| 1. |
- Chang, Jui-Che, et al.
(författare)
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Orthorhombic Ta3-xN5-yOy thin films grown by unbalanced magnetron sputtering : The role of oxygen on structure, composition, and optical properties
- 2021
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Ingår i: Surface & Coatings Technology. - : Elsevier. - 0257-8972 .- 1879-3347. ; 406
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Tidskriftsartikel (refereegranskat)abstract
- Direct growth of orthorhombic Ta3N5-type Ta-O-N compound thin films, specifically Ta3-xN5-yOy, on Si and sapphire substrates with various atomic fractions is realized by unbalanced magnetron sputtering. Low-degree fiber-textural Ta3-xN5-yOy films were grown through reactive sputtering of Ta in a gas mixture of N-2, Ar, and O-2 with keeping a partial pressure ratio of 3:2:0.1 in a total working pressure range of 5-30 mTorr. With increasing total pressure from 5 to 30 mTorr, the atomic fraction of O in the as-grown Ta3-xN5-yOy films was found to increase from 0.02 to 0.15 while that of N and Ta decrease from 0.66 to 0.54 and 0.33 to 0.31, respectively, leading to a decrease in b lattice constant up to around 1.3%. Metallic TaNx phases were formed without oxygen. For a working pressure of 40 mTorr, an amorphous, O-rich Ta-N-O compound film with a high O fraction of similar to 0.48, was formed, mixed with non-stoichiometric TaON and Ta2O5. By analyzing the plasma discharge, the increasing O incorporation is associated with oxide formation on top of the Ta target due to a higher reactivity of Ta with O than with N. The increase of O incorporation in the films also leads to a optical bandgap widening from similar to 2.22 to similar to 2.96 eV, which is in agreement with the compositional and structural changes from a crystalline Ta3-xN5-yOy to an amorphous O-rich Ta-O-N compound.
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| 2. |
- Periyathambi, Prabu, et al.
(författare)
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Activatable MRI probes for the specific detection of bacteria
- 2021
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Ingår i: Analytical and Bioanalytical Chemistry. - : Springer Science and Business Media LLC. - 1618-2642 .- 1618-2650. ; 413:30, s. 7353-7362
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Tidskriftsartikel (refereegranskat)abstract
- Activatable fluorescent probes have been successfully used as molecular tools for biomedical research in the last decades. Fluorescent probes allow the detection of molecular events, providing an extraordinary platform for protein and cellular research. Nevertheless, most of the fluorescent probes reported are susceptible to interferences from endogenous fluorescence (background signal) and limited tissue penetration is expected. These drawbacks prevent the use of fluorescent tracers in the clinical setting. To overcome the limitation of fluorescent probes, we and others have developed activatable magnetic resonance probes. Herein, we report for the first time, an oligonucleotide-based probe with the capability to detect bacteria using magnetic resonance imaging (MRI). The activatable MRI probe consists of a specific oligonucleotide that targets micrococcal nuclease (MN), a nuclease derived from Staphylococcus aureus. The oligonucleotide is flanked by a superparamagnetic iron oxide nanoparticle (SPION) at one end, and by a dendron functionalized with several gadolinium complexes as enhancers, at the other end. Therefore, only upon recognition of the MRI probe by the specific bacteria is the probe activated and the MRI signal can be detected. This approach may be widely applied to detect bacterial infections or other human conditions with the potential to be translated into the clinic as an activatable contrast agent.
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| 3. |
- Wang, Hui, et al.
(författare)
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Mitochondria-targeted iridium (III) complexes as two-photon fluorogenic probes of cysteine/homocysteine
- 2018
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Ingår i: Sensors and actuators. B, Chemical. - : ELSEVIER SCIENCE SA. - 0925-4005 .- 1873-3077. ; 255, s. 408-415
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Tidskriftsartikel (refereegranskat)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. |
- Zhang, Tiankai, et al.
(författare)
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Ion-modulated radical doping of spiro-OMeTAD for more efficient and stable perovskite solar cells
- 2022
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Ingår i: Science. - : AMER ASSOC ADVANCEMENT SCIENCE. - 0036-8075 .- 1095-9203. ; 377:6605, s. 495-501
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Tidskriftsartikel (refereegranskat)abstract
- Record power conversion efficiencies (PCEs) of perovskite solar cells (PSCs) have been obtained with the organic hole transporter 2,2,7,7-tetrakis(N,N-di-p-methoxyphenyl-amine)9,9-spirobifluorene (spiro-OMeTAD). Conventional doping of spiro-OMeTAD with hygroscopic lithium salts and volatile 4-tert-butylpyridine is a time-consuming process and also leads to poor device stability. We developed a new doping strategy for spiro-OMeTAD that avoids post-oxidation by using stable organic radicals as the dopant and ionic salts as the doping modulator (referred to as ion-modulated radical doping). We achieved PCEs of >25% and much-improved device stability under harsh conditions. The radicals provide hole polarons that instantly increase the conductivity and work function (WF), and ionic salts further modulate the WF by affecting the energetics of the hole polarons. This organic semiconductor doping strategy, which decouples conductivity and WF tunability, could inspire further optimization in other optoelectronic devices.
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| 5. |
- Hu, Zhangjun, et al.
(författare)
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Highly Water-Dispersible Surface-Modified Gd2O3 Nanoparticles for Potential Dual-Modal Bioimaging
- 2013
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Ingår i: Chemistry - A European Journal. - : Wiley-VCH Verlagsgesellschaft. - 0947-6539 .- 1521-3765. ; 19:38, s. 12658-12667
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Tidskriftsartikel (refereegranskat)abstract
- Water-dispersible and luminescent gadolinium oxide (GO) nanoparticles (NPs) were designed and synthesized for potential dual-modal biological imaging. They were obtained by capping gadolinium oxide nanoparticles with a fluorescent glycol-based conjugated carboxylate (HL). The obtained nanoparticles (GO-L) show long-term colloidal stability and intense blue fluorescence. In addition, L can sensitize the luminescence of europium(III) through the so-called antenna effect. Thus, to extend the spectral ranges of emission, europium was introduced into L-modified gadolinium oxide nanoparticles. The obtained Eu-III-doped particles (Eu:GO-L) can provide visible red emission, which is more intensive than that without L capping. The average diameter of the monodisperse modified oxide cores is about 4nm. The average hydrodynamic diameter of the L-modified nanoparticles was estimated to be about 13nm. The nanoparticles show effective longitudinal water proton relaxivity. The relaxivity values obtained for GO-L and Eu:GO-L were r(1)=6.4 and 6.3s(-1)mM(-1) with r(2)/r(1) ratios close to unity at 1.4T. Longitudinal proton relaxivities of these nanoparticles are higher than those of positive contrast agents based on gadolinium complexes such as Gd-DOTA, which are commonly used for clinical magnetic resonance imaging. Moreover, these particles are suitable for cellular imaging and show good biocompatibility.
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| 6. |
- Siribbal, Shifaa M., et al.
(författare)
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Air-Stable Gadolinium Precursors for the Facile Microwave-Assisted Synthesis of Gd2O3 Nanocontrast Agents for Magnetic Resonance Imaging
- 2018
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Ingår i: Crystal Growth & Design. - : American Chemical Society (ACS). - 1528-7483 .- 1528-7505. ; 18:2, s. 633-641
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Tidskriftsartikel (refereegranskat)abstract
- Using metal organic precursors in materials synthesis remains a challenge due to their high moisture susceptibility. In this work, we describe a facile methodology for the synthesis of Gd2O3-based contrast agents from two new gadolinium-based complexes. [Gd(PyTFP)(4)] (PyH) 1 (PyTFP = C8H5NOF3, Py = C5H5N) and [Gd(DMOTFP)(3)Py] 2 (DMOTFP = C8H7NO2F3) were synthesized via a classical ligand exchange reaction of [Gd{N(SiMe3)(2)}(3)] under inert conditions. As a result, X-ray diffraction analysis revealed a distorted square antiprismatic coordination and an augmented triangular prismatic arrangement of ligands around gadolinium atoms in 1 and 2, respectively. It also showed that 1 is an anionic complex of formula [Gd(PyTFP)(4)](PyH), while a neutral tris-compound, [Gd(DMOTFP)(3)Py], was obtained as a pyridine adduct in 2. Fast and reproducible microwave-assisted decomposition of 1 and 2 provided homogeneous Gd(OH)(3) nanorods at mild temperature without using any surfactant or capping reagent. As-synthesized nanorods were easily transformed into a cubic phase of Gd2O3 nanoparticles by thermal treatment under ambient conditions. The magnetic measurement showed the typical paramagnetic behavior of the Gd2O3 nanoparticles (NPs). The cytotoxicity profile demonstrates the biocompatibility and negligible toxicity of the as-synthesized nanoprobes. The suggested approach provides a new class of gadolinium-based precursors which allows facile synthesis of highly crystalline Gd2O3 NPs.
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| 7. |
- Zhang, Xuanjun, 1976-, et al.
(författare)
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Coordination polymers for energy transfer: Preparations, properties, sensing applications, and perspectives
- 2015
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Ingår i: Coordination chemistry reviews. - : Elsevier. - 0010-8545 .- 1873-3840. ; 284, s. 206-235
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Forskningsöversikt (refereegranskat)abstract
- This review highlights the recent progress of bulk and nanoscale coordination polymer (CP) materials forenergy transfer. Artificial light-harvesting materials with efficient energy transfer are practically usefulfor a variety of applications including photovoltaic, white emitting devices, and sensors. In the pastdecades CP (aka Metal-organic framework, MOF) has experienced rapid development due to a multitude of applications, including catalyst, gas storage and separations, non-linear optics, luminescence, and soon. Recent research has shown that CP is a very promising light-harvesting platform because the energytransfers can occur between different ligands, from ligand to metal centers, or from MOF skeleton to guestspecies. This review comprehensively surveyed synthetic approaches to light-harvesting CPs, and postfunctionalization. Sensing applications and achievements in energy-transfer CP nanoparticles and thinfilms were also discussed.
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| 8. |
- Zhang, Xin, 1990-
(författare)
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Tailoring Fluorescent Probes for Organelle-Specific Imaging and Sensing
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Exploring and visualizing biological and pathological processes in living cells are useful for both fundamental research and applications. An understanding on the molecular level for these processes with focus on tracking biomarkers, collecting information about their surroundings, and uncovering essential molecular pathways and functions in live cells are of vital interest for cell biological study and clinical diagnosis application. Fluorescent imaging technologies have become essential tools in cell biology studies, providing dynamic information about the localization and quantity of the analytes in living systems that we can not see by our naked eyes. Since the discovery of organic fluorescent dyes, unremitting efforts have been made to visualize the behaviors of specific targets by using these fluorophores as labels. Today, a variety of probes and nanoprobes have been developed for specific targeting and sensing. However, the current probes and nanoprobes still show some inherent deficiencies, such as poor specificity, strong photobleaching, high toxicity, low signal-to-noise ratio, poor cell membrane penetration, etc. To conquer these limitations, this thesis will focus on developing fluorescent platforms for bioimaging and biosensing with improved sensitivity, selectivity, specificity, and stability.A red-emitting fluorescent probe is first proposed that not only tracks the dynamic changes in real-time, during migration and fusion of lipid droplets but also monitors starvation-induced lipophagy (Paper I). In addition to organic fluorophores, hybrid fluorescent silica nanoparticles (SiNPs) are very promising for bioimaging/sensing owing to the advantages of low toxicity, high biocompatibility, multifunctionality, hydrophilicity and accessible surface functionality. Nonetheless, to apply SiNPs for such purposes, it is mandatory to address common problems of poor cell penetration and lack of specificity. Therefore, in this thesis, an efficient membrane-penetration SiNP is tailored with the intention to enable subcellular imaging/sensing. The proposed SiNPs are characterized by rapid cellular uptake (˂ 30 min) and specific subcellular targeting capabilities with surface modification. Finally, real-time tracking of dynamic changes in mitochondria and lysosomes during autophagy process is successfully performed (Paper II). Through the rational design of new functionalities on the established SiNPs, mitochondria- and lysosome-specific pH nanoprobes are further tailored for real-time monitoring of pH variations under various stimuli (Paper III and IV). Another ratiometric nanoprobe is developed for quantitative indication of lysosomal adenosine 5'-triphosphate (ATP) levels in living cells. The nanoprobe enables a deeper understanding of the interplay between energy metabolism and autophagy (Paper V).In conclusion, throughout the studies in this thesis, the fabrication and utilization of fluorescent molecular probes and SiNP-based nanoprobes for cellular probing have been investigated and analyzed. The strategies and the fabricated SiNPs can facilitate our deeper understanding of cellular pathological processes and provide basic knowledge for the development of other functional materials for life science applications.
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