Search results for " photoluminescence"

showing 10 items of 77 documents

Rapid and eco-friendly synthesis of graphene oxide-silica nanohybrids

2014

The increasing interest in Graphene oxide (GO) is due to many issues: the presence of both sp2-conjugated atoms and oxygen-containing functional groups provides a strong hydrophilicity and the possibility to further functionalize it with other molecules (i.e. π-π interactions covalent attachment etc.) [1]. Furthermore since the GO is biocompatible and noncytotoxic many studies have been recently focused on the development of GO-based nanodevices for bioimaging DNA detection drug delivery. Due to their low cytotoxicity and large internal surface area silica nanoparticles have been taken into account as promising material for biolabeling and drug loading/delivery. Particular consideration has recently been demonstrated for GO-silica composites because of the potentialities for electrical applications their chemical inertia and stability toward ions exposure. The possibility to combine the extraordinary properties of GO and silica offers several advantages for the realization of nanoprobes for biological applications and of biosensor [12]. The strategy for the fabrication of GO-nanosilica nanohybrids can be schematized as follows: (i) synthesis of GO by oxidizing graphite powder with the method described by Marcano et al. [3] (ii) Preparation of oxygen-loaded silica nanoparticles by thermal treatments in controlled atmosphere in order to induce high NIR emission at 1272 nm from high purity silica nanoparticles. (iii) preparation of GrO-silica nanohybrid films via rapid solvent casting in water. The nanohybrids were tested by XPS FTIR Raman analysis UV photoluminescence analysis TGA Zeta potential measurements electrical tests AFM and SEM. Several nanohybrids were prepared by combining two different typologies of GO and two different samples of silica.
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Toward development of optical biosensors based on photoluminescence of TiO2 nanoparticles for the detection of Salmonella

2017

Quality control of food and agriculture production is an inseparable part of human safety and wellbeing. Salmonella infections belong to one of the most monitored pathogens in the world, therefore advanced determination of this pathogen can decrease the risks of human diseases caused by this microorganism. In this research we introduce a novel optical immunosensor for determination of Salmonella typhimurium. The immunosensor is based on Titanium dioxide (TiO2) nanoparticles deposited on glass substrates (glass/TiO2)center dot TiO2 nanoparticles exhibit an intense photoluminescence (PL) in the visible range of spectrum at room temperature. The direct immobilization of antibodies (anti-S-Ab) …

TiO2 nanoparticles; Photoluminescence based biosensor; Immunosensor; Salmonella infection; AntibodySalmonellaPhotoluminescenceMaterials scienceNanoparticleNanotechnology02 engineering and technology010402 general chemistrymedicine.disease_cause01 natural sciencesAnalytical Chemistrychemistry.chemical_compoundAnalytisk kemiMaterials ChemistrymedicineHuman safetyElectrical and Electronic EngineeringInstrumentationTio2 nanoparticlesMetals and Alloys021001 nanoscience & nanotechnologyCondensed Matter Physics0104 chemical sciencesSurfaces Coatings and FilmsElectronic Optical and Magnetic MaterialschemistryTitanium dioxideVisible range0210 nano-technologyBiosensorSensors and Actuators B: Chemical
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Photoluminescence Enhancement by Band Alignment Engineering in MoS 2 /FePS 3 van der Waals Heterostructures

2022

Single-layer semiconducting transition metal dichalcogenides (2H-TMDs) display robust excitonic photoluminescence emission, which can be improved by controlled changes to the environment and the chemical potential of the material. However, a drastic emission quench has been generally observed when TMDs are stacked in van der Waals heterostructures, which often favor the nonradiative recombination of photocarriers. Herein, we achieve an enhancement of the photoluminescence of single-layer MoS2 on top of van der Waals FePS3. The optimal energy band alignment of this heterostructure preserves light emission of MoS2 against nonradiative interlayer recombination processes and favors the charge t…

Transition metal dichalcogenide monolayersAlignment engineeringVan der Waals heterostructuresEnhanced photoluminescenceOptoelectronic tunabilityGeneral Materials ScienceMaterialsACS Applied Materials & Interfaces
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Antioxidative and Photo-Induced Effects of Different Types of N-Doped Graphene Quantum Dots.

2022

Due to the increasing number of bacterial infections and the development of resistivity toward antibiotics, new materials and approaches for treatments must be urgently developed. The production of new materials should be ecologically friendly considering overall pollution with chemicals and economically acceptable and accessible to the wide population. Thus, the possibility of using biocompatible graphene quantum dots (GQDs) as an agent in photodynamic therapy was studied. First, dots were obtained using electrochemical cutting of graphite. In only one synthetic step using gamma irradiation, GQDs were doped with N atoms without any reagent. Obtained dots showed blue photoluminescence, with…

antioxidantgraphene quantum dotsGraphene quantum dotsGamma-irradiationPhotodynamic therapygraphene quantum dots; N-doping; gamma-irradiation; photoluminescence; photodynamic therapy; antioxidant; antibacterial effectsphotodynamic therapygamma-irradiationAntibacterial effectsantibacterial effectsphotoluminescenceGeneral Materials ScienceAntioxidantPhotoluminescenceSettore CHIM/02 - Chimica FisicaN-dopingMaterials (Basel, Switzerland)
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Synthesis, structural and luminescent properties of Mn-doped calcium pyrophosphate (Ca2P2O7) polymorphs

2022

The study was partially funded by the Swedish Research Council FORMAS project “Utilization of solid inorganic waste from the aquaculture industry as wood reinforcement material for flame retardancy” (grant no. 2018-01198). Vilnius University is highly acknowledged for financial support from the Science Promotion Foundation (MSF-JM-5/2021). This project has also received funding from European Social Fund (project No 09.3.3-LMT-K-712-19-0069) under grant agreement with the Research Council of Lithuania (LMTLT). The authors acknowledge the Center of Spectroscopic Characterization of Materials and Electronic/Molecular Processes ("SPECTROVERSUM" www.spectroversum.ff.vu.lt ) at the Lithuanian Nat…

calcium pyrophosphate ; polymorphs ; Mn doping ; photoluminescence.Multidisciplinary:NATURAL SCIENCES::Physics [Research Subject Categories]Scientific Reports
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Engineered Ferritin with Eu3+ as a Bright Nanovector: A Photoluminescence Study

2022

Ferritin nanoparticles play many important roles in theranostic and bioengineering applications and have been successfully used as nanovectors for the targeted delivery of drugs due to their ability to specifically bind the transferrin receptor (TfR1, or CD71). They can be either genetically or chemically modified for encapsulating therapeutics or probes in their inner cavity. Here, we analyzed a new engineered ferritin nanoparticle, made of the H chain mouse ferritin (HFt) fused with a specific lanthanide binding tag (LBT). The HFt-LBT has one high affinity lanthanide binding site per each of the 24 subunits and a tryptophane residue within the tag that acts as an antenna able to transfer …

engineered ferritin photoluminescence europium nanovectorGeneral MedicinePhysical and Theoretical ChemistryBiochemistry
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Synthesis and characterization of perfluoroalkyl-pyrenes embedded in a polymethylmethacrylate matrix

2012

fluorinated molecules pyrene PMMA photochemical synthesis structural characterization photoluminescence
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Gamma-Ray-Induced Structural Transformation of GQDs towards the Improvement of Their Optical Properties, Monitoring of Selected Toxic Compounds, and …

2022

Structural modification of different carbon-based nanomaterials is often necessary to improve their morphology and optical properties, particularly the incorporation of N-atoms in graphene quantum dots (GQDs). Here, a clean, simple, one-step, and eco-friendly method for N-doping of GQDs using gamma irradiation is reported. GQDs were irradiated in the presence of the different ethylenediamine (EDA) amounts (1 g, 5 g, and 10 g) and the highest % of N was detected in the presence of 10 g. N-doped GQDs emitted strong, blue photoluminescence (PL). Photoluminescence quantum yield was increased from 1.45, as obtained for non-irradiated dots, to 7.24% for those irradiated in the presence of 1 g of …

graphene quantum dots3-amino-124-triazolegamma-irradiationGeneral Chemical Engineeringgraphene quantum dots; N-doping; gamma-irradiation; photoluminescence; carbofuran; 3-amino-124-triazole; detection; antibacterial effectsdetectionGeneral Materials Sciencephotoluminescenceantibacterial effectsSettore CHIM/02 - Chimica FisicaN-dopingcarbofuranNanomaterials (Basel, Switzerland)
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Optical Properties of Natural and Synthetic Minerals

2015

The results of investigation of optical absorption and photoluminescence (PL) of topaz, beryl and yttrium aluminium garnet crystals doped with different concentrations of transition ions exposed to fast neutron irradiation and electron irradiation are presented. We suppose that irradiation leads to the formation of two types of complex centers: "Me2+-F+ (or F) centre" and complex centers, which consist of a cation vacancy and an impurity (iron, manganese and chromium) ion. Exchange interaction between radiation defects and impurity ions during neutron or electron irradiation gives rise to appearance of additional absorption and luminescence band broadening in investigated crystals.

inorganic chemicalsMaterials sciencePhotoluminescenceAbsorption spectroscopyAnalytical chemistrytechnology industry and agriculturechemistry.chemical_compoundCondensed Matter::Materials SciencechemistryYttrium aluminium garnetImpurityVacancy defectElectron beam processingPhysics::Atomic and Molecular ClustersIrradiationAbsorption (chemistry)inorganic compounds; absorption spectra; photoluminescence; neutron irradiationNuclear chemistryEnvironment. Technology. Resources.
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Preparation of Nd:YAG Nanopowder in a Confined Environment

2007

Nanopowder of yttrium aluminum garnet (YAG, Y3Al5O12) doped with neodymium ions (Nd:YAG) was prepared in the water/cetyltrimethylammonium bromide/1-butanol/n-heptane system. Aluminum, yttrium, and neodymium nitrates were used as starting materials, and ammonia was used as a precipitating agent. Coprecipitate hydroxide precursors where thermally treated at 900 degrees C to achieve the garnet phase. The starting system with and without reactants was characterized by means of the small-angle neutron scattering technique. The system, without reactants, is constituted by a bicontinuous structure laying near the borderline with the lamellar phase region. The introduction of nitrates stabilizes th…

nanopowderswide angle x-ray scatteringAnalytical chemistrychemistry.chemical_elementMineralogyNeodymiummicroemulsionsYAG [Nd]Lamellar phasePhase (matter)transmission electron microscopyElectrochemistryGeneral Materials ScienceMicroemulsionYAG; nanopowders; syntheisi in confined environment; microemulsions; wide angle x-ray scattering; transmission electron microscopy; photoluminescence spectroscopy [Nd]Wide-angle X-ray scatteringSpectroscopySurfaces and InterfacesYttriumCondensed Matter PhysicsSmall-angle neutron scatteringchemistrysyntheisi in confined environmentphotoluminescence spectroscopyTransmission electron microscopyNdYAG microemulsion synthesis in confined environmentLangmuir
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