Search results for "DOTS"
showing 10 items of 181 documents
Blue luminescent amino-functionalized graphene quantum dots as a responsive material for potential detection of metal ions and malathion
2022
Large amounts of hazardous and toxic substances in the environment require non-toxic, cheap, easy, rapid, and sensitive methods for their detection. Blue luminescent graphene quantum dots (GQDs) were produced by electrochemical cleavage of graphite electrodes followed by gamma irradiation in the presence of ethylenediamine (EDA). Modified dots were able to detect metal ions (Co2+, Pd2+, Fe3+) due to photoluminescence quenching. The highest sensitivity was detected for the sample irradiated at a dose of 25 kGy. The limits of detection (LODs) were 1.79, 2.55, and 0.66 μmol L−1 for Co2+, Fe3+, and Pd2+, respectively. It was observed that GQDs irradiated at 200 kGy act as an ultra-sensitive tur…
Electroluminescence and transport properties in amorphous silicon nanostructures
2006
We report the results of a detailed study on the structural, electrical and optical properties of light emitting devices based on amorphous Si nanostructures. Amorphous nanostructures may constitute an interesting system for the monolithic integration of optical and electrical functions in Si ULSI technology. In fact, they exhibit an intense room temperature electroluminescence (EL), with the advantage of being formed at a temperature of 900 °C, while at least 1100 °C is needed for the formation of Si nanocrystals. Optical and electrical properties of amorphous Si nanocluster devices have been studied in the temperature range between 30 and 300 K. The EL is seen to have a bell-shaped trend …
Single-Exciton Amplified Spontaneous Emission in Thin Films of CsPbX3 (X = Br, I) Perovskite Nanocrystals
2019
CsPbX3 perovskite nanocrystals (PNCs) have emerged as an excellent material for stimulated emission purposes, with even more prospective applications than conventional colloidal quantum dots. However, a better understanding of the physical mechanisms responsible for amplified spontaneous emission (ASE) is required to achieve more ambitious targets (lasing under continuous wave optical or electrical excitation). Here, we establish the intrinsic mechanisms underlying ASE in PNCs of three different band gaps (CsPbBr3, CsPbBr1.5I1.5, and CsPbI3). Our characterization at cryogenic temperatures does not reveal any evidence of the biexciton mechanism in the formation of ASE. Instead, the measured …
Characterization of porous alumina membranes for efficient, real-time, flow through biosensing
2015
Abstract Nanofluidic sensing devices promise high performance by overcoming issues of mass transport of analyte molecules to the sensing surface, whilst micro-porous membranes promise high sensitivity due to a large surface for their capture. Anodic alumina (AAO) filter membranes allow the flow through of samples, and could be used as a convenient and readily available fluidic platform for the targeted delivering of analytes to bioreceptors immobilized on the pore walls. The relatively small pore dimensions, compared to fluidic diffusion lengths, promise highly efficient capture of analytes from the whole sample volume, enabling relatively fast sensing response times and the use of small sa…
Flow cytometry and spectral imaging multiphoton microscopy analysis of CD36 expression with quantum dots 605 of untreated and 7-ketocholesterol-treat…
2006
To evaluate CD36 expression with quantum dots 605 (QDs 605) on untreated and 7-ketocholesterol (7KC)-treated monocytic U937 cells by flow cytometry (FCM) and confocal and multiphoton laser scanning microscopy (CLSM).Cells were analyzed by CLSM, following flow cytometric quantification of CD36 expression and 7KC uptake. Image sequences were obtained by spectral analysis in monophoton and multiphoton CLSM and analyzed by the factor analysis of medical image sequences (FAMIS) algorithm to differentiate emission spectra. In CLSM analysis, cell deposits were screened in ultraviolet excitation modes to optimize the possibilities of QDs 605 and have the benefit of nuclei counterstaining by DAPI.FC…
Segmented Flow-Based Multistep Synthesis of Cadmium Selenide Quantum Dots with Narrow Particle Size Distribution
2015
A continuous-flow microreactor was used to synthetize II-VI semiconductor quantum dots (CdSe). In order to improve the size distribution of the nanoparticles, the synthesis was carried out in a two-step procedure. A seed solution was obtained in a separate nucleation step, followed by a controllable growth step. Quantum dots that are synthesized with the two-step method show a much narrower size distribution in comparison to those obtained in a conventional batch synthesis.
Highly Efficient Electron Transfer in a Carbon Dot–Polyoxometalate Nanohybrid
2020
Using solar radiation to fuel catalytic processes is often regarded as the solution to our energy needs. However, developing effective photocatalysts that are active under visible light has proven to be difficult, often due to the toxicity, instability, and high cost of suitable catalysts. We engineered a novel photoactive nanomaterial obtained by the spontaneous electrostatic coupling of carbon nanodots with [P2W18O62]6-, a molecular catalyst belonging to the class of polyoxometalates. While the former are used as photosensitizers, the latter was chosen for its ability to catalyze reductive reactions such as dye decomposition and water splitting. We find the electron transfer within the na…
Functionalization of Metal and Carbon Nanoparticles with Potential in Cancer Theranostics
2021
Cancer theranostics is a new concept of medical approach that attempts to combine in a unique nanoplatform diagnosis, monitoring and therapy so as to provide eradication of a solid tumor in a non-invasive fashion. There are many available solutions to tackle cancer using theranostic agents such as photothermal therapy (PTT) and photodynamic therapy (PDT) under the guidance of imaging techniques (e.g., magnetic resonance—MRI, photoacoustic—PA or computed tomography—CT imaging). Additionally, there are several potential theranostic nanoplatforms able to combine diagnosis and therapy at once, such as gold nanoparticles (GNPs), graphene oxide (GO), superparamagnetic iron oxide nanoparticles (SP…
Comparison of quantum dot-binding protein tags: Affinity determination by ultracentrifugation and FRET
2013
Abstract Background Hybrid complexes of proteins and colloidal semiconductor nanocrystals (quantum dots, QDs) are of increasing interest in various fields of biochemistry and biomedicine, for instance for biolabeling or drug transport. The usefulness of protein–QD complexes for such applications is dependent on the binding specificity and strength of the components. Often the binding properties of these components are difficult and time consuming to assess. Methods In this work we characterized the interaction between recombinant light harvesting chlorophyll a / b complex (LHCII) and CdTe/CdSe/ZnS QDs by using ultracentrifugation and fluorescence resonance energy transfer (FRET) assay exper…
Assembly and Separation of Semiconductor Quantum Dot Dimers and Trimers
2011
Repeated precipitation of colloidal semiconductor quantum dots (QD) from a good solvent by adding a poor solvent leads to an increasing number of QD oligomers after redispersion in the good solvent. By using density gradient ultracentrifugation we have been able to separate QD monomer, dimer, and trimer fractions from higher oligomers in such solutions. In the corresponding fractions QD dimers and trimers have been enriched up to 90% and 64%, respectively. Besides directly coupled oligomers, QD dimers and trimers were also assembled by linkage with a rigid terrylene diimide dye (TDI) and separated again by ultracentrifugation. High-resolution transmission electron micrographs show that the …