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Quantum dots

Valentina Zannier, Francesca Rossi, Daniele Ercolani, Lucia Sorba
The steady-state chemical composition of the In/Au alloy nanoparticles during isothermal growth of Au-assisted InAs and InP nanowires is different for the two materials. Therefore, when switching from one material to the other, to grow axial nanowire heterostructures, transient effects dominate during the time period of the nanoparticle reconfiguration. As a consequence, the precise control of the thickness of thin InP and InAs segments, which is fundamental for the realization of quantum dot structures and superlattices, can be very challenging...
December 11, 2018: Nanotechnology
Yingping Li, Yong Jia, Qi Zeng, Xiaohui Jiang, Zhengjun Cheng
We used thiamine nitrate (TN) as single material to fabricate nitrogen and sulfur co-doped carbon quantum dots (N,S-CQDs) with a quantum yield of 10.4% through one-pot hydrothermal method, and its properties were characterized by TEM, XPS, FTIR, fluorescence (FL) and UV-vis spectrophotometer, respectively. The fluorescence of N,S-CQDs was effectively quenched in the presence of vitamin B12 (VB12)/tartrazine due to Förster resonance energy transfer (FRET). Moreover, the rate (KT ) and efficiency (E%) of energy transfer from N,S-CQDs (as a donor) to VB12/tartrazine (as an acceptor) enhanced with increasing the concentrations of acceptor, and the KT and E% were also varied with the change of excitation wavelengths (from 338 to 408 nm)...
December 4, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Sicilia T Grady, Lorraine Britton, Katrin Hinrichs, Alan J Nixon, Ashlee E Watts
Mesenchymal stem cells (MSCs) improve the osteoarthritis condition, but the fate of MSCs after intra-articular injection is unclear. We used fluorescent nanoparticles (quantum dots; QDs) to track equine MSCs (QD-MSCs) in vivo after intra-articular injection to normal and osteoarthritic joints. One week after injection of QD-MSCs, unlabeled MSCs, or vehicle we determined the presence of QD-MSCs in synovium and articular cartilage histologically. In vitro, we evaluated the persistence of QDs in MSCs and whether QDs affected proliferation, immunophenotype or differentiation...
December 7, 2018: Journal of Tissue Engineering and Regenerative Medicine
Chi Hong Sum, Samantha Marisha Shortall, Jessica Antoinetta Nicastro, Roderick Slavcev
Microscopy allows for the characterization of small objects invisible to the naked eye, a technique that, since its conception, has played a key role in the development across nearly every field of science and technology. Given the nanometer size of the materials explored in the field of nanotechnology, the contributions of modern microscopes that can visualize these materials are indispensable, and the ever-improving technology is paramount to the future success of the field. This chapter will focus on four fundamental areas of microscopy used in the field of nanotechnology including fluorescence microscopy (Sect...
2018: Experientia. Supplementum
Lining Zhao, Wansong Zong, Hao Zhang, Rutao Liu
The toxic mechanism of cadmium-quantum dot (Cd-QDs) to organisms is still debating. In this paper, it was found that Cd-QDs could induce adverse effects to kidney by entering into cells in a time and dose manner and disturbing the redox balance in vivo. As a selenium containing protein, glutathione peroxidase3 (Gpx3) plays a crucial role in maintaining the balance of redox system. The decrease of Gpx3 activity might be related to the imbalance of redox system. Similar to the animal results, it was demonstrated that Gpx3 activity is also inhibited by Cd-QDs in vitro...
December 10, 2018: Toxicological Sciences: An Official Journal of the Society of Toxicology
Hongzhi Lu, Chunwei Yu, Shuai Quan, Shoufang Xu
Based on the inner filter effect and charge transfer dual response mechanism, a dual response ratiometric fluorescent probe (D-RFP) with two reversible signal changes for sensing H2O2 and glucose was developed. The D-RFP was proposed by embedding glycine-derived carbon dots (CDs) (λem = 400 nm) into silica nanoparticles and covalently linking CdTe quantum dots (QDs) (λem = 600 nm) onto the surface of silica nanoparticles. When silver nanoparticles (Ag NPs) were mixed with D-RFP, the fluorescence intensity of CDs can be quenched by Ag NPs via the inner filter effect...
December 11, 2018: Analyst
Yi Wei, Ziyong Cheng, Jun Lin
Correction for 'An overview on enhancing the stability of lead halide perovskite quantum dots and their applications in phosphor-converted LEDs' by Yi Wei et al., Chem. Soc. Rev., 2019, DOI: 10.1039/c8cs00740c.
December 11, 2018: Chemical Society Reviews
Piaopiao Chen, Shixin Yan, Erica Sawyer, Binwu Ying, Xiawei Wei, Zhengzhi Wu, Jia Geng
Ascorbic acid (AA) and alkaline phosphatase (ALP) serve as an important coenzyme and enzyme in multiple biological metabolism reactions, respectively, and abnormal levels of these substrates have been associated with several diseases. Herein, a new and simple fluorescence strategy has been developed for AA and ALP sensing by exploiting CdTe quantum dots (QDs) as an effective signal indicator. This method is mainly based on the selective fluorescence-quenching reaction between Ag+ and CdTe QDs, as opposed to silver nanoparticles (Ag NPs); Ag+ can be reduced to Ag NPs by AA...
December 10, 2018: Analyst
Gwénaëlle Lamri, Artur Movsesyan, Edite Figueiras, Jana B Nieder, Jean Aubard, Pierre-Michel Adam, Christophe Couteau, Nordin Felidj, Anne-Laure Baudrion
The control of quantum dot (QD) photoluminescence (PL) is a challenge for many applications. It is well known that plasmonic resonances can enhance this PL. In this work, we couple QDs with silver nanoparticles and immerse the system in a photochromic organic material. As these molecules are optical switches going from a transparent to a colored isomer by absorbing UV light, we observe on one hand a Förster Resonant Energy Transfer (FRET) between the QD emission and the absorbing isomer and on the other hand a plasmonic PL enhancement...
December 10, 2018: Nanoscale
Anna Shahmuradyan, Maryam Moazami-Goudarzi, Fasika Kitazume, George S Espie, Ulrich J Krull
A paper-based platform was investigated in which the selective detection of oligonucleotide targets by hybridization was accomplished via the enhancement of fluorescence emission from intrinsically labeled DNA probes that were immobilized on the surface of quantum dots (QDs). Multiple copies of a derivative of thiazole orange, an intercalating dye known to form non-emissive dimers, were conjugated to single-stranded oligonucleotide probes. Dimerization resulted in the formation of H-aggregates where excitonic interactions led to the suppression of fluorescence...
December 11, 2018: Analyst
Li-Juan Zhang, Li Xia, Hai-Yan Xie, Zhi-Ling Zhang, Dai-Wen Pang
Quantum dots (QDs) are a kind of quasi-zero-dimensional semiconductor nanocrystal, with a radius smaller than or close to their exciton Bohr radius. In 1977, Katzschmann observed the anomalous luminescence of particles with 1-5 nm size composed of II-VI family elements and proposed a relationship between band gap and particle size.1 This is the earliest report about QDs and quantum size effect. In the early 1980s, Elimov, Efros and Brus did a great deal of pioneering work on the quantum size effect in semiconductor nanocrystals...
December 11, 2018: Analytical Chemistry
Ahmed A H Abdellatif, Heba A Abou-Taleb, Ahmed A Abd El Ghany, Ilka Lutz, Abdellatif Bouazzaoui
Cancer may be difficult to target, however, if cancer targeted this provides the chance for a better and more effective treatment. Q uantum dots (Qdots) coated vapreotide (VAP) as a somatostatin receptors (SSTRs) agonist can be efficient targeting issue since may reduce side effects and increase drug delivery to the target tissue. This study highlights the active targeting of cancer cells by cells imaging with improving the therapeutic outcomes. VAP was conjugated to Qdots using amine-to-sulfhydryl crosslinker...
December 2018: Saudi Pharmaceutical Journal: SPJ: the Official Publication of the Saudi Pharmaceutical Society
Margaret Chern, Joshua C Kays, Shashi Bhuckory, Allison Dennis
Fluorescent sensors benefit from high signal-to-noise and multiple measurement modalities, allowing for a multitude of applications and flexibility of design. Semiconductor nanocrystal quantum dots (QDs) are excellent fluorophores for sensors because of their extraordinary optical properties. They have high thermal and photochemical stability compared to organic dyes or fluorescent proteins and are extremely bright due to their large molar cross-sections. In contrast to organic dyes, QD emission profiles are symmetric, with relatively low full width half maxima...
December 7, 2018: Methods and Applications in Fluorescence
Sandra Skorupska, Ilona Grabowska-Jadach
In this study, the cytotoxicity of CdTe quantum dots (QDs) of various dimensions was examined using the electroporation method. The influence of the size of QDs on normal and tumour cell viability after 24 h of incubation with nanomaterials was examined. The three human cell lines were chosen for the tests: A549 (a tumour cell line derived from the lung), MRC-5 (normal fibroblasts from the lung) and HaCaT (normal keratinocytes from the skin). Accordingly, we modelled the effect of nanocrystals on various human tissues because nanoparticles can be introduced into an organism through different routes...
December 1, 2018: Bioelectrochemistry
Dan Wang, Xian Xia, Shijuan Wu, Shixue Zheng, Gejiao Wang
Pseudomonas stutzeri TS44 was able to aerobically reduce Se(IV) into SeNPs and transform Se(IV)/Cd(II) mixture into CdSe-QDs. The SeNPs and CdSe-QDs were systematically characterized by surface feature analyses, and the molecular mechanisms of SeNPs and CdSe-QD formation in P. stutzeri TS44 were characterized in detail. In vivo, under 2.5 mmol/L Se(IV) exposure, GorA was essential for catalyzing of Se(IV) reduction rate decreased by 67% when the glutathione reductase gene gorA was disrupted, but it was not decreased in the glutathione synthesis rate-limiting gene gshA mutated strain compared to the wild type...
November 23, 2018: Journal of Hazardous Materials
Niloy Chandra Sarker, Shafiqur Rahman, Md Saidul Borhan, Parthiban Rajasekaran, Swadeshmukul Santra, Ali Ozcan
A number of mitigation techniques exist to reduce the emissions of pollutant gases and greenhouse gases (GHGs) from anaerobic storage of livestock manure. Nanoparticle (NP) application is a promising mitigating treatment option for pollutant gases, but limited research is available on the mode of NP application and their effectiveness in gaseous emission reduction. In this study, zinc silica nanogel (ZnSNL), copper silica nanogel (CuSNL), and N-acetyl cysteine (NACL) coated zinc oxide quantum dot (Qdot) NPs were compared to a control lacking NPs...
February 2019: Journal of Environmental Sciences (China)
Prashant Kumar, Jing Liu, Maithilee Motlag, Lei Tong, Yaowu Hu, Xinyu Huang, Arkamita Bandopadhyay, Swapan K Pati, Joseph Irudayaraj, Lei Ye, Gary J Cheng
Following in the emerging of graphene and many two-dimensional (2D) materials, the most exciting applications come from stacking them into 3D devices, promising many excellent possibilities for neoteric electronics and optoelectronics. Layers of semiconductors, insulators and conductors can be stacked to form van der Waals heterostructures, after the weak bonds formed between the layers. However, the interlayer coupling in these heterostructures is usually hard to modulate, resulting in difficulty to realize their emerging optical or electronic properties...
December 10, 2018: Nano Letters
Xiao Luo, Tao Ding, Xue Liu, Yuan Liu, Kaifeng Wu
We introduce and demonstrate the concept of quantum-cutting luminescent solar concentrators (QC-LSCs) using Yb3+-doped perovskite nanocrystals. These NCs feature a photoluminescence quantum yield approaching 200% and virtually zero self-absorption loss of PL photons, defining a new upper limit of 150% for the internal optical efficiency (ηint) of LSCs that is almost independent of LSC sizes. An unoptimized 25 cm2 QC-LSC fabricated from Yb3+-doped CsPbCl3 NCs already displayed an ηint of 118.1±6.7% that is 2-fold higher than previous records using Mn2+-doped quantum dots (QDs)...
December 10, 2018: Nano Letters
Piumi Y Liyanage, Regina M Graham, Raja R Pandey, Charles C Chusuei, Keenan J Mintz, Yiqun Zhou, James K Harper, Wei Wu, Athula H Wikramanayake, Steven Vanni, Roger M Leblanc
In contrast to the recent immense attention in carbon nitride quantum dots (CNQDs) as a heteroatom-doped carbon quantum dot (CQD), their biomedical applications have not thoroughly investigated. The targeted cancer therapy is a prominently researched area in biomedical field. Here, the ability of CNQDs as a selective bioimaging nanomaterial was investigated to assist the targeted cancer therapy. CNQDs were first synthesized using four different precursor sets, involving urea derivatives and the characteristics were compared to select the best candid material for bioapplications...
December 10, 2018: Bioconjugate Chemistry
Aarti Mehta, Jino Im, Bo Hyung Kim, Hanul Min, Riming Nie, Sang Il Seok
Recently, lead-tin-based alloyed halide perovskite quantum dots (QDs) with improved stability and less toxicity have been introduced. However, the perovskite QDs containing tin are still unstable and exhibit low photoluminescence quantum yields (PLQYs), owing to the presence of defects in the alloyed system. Here, we have attempted to introduce sulfur anions (S2- ) into the host lattice (MAPb0.75 Sn0.25 Br3 ) as a promising route to stable alloyed perovskite QDs with improved stability and PLQY. In this study, we used elemental sulfur as a sulfur precursor...
December 11, 2018: ACS Nano
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