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Red dot

Xiaoyan Wang, Shuangmei Yu, Wen Liu, Longwen Fu, Yunqing Wang, Jinhua Li, Lingxin Chen
We describe a simple and effective strategy to construct molecular imprinting ratiometric fluorescence sensor (MIR sensor) for the visual detection of bovine hemoglobin (BHb) used as a model protein. The sensor was prepared by simply mixing the solution of green and red CdTe quantum dots (QDs), which were embedded in core-shell structured molecularly imprinted polymers and silica nanoparticles, respectively. The resultant hybrid MIR sensor can selectively bind with BHb and thus quench the fluorescence of the green QDs, while the red QDs wrapped with silica is insensitive to BHb with the fluorescence intensity unchanged...
January 16, 2018: ACS Sensors
L Dworak, S Roth, M P Scheffer, A S Frangakis, J Wachtveitl
CdTe core and CdTe/CdSe core/shell quantum dots (QD) are investigated with steady state and time-resolved spectroscopic methods. The coating of the CdTe core with a 0.7 nm thick CdSe shell shifts the lowest exciton absorption band to the red by more than 70 nm making the CdTe/CdSe QD an interesting candidate for application in solar energy conversion. Femtosecond transient absorption measurements are applied to study the photoinduced electron transfer (ET) to the molecular acceptor methylene blue (MB). ET times after single excitation of the QD are determined for different MB : QD ratios...
January 12, 2018: Nanoscale
Jingling Li, Zheng Liang, Qiucheng Su, Hu Jin, Kelai Wang, Gang Xu, Xueqing Xu
For an organic-inorganic hybrid quantum dot light emitting diode (QD-LED), enhancing hole-injection into the emitter for charge balance is a priority to achieve efficient device performance. Aiming at this, we employ N,N'-Bis(3-methylphenyl)-N,N'-bis(phenyl)benzidine (TPD) as the additional hole transport material which was mixed with the poly(9-vinlycarbazole) (PVK) to form a composite hole transport layer (HTL), or was employed to construct a TPD/PVK bilayer structure. Enabled by this TPD modification, the green QD-LED (at wavelength of 515 nm) exhibits a sub-bandgap turn-on voltage of 2...
January 5, 2018: ACS Applied Materials & Interfaces
Boris le Feber, Ferry Prins, Eva De Leo, Freddy T Rabouw, David J Norris
To improve the photophysical performance of colloidal quantum dots for laser applications, sophisticated core/shell geometries have been developed. Typically, a wider bandgap semiconductor is added as a shell to enhance the gain from the quantum-dot core. This shell is designed to electronically isolate the core, funnel excitons to it, and reduce non-radiative Auger recombination. However, the shell could also potentially provide a secondary source of gain, leading to further versatility in these materials...
December 28, 2017: Nano Letters
Jinyang Zhu, Xue Bai, Jialin Bai, Gencai Pan, Yongsheng Zhu, Yue Zhai, He Shao, Xu Chen, Biao Dong, Hanzhuang Zhang, Hongwei Song
Carbon dots (CDs), one of the most significant classes of carbon-based nanophosphors, have attracted extensive attentions recent years. However, few attempts have been reported for realizing CDs with tunable emissions, especially for obtaining the red-light emissions with high photoluminescence quantum yields. Herein, we synthesized CDs with different chromatic blue, green and red emissions by facilely changing the reaction solvent during the hydrothermal conditions. The photoluminescence quantum yields (QYs) of 34%, 19% and 47% for the blue, green and red emissions were achieved...
December 20, 2017: Nanotechnology
Alexandra A P Mansur, Herman S Mansur, Sandhra M Carvalho, Anderson J Caires
Cancer research has experienced astonishing advances recently, but cancer remains a major threat because it is one of the leading causes of death worldwide. Glioblastoma (GBM) is the most malignant brain tumor, where the early diagnosis is vital for longer survival. Thus, this study reports the synthesis of novel water-dispersible ternary AgInS2 (AIS) and quaternary AgInS2-ZnS (ZAIS) fluorescent quantum dots using carboxymethylcellulose (CMC) as ligand for multiplexed bioimaging of malignant glioma cells (U-87 MG)...
2017: Contrast Media & Molecular Imaging
Mara Werwie, Lars Dworak, Anne Bottin, Lisa Mayer, Thomas Basché, Josef Wachtveitl, Harald Paulsen
Type-II quantum dots (QDs) are capable of light-driven charge separation between their core and the shell structures; however, their light absorption is limited in the longer-wavelength range. Biological light-harvesting complex II (LHCII) efficiently absorbs in the blue and red spectral domains. Therefore, hybrid complexes of these two structures may be promising candidates for photovoltaic applications. Previous measurements had shown that LHCII bound to QD can transfer its excitation energy to the latter, as indicated by the fluorescence emissions of LHCII and QD being quenched and sensitized, respectively...
December 13, 2017: Biochimica et Biophysica Acta
Hsuan-Ching Ho, Miranda VAN Heden
A new species sandperch, Parapercis altipinnis, is described based on the holotype collected from Cebu, the Philippines at 55-65 m by SCUBA. The new species belongs to the P. cylindrica complex and can be distinguished by an extremely high first dorsal fin, the first spine slightly longer than the head; 3 predorsal scales; 42 or 43 lateral-line scales; teeth present on vomer and palatines. The body is reddish dorsally and blackish ventrally, with 5 large brownish saddles alternating with white bands on dorsal surface; scattered dots on top of head, first dorsal fin and dorsal surface; first dorsal fin milky white with 5 black marks on anterior margin; a black broad band below eye; cheek and throat blackish red surrounding by white color; row of 10 short white bars along the lateral side of body axis; row of 9 deep red to blackish bars on lower half of lateral side of body; base of pelvic fin and lower margin of caudal fin blackish; rows of black spots on soft dorsal fin...
November 1, 2017: Zootaxa
Wenli Gao, Haohan Song, Xiao Wang, Xiaoqiang Liu, Xiaobin Pang, Yanmei Zhou, Bin Gao, Xiaojun Peng
Red emissive carbon dots (CDs) have drawn more and more attention due to their good organ penetration depth and slight biological tissues photodamage. Herein, the fluorescent CDs with red emission were synthesized by facile one-pot hydrothermal treatment of citric acid and neutral red, and they show red fluorescence both in aqueous solution and solid state. The solution of CDs exhibits the quantum yield (QY) of 12.1%, good stability against photobleaching, and low cytotoxicity. As-prepared CDs can be used as fluorescent probe for peculiar detection of Pt2+, Au3+ and Pd2+...
December 13, 2017: ACS Applied Materials & Interfaces
Jiangyong Pan, Changting Wei, Lixi Wang, Jinyong Zhuang, Qianqian Huang, Wenming Su, Zheng Cui, Arokia Nathan, Wei Lei, Jing Chen
We report an inverted and multilayer quantum dot light emitting diode (QLED) which boosts high efficiency by tuning the energy band alignment between charge transport and light emitting layers. The electron transport layer (ETL) was ZnO nanoparticles (NPs) with an optimized doping concentration of cesium azide (CsN3) to effectively reduce electron flow and balance charge injection. This is by virtue of a 0.27 eV upshift of the ETL's conduction band edge, which inhibits the quenching of excitons and preserves the superior emissive properties of the quantum dots due to the insulating characteristics of CsN3...
December 13, 2017: Nanoscale
Ryan T Maloney, Colin W G Clifford, Isabelle Mareschal
Motion-defined transparency is the perception of two or more distinct moving surfaces at the same retinal location. We explored the limits of motion transparency using superimposed surfaces of randomly positioned dots defined by differences in motion direction and colour. In one experiment, dots were red or green and we varied the proportion of dots of a single colour that moved in a single direction ('colour-motion coherence') and measured the threshold direction difference for discriminating between two directions...
January 1, 2017: Perception
Hyung-Jun Song, Byeong Guk Jeong, Jaehoon Lim, Doh C Lee, Wan Ki Bae, Victor I Klimov
Luminescent solar concentrators (LSCs) can serve as large-area sunlight collectors for photovoltaic devices. An important LSC characteristic is a concentration factor (C), which is defined as the ratio of the output and the input photon flux densities. This parameter can be also thought of as an effective enlargement factor of a solar cell active area. Based on thermodynamic considerations, the C-factor can reach extremely high values that exceed those accessible with traditional concentrating optics. In reality, however, the best reported values of C are around 30...
December 11, 2017: Nano Letters
Jongho Lee, Kyungtaek Min, Yeonsang Park, Kyung-Sang Cho, Heonsu Jeon
Following the proof-of-concept experiment in the unit structure level, photonic crystal (PhC) phosphors-structurally engineered phosphor materials based on the nanophotonics principles-are integrated with a blue light-emitting diode (LED) chip to demonstrate a compact and efficient white light source. Red- or green-emitting CdSe-based colloidal quantum dots (CQDs) are coated on a Si3 N4 thin-film grating to fabricate PhC phosphors. The underlying PhC structure is designed such that the photonic band-edge modes at the zone center (k∣∣ = 0) are tuned to the energy of the blue excitation photons...
November 30, 2017: Advanced Materials
Bin Xie, Yanhua Cheng, Junjie Hao, Weicheng Shu, Kai Wang, Xiaobing Luo
Quantum dots (QDs)-based white light-emitting diodes (QDs-WLEDs) have been attracting numerous attentions in lighting and flat panel display applications, by virtue of their high luminous efficacy and excellent color rendering ability. However, QDs' key optical parameters including scattering, absorption and anisotropy coefficients for optical modeling are still unclear, which are severely against the design and optimization of QDs-WLEDs. In this work, we proposed a new precise optical modeling approach towards QDs...
November 30, 2017: Scientific Reports
Xiang Miao, Dan Qu, Dongxue Yang, Bing Nie, Yikang Zhao, Hongyou Fan, Zaicheng Sun
Multiple-color-emissive carbon dots (CDots) have potential applications in various fields such as bioimaging, light-emitting devices, and photocatalysis. The majority of the current CDots to date exhibit excitation-wavelength-dependent emissions with their maximum emission limited at the blue-light region. Here, a synthesis of multiple-color-emission CDots by controlled graphitization and surface function is reported. The CDots are synthesized through controlled thermal pyrolysis of citric acid and urea. By regulating the thermal-pyrolysis temperature and ratio of reactants, the maximum emission of the resulting CDots gradually shifts from blue to red light, covering the entire light spectrum...
November 27, 2017: Advanced Materials
Jessica Cervantes, Farhaan Hafeez, Mariya Miteva
Dermoscopic features of discoid lupus erythematosus (DLE) depend on the stage of the lesions: active lesions include yellow-brown dots and red dots, whereas longstanding inactive lesions show absence of follicular openings, cicatricial milky red or white patches, structureless white and brown areas, and thick arborizing vessels. Loss of pinpoint white dots, blue-gray dots in a speckled pattern, and a peripheral pigmented network have been described on dermoscopy of DLE in dark skin. We report a blue-white veil as a novel dermoscopic feature in 2 cases of biopsy-proven DLE in African-American patients...
October 2017: Skin Appendage Disorders
Guangcun Chen, Suying Lin, Dehua Huang, Yejun Zhang, Chunyan Li, Mao Wang, Qiangbin Wang
Stem-cell-based regenerative medicine holds great promise in clinical practices. However, the fate of stem cells after transplantation, including the distribution, viability, and the cell clearance, is not fully understood, which is critical to understand the process and the underlying mechanism of regeneration for better therapeutic effects. Herein, we develop a dual-labeling strategy to in situ visualize the fate of transplanted stem cells in vivo by combining the exogenous near-infrared fluorescence imaging in the second window (NIR-II) and endogenous red bioluminescence imaging (BLI)...
November 24, 2017: Small
Ruilin Xu, Chen Liao, Yanqing Xu, Chunfeng Zhang, Min Xiao, Lei Zhang, Changgui Lu, Yiping Cui, Jiayu Zhang
Mn(2+) ions were introduced as exciton couplers to enhance the quantum yield (QY) of type-II photoluminescence (PL) from CdS/ZnSe/ZnS quantum dots (QDs) with slow hot-exciton cooling and low radiative rate. Transient absorption spectroscopy verifies the faster bleach recovery and faster peak red-shifting at the charge-transfer state. And the transient PL peak of the QDs changes from blue-shifting to red-shifting due to Mn(2+) doping. The QY of type-II PL can be enhanced from ∼35% to ∼60% by Mn(2+) doping...
November 15, 2017: Nanoscale
Weijie He, Rijun Gui, Hui Jin, Benqian Wang, Xiangning Bu, Yongxin Fu
In this article, blue-emitting carbon dots (CDs) were prepared via hydrothermal treatment of sodium citrate and NH4HCO3, and then combined with 3-aminophenylboronic acid (APBA) to prepare APBA modified-CDs. APBA acted as the receptor of dopamine (DA). Using bovine serum albumin (BSA) as a stabilizer and N2H4·H2O as a reducing reagent, BSA-stabilized and red-emitting copper nanoclusters (CuNCs) were prepared. By carbodiimide-activated coupling, novel nanohybrids consisting of CDs and CuNCs were constructed and exhibited dual-emitting fluorescence (FL)...
February 1, 2018: Talanta
Kateřina Holá, Mária Sudolská, Sergii Kalytchuk, Dana Nachtigallová, Andrey L Rogach, Michal Otyepka, Radek Zbořil
Carbon dots (CDs) are a stable and highly biocompatible fluorescent material offering great application potential in cell labeling, optical imaging, LED diodes, and optoelectronic technologies. Because their emission wavelengths provide the best tissue penetration, red-emitting CDs are of particular interest for applications in biomedical technologies. Current synthetic strategies enabling red-shifted emission include increasing the CD particle size (sp(2) domain) by a proper synthetic strategy and tuning the surface chemistry of CDs with suitable functional groups (e...
November 20, 2017: ACS Nano
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