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Quantum dot

Feng Li, Chao Nie, Lai You, Xiao Jin, Qin Zhang, Yuancheng Qin, Feng Zhao, Yinglin Song, Zhongping Chen, Qinghua Li
White light emitting diodes (WLEDs) based on quantum dots (QDs) are emerging as robust candidates for white light source, however they are suffering from the problem of energy loss resulted from the re-absorption and self-absorption among the employed QDs of different peak wavelengths. It still remains a challenging task to construct WLEDs based on single-phase QD emitters. Here, CdS QDs with short synthesis time is introduced to the fabrication of WLEDs. With short synthesis time, on one hand, CdS QD of small diameter with blue emission can be obtained...
February 22, 2018: Nanotechnology
Yan Li, Shu-Xiao Li, Fei Gao, Hai-Ou Li, Gang Xu, Ke Wang, Di Liu, Gang Cao, Ming Xiao, Ting Wang, Jianjun Zhang, Guang-Can Guo, Guo-Ping Guo
Realizing a strong coupling between spin and resonator is an important issue for scalable quantum computation in semiconductor systems. Benefiting from the advantages of strong spin-orbit coupling strength and long coherence time, the Ge hut wire, which is proposed to be site-controlled grown for scalability, is considered as a promising candidate to achieve this goal. Here we present a hybrid architecture in which an on-chip superconducting microwave resonator is coupled to the holes in a Ge quantum dot. The charge stability diagram can be obtained from the amplitude and phase response of the resonator independently from the DC transport measurement...
February 22, 2018: Nano Letters
Kevin J McHugh, Lihong Jing, Adam M Behrens, Surangi Jayawardena, Wen Tang, Mingyuan Gao, Robert Langer, Ana Jaklenec
Approximately 1.7 million new cases of cancer will be diagnosed this year in the United States leading to 600 000 deaths. Patient survival rates are highly correlated with the stage of cancer diagnosis, with localized and regional remission rates that are much higher than for metastatic cancer. The current standard of care for many solid tumors includes imaging and biopsy with histological assessment. In many cases, after tomographical imaging modalities have identified abnormal morphology consistent with cancer, surgery is performed to remove the primary tumor and evaluate the surrounding lymph nodes...
February 22, 2018: Advanced Materials
Xiang-Bin Su, Ying Ding, Ben Ma, Ke-Lu Zhang, Ze-Sheng Chen, Jing-Lun Li, Xiao-Ran Cui, Ying-Qiang Xu, Hai-Qiao Ni, Zhi-Chuan Niu
The device characteristics of semiconductor quantum dot lasers have been improved with progress in active layer structures. Self-assembly formed InAs quantum dots grown on GaAs had been intensively promoted in order to achieve quantum dot lasers with superior device performances. In the process of growing high-density InAs/GaAs quantum dots, bimodal size occurs due to large mismatch and other factors. The bimodal size in the InAs/GaAs quantum dot system is eliminated by the method of high-temperature annealing and optimized the in situ annealing temperature...
February 21, 2018: Nanoscale Research Letters
Jian He, Jing Xu, Ping Wu, Lingfeng Liao, Huatao Quan, Jing Kang, Yongquan Tian, Yaoyun Tang
This study explored the 605 nm carboxyl of water-soluble quantum dots to assess the practicability of the nasopharyngeal carcinoma marker EBNA1 antibody. We used 605 nm carboxyl water-soluble quantum dots and nasopharyngeal carcinoma EBNA1 antigen in 1-(3-dimethylaminopropyl-3-2-ethylcarbonimine hydrochloride to generate quantum dot-labeled antigen. Gel imaging system showed that serum group and 60 patients with nasopharyngeal carcinoma had significant differences in 30 cases of normal adult serogroup brightness, Levene test in the two groups ELISA absorbance value was P<0...
March 2018: Oncology Letters
Markus Pfeiffer, Paola Atkinson, Armando Rastelli, Oliver G Schmidt, Harald Giessen, Markus Lippitz, Klas Lindfors
Plasmon resonant arrays or meta-surfaces shape both the incoming optical field and the local density of states for emission processes. They provide large regions of enhanced emission from emitters and greater design flexibility than single nanoantennas. This makes them of great interest for engineering optical absorption and emission. Here we study the coupling of a single quantum emitter, a self-assembled semiconductor quantum dot, to a plasmonic meta-surface. We investigate the influence of the spectral properties of the nanoantennas and the position of the emitter in the unit cell of the structure...
February 21, 2018: Scientific Reports
Zhide Zhou, Le Zhao, Zhihong Wang, Wen Xue, Yunxiao Wang, Yong Huang, Jintao Liang, Jiejing Chen, Guiyin Li
Early diagnosis of diabetes yields significant clinical benefits. The serum level of 1,5‑anhydroglucitol (1,5‑AG) has been a new biochemical marker for postprandial hyperglycemia. In this study, a simple colorimetric method for 1,5‑AG detection has been designed based on highly efficient peroxidase mimetic activity of GQDs and enzyme-catalyzed reaction. By the catalytic action of pyranose oxidase (PROD), the 1,5‑AG was oxidized to 1,5‑anhydrofuctose and H2 O2 . The GQDs in the presence of H2 O2 exhibited highly efficient catalytic activity toward the oxidation of 3, 3', 5, 5'‑tetramethylbenzidine (TMB) to a blue colored product...
February 18, 2018: International Journal of Biological Macromolecules
Guoneng Cai, Zhengzhong Yu, Rongrong Ren, Dianping Tang
A competitive-displacement reaction strategy based on target-induced dissociation of gold nanoparticles-coated graphene nanosheet (AuNPs/GN) from CdS quantum dots-functionalized mesoporous titanium dioxide (CdS QDs/TiO2) was designed for the sensitive photoelectrochemical (PEC) aptasensing of prostate-specific antigen (PSA) through the exciton-plasmon interaction (EPI) between CdS QDs and AuNPs. To construct such an aptasensing system, capture DNA was initially conjugated covalently onto CdS QDs/TiO2-modified electrode, and then AuNPs/GN-labeled PSA aptamer was bound onto biofunctionalized CdS QDs/TiO2 via hybridization chain reaction of partial bases with capture DNA...
February 21, 2018: ACS Sensors
William J Peveler, W Russ Algar
Fluorescence is a powerful and sensitive tool in biological detection, used widely for cellular imaging and in vitro molecular diagnostics. Over time, three prominent conventions have emerged in the design of fluorescent biosensors: a sensor is ideally specific for its target, only one fluorescence signal turns on or off in response to the target, and each target requires its own sensor and signal combination. These are conventions but not requirements, and sensors that break with one or more of these conventions can offer new capabilities and advantages...
February 20, 2018: ACS Chemical Biology
Javad Fouladi Oskouei, Saeid Shojaei, Liu Zheng
The effects of quantum confinement on excitons in a parabolic quantum dots of monolayer transition metal dichalcogenides (TMDC QDs) are investigated within massive Dirac fermion model. A giant spin-valley coupling of the TMDC QDs obtained, which are larger than that of monolayer TMDC sheets and in consistent with the recent experimental measurements. The exciton transition energy and the binding energy are calculated and found that the strong quantum confinement results in extremely high exciton binding energies...
February 20, 2018: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Mariadoss Asha Jhonsi, Devanesan Arul Ananth, Gayathri Nambirajan, Thilagar Sivasudha, Rekha Yamini, Soumen Bera, Arunkumar Kathiravan
In recent years, quantum dots (QDs) are one of the most promising nanomaterials in life sciences community due to their unexploited potential in biomedical applications; particularly in bio-labeling and sensing. In the advanced nanomaterials, carbon dots (CDs) have shown promise in next generation bioimaging and drug delivery studies. Therefore the knowledge of the exact nature of interaction with biomolecules is of great interest to designing better biosensors. In this study, the interaction between CDs derived from tamarind and calf thymus DNA (ct-DNA) has been studied by vital spectroscopic techniques, which revealed that the CDs could interact with DNA via intercalation...
February 8, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Hong-Bin Yu, Zi-Jia Rong, Ying Lu, Xin-Hong Wang, Xu-Biao Luo
To improve the efficiency of photocatalysts, a composite of CeO2-quantum dots/Cu2O (CeO2-QDs/Cu2O) was prepared through a one-step hydrothermal procedure in alkaline carbonate solution with Cu2(OH)2CO3 and Ce(NO3)3. 6H2O as precursors and glucose as reducing agent. The morphologies and structures of the prepared photocatalysts were well characterized utilizing Transmission Electron Microscopy (TEM), X-ray Diffractometry (XRD), X-ray Photoelectron Spectroscopy (XPS) and UV-Vis Diffuse Reflectance Spectrophotometer (DRS)...
August 1, 2018: Journal of Nanoscience and Nanotechnology
Xia Yang, Yan-Qing Yu, Ling-Zhi Peng, Yan-Mei Lei, Ya-Qin Chai, Ruo Yuan, Ying Zhuo
Sensitive and feasible electrochemiluminescence (ECL) bioassay relies on the achievement of the ECL signal tags with high and stable signal intensity. In this work, strong electrochemiluminescence (ECL) emission was achieved from metal organic framework (MOFs) accelerator enriched Quantum Dots (CdTe), which was applied as an efficient ECL signal tag for trace biomarker detection. It is particularly worth noting that a novel mechanism to drastically enhance the ECL intensity of CdTe is established because the isoreticular metal organic framework-3 (IRMOF-3) with 2-amino terephthalic acid (2-NH2-BDC) as organic ligand is not only devoted for loading large amount of CdTe via encapsulating effect and internal/external decoration, but also as a novel co-reactant accelerator for promoting the conversion of co-reactant S2O82- into the sulfate radical anion (SO4•-), further boosting the electrochemiluminescence (ECL) emission of CdTe...
February 19, 2018: Analytical Chemistry
Qi Xu, Hao Yuan, Xulin Dong, Yan Zhang, Muhammad Asif, Zehua Dong, Wenshan He, Jinghua Ren, Yimin Sun, Fei Xiao
The development of high-efficient technologies for cancer biomarkers detection has attracted tremendous research effort for its great clinic significance. In this work, we designed a new type of flexible and robust nanohybrid microelectrode by modifying carbon fiber with dual nanoenzyme, i.e., AuPd alloy nanoparticles (AuPd-ANPs) decorated graphene quantum dots (GQDs) assembly, and explored its practical application in electrochemical sensing system for sensitive detection of cancer biomarker hydrogen peroxide (H2 O2 ) in human breast cancer cells and tissue...
February 9, 2018: Biosensors & Bioelectronics
Svetlana Pleskova, Elza Mikheeva, Ekaterina Gornostaeva
Quantum dots are nanoparticles, which due to their unique physical and chemical (first of all optical) properties, are promising in biology and medicine. There are many ways for quantum dots synthesis, both in the form of nanoislands self-forming on the surfaces, which can be used as single-photon emitters in electronics for storing information, and in the form of colloidal quantum dots for diagnostic and therapeutic purposes in living systems. The paper describes the main methods of quantum dots synthesis and summarizes medical and biological ways of their use...
2018: Advances in Experimental Medicine and Biology
Xiaowei Li, Hiro Minamimoto, Kei Murakoshi
The vibrational characteristics of ligand-capped lead sulfide (PbS) quantum dots (QDs) were clarified via electrochemical surface-enhanced Raman spectroscopy (EC-SERS) using a hybridized system of gold (Au) nanodimers and PbS QDs under electrochemical potential control. Enhanced electromagnetic field caused by the coupling of QDs with plasmonic Au nanodimers allowed the characteristic behavior of the ligand oleic acid (OA) on the PbS QD surface to be detected under electrochemical potential control. Binding modes between the QDs and OA molecules were characterized using synchronous two-dimensional correlation spectra at distinct electrochemical potentials, confirming that the bidentate bridging mode was probably the most stable mode even under relatively negative potential polarization...
February 7, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Jungmin Lee, Xinyi Feng, Ou Chen, Moungi G Bawendi, Jun Huang
We have developed a strategy for synthesizing immediately activable, water-soluble, compact (∼10-12 nm hydrodynamic diameter) quantum dots with a small number of stable and controllable conjugation handles for long distance delivery and subsequent biomolecule conjugation. Upon covalent conjugation with engineered monovalent streptavidin, the sample results in a population consisting of low-valency quantum dots. Alternatively, we have synthesized quantum dots with a small number of biotin molecules that can self-assemble with engineered divalent streptavidin via high-affinity biotin-streptavidin interactions...
February 16, 2018: Nanoscale
Minsu Kim, Kangwon Lee, Ji Eon Kwon, Won Gun Koh
In this study, we developed an enzyme-based miniaturized fluorescence biosensor to detect paraoxon, one of the most well-known neurotoxic organophosphorus compounds (OPs). The biosensor was fabricated with poly(ethylene glycol) (PEG) hydrogel microarrays that entrapped acetylcholinesterase (AChE) and quantum dots (QDs) as fluorescence reporters. Metal-enhanced fluorescence (MEF) was utilized to amplify the fluorescence signal, which was achieved by decorating QDs on the surface of silica-coated silver nanoparticles (Ag@Silica)...
February 16, 2018: Biofabrication
Xiao-Qing Luo, Zeng-Zhao Li, Jun Jing, Wei Xiong, Tie-Fu Li, Ting Yu
We theoretically investigate the spectral features of tunneling-induced transparency (TIT) and Autler-Townes (AT) doublet and triplet in a triple-quantum-dot system. By analyzing the eigenenergy spectrum of the system Hamiltonian, we can discriminate TIT and double TIT from AT doublet and triplet, respectively. For the resonant case, the presence of the TIT does not exhibit distinguishable anticrossing in the eigenenergy spectrum in the weak-tunneling regime, while the occurrence of double anticrossings in the strong-tunneling regime shows that the TIT evolves to the AT doublet...
February 15, 2018: Scientific Reports
Duc Nguyen, Joshua J Goings, Huy A Nguyen, Joseph Lyding, Xiaosong Li, Martin Gruebele
We previously demonstrated that we can image electronic excitations of quantum dots by single-molecule absorption scanning tunneling microscopy (SMA-STM). With this technique, a modulated laser beam periodically saturates an electronic transition of a single nanoparticle, and the resulting tunneling current modulation ΔI(x 0 , y 0 ) maps out the SMA-STM image. In this paper, we first derive the basic theory to calculate ΔI(x 0 , y 0 ) in the one-electron approximation. For near-resonant tunneling through an empty orbital "i" of the nanostructure, the SMA-STM signal is approximately proportional to the electron density φ i x 0 ,y 0 2 of the excited orbital in the tunneling region...
February 14, 2018: Journal of Chemical Physics
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