of traditional technologies. They have significant research value and application prospects in biological imaging and medical detection. Although the studies on microsphere-modulated light field to achieve fluorescence enhancement has made significant progress in recent years, review papers focusing on this topic are still limited. A systematic summary of microsphere-enhanced fluorescence and microsphere-modulated light field is critical for future studies and developments in this field. First, microsphere-based optical super-resolution imaging, including bright field super-resolution imaging and fluorescence super resolution imaging, is introduced. Subsequently, the microspheres-based fluorescence enhancement research is described, including phenomenon research, mechanism exploration, and discussion of influencing factors. Finally, the progress and applications of microsphere-based super-resolution imaging and fluorescence enhancement are summarized, and the future development challenges and trends in this field are discussed and prospected.
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| 9. |
- Zhan, Qiuqiang, et al.
(författare)
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Achieving high-efficiency emission depletion nanoscopy by employing cross relaxation in upconversion nanoparticles
- 2017
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Ingår i: Nature Communications. - : Nature Publishing Group. - 2041-1723. ; 8:1
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Tidskriftsartikel (refereegranskat)abstract
- Stimulated emission depletion microscopy provides a powerful sub-diffraction imaging modality for life science studies. Conventionally, stimulated emission depletion requires a relatively high light intensity to obtain an adequate depletion efficiency through only light–matter interaction. Here we show efficient emission depletion for a class of lanthanide-doped upconversion nanoparticles with the assistance of interionic cross relaxation, which significantly lowers the laser intensity requirements of optical depletion. We demonstrate two-color super-resolution imaging using upconversion nanoparticles (resolution ~ 66 nm) with a single pair of excitation/depletion beams. In addition, we show super-resolution imaging of immunostained cytoskeleton structures of fixed cells (resolution ~ 82 nm) using upconversion nanoparticles. These achievements provide a new perspective for the development of photoswitchable luminescent probes and will broaden the applications of lanthanide-doped nanoparticles for sub-diffraction microscopic imaging.
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| 10. |
- Zhan, Qiuqiang, et al.
(författare)
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Controlling the excitation of upconverting luminescence for biomedical theranostics : neodymium sensitizing
- 2016
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Ingår i: Optical Materials Express. - : Optical Society of America. - 2159-3930 .- 2159-3930. ; 6:4, s. 1011-1023
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Tidskriftsartikel (refereegranskat)abstract
- With the rapid development of nanotechnology over the past decade, lanthanide doped upconverting nanoparticles (UCNPs) have been successfully synthesized and have emerged as an important class of nanomaterials. In contrast to the traditional Yb3+-sensitized UCNPs, the emerging Nd3+-sensitized UCNPs have many merits in controlling the excitation of upconverting luminescence, including minimizing overheating effect, increasing the imaging depth and so on. In this review paper, we provide a comprehensive survey of the most recent advances in developing Nd3+-sensitized UCNPs, which include nanocomposition, mechanisms, and some typical nanostructures of Nd3+-sensitized UCNPs. Furthermore, an important emphasis is placed on various applications including downconversion and upconversion photoluminescence for bioimaging, high-resolution, and deep tissue imaging and tumor diagnosis and therapy. Potential challenges and prospective development are also discussed. (C) 2016 Optical Society of America
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