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https://www.readbyqxmd.com/read/28822859/a-facile-method-to-prepare-green-nano-phosphors-with-a-large-stokes-shift-and-solid-state-enhanced-photophysical-properties-based-on-surface-modified-gold-nanoclusters
#1
C H Cheng, H Y Huang, M J Talite, W C Chou, J M Yeh, C T Yuan
Colloidal nano-materials, such as quantum dots (QDs) have been applied to light-conversion nano-phosphors due to their unique tunable emission. However, most of the QDs involve toxic elements and are synthesized in a hazardous solvent. In addition, conventional QD nano-phosphors with a small Stokes shift suffered from reabsorption losses and aggregation-induced quenching in the solid state. Here, we demonstrate a facile, matrix-free method to prepare eco-friendly nano-phosphors with a large Stokes shift based on aqueous thiolate-stabilized gold nanoclusters (GSH-AuNCs) with simple surface modifications...
August 8, 2017: Journal of Colloid and Interface Science
https://www.readbyqxmd.com/read/28821436/carbon-quantum-dot-tailored-calcium-alginate-hydrogel-for-ph-responsive-controlled-delivery-of-vancomycin
#2
Niladri Sarkar, Gyanaranjan Sahoo, Rashmita Das, Gyanaranjan Prusty, Sarat K Swain
Herein, we demonstrate the preparation of highly luminescent carbon quantum dots (CQDs) from Aloe vera leaf gel; in just 2h at 250°C through carbonization pathway. The prepared CQDs are structurally characterized with high resolution transmission electron microscopy (HRTEM), hydrodynamic diameter and surface polarity, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), Raman, UV-visible absorption spectrophotometry and fluorescence spectroscopy. The functional carbon nanoparticles are observed as non-cytotoxic materials...
August 15, 2017: European Journal of Pharmaceutical Sciences
https://www.readbyqxmd.com/read/28820986/an-ultrasensitive-sandwich-type-electrochemical-immunosensor-based-on-the-signal-amplification-strategy-of-echinoidea-shaped-au-ag-cu2o-nanoparticles-for-prostate-specific-antigen-detection
#3
Yuying Yang, Qin Yan, Qing Liu, Yongpeng Li, Hui Liu, Ping Wang, Lei Chen, Daopeng Zhang, Yueyun Li, Yunhui Dong
Highly sensitive determination of tumor markers plays an important role in early diagnosis of cancer. Herein, a novel and ultrasensitive sandwich-type electrochemical immunosensor was fabricated for quantitative detection of prostate specific antigen (PSA). In this process, gold nanoparticles functionalized nitrogen-doped graphene quantum dots (Au@N-GQDs) was synthesized through a simple and green hydrothermal procedure to enhance conductivity, specific electrode surface area and quantity of immobilized primary antibodies (Ab1)...
August 10, 2017: Biosensors & Bioelectronics
https://www.readbyqxmd.com/read/28820937/impact-of-shell-thickness-on-photoluminescence-and-optical-activity-in-chiral-cdse-cds-core-shell-quantum-dots
#4
Finn Purcell-Milton, Anastasia K Visheratina, Vera A Kuznetsova, Aisling Ryan, Anna O Orlova, Yurii K Gun'ko
Core/Shell quantum dots (QDs) are of high scientific and technological importance as these nanomaterials have found a number of valuable applications. In this paper, we have investigated the dependence of optical activity and photoluminescence upon CdS shell thickness in a range of core-shell structured CdSe/CdS QDs capped with chiral ligands. For our study, five samples of CdSe/CdS were synthesised utilizing successive ion layer adsorption and reaction (SILAR) to vary the thickness of the CdS shell from 0...
August 18, 2017: ACS Nano
https://www.readbyqxmd.com/read/28820244/rapid-and-quantitative-measurement-of-single-quantum-dots-in-a-sheath-flow-cuvette
#5
Shuo Wang, Lihong Li, Shenghao Jin, Weifeng Li, Wei Hang, Xiaomei Yan
Semiconducting quantum dots (QDs) are finding a wide range of biomedical applications due to their intense fluorescence brightness and long-term photostability. Here, we report precise quantification of the fluorescence intensity of single QDs on a laboratory-built high-sensitivity flow cytometer (HSFCM). The nearly uniform illumination of the particles at the intense portions of the radiation field resulted in narrowly distributed signals with high signal-to-noise ratios. By analyzing thousands of QDs individually in as little time as 1 min, intrinsic polydispersity was quickly revealed in a statistically robust manner...
August 18, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28820224/label-free-fluorescent-immunoassay-for-cu-2-ion-detection-based-on-uv-degradation-of-immunocomplex-and-metal-ion-chelates
#6
Qi Shu, Mengli Liu, Hui Ouyang, Zhifeng Fu
A mouse anti Cu(2+)-EDTA monoclonal antibody was used to capture EDTA chelated Cu(2+) ions. Then UV radiation was utilized to degrade immunocomplex and Cu(2+)-EDTA chelates to release free Cu(2+) ions. Based on their quenching effect to the fluorescent emission of CdSe/ZnS quantum dots, the released Cu(2+) ions could be detected with ideal specificity and high sensitivity.
August 18, 2017: Nanoscale
https://www.readbyqxmd.com/read/28819974/room-temperature-synthesis-of-mn-doped-cesium-lead-halide-quantum-dots-with-high-mn-substitution-ratio
#7
Jingrun Zhu, Xiaoling Yang, Yihua Zhu, Yuanwei Wang, Jin Cai, Jianhua Shen, Luyi Sun, Chunzhong Li
Here we report the room-temperature, atmospheric synthesis of Mn-doped cesium lead halide (CsPbX3) perovskite quantum dots (QDs). The synthesis is performed without any sort of protection, and the dual-color emission mechanism is revealed by density functional theory. The Mn concentration reaches a maximum atomic percentage of 37.73 at%, which is significantly higher in comparison to those achieved in earlier reports via high temperature hot injection method. The optical properties of as-prepared nanocrystals (NCs) remain consistent even after several months...
August 21, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28819900/effect-of-polyethylene-glycol-on-the-nio-photocathode
#8
Shengjun Li, Zeng Chen, Wenping Kong, Xiyang Jia, Junhao Cai, Shaokang Dong
In this study, a uniform nanoporous NiO film, with a thickness of up to 2.6 μm, was prepared using polyethylene glycol (PEG). The addition of PEG significantly decreased the cracks in the NiO film and prevented the peeling of the NiO film from a fluorine-doped tin oxide substrate. The NiO cathode was prepared using CdSeS quantum dots (QDs) as the sensitizer, with an optimized photoelectric conversion of 0.80%. The optimized QD-sensitized NiO films were first assembled with the TiO2 anode to prepared QD-sensitized p-n-type tandem solar cells...
August 17, 2017: Nanoscale Research Letters
https://www.readbyqxmd.com/read/28819800/nanotechnology-from-in-vivo-imaging-system-to-controlled-drug-delivery
#9
REVIEW
Maria Mir, Saba Ishtiaq, Samreen Rabia, Maryam Khatoon, Ahmad Zeb, Gul Majid Khan, Asim Ur Rehman, Fakhar Ud Din
Science and technology have always been the vitals of human's struggle, utilized exclusively for the development of novel tools and products, ranging from micro- to nanosize. Nanotechnology has gained significant attention due to its extensive applications in biomedicine, particularly related to bio imaging and drug delivery. Various nanodevices and nanomaterials have been developed for the diagnosis and treatment of different diseases. Herein, we have described two primary aspects of the nanomedicine, i.e...
August 17, 2017: Nanoscale Research Letters
https://www.readbyqxmd.com/read/28819669/drastic-difference-between-hole-and-electron-injection-through-the-gradient-shell-of-cdxseyzn1-xs1-y-quantum-dots
#10
Mohamed Abdellah, Felipe Poulsen, Qiushi Zhu, Nan Zhu, Karel Žídek, Pavel Chábera, Annamaria Corti, Thorsten Hansen, Qijin Chi, Sophie E Canton, Kaibo Zheng, Tõnu Pullerits
Ultrafast fluorescence spectroscopy was used to investigate the hole injection in CdxSeyZn1-xS1-y gradient core-shell quantum dot (CSQD) sensitized p-type NiO photocathodes. A series of CSQDs with a wide range of shell thicknesses was studied. Complementary photoelectrochemical cell measurements were carried out to confirm that the hole injection from the active core through the gradient shell to NiO takes place. The hole injection from the valence band of the QDs to NiO depends much less on the shell thickness when compared to the corresponding electron injection to n-type semiconductor (ZnO)...
August 18, 2017: Nanoscale
https://www.readbyqxmd.com/read/28818774/a-quantum-dot-based-fluoroassay-for-detection-of-food-borne-pathogens
#11
Elaheh Mohamadi, Mohammadali Moghaddasi, Afshin Farahbakhsh, Abbass Kazemi
Evaluation of the distribution capability of food-borne pathogens existing in food products by taking the advantage of quantum dots (QDs) for their photoluminescence properties was carried out. Bacteria namely Escherichia coli (E. coli) labelled with CdSe-QDs were examined both on an Agar nutrient and ground fish substrates in order to observe their growth rate in different environments in the Lab. A sample with an appropriate concentration ratio 10(7)CFU/mL of bacteria/CdSe-QDs was empirically selected from the samples which were grown on the Agar containing plates...
August 7, 2017: Journal of Photochemistry and Photobiology. B, Biology
https://www.readbyqxmd.com/read/28818765/cu-2-modulated-nitrogen-doped-grapheme-quantum-dots-as-a-turn-off-on-fluorescence-sensor-for-the-selective-detection-of-histidine-in-biological-fluid
#12
Zhiyu Wang, ZheFeng Fan
A highly sensitive sensor for detection of histidine (His) based on the nitrogen-doped graphene quantum dots (N-GQDs)-Cu(2+) system has been designed. The N-GQDs were synthesized by one-step hydrothermal approach according to previous report. The fluorescence of N-GQDs can be effectively quenched by Cu(2+) due to the binding between Cu(2+) and functional groups on the surface of N-GQDs. The high affinity of His to Cu(2+) enables Cu(2+) to be dissociated from the surface of N-GQDs and recovering the fluorescence...
August 3, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/28816428/aqueous-exfoliation-of-graphite-into-graphene-assisted-by-sulfonyl-graphene-quantum-dots-for-photonic-crystal-applications
#13
Minxiang Zeng, Smit A Shah, Dali Huang, Dorsa Parviz, Yi-Hsien Yu, Xuezhen Wang, Micah J Green, Zhengdong Cheng
We investigate the π-π stacking of polyaromatic hydrocarbons (PAHs) with graphene surfaces, showing that such interactions are general across a wide range of PAH sizes and species, including graphene quantum dots. We synthesized a series of graphene quantum dots with sulfonyl, amino and carboxylic functional groups and employed them to exfoliate and disperse pristine graphene in water. We observed that sulfonyl-functionalized graphene quantum dots were able to stabilize the highest concentration of graphene in comparison to other functional groups; this is consistent with prior findings by pyrene...
August 17, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28816319/novel-multiple-phosphorescence-in-nanostructured-zinc-oxide-and-calculations-of-correlated-colour-temperature
#14
Sagnik Das, Uttam Kumar Ghorai, Rajib Dey, Chandan Kumar Ghosh, Mrinal Pal
The design and development of novel and high quantum efficiency luminescent materials, such as phosphors, having tuneability in properties, have received tremendous interest among scientists. In this paper, we have achieved for the first-time multiple phosphorescence (blue and green) having a life-time of ∼10 μs in nanostructured zinc oxide that was synthesized using an easy and facile sol-gel method. Importantly, the photoluminescence (PL) intensity and the phosphorescence life-time could be tuned by controlling the annealing temperature under a reducing atmosphere...
August 17, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28815235/growth-kinetics-and-mechanisms-of-multinary-copper-based-metal-sulfide-nanocrystals
#15
Keqiang Chen, Jing Zhou, Wen Chen, Qiaohui Zhong, Tingqiang Yang, Xue Yang, Chunyu Deng, Yueli Liu
Multinary copper-based metal sulfide (Cu-M-S) nanocrystals (NCs) usually have high absorption coefficients and near-optimum direct band gaps, which have been considered as novel photo-absorption materials for quantum dot-sensitized solar cells (QDSCs) and hole-transport materials for perovskite solar cells (PSCs). However, the formation and phase transformation mechanisms of Cu-M-S NCs during the solution-based preparing approaches are complicated. Herein, Cu-M-S NCs, including Cu2ZnSnS4 (CZTS), Cu2SnS3 (CTS), CuInS2 (CIS), and CuSbS2 (CAS), have been synthesized through solution-based hot-injection methods...
August 17, 2017: Nanoscale
https://www.readbyqxmd.com/read/28814860/quantum-dots-in-imaging-drug-delivery-and-sensor-applications
#16
REVIEW
Cristian T Matea, Teodora Mocan, Flaviu Tabaran, Teodora Pop, Ofelia Mosteanu, Cosmin Puia, Cornel Iancu, Lucian Mocan
Quantum dots (QDs), also known as nanoscale semiconductor crystals, are nanoparticles with unique optical and electronic properties such as bright and intensive fluorescence. Since most conventional organic label dyes do not offer the near-infrared (>650 nm) emission possibility, QDs, with their tunable optical properties, have gained a lot of interest. They possess characteristics such as good chemical and photo-stability, high quantum yield and size-tunable light emission. Different types of QDs can be excited with the same light wavelength, and their narrow emission bands can be detected simultaneously for multiple assays...
2017: International Journal of Nanomedicine
https://www.readbyqxmd.com/read/28812351/structural-investigation-of-cesium-lead-halide-perovskites-for-high-efficiency-quantum-dot-light-emitting-diodes
#17
Quyet Van Le, Jong Beom Kim, Soo Young Kim, Byeongdu Lee, Dong Ryeol Lee
In this study, we have intensively investigated the effect of the reaction temperature of hot-injection method on the structural properties of CsPbX3 (X: Br, I, Cl) perovskite nanocrystals (NCs) using the small- and wide-angle X-ray scattering. Furthermore, light emitting diodes (LEDs) performance as well as photoluminescence characteristics for high-efficient LEDs is compared with reaction temperature. It is confirmed that the size of the NCs decreased as the reaction temperature decreased, resulting stronger quantum confinement...
August 16, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28811577/dirac-point-induced-ultralow-threshold-laser-and-giant-optoelectronic-quantum-oscillations-in-graphene-based-heterojunctions
#18
Golam Haider, Rini Ravindranath, Tzu-Pei Chen, Prathik Roy, Pradip Kumar Roy, Shu-Yi Cai, Huan-Tsung Chang, Yang-Fang Chen
The occurrence of zero effective mass of electrons at the vicinity of the Dirac point is expected to create new paradigms for scientific research and technological applications, but the related discoveries are rather limited. Here, we demonstrate that a simple architecture composed of graphene quantum dots sandwiched by graphene layers can exhibit several intriguing features, including the Dirac point induced ultralow-threshold laser, giant peak-to-valley ratio (PVR) with ultra-narrow spectra of negative differential resistance and quantum oscillations of current as well as light emission intensity...
August 15, 2017: Nature Communications
https://www.readbyqxmd.com/read/28811164/corrigendum-to-functional-quantum-dot-sirna-nanoplexes-to-regulate-chondrogenic-differentiation-of-mesenchymal-stem-cells-acta-biomater-46-2016-165-176
#19
Yang Wu, Bo Zhou, Fuben Xu, Xiaoyong Wang, Gang Liu, Li Zheng, Jinmin Zhao, Xingdong Zhang
No abstract text is available yet for this article.
August 12, 2017: Acta Biomaterialia
https://www.readbyqxmd.com/read/28811023/agnps-3d-nanostructure-enhanced-electrochemiluminescence-of-cdse-quantum-dot-coupled-with-strand-displacement-amplification-for-sensitive-biosensing-of-dna
#20
Meng Jiao, Guifen Jie, Lu Tan, Shuyan Niu
A novel strategy using Ag nanoparticles-3D (AgNPs-3D) nanostructure enhanced electrochemiluminescence (ECL) of CdSe quantum dots (QDs) coupled with strand displacement amplification (SDA) for sensitive biosensing of DNA was successfully designed. The prepared CdSe QDs with intense ECL were assembled on the poly (diallyldimethylammonium chloride) (PDDA) graphene oxide (GO) nanocomposites modified electrode, then gold nanoparticles (NPs) as the quenching probe was conjugated to the QDs, ECL signal was efficiently quenched...
August 29, 2017: Analytica Chimica Acta
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