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Quantum dots

Huajun Feng, Qiaoqi Guo, Yingfeng Xu, Ting Chen, Yuyang Zhou, Yigang Wang, Meizhen Wang, Dongsheng Shen
The concept of photocatalytic CO2 conversion provides simultaneous solutions for global warming mitigation and fuels generation, which, however, is limited by the unsatisfactory photoconversion efficiency. Despite light harvesting and charge separation, enhancing adsorption of CO2 via surface modification could be an efficient way to improve CO2 photoconversion efficiency. Herein, we doped nonpolar carbon quantum dots (denoted as CQDs) on g-C3N4 to construct a metal-free heterojunction photocatalyst (denoted as CQDs/g-C3N4)...
October 12, 2018: ChemSusChem
Xuetao Hu, Jiyong Shi, Yongqiang Shi, Xiaobo Zou, Muhammad Arslan, Wen Zhang, Xiaowei Huang, Zhihua Li, Yiwei Xu
Gold nanoparticles@Carbon quantum dots nanocomposites (Au@CQDs) were designed for analyzing melamine in milk visually. Fluorescent emission of Au@CQDs enhanced with the increase of melamine concentration. A calibration curve (R2  = 0.9856) and fluorescence standard array were established for detection of melamine in the range of 1 μM-10 μM. Limit of quantification and limit of detection were 12 nM and 3.6 nM, respectively. The approximate concentration of melamine adulterated in milk samples were detected visually by the fluorescence standard array and smartphone...
January 30, 2019: Food Chemistry
Liyuan Long, Xianghong Niu, Kun Yan, Gang Zhou, Jinlan Wang, Xinglong Wu, Paul K Chu
Although 2D black phosphorous (BP) shows excellent optical and electronic properties, there are few reports on the photoluminescence (PL) properties of BP nanostructures because of the low yield of mechanical exfoliation, instability in water, and relatively weak emission. Herein, liquid exfoliation is combined with surface passivation to produce fluorescent BP quantum dots (BPQDs) with a high yield. The BPQDs exhibit strong PL in both ethanol and water and the absolute fluorescent quantum yield in water reaches 70%...
October 11, 2018: Small
Xiaoqiang Chen, Yu Luan, Ningwei Wang, Zhiping Zhou, Xiaoni Ni, Yunfei Cao, GuangShe Zhang, Yufeng Lai, Wenming Yang
Sulfadiazine is an environmental pollutant derived from abuse of antibiotics. Its content in environmental water is closely related to human health. Thus, a novel dual emission surface molecularly imprinted nanosensor is designed for specific adsorption and detection of sulfadiazine. In the system, blue emissive carbon quantum dots wrapped with silica served as the internal reference signal for eliminating background interference while red emissive thioglycolic acid-modified CdTe quantum dots were encapsulated in the imprinted layer to offer recognition signal...
October 11, 2018: Journal of Separation Science
Seong Jae Kang, Hwa Yeon Jeong, Min Woo Kim, In Ho Jeong, Moon Jung Choi, Young Myoung You, Chan Su Im, In Ho Song, Tae Sup Lee, Yong Serk Park
Cancer theranosis is an emerging field of personalized medicine which enables individual anti-cancer treatment by monitoring the therapeutic responses of cancer patients. Based on a consideration of the nano-bio interactions related to the blood circulation of systemically administered nanoparticles in humans, as well as extravasation and active targeting, lipid micellar nanoparticles were co-loaded with paclitaxel (PTX) and quantum dots (QDs) to generate a theranostic delivery vehicle. To provide with a tumor-targeting capability, either an antibody or an aptamer against the epidermal growth factor receptor (EGFR) was conjugated to the micelle surface...
October 11, 2018: Nanoscale
Jizhong Song, Tao Fang, Jianhai Li, Leimeng Xu, Fengjuan Zhang, Boning Han, Qingsong Shan, Haibo Zeng
Perovskite quantum dots (QDs) with high photoluminescence quantum yields (PLQYs) and narrow emission peak hold promise for next-generation flexible and high-definition displays. However, perovskite QD films often suffer from low PLQYs due to the dynamic characteristics between the QD's surface and organic ligands and inefficient electrical transportation resulting from long hydrocarbon organic ligands as highly insulating barrier, which impair the ensuing device performance. Here, a general organic-inorganic hybrid ligand (OIHL) strategy is reported on to passivate perovskite QDs for highly efficient electroluminescent devices...
October 10, 2018: Advanced Materials
Yajun Wang, Juan Chen, Liming Liu, Xiaoxu Xi, Yuming Li, Zhouliang Geng, Guiyuan Jiang, Zhen Zhao
Carbon quantum dots (CDs) are rising stars for photocatalytic applications due to their low toxicity and excellent electron transfer characteristics. Doping with heteroatoms is expected to adjust the band levels and electron transfer properties of CDs, and understanding the effect of doping on CDs can aid the rational preparation of highly efficient CD-based photocatalysts. Herein, we prepared a series of metal atom (Zn, Co, Bi, Cd, or Ti) doped CDs by pyrolysis and explored the photocatalytic application of these metal doped CDs for the first time...
October 11, 2018: Nanoscale
Kebin Lin, Jun Xing, Li Na Quan, F Pelayo García de Arquer, Xiwen Gong, Jianxun Lu, Liqiang Xie, Weijie Zhao, Di Zhang, Chuanzhong Yan, Wenqiang Li, Xinyi Liu, Yan Lu, Jeffrey Kirman, Edward H Sargent, Qihua Xiong, Zhanhua Wei
Metal halide perovskite materials are an emerging class of solution-processable semiconductors with considerable potential for use in optoelectronic devices1-3 . For example, light-emitting diodes (LEDs) based on these materials could see application in flat-panel displays and solid-state lighting, owing to their potential to be made at low cost via facile solution processing, and could provide tunable colours and narrow emission line widths at high photoluminescence quantum yields4-8 . However, the highest reported external quantum efficiencies of green- and red-light-emitting perovskite LEDs are around 14 per cent7,9 and 12 per cent8 , respectively-still well behind the performance of organic LEDs10-12 and inorganic quantum dot LEDs13 ...
October 2018: Nature
Kefilwe Vanessa Mokwebo, Oluwatobi Samuel Oluwafemi, Omotayo Ademola Arotiba
We report the preparation of poly (propylene imine) dendrimer (PPI) and CdTe/CdSe/ZnSe quantum dots (QDs) as a suitable platform for the development of an enzyme-based electrochemical cholesterol biosensor with enhanced analytical performance. The mercaptopropionic acid (MPA)-capped CdTe/CdSe/ZnSe QDs was synthesized in an aqueous phase and characterized using photoluminescence (PL) spectroscopy, ultraviolet-visible (UV-Vis) spectroscopy, transmission electron microscopy (TEM), X-ray power diffraction (XRD), energy dispersive X-ray (EDX) spectroscopy...
October 9, 2018: Sensors
Xueqing Yong, Xuan Yang, Steven R Emory, Jun Wang, Jie Dai, Xiaoya Yu, Ling Mei, Jinbing Xie, Gang Ruan
Targeted delivery of nanomaterials to specific intracellular locations is essential for the development of many nanomaterials-based biological applications. Thus far the targeting performance has been limited due to various intracellular transport barriers, especially intracellular vesicle trapping. Here we report the application of permeation enhancers based on organic solvents in small percentage to enhance the intracellular targeted delivery of nanomaterials. Previously permeation enhancers based on organic solvents and ionic liquids have been used in overcoming biological transport barriers at tissue, organ, and cellular levels, but this strategy has so far rarely been examined for its potential in facilitating transport of nanometer-scale entities across intracellular barriers, particularly intracellular vesicle trapping...
October 10, 2018: Biomaterials Science
Xin-Yang Yue, Zhong Yan, Yun Song, Xiao-Jing Wu, Yong-Ning Zhou
Si/C composites are considered as the most promising anode materials for next-generation lithium-ion batteries (LIBs) due to their high specific capacity and low cost. However, the commercialized Si/C composites cannot maintain a Si content over 10 wt% for sustaining an acceptable cycle life. To achieve long-term cycle stability for Si/C composites with high Si content is still very challenging. Here, we report a rationally designed double-morphology Si/graphene (DMSiG) composite with a high Si content of 78 wt%, and prove its feasibility as a high performance anode material for LIBs...
October 10, 2018: Nanoscale
Hanifeh Shariatifar, Mohammad-Saeed Hakhamaneshi, Maryam Abolhasani, Fahimeh Haji Ahmadi, Daem Roshani, Bahram Nikkhoo, Mohammad Abdi, Davoud Ahmadvand
Fluorescent semiconductor quantum dots (QDs) are newfound nanocrystal probes which have been used in bioimaging filed in recent years. The purpose of this study is to evaluate the diagnostic value of specific QDs coupled to rituximab monoclonal antibody against CD20 tumor markers for patients with diffuse large B-cell lymphoma (DLBCL). In current study rituximab-conjugated quantum dots (QDs-rituximab) were prepared against CD20 tumor markers for detection of CD20-positive cells (human Raji cell line) using flowcytometry...
October 9, 2018: Journal of Cellular Biochemistry
Azam Akbarnia, Hamid R Zare
The authors describe a DNA based voltammetric assay for the cancer biomarker microRNA-25. A glassy carbon electrode (GCE) was modified with amino-functionalized graphene quantum dots and used as an amplifier of electrochemical signals. p-Biphenol is introduced as a new electroactive probe with a fairly low working potential of 0.3 V (vs. Ag/AgCl). The stages of fabricating the electrode were characterized by cyclic voltammetry and electrochemical impedance spectroscopy. ss-Probe DNA was immobilized on the modified GCE and then exposed to a sample containing microRNA-25...
October 9, 2018: Mikrochimica Acta
Yu-Long Tong, Zhijie Zhu, Gang Peng, Tingting Cui, Su Chen
Gold nanoparticle (Au NP) incorporated photonic crystals (PCs) have been extensively studied due to the intricate interplay between the surface plasmon resonance of Au NPs and the periodic nanostructure of PCs. Herein, we successfully synthesized Au NP decorated poly(styrene-co-(generation 3 carbosilane-thioether vinyl-terminated dendrimer)) (P(st-co-G3Vi)) microspheres via in situ reduction of Au ions based on the strong coordination between the Au ions and the sulfur atom in G3Vi dendrimers. These composite Au-doped microspheres demonstrate a bumpy surface topography, which gives rise to a higher hydrophobicity and could effectively suppress the formation of an ubiquitous coffee-ring during the drying process of a colloidal suspension...
October 10, 2018: Nanoscale
Zheng-Long Xu, Shenghuang Lin, Nicolas Onofrio, Limin Zhou, Fangyi Shi, Wei Lu, Kisuk Kang, Qiang Zhang, Shu Ping Lau
Lithium sulfur batteries with high energy densities are promising next-generation energy storage systems. However, shuttling and sluggish conversion of polysulfides to solid lithium sulfides limit the full utilization of active materials. Physical/chemical confinement is useful for anchoring polysulfides, but not effective for utilizing the blocked intermediates. Here, we employ black phosphorus quantum dots as electrocatalysts to overcome these issues. Both the experimental and theoretical results reveal that black phosphorus quantum dots effectively adsorb and catalyze polysulfide conversion...
October 9, 2018: Nature Communications
Fatemeh Ansari, Danial Kahrizi
Herein, green, environmental-friendly and economical synthesize of luminescent carbon dots (CDs) was reported using the plant-based material, Stevia rebaudiana Bertoni, as a herbal bio-sweetener. In this regard, hydrothermal carbonization of Stevia was performed under mild conditions and without any chemical oxidizing agents. Exploring the morphological aspect, surface groups, chemical composition and structure of Stevia-based CDs have been carried out systematically using SEM-EDS, TEM, fluorescence, FT-IR, UV-Vis, and XRD techniques...
September 30, 2018: Cellular and Molecular Biology
Die Ling Zhao, Tai-Shung Chung
Carbon quantum dots (CQDs), which are a fascinating class of nanostructured carbons, have recently attracted extensive attention in the field of membrane technologies for their applications in separation processes. This is because they possess two unique advantages. Their productions are facile and inexpensive, while their physicochemical properties such as ultra-small sizes, good biocompatibility, high chemical inertness, tunable hydrophilicity, rich surface functional groups and antifouling characteristics are highly desirable...
September 27, 2018: Water Research
Joshua O Island, Marvin Ostermann, Lee Aspitarte, Ethan D Minot, Daniele Varsano, Elisa Molinari, Massimo Rontani, Gary A Steele
Carbon nanotubes continue to be model systems for studies of confinement and interactions. This is particularly true in the case of so-called "ultraclean" carbon nanotube devices offering the study of quantum dots with extremely low disorder. The quality of such systems, however, has increasingly revealed glaring discrepancies between experiment and theory. Here, we address the outstanding anomaly of exceptionally large orbital magnetic moments in carbon nanotube quantum dots. We perform low temperature magnetotransport measurements of the orbital magnetic moment and find it is up to 7 times larger than expected from the conventional semiclassical model...
September 21, 2018: Physical Review Letters
Z Su, A Zarassi, J-F Hsu, P San-Jose, E Prada, R Aguado, E J H Lee, S Gazibegovic, R L M Op Het Veld, D Car, S R Plissard, M Hocevar, M Pendharkar, J S Lee, J A Logan, C J Palmstrøm, E P A M Bakkers, S M Frolov
We study transport mediated by Andreev bound states formed in InSb nanowire quantum dots. Two kinds of superconducting source and drain contacts are used: epitaxial Al/InSb devices exhibit a doubling of tunneling resonances, while, in NbTiN/InSb devices, Andreev spectra of the dot appear to be replicated multiple times at increasing source-drain bias voltages. In both devices, a mirage of a crowded spectrum is created. To describe the observations a model is developed that combines the effects of a soft induced gap and of additional Andreev bound states both in the quantum dot and in the finite regions of the nanowire adjacent to the quantum dot...
September 21, 2018: Physical Review Letters
Ignacio Piquero-Zulaica, Aran Garcia-Lekue, Luciano Colazzo, Claudio K Krug, Mohammed S G Mohammed, Zakaria M Abd El-Fattah, J Michael Gottfried, Dimas G de Oteyza, J Enrique Ortega, Jorge Lobo-Checa
Designing molecular organic semiconductors with distinct frontier orbitals is key for the development of devices with desirable properties. Generating defined organic nanostructures with atomic precision can be accomplished by on-surface synthesis. We use this 'dry' chemistry to introduce topological variations in a conjugated poly-( para-phenylene) chain in the form of meta-junctions. As evidenced by STM and LEED, we produce a macroscopically ordered, monolayer thin zigzag chain film on a vicinal silver crystal...
October 8, 2018: ACS Nano
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