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| 2. |
- Chen, Yun, 1966, et al.
(författare)
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Characterization of VCAM-1-Binding Peptide-Functionalized Quantum Dots for Molecular Imaging of Inflamed Endothelium
- 2013
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Ingår i: Plos One. - : Public Library of Science (PLoS). - 1932-6203. ; 8:12
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Tidskriftsartikel (refereegranskat)abstract
- Inflammation-induced activation of endothelium constitutes one of the earliest changes during atherogenesis. New imaging techniques that allow detecting activated endothelial cells can improve the identification of persons at high cardiovascular risk in early stages. Quantum dots (QDs) have attractive optical properties such as bright fluorescence and high photostability, and have been increasingly studied and developed for bio-imaging and bio-targeting applications. We report here the development of vascular cell adhesion molecule-1 binding peptide (VCAM-1 binding peptide) functionalized QDs (VQDs) from amino QDs. It was found that the QD fluorescence signal in tumor necrosis factor alpha (TNF-alpha) treated endothelial cells in vitro was significantly higher when these cells were labeled with VQDs than amino QDs. The VQD labeling of TNF-alpha-treated endothelial cells was VCAM-1 specific since pre-incubation with recombinant VCAM-1 blocked cells' uptake of VQDs. Our ex vivo and in vivo experiments showed that in the inflamed endothelium, QD fluorescence signal from VQDs was also much stronger than that of amino QDs. Moreover, we observed that the QD fluorescence peak was significantly blue-shifted after VQDs interacted with aortic endothelial cells in vivo and in vitro. A similar blue-shift was observed after VQDs were incubated with recombinant VCAM-1 in tube. We anticipate that the specific interaction between VQDs and VCAM-1 and the blue-shift of the QD fluorescence peak can be very useful for VCAM-1 detection in vivo.
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| 3. |
- Chen, Zhihui, et al.
(författare)
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Exciton Polariton Contribution to the Stokes Shift in Colloidal Quantum Dots
- 2011
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 115:13, s. 5286-5293
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Tidskriftsartikel (refereegranskat)abstract
- We study the exciton polariton contribution to the Stokes shift in colloidal quantum dots (QDs). By detailed quantum mechanical description of light-matter interaction and temporal analysis of incident electromagnetic field across the QD using the finite-difference time-domain method, we have shown that the optical excitation of an exciton in the QD and its coupling with the excitation radiation (i.e., exciton polariton) induce strong variations in the dielectric constant of the QD which contribute significantly to the Stokes shift and cause modifications 50 in the absorption spectrum that agrees well with experiments.
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| 4. |
- Chen, Zhi-Hui, et al.
(författare)
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Comb-shaped photonic crystal structure for efficient broadband light diffraction and funnelling in solar cells
- 2012
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Ingår i: Solar Energy Materials and Solar Cells. - : Elsevier BV. - 0927-0248 .- 1879-3398. ; 99, s. 316-320
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Tidskriftsartikel (refereegranskat)abstract
- We present a comb-shaped photonic-crystal (PhC) rods-lattice structure of broadband light diffraction and funnelling for solar cell applications. It is shown that the photonic band of this PhC structure is very dispersive over a broad bandwidth so that light will be efficiently diffracted in the wavelength region of solar radiation. The PhC structure also creates resonance modes leading to further diffraction and funnelling of light so that the light propagates in many pathways in the whole PhC lattice region, which will greatly facilitate light-matter interaction when light-absorbing elements are embedded in the PhC structure. The proposed structure is also valid for photodetection applications.
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| 5. |
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| 6. |
- Chen, Zhihui, et al.
(författare)
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Multiple beam splitting to free space from a V groove in a photonic crystal waveguide
- 2011
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Ingår i: Applied physics. B, Lasers and optics (Print). - : Springer Science and Business Media LLC. - 0946-2171 .- 1432-0649. ; 102:4, s. 857-861
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Tidskriftsartikel (refereegranskat)abstract
- We present multiple-beam splitting to free space from a V groove in a two-dimensional photonic crystal waveguide (PCW) with a few additional dielectric rods at the exit of the PCW. Numerical study shows that 'one-beam-in to two-beams-out' (one-to-two, also denoted as Y-shaped), one-to-three, and one-to-five beam splittings can be easily realized over a wide bandwidth, and the split beams have remarkable properties such as symmetric energy distributions and high directional transmissions. Off-axis directional emission can also be achieved by simple displacements of the additional rods at the exit of the PCW.
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| 7. |
- Chen, Zhihui, et al.
(författare)
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Time-resolved photocurrents in quantum well/dot infrared photodetectors with different optical coupling structures
- 2012
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 100:4, s. 043502-
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Tidskriftsartikel (refereegranskat)abstract
- Temporal developments of photocurrents excited by an infrared radiation pulse in quantum well/dot infrared photodetectors with different optical coupling structures have been theoretically studied. It is shown that the light diffraction in a conventional reflective grating structure is a near-field effect containing severe crosstalk from neighboring pixels. A concave reflector not only eliminates the crosstalk but also strongly diffracts and focuses the incident electric field into deep active layers, which significantly increases the photocurrents in the photodetectors.
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| 8. |
- de Melo, Fernando Menegatti, et al.
(författare)
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Superparamagnetic Maghemite-Based CdTe Quantum Dots as Efficient Hybrid Nanoprobes for Water-Bath Magnetic Particle Inspection
- 2018
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Ingår i: ACS Applied Nano Materials. - : American Chemical Society (ACS). - 2574-0970. ; 1:6, s. 2858-2868
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Tidskriftsartikel (refereegranskat)abstract
- Fluorescent water-based cadmium telluride quantum dots (QDs) and citrate-functionalized maghemite nanoparticles (MghNPs) were synthesized and assembled together (MghNPs@QDs) through electrostatic interactions by using cetyltrimethylammonium bromide (CTAB) as a linker and steric spacer to minimize the Forster resonance energy transfer (FRET) restriction. A whole family of hybrid and multifunctional nanoparticles has been successfully obtained, exhibiting good performance in nondestructive water-bath magnetic particle inspection (MPI) assays.
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| 9. |
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| 10. |
- Engström, Olof, 1943, et al.
(författare)
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Electron capture cross sections of InAs/GaAs quantum dots
- 2004
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 85:14, s. 2908-2910
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Tidskriftsartikel (refereegranskat)abstract
- The thermal emission rates of electrons from InAs/GaAs quantum dots were measured, to found the capture cross sections in the extremely high region of 10-11-10-10 cm2. An additional method based on a static measurement at thermal equilibrium was used where the Fermi level was positioned at the free energy level of the quantum dot s shell. A Schottky diode with a plane of QDs grown in its depletion region and back-biased in such a way that the Fermi level coincides with the electron energy level. The Fermi level passes the lowest energy level of the QD, at the voltage marked by Vp in the graphs.
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