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Quantum dot

Paul C Spruijtenburg, Sergey V Amitonov, Filipp Mueller, Wilfred G van der Wiel, Floris A Zwanenburg
In this Report we show the role of charge defects in the context of the formation of electrostatically defined quantum dots. We introduce a barrier array structure to probe defects at multiple locations in a single device. We measure samples both before and after an annealing process which uses an Al2O3 overlayer, grown by atomic layer deposition. After passivation of the majority of charge defects with annealing we can electrostatically define hole quantum dots up to 180 nm in length. Our ambipolar structures reveal amphoteric charge defects that remain after annealing with charging energies of 10 meV in both the positive and negative charge state...
December 6, 2016: Scientific Reports
M Vibin, R Vinayakan, F B Fernandez, Annie John, Annie Abraham
A simple probe - antibody conjugated silica over coated cadmium selenide quantum dots (QD-Ab probe) for efficient and rapid diagnostic in vivo imaging of tumors is developed. Compared to unconjugated quantum dots (QD), these probes underwent efficient cellular internalization and tumor targeting behavior, retaining bright emission under in vivo cancer models. Silica over coated cadmium selenide quantum dots were conjugated with Epidermal growth factor receptor (EGFR) monoclonal antibody to detect the over expression of EGFR in cancer models...
December 5, 2016: Journal of Fluorescence
Anusuya Banerjee, Thomas Pons, Nicolas Lequeux, Benoit Dubertret
Semiconductor nanoparticles particularly quantum dots (QDs) are interesting alternatives to organic fluorophores for a range of applications such as biosensing, imaging and therapeutics. Addition of a programmable scaffold such as DNA to QDs further expands the scope and applicability of these hybrid nanomaterials in biology. In this review, the most important stages of preparation of QD-DNA conjugates for specific applications in biology are discussed. Special emphasis is laid on (i) the most successful strategies to disperse QDs in aqueous media, (ii) the range of different conjugation with detailed discussion about specific merits and demerits in each case, and (iii) typical applications of these conjugates in the context of biology...
December 6, 2016: Interface Focus
Hong-Wei Yu, Jing-Hui Jiang, Ze Zhang, Guang-Cai Wan, Zhi-Yong Liu, Dong Chang, Hong-Zhi Pan
The assembly of quantum dots (QDs) in a simply method opens up opportunities to obtain access to the full potential of assembled QDs by virtue of the collective properties of the ensembles. In this study, quantum dots CdTe and graphene (Gr) nanocomposite was constructed for the simultaneous determination of uric acid (UA) and dopamine (DA). The CdTe QDs-Gr nanocomposite was prepared by ultrasonication and was characterized with microscopic techniques. The nanocomposite modified electrode was characterized by cyclicvoltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS)...
December 2, 2016: Analytical Biochemistry
Bhaskar Garg, Tanuja Bisht
'Nanozymes', a term coined by Scrimin, Pasquato, and co-workers to describe nanomaterials with enzyme-like characteristics, represent an exciting and emerging research area in the field of artificial enzymes. Indubitably, the last decade has witnessed substantial advancements in the design of a variety of functional nanoscale materials, including metal oxides and carbon-based nanomaterials, which mimic the structures and functions of naturally occurring enzymes. Among these, carbon nanodots (C-dots) or carbon quantum dots (CQDs) offer huge potential due to their unique properties as compared to natural enzymes and/or classical artificial enzymes...
December 2, 2016: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Qiu-Mei Feng, Zhen Zhou, Mei-Xing Li, Wei Zhao, Jing-Juan Xu, Hong-Yuan Chen
Proximal metallic nanoparticles (NPs) could quench the electrochemiluminescence (ECL) emission of semiconductor quantum dots (QDs) due to Förster energy transfer (FRET), but at a certain distance, the coupling of light-emission with surface plasmon resonance (SPR) result in enhanced ECL. Thus, the modification strategies and distances control between QDs and metallic NPs are critical for the ECL intensity of QDs. In this strategy, a SPR enhanced ECL sensor based on DNA tetrahedral scaffolds modified platform was reported for the detection of telomerase activity...
November 27, 2016: Biosensors & Bioelectronics
Tingting Zhao, Xin Liu, Yuebin Li, Mingguang Zhang, Jian He, Xuewen Zhang, Hui Liu, Xingguo Wang, Haoshuang Gu
Hydrophobic ZnSe:Mn/ZnS core-shell fluorescence quantum dots (QDs) and anticancer drug paclitaxel (PTX) have been co-loaded into folate conjugated hybrid silica nanocapsules via F127 micelles based soft-template method in a mild aqueous environment at room temperature. The encapsulation of QDs shows a F127: QDs mass ratio dependent behavior, which impact much on the morphology and optical properties of composite nanocapsules. These as prepared composite nanocapsules also exhibit good photoluminescence stability under the temperature ranges from 19°C to 49°C...
November 23, 2016: Journal of Colloid and Interface Science
Mingxuan Gao, Lin Yang, Yi Zheng, Xiaoxi Yang, Hongyan Zou, Jing Han, Zexi Liu, Yuanfang Li, Cheng Zhi Huang
Surface functionalization is an essential prerequisite for wide and specific applications of nanoparticles such as photoluminescent (PL) carbon quantum dots (CQDs), but still remains as a major challenge. In this report, alkynylated CQDs, which were prepared at first from carboxyl-rich CQDs through amidation with propargylamine in the presence of 1,1'-carbonyldiimidazole, were efficiently modified with azido molecular beacon DNA through copper(I)-catalyzed alkyne-azide cycloaddition reaction (CuAAC). As the proof of concept, the DNA-modified CQDs was then bonded with 5-nm gold nanoparticles (AuNPs) through gold-sulfur bond...
December 3, 2016: Chemistry: a European Journal
Livesey David Olerile, Yongjun Liu, Bo Zhang, Tianqi Wang, Shengjun Mu, Jing Zhang, Lesego Selotlegeng, Na Zhang
Timing is an important factor in cancer management. Theragnostic systems have benefit of improving patients' life-quality by expediting therapeutic decisions. The objective of this study was to explore the potential of co-loaded [quantum dots (CdTe/CdS/ZnS) and paclitaxel] NLC (nanostructured lipid carriers) as a parenteral multifunctional delivery system. The co-loaded NLC was prepared by emulsion-evaporation and low temperature-solidification method utilising glyceryl monostearate, oleic acid, and soya phosphatidylcholine as lipid matrix...
November 24, 2016: Colloids and Surfaces. B, Biointerfaces
Weijie Mai, Xiaokang Song, Ping Jiang, Wenzhong Wang, Li Yu, Jiasen Zhang
Plasmon-based fluorescence modulation has led to important advances in various fields and has paved the way toward promising scientific research aimed at enabling new applications. However, the modulation of fluorescence properties based on both localized surface plasmon (LSP) and cavity modes of propagating surface plasmon polaritons (SPPs) are rarely reported. Here, we raster scanned a hybrid nanowire (HNW) with quantum dots (QDs) adsorbed onto a Ag nanowire (NW) and obtained two-photon fluorescence (TPF) maps of the intensity and decay rate...
November 28, 2016: Optics Express
Yingbo Liu, Liang Zhou, Yanan Li, Ruiping Deng, Hongjie Zhang
High quantum yields (QY) and stable performances are prerequisites for implementing carbon dots in practical applications. In this study, we demonstrate that nitrogen-doped carbon dots (N-CDs), which were prepared via the hydrothermal treatment of citric acid (CA) and tris(hydroxymethyl)methyl aminomethane (Tris), have a high QY of 75%, together with excellent thermal and photo stability. These N-CDs deliver an excellent thermal stability performance over the temperature range of 25 °C to 95 °C, and even at a heating temperature of 90 °C for 360 min...
December 1, 2016: Nanoscale
Amirul Edham Roslee, Saifful Kamaluddin Muzakir, Jamil Ismail, Mashitah M Yusoff, Rajan Jose
This article addresses the heat capacity of quantum dots (QDs) using density functional theory (DFT). By analyzing the evolution of phonon density of states and heat capacity as CdSe clusters grow from a molecular cluster into larger quantum confined solids, we have shown that their heat capacity does not fit very well with the Debye T(3) model. We observed that the number of phonon modes, which is discrete, increases as the particles grow, and the dispersion relation shows a quadratic behavior in contrast to the bulk solids whose dispersion relation is linear and equal to the sound velocity...
December 1, 2016: Physical Chemistry Chemical Physics: PCCP
A S Minin, A V Belousova, L T Smolyuk, M V Ulitko, M A Uimin, I V Byzov
Interactions of bimodal (fluorescent and magnetic) nanoparticles with HeLa cells were studied. The nanoparticles, characterized by high magnetic moment and relaxing capacity, exhibited fluorescence sufficient for their use as labels in confocal microscopy and flow cytometry. Penetration of these nanoparticles into the cell depended on their surface charge: positively charged nanoparticles of this structure penetrated inside, while negatively charged particles were not found in the cells.
December 1, 2016: Bulletin of Experimental Biology and Medicine
S Bhuckory, L Mattera, K D Wegner, X Qiu, Y-T Wu, L J Charbonnière, P Reiss, N Hildebrandt
Compact and functional nanoparticle-antibody conjugates are of paramount importance for the development of quantum dot (QD)-based immunoassays. Here, we present a simple strategy to directly conjugate IgG, F(ab')2, and Fab antibodies via their endogenous disulfide groups directly to the inorganic ZnS shell of compact penicillamine-coated QDs. The functionality of the conjugates was demonstrated by terbium (Tb)-to-QD FRET immunoassays against prostate specific antigen in serum samples. Detection limits of 2...
November 30, 2016: Chemical Communications: Chem Comm
Jin Chang, Yuhei Ogomi, Chao Ding, Yao Hong Zhang, Taro Toyoda, Shuzi Hayase, Kenji Katayama, Qing Shen
The surface chemistry of colloidal quantum dots (QDs) plays an important role in determining the photoelectric properties of QD films and the corresponding quantum dot heterojunction solar cells (QDHSCs). To investigate the effects of the ligand structure on the photovoltaic performance and exciton dynamics of QDHSCs, PbS QDHSCs were fabricated by the solid state ligand exchange method with mercaptoalkanoic acid as the cross-linking ligand. Temperature-dependent photoluminescence and ultrafast transient absorption spectra show that the electronic coupling and charge transfer rate within QD ensembles were monotonically enhanced as the ligand length decreased...
November 30, 2016: Physical Chemistry Chemical Physics: PCCP
Yu Wang, Chin-Yi Chen, Gerhard Klimeck, Michelle Y Simmons, Rajib Rahman
No abstract text is available yet for this article.
November 30, 2016: Scientific Reports
M Frank Erasmus, Ksenia Matlawska-Wasowska, Ichiko Kinjyo, Avanika Mahajan, Stuart S Winter, Li Xu, Michael Horowitz, Diane S Lidke, Bridget S Wilson
The pre-B cell receptor (pre-BCR) is an immature form of the BCR critical for early B lymphocyte development. It is composed of the membrane-bound immunoglobulin (Ig) heavy chain, surrogate light chain components, and the signaling subunits Igα and Igβ. We developed monovalent quantum dot (QD)-labeled probes specific for Igβ to study the behavior of pre-BCRs engaged in autonomous, ligand-independent signaling in live B cells. Single-particle tracking revealed that QD-labeled pre-BCRs engaged in transient, but frequent, homotypic interactions...
November 29, 2016: Science Signaling
Alfred J Baca, Heather A Meylemans, Lawrence Baldwin, Lee R Cambrea, Ji Feng, Yadong Yin, M Joseph Roberts
AgInS2 (AIS) quantum dots (QDs) were synthesized via a thermal decomposition reaction with dodecylamine as the ligand to help stabilize the QDs. This reaction procedure is relatively easy to implement, scalable to large batches (up to hundreds of milligrams of QDs are produced), and a convenient method for the synthesis of chalcogenide QDs. Metal powders of AgNO3 and In(NO3)3, were used as the metal precursors while diethyldithiocarbamate was used as the sulfur source. The AIS QDs were characterized via transmission electron microscopy, atomic force microscopy, and energy dispersive x-ray spectroscopy...
January 6, 2017: Nanotechnology
Daniele Barettin, Matthias Auf der Maur, Aldo di Carlo, Alessandro Pecchia, Andrei F Tsatsulnikov, Alexei V Sakharov, Wsevolod V Lundin, Andrei E Nikolaev, Sergey O Usov, Nikolay Cherkashin, Martin J Hÿtch, Sergey Yu Karpov
The impact of electromechanical coupling on optical properties of light-emitting diodes (LEDs) with InGaN/GaN quantum-dot (QD) active regions is studied by numerical simulations. The structure, i.e. the shape and the average In content of the QDs, has been directly derived from experimental data on out-of-plane strain distribution obtained from the geometric-phase analysis of a high-resolution transmission electron microscopy image of an LED structure grown by metalorganic vapor-phase epitaxy. Using continuum [Formula: see text] calculations, we have studied first the lateral and full electromechanical coupling between the QDs in the active region and its impact on the emission spectrum of a single QD located in the center of the region...
January 6, 2017: Nanotechnology
Bingping Liu, Shihai Yan, Zhongqian Song, Mengli Liu, Xuqiang Ji, Wenrong Yang, Jingquan Liu
Herein, a conceptually new and straightforward aqueous route is described for the synthesis of hydroxyl- and amino-functionalized boron nitride quantum dots (BNQDs) with quantum yields (QY) as high as 18.3 % by using a facile bottom-up approach, in which a mixture of boric acid and ammonia solution was hydrothermally treated in one pot at 200 °C for 12 h. The functionalized BNQDs, with excellent photoluminescence properties, could be easily dispersed in an aqueous medium and applied as fluorescent probes for the detection of ferrous (Fe(2+) ) and ferric (Fe(3+) ) ions with excellent selectivity and low detection limits...
November 29, 2016: Chemistry: a European Journal
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