| 1. |
- Kristan, Matej, et al.
(author)
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The Sixth Visual Object Tracking VOT2018 Challenge Results
- 2019
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In: Computer Vision – ECCV 2018 Workshops. - Cham : Springer Publishing Company. - 9783030110086 - 9783030110093 ; , s. 3-53
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Conference paper (peer-reviewed)abstract
- The Visual Object Tracking challenge VOT2018 is the sixth annual tracker benchmarking activity organized by the VOT initiative. Results of over eighty trackers are presented; many are state-of-the-art trackers published at major computer vision conferences or in journals in the recent years. The evaluation included the standard VOT and other popular methodologies for short-term tracking analysis and a “real-time” experiment simulating a situation where a tracker processes images as if provided by a continuously running sensor. A long-term tracking subchallenge has been introduced to the set of standard VOT sub-challenges. The new subchallenge focuses on long-term tracking properties, namely coping with target disappearance and reappearance. A new dataset has been compiled and a performance evaluation methodology that focuses on long-term tracking capabilities has been adopted. The VOT toolkit has been updated to support both standard short-term and the new long-term tracking subchallenges. Performance of the tested trackers typically by far exceeds standard baselines. The source code for most of the trackers is publicly available from the VOT page. The dataset, the evaluation kit and the results are publicly available at the challenge website (http://votchallenge.net).
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| 2. |
- Tian, Xiaohe, et al.
(author)
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Probe for simultaneous membrane and nucleus labeling in living cells and in vivo bioimaging using a two-photon absorption water-soluble Zn(II) terpyridine complex with a reduced pi-conjugation system
- 2017
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In: Chemical Science. - : ROYAL SOC CHEMISTRY. - 2041-6520 .- 2041-6539. ; 8:1, s. 142-149
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Journal article (peer-reviewed)abstract
- Small, biocompatible and water-soluble molecules with high two-photon absorption (2PA) cross-section values (delta) are in high demand for specific bioimaging applications. Here, two novel terpyridine derivative ligands with donor-acceptor (D-A) (L1) and donor-pi-acceptor (D-pi-A) (L2) models, and their corresponding Zn(II) complexes are designed and characterized. It was found that the two-photon absorption cross section values (d) in the near-infrared region (NIR, about 800 nm) are significantly enhanced for complexes 1 and 2 compared to their free D-A type ligand L1, while those of complexes 3 and 4 were greatly decreased relative to their free ligand L2, thus confirming that the smaller ligand (D-A type) displays a suitable Turn-ON fluorescence pair for two-photon fluorescence microscopy (2PFM). Firstly, the potential of simultaneously labeling a live cell plasma membrane and nucleus using complex 1 is demonstrated. In addition, live larval and adult zebrafish incubated with an optimal concentration of 1 demonstrated clear brain uptake. Lastly and importantly, using such a probe to visualize the blood-brain- barrier (BBB) capillary endothelial cells and penetrate the BBB into the central nervous system (CNS) intravenously in a mouse model is also explored.
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| 3. |
- Wang, Hui, et al.
(author)
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Mitochondria-targeted iridium (III) complexes as two-photon fluorogenic probes of cysteine/homocysteine
- 2018
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In: Sensors and actuators. B, Chemical. - : ELSEVIER SCIENCE SA. - 0925-4005 .- 1873-3077. ; 255, s. 408-415
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Journal article (peer-reviewed)abstract
- Fluorescent imaging of cysteine (Cys) and homocysteine (Hcy) is crucial to understand sulphur metabolism in living cells. Whereas two-photon active cyclometalated Ir(III) complex for detecting Cys/Hcy has been rarely reported. Herein, two novel cyclometalated iridium (III) complexes Ir1-1r2 with different electron-donor were designed, synthesized and fully characterized as well as confirmed by single-crystal X-ray diffraction analysis, which could selectively react with Cys/Hcy, accompanying with an obvious one- and two-photon fluorescence enhancement in vitro. The mechanism for sensing Cys/Hcy was further analyzed in detail by mass spectra and time-dependent density functional theory calculations. It was found that Ir2, bearing ester group, exhibited higher performance on the selective detection of Cys and Hcy compared to In. Notably, the two-photon action cross-section value in the near-infrared region (similar to 800 nm) of Ir2 is significantly enhanced upon the addition of Cys/Hcy. Further application to cellular imaging indicated that Ir2 is membrane permeable and capable of monitoring the changes of intracellular mitochondrial Cys/Hcy. These results support that such two-photon active complexes might provide a promising platform for the detection of mitochondrial Cys/Hcy in living biological systems. (C) 2017 Published by Elsevier B.V.
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| 4. |
- Wang, Hui, et al.
(author)
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Two-Photon Active Organotin(IV) Carboxylate Complexes for Visualization of Anticancer Action
- 2017
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In: ACS Biomaterials Science & Engineering. - : AMER CHEMICAL SOC. - 2373-9878. ; 3:5, s. 836-842
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Journal article (peer-reviewed)abstract
- It is still a challenge that organotin(IV) carboxylate complexes with high-performance two-photon activity for cancer therapy. At present work, two novel organotin carboxylate complexes LSn1 and LSn2, containing coumarin moiety, were rationally designed for two-photon fluorescent imaging and anticancer purpose. The complexes possessed large two-photon action cross-sections and high quantum yields. Living cells evaluation revealed that complexes LSn1 and LSn2 exhibited good biocompatibility and deep tissue penetration over femtosecond laser with wavelength of 840 nm. Furthermore, the antitumor active and as well as possible mechanism of complexes LSn1 and LSn2 have been investigated systematically. The results indicated that complexes LSn1 and LSn2 could induce apoptotic cell death through a mitochondria] dysfunction and ROS elevation pathway. The present work provides a strategy for rationally designing organotin(IV) carboxylate complexes with two-photon activity and antitumor activity.
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| 5. |
- Zhang, Qiong, et al.
(author)
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A series of Zn(II) terpyridine complexes with enhanced two-photon-excited fluorescence for in vitro and in vivo bioimaging
- 2015
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In: Journal of materials chemistry. B. - : ROYAL SOC CHEMISTRY. - 2050-750X .- 2050-7518. ; 3:36, s. 7213-7221
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Journal article (peer-reviewed)abstract
- It is still a challenge to obtain two-photon excited fluorescent bioimaging probes with intense emission, high photo-stability and low cytotoxicity. In the present work, four Zn(II)-coordinated complexes (1-4) constructed from two novel D-A and D-p-A ligands (L-1 and L-2) are investigated both experimentally and theoretically, aiming to explore efficient two-photon probes for bioimaging. Molecular geometry optimization used for theoretical calculations is achieved using the crystallographic data. Notably, the results indicate that complexes 1 and 2 display enhanced two-photon absorption (2PA) cross sections compared to their corresponding D-A ligand (L1). Furthermore, it was found that complex 1 has the advantages of moderate 2PA cross section in the near-infrared region, longer fluorescence lifetime, higher quantum yield, good biocompatibility and enhanced two-photon excited fluorescence. Therefore, complex 1 is evaluated as a bioimaging probe for in vitro imaging of HepG2 cells, in which it is observed under a two-photon scanning microscope that complex 1 exhibits effective co-staining with endoplasmic reticulum (ER) and nuclear membrane; as well as for in vivo imaging of zebrafish larva, in which it is observed that complex 1 exhibits specificity in the intestinal system.
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| 6. |
- Zhang, Qiong, et al.
(author)
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NIR-region two-photon fluorescent probes for Fe3+/Cu2+ ions based on pyrimidine derivatives with different flexible chain
- 2016
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In: Sensors and actuators. B, Chemical. - : ELSEVIER SCIENCE SA. - 0925-4005 .- 1873-3077. ; 222, s. 574-578
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Journal article (peer-reviewed)abstract
- Two novel NIR-region two-photon fluorescent probes CCP and COP, show strong fluorescence quenching and good ratiometric responses toward Fe3+ and Cu2+, respectively; and their two-photon fluorescence are reversible by the subsequent addition of EDTA. CCP and COP are valuable candidates for two-photon imaging in the biological transparency window. (C) 2015 Elsevier B.V. All rights reserved.
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| 7. |
- Zhang, Qiong, et al.
(author)
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Nonlinear optical response and two-photon biological applications of a new family of imidazole-pyrimidine derivatives
- 2016
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In: Dyes and pigments. - : ELSEVIER SCI LTD. - 0143-7208 .- 1873-3743. ; 126, s. 286-295
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Journal article (peer-reviewed)abstract
- A series of novel D-pi-A type two-photon absorption (2PA) imidazole-pyrimidine derivatives (EX-1 similar to EX-4) have been synthesized and characterized, with EX-1 was crystallography confirmed. Based on systematic photophysical investigations, the structure property relationships can be drawn as follows: (1) Both theoretical and experimental studies indicated that the different donor groups have large influences on the optical properties. (2) The 2PA cross-section values (sigma) were obtained both by Z-Scan and two photon excited fluorescence (2PEF) measurements. 2PA cross sections show an increasing trend with increasing electron-donating strength and the number of branches. (3) Comprehensively considered the optical performance, molecular volume, cytotoxicity and solubility, EX-1 and EX-2 were identified to be the best candidates for living cells (HepG2) imaging. Moreover, the 2PA excitable features of EX-1 and EX-2 are capable of imaging in fresh mouses liver tissues with a depth of ca. 70 mu m. (C) 2015 Elsevier Ltd. All rights reserved.
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| 8. |
- Ou, Pan, et al.
(author)
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Gasotransmitter Regulation of Phosphatase Activity in Live Cells Studied by Three-Channel Imaging Correlation
- 2019
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In: Angewandte Chemie International Edition. - : WILEY-V C H VERLAG GMBH. - 1433-7851 .- 1521-3773. ; 58:8, s. 2261-2265
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Journal article (peer-reviewed)abstract
- Enzyme activity in live cells is dynamically regulated by small-molecule transmitters for maintaining normal physiological functions. A few probes have been devised to measure intracellular enzyme activities by fluorescent imaging, but the study of the regulation of enzyme activity via gasotransmitters in situ remains a long-standing challenge. Herein, we report a three-channel imaging correlation by a single dual-reactive fluorescent probe to measure the dependence of phosphatase activity on the H2S level in cells. The two sites of the probe reactive to H2S and phosphatase individually produce blue and green fluorescent responses, respectively, and resonance energy transfer can be triggered by their coexistence. Fluorescent analysis based on the three-channel imaging correlation shows that cells have an ideal level of H2S to promote phosphatase activity up to its maximum. Significantly, a slight deviation from this H2S level leads to a sharp decrease of phosphatase activity. The discovery further strengthens our understanding of the importance of H2S in cellular signaling and in various human diseases.
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| 9. |
- Shen, Jie, et al.
(author)
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Real-time monitoring of lipid droplets growth via the fusion with fluorescent dye-labeled adiposomes
- 2020
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In: Dyes and pigments. - : ELSEVIER SCI LTD. - 0143-7208 .- 1873-3743. ; 182
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Journal article (peer-reviewed)abstract
- Investigating lipid droplets (LDs) behaviours is essential to deeply understand the physiology of LDs, such as their growths, movements, fusion/division, and autophagy. Among these behaviours, the growth of LDs is one of the most difficult to track due to the very subtle morphology evolution in a short time window. The major obstacle is that conventional LDs-specific dyes with low photostability cannot indicate the LDs size change. To address this issue, we synthesize a hydrophobic and photostable fluorescent dye (TPA-AD) and load it into the neutral lipid micelles (as artificial adiposomes). The highly hydrophobic TPA-AD enables the specific accumulation into intracellular LDs and the ready loading artificial adiposomes. When the intracellular LDs take TPA-AD-labeled adiposomes, by fusion, the sizes of LDs gradually grow, and LDs are simultaneously lighted up by the fluorescence of TPA-AD. Importantly, the high photostability of TPA-AD ensures the enhanced fluorescence signals. The finding here will further strengthen the understanding of LDs dynamics and fat metabolism.
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| 10. |
- Yang, Guanqing, et al.
(author)
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A Multi-responsive Fluorescent Probe Reveals Mitochondrial Nucleoprotein Dynamics with Reactive Oxygen Species Regulation through Super-resolution Imaging
- 2020
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In: Angewandte Chemie International Edition. - : WILEY-V C H VERLAG GMBH. - 1433-7851 .- 1521-3773. ; 59:37, s. 16154-16160
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Journal article (peer-reviewed)abstract
- Understanding the biomolecular interactions in a specific organelle has been a long-standing challenge because it requires super-resolution imaging to resolve the spatial locations and dynamic interactions of multiple biomacromolecules. Two key difficulties are the scarcity of suitable probes for super-resolution nanoscopy and the complications that arise from the use of multiple probes. Herein, we report a quinolinium derivative probe that is selectively enriched in mitochondria and switches on in three different fluorescence modes in response to hydrogen peroxide (H2O2), proteins, and nucleic acids, enabling the visualization of mitochondrial nucleoprotein dynamics. STED nanoscopy reveals that the proteins localize at mitochondrial cristae and largely fuse with nucleic acids to form nucleoproteins, whereas increasing H(2)O(2)level leads to disassociation of nucleic acid-protein complexes.
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| 11. |
- Zhang, Xin, et al.
(author)
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Light-Up Lipid Droplets Dynamic Behaviors Using a Red-Emitting Fluorogenic Probe
- 2020
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In: Analytical Chemistry. - : AMER CHEMICAL SOC. - 0003-2700 .- 1520-6882. ; 92:5, s. 3613-3619
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Journal article (peer-reviewed)abstract
- Intracellular lipid metabolism occurs in lipid droplets (LDs), which is critical to the survival of cells. Imaging LDs is an intuitive way to understand their physiology in live cells. However, this is limited by the availability of specific probes that can properly visualize LDs in vivo. Here, an LDs-specific red-emitting probe is proposed to address this need, which is not merely with an ultrahigh signal-to-noise (S/N) ratio and a large Stokes shift (up to 214 nm) but also with superior resistance to photobleaching. The probe has been successfully applied to real-time tracking of intracellular LDs behaviors, including fusion, migration, and lipophagy processes. We deem that the proposed probe here offers a new possibility for deeper understanding of LDs-associated behaviors, elucidation of their roles and mechanisms in cellular metabolism, and determination of the transition between adaptive lipid storage and lipotoxicity as well.
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