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https://www.readbyqxmd.com/read/29793133/an-ultrasensitive-and-selective-electrochemical-aptasensor-based-on-rgo-mwcnts-chitosan-carbon-quantum-dot-for-the-detection-of-lysozyme
#1
Behzad Rezaei, Hamid Reza Jamei, Ali Asghar Ensafi
An aptamer-based method is described for the electrochemical determination of lysozyme. A glassy carbon electrode was modified with a nanocomposite composed of reduced graphene oxide (rGO), multi-walled carbon nanotubes (MWCNTs), chitosan (CS), and a synthesized carbon quantum dot (CQD) from CS. The composition of the nanocomposite (rGO-MWCNT/CS/CQD) warrants a high surface-to-volume ratio, high conductivity, high stability, and great electrocatalytic activity. This nanocomposite provides a suitable site for better immobilization of aptamers due to the existence of many amino and carboxyl functional groups, and remaining oxygen-related defects properties in rGO...
May 9, 2018: Biosensors & Bioelectronics
https://www.readbyqxmd.com/read/29792675/electron-phonon-coupling-and-resonant-relaxation-from-1d-and-1p-states-in-pbs-quantum-dots
#2
Eric R Kennehan, Grayson S Doucette, Ashley R Marshall, Christopher Grieco, Kyle T Munson, Matthew C Beard, John B Asbury
Observations of the hot-phonon bottleneck, which is predicted to slow the rate of hot carrier cooling in quantum confined nanocrystals, have been limited to date for reasons that are not fully understood. We used time-resolved infrared spectroscopy to directly measure higher energy intraband transitions in PbS colloidal quantum dots. Direct measurements of these intraband states permitted detailed analysis of the electronic overlap of the quantum confined states that may influence their relaxation processes...
May 24, 2018: ACS Nano
https://www.readbyqxmd.com/read/29792664/tricolor-white-light-emitting-carbon-dots-with-multiple-cores-shell-structure-for-wled-application
#3
Tianyi Zhang, Feifei Zhao, Li Li, Bin Qi, Dongxia Zhu, Jianhua Lü, Changli Lü
The past few years have witnessed the rapid development of carbon dots (CDs) due to their outstanding optical properties and a wide range of applications. However, the design and control of CDs with long-wavelength and multicolor emission are still huge challenges to be addressed for their practical use in different fields. Here, novel nitrogen doped multiple-cores@shell structured CDs with tricolor emissions of red, green and blue were constructed via one pot hydrothermal method from citric acid (CA) and 5-amino-1,10-phenanthroline (Aphen) as reactants and the growth process of CDs was monitored with the reaction time in the synthetic system...
May 24, 2018: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/29792333/characterisation-of-a-scalable-donor-based-singlet-triplet-qubit-architecture-in-silicon
#4
Prasanna Pakkiam, Matthew Gregory House, Dr Matthias Koch, Michelle Y Simmons
We present a donor based quadruple quantum dot device, designed to host two singlet-triplet qubits fabricated by scanning tunnelling microscope lithography, with just two leads per qubit. The design is geometrically compact with each pair of dots independently controlled via one gate and one reservoir. The reservoirs both supply electrons for the dots and measure the singlet-triplet state of each qubit via dispersive sensing. We verify the locations of the four phosphorus donor dots via an electrostatic model of the device...
May 24, 2018: Nano Letters
https://www.readbyqxmd.com/read/29791135/optically-active-cdse-dot-cds-rod-nanocrystals-with-induced-chirality-and-circularly-polarized-luminescence
#5
Jiaji Cheng, Junjie Hao, Haochen Liu, Jiagen Li, Junzi Li, Xi Zhu, Xiaodong Lin, Kai Wang, Tingchao He
Ligand-induced chirality in semiconductor nanocrystals (NCs) has attracted attention because of the tunable optical properties of the NCs. Induced circular dichroism (CD) has been observed in CdX (X = S, Se, Te) NCs and their hybrids, but circularly polarized luminescence (CPL) in these fluorescent nanomaterials has been seldom reported. Herein, we describe the successful preparation of L- and D-cysteine-capped CdSe-dot/CdS-rods (DRs) with tunable CD and CPL behaviors and a maximum anisotropic factor (glum) of 4...
May 23, 2018: ACS Nano
https://www.readbyqxmd.com/read/29791131/sensitivity-enhancement-of-fret-immunoassays-by-multiple-antibody-conjugation-on-quantum-dots
#6
Giacomo Annio, Travis Jennings, Oya Tagit, Niko Hildebrandt
Quantum dots (QDs) are not only advantageous for color-tuning, improved brightness, and high stability, but their nanoparticle surfaces also allow for the attachment of many biomolecules. Because IgG antibodies (ABs) are in the same size range of biocompatible QDs and the AB orientation after conjugation to the QD is often random, it is difficult to predict if few or many ABs per QD will lead to an efficient AB-QD conjugate. This is particularly true for homogeneous Förster resonance energy transfer (FRET) sandwich immunoassays, for which the ABs on the QD must bind a biomarker that needs to bind a second AB-FRET-conjugate...
May 23, 2018: Bioconjugate Chemistry
https://www.readbyqxmd.com/read/29790559/pbte-quantum-dots-as-electron-transfer-intermediates-for-the-enhanced-hydrogen-evolution-reaction-of-amorphous-mos-x-tio-2-nanotube-arrays
#7
Shiyuan Gao, Bin Wang, Xinyu Liu, Zhanhu Guo, Zhongqing Liu, Yichao Wang
Amorphous molybdenum sulfides (a-MoSx) have been demonstrated as economic and efficient hydrogen evolution catalysts for water splitting. Further improvements of their hydrogen evolution reaction (HER) activities could be achieved by coupling them with appropriate electron transfer intermediates via interfacial engineering. In this study, a novel ternary composite electrode comprising PbTe quantum dots (QDs), a-MoSx and TiO2 nanotube arrays (TNAs) was successfully fabricated by a facile combination of successive ionic layer adsorption and reaction (SILAR) and electrodeposition routes...
May 23, 2018: Nanoscale
https://www.readbyqxmd.com/read/29790557/controlling-the-magic-size-of-white-light-emitting-cdse-quantum-dots
#8
Sheng Dai, Yu-Sheng Su, Shu-Ru Chung, Kuan-Wen Wang, Xiaoqing Pan
White light-emitting quantum dots (QDs) have shown brilliant prospects as a white-light source in solid-state lighting devices, however their commercial application is limited by their low fluorescence quantum yield (QY). Here, we report a facile thermal pyrolyzed organometallic route to synthesize white-light emitting CdSe QDs with enhanced QY, by employing a particular non-coordinating solvent and long carbon chain amine. By clarifying the three distinct growing stages of CdSe nanocrystals, we are able to determine the critical growth parameters for high quality magic size QDs...
May 23, 2018: Nanoscale
https://www.readbyqxmd.com/read/29790552/quantum-dot-polymer-conjugates-for-stable-luminescent-displays
#9
Sushant Ghimire, Anjali Sivadas, Ken-Ichi Yuyama, Yuta Takano, Raju Francis, Vasudevanpillai Biju
The broad absorption of light in the UV-Vis-NIR region and the size-based tunable photoluminescence color of semiconductor quantum dots make these tiny crystals one of the most attractive antennae in solar cells and phosphors in electrooptical devices. One of the primary requirements for such real-world applications of quantum dots is their stable and uniform distribution in optically transparent matrices. In this work, we prepare transparent thin films of polymer-quantum dot conjugates, where CdSe/ZnS quantum dots are uniformly distributed at high densities in a chitosan-polystyrene copolymer (CS-g-PS) matrix...
May 23, 2018: Nanoscale
https://www.readbyqxmd.com/read/29790493/quantum-dot-conjugated-nanobodies-for-multiplex-imaging-of-protein-dynamics-at-synapses
#10
Souvik Modi, Nathalie F Higgs, David Sheehan, Lewis D Griffin, Josef T Kittler
Neurons communicate with each other through synapses, which show enrichment for specialized receptors. Although many studies have explored spatial enrichment and diffusion of these receptors in dissociated neurons using single particle tracking, much less is known about their dynamic properties at synapses in complex tissue like brain slices. Here we report the use of smaller and highly specific quantum dots conjugated with a recombinant single domain antibody fragment (VHH fragment) against green fluorescent protein to provide information on diffusion of adhesion molecules at the growth cone and neurotransmitter receptors at synapses...
May 23, 2018: Nanoscale
https://www.readbyqxmd.com/read/29789854/theoretical-study-on-the-optical-and-electronic-properties-of-graphene-quantum-dots-doped-with-heteroatoms
#11
Jianguang Feng, Hongzhou Dong, Beili Pang, Feifei Shao, ChunKai Zhang, Liyan Yu, Lifeng Dong
The effects of four heteroatoms (B, N, P, and S) with three doping patterns on graphene quantum dots (GQDs) are systematically investigated using time-dependent density functional theory (TD-DFT). The absorption spectra and HOMO-LUMO gaps are quantitatively analyzed to study the correlations between the optical properties and heteroatom doping of doped GQDs. Heteroatom doping can endow GQDs with various new optical and structural properties, depending on the dopants and doping configurations. Compared with the absorption spectra of pristine GQD, both N and S surface doping demonstrate a slight blue shift, whereas B and P doping lead to a blue shift for edge-doped GQDs with heteroatoms in a pentatomic ring...
May 23, 2018: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/29789656/distribution-of-different-surface-modified-carbon-dots-in-pumpkin-seedlings
#12
Kun Qian, Huiyuan Guo, Guangcai Chen, Chuanxin Ma, Baoshan Xing
The distribution of surface modified carbon dots (CDs) in the pumpkin seedlings was studied by visualization techniques and their potential phytotoxicity was investigated at both the physiological and biochemical levels. The average size of carbon dots was approximately 4 nm. The fluorescent peaks of bared CDs, CD-PEI and CD-PAA were between 420 nm and 500 nm, indicating CDs could emit blue and green fluorescence. Fluorescent images showed that all three types of CDs could accumulate in the pumpkin roots and translocate to the shoots, although the distribution pattern of each CDs was obviously different...
May 22, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29788963/cervical-small-cell-carcinoma-frequently-presented-in-multiple-high-risk-hpv-infection-and-often-associated-with-other-type-of-epithelial-tumors
#13
Peifeng Li, Jing Ma, Xiumin Zhang, Yong Guo, Yixiong Liu, Xia Li, Danhui Zhao, Zhe Wang
BACKGROUND: Small cell carcinoma of the uterine cervix is a rare and highly malignant tumor, and its etiopathogenesis is strongly related to high-risk HPV infections. METHODS: The clinicopathological data of 30 cases of cervical primary small cell carcinoma were retrospectively analyzed. In situ hybridization, polymerase chain reaction and reverse dot-blot hybridization were employed to detect HPV DNA in both small cell carcinoma and other coexisting epithelial tumors...
May 22, 2018: Diagnostic Pathology
https://www.readbyqxmd.com/read/29787949/liquid-phase-laser-ablation-synthesis-of-graphene-quantum-dots-from-carbon-nano-onions-comparison-with-chemical-oxidation
#14
Rosemary L Calabro, Dong-Sheng Yang, Doo Young Kim
Graphene quantum dots (GQDs) have been synthesized reproducibly by chemical oxidation (CO) of carbon nano-onions (nCNOs) and a one-step pulsed laser ablation (LA) of nCNOs in deionized water. The photoluminescence (PL) spectra show that the LA-GQDs have blue shifted emission relative to the CO-GQDs which is attributed to the effects of both particle sizes and surface functional groups. The CO-GQDs have an average diameter of 4.1(8) nm and a thickness corresponding to two or three graphene layers, while the LA-GQDs have an average diameter of 1...
May 9, 2018: Journal of Colloid and Interface Science
https://www.readbyqxmd.com/read/29787674/single-quantum-dot-tracking-reveals-serotonin-transporter-diffusion-dynamics-are-correlated-with-cholesterol-sensitive-threonine-276-phosphorylation-status-in-primary-midbrain-neurons
#15
Danielle M Bailey, Mackenzie A Catron, Oleg Kovtun, Robert L Macdonald, Qi Zhang, Sandra J Rosenthal
Serotonin transporter (SERT) terminates serotonin signaling in the brain by enabling rapid clearance of the neurotransmitter. SERT dysfunction has been associated with a variety of psychiatric disorders, including depression, anxiety, and autism. Visualizing SERT behavior at the single molecule level in endogenous systems remains a challenge. In this study, we utilize quantum dot (QD) single particle tracking (SPT) to capture SERT dynamics in primary rat midbrain neurons. Membrane microenvironment, specifically membrane cholesterol, plays a key role in SERT regulation and has been found to affect SERT conformational state...
May 24, 2018: ACS Chemical Neuroscience
https://www.readbyqxmd.com/read/29787492/dot-motion-perception-in-young-adult-emmetropes-and-myopes
#16
Hui-Ying Kuo, David A Atchison, Katrina Leanne Schmid
SIGNIFICANCE: Central motion perception, as assessed by minimum displacement detection, was reduced in highly myopic eyes. Peripheral motion detection may be influenced by myopia, particularly in the inferior-nasal retina. PURPOSE: Motion discrimination is a complex visual task processed mainly via the magnocellular pathway. We investigated whether it is affected in myopia. METHODS: Ninety young adults aged 18 to 28 years participated: 30 emmetropes (spherical equivalent refractions +1...
May 21, 2018: Optometry and Vision Science: Official Publication of the American Academy of Optometry
https://www.readbyqxmd.com/read/29787486/a-random-dot-computer-video-game-improves-stereopsis
#17
Juan A Portela-Camino, Santiago Martín-González, Javier Ruiz-Alcocer, Igor Illarramendi-Mendicute, Rafaela Garrido-Mercado
SIGNIFICANCE: Currently, treatments for amblyopia are occlusion or penalization of the stronger fellow eye. Fewer than 30% of patients improve stereoacuity using these treatments. In order to improve these outcomes, this group proposes a treatment to stimulate the stereoacuity through perceptual learning in a game format for use at home. PURPOSE: The aim of this study was to determine whether perceptual learning with random dot stimuli (RDS) in the form of a computer video game improves stereopsis in patients with a history of amblyopia...
May 21, 2018: Optometry and Vision Science: Official Publication of the American Academy of Optometry
https://www.readbyqxmd.com/read/29787230/wavefunction-engineering-in-cdse-pbs-core-shell-quantum-dots
#18
Brian M Wieliczka, Alexey Leonid Kaledin, William E Buhro, Richard A Loomis
The synthesis of epitaxial CdSe/PbS core/shell quantum dots (QDs) is reported. The PbS shell grows in a rock salt structure on the zinc blende CdSe core, thereby creating a crystal structure mismatch through additive growth. Absorption and photoluminescence (PL) band edge features shift to lower energies with increasing shell thickness, but remain above the CdSe bulk band gap. Nevertheless, the profiles of the absorption spectra vary with shell growth, indicating that the overlap of the electron and hole wavefunctions is changing significantly...
May 22, 2018: ACS Nano
https://www.readbyqxmd.com/read/29786723/a-highly-sensitive-and-fast-graphene-nanoribbon-cspbbr-3-quantum-dot-phototransistor-with-enhanced-vertical-metal-oxide-heterostructures
#19
Xiang Liu, Wenjian Kuang, Haibing Ni, Zhi Tao, Qianqian Huang, Jing Chen, Qingquan Liu, Jianhua Chang, Wei Lei
Although recent breakthroughs in reported graphene-based phototransistors with embedded quantum dots (QDs) have definitely been astonishing, there are still some obstacles in their practical use with regard to their electrical and optical performances. We show that through optimization of the vertical graphene nanoribbon (GNR)/QD/IGZO heterostructure and the ultrahigh efficiency of CsPbBr3 QDs, it is possible to significantly increase the on/off ratio (>103), the subthreshold slope (S.S., 0.9 V dec-1), the device's field effect mobility (μFET, 13 cm-1 V-1 S-1) and other electrical properties...
May 22, 2018: Nanoscale
https://www.readbyqxmd.com/read/29786630/effect-of-cadence-on-time-trial-performance-in-recreational-female-cyclists
#20
Patricia L Graham, Robert F Zoeller, Patrick L Jacobs, Michael A Whitehurst
Graham, PL, Zoeller, RF, Jacobs, PL, and Whitehurst, MA. Effect of cadence on time trial performance in recreational female cyclists. J Strength Cond Res 32(6): 1739-1744, 2018-The impact of pedaling cadence on cycling performance remains unresolved especially in female cyclists. The purpose of this study was to determine the effect of cadence on time trial (TT) performance in recreational female cyclists. Ten recreational female cyclists volunteered to participate in this study. Subjects performed 3 exercise sessions: 1 to assess peak oxygen uptake (V[Combining Dot Above]O2peak) and 2 TTs...
June 2018: Journal of Strength and Conditioning Research
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