Random Lasers Based on Organic-Inorganic Hybrids

2002 ◽  
Vol 726 ◽  
Author(s):  
E.P. Giannelis ◽  
A. Stasinopoulos ◽  
M. Psyllaki ◽  
G. Zacharakis ◽  
R. N. Das ◽  
...  
Keyword(s):  
Polymer Matrix ◽  
Light Trapping ◽  
Fluorescence Emission ◽  
Laser Action ◽  
Threshold Value ◽  
Flat Panel Displays ◽  
Inorganic Nanocomposites ◽  
Modified Zno Nanoparticles ◽  
Surface Modified ◽  
Strong Scattering

AbstractLaser action is demonstrated in organic/inorganic nanocomposites consisting of pristine and surface-modified ZnO nanoparticles dispersed in an optically inert polymer matrix. The semiconductor particles feature simultaneously gain behavior and strong scattering ability, whereas the polymer matrix provides better processability and mechanical robustness. When excited by a laser pulse of appropriately short duration (pico- to nanoseconds), the composites give off fluorescence emission, which is strongly amplified as a result of light trapping due to multiple scattering. This laser action is manifested as a dramatic increase in the emitted light intensity accompanied by a significant spectral and temporal narrowing above a threshold value of the pumping laser intensity. Applications may include brighter flat-panel displays, inexpensive lasers for communications, military countermeasures, and lasers for search and rescue operations.

Surface Modification of the ZnO Nanoparticles with γ-Aminopropyltriethoxysilane and Study of Their Photocatalytic Activity, Optical Properties and Antibacterial Activities

2016 ◽  
Vol 14 (3) ◽  
pp. 785-794 ◽  
Author(s):  
Nurun Nahar Rabin ◽  
Jannatul Morshed ◽  
Hashi Akhter ◽  
Md. Saidul Islam ◽  
Md. Asjad Hossain ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
Surface Modification ◽  
Zno Nanoparticles ◽  
Photoelectron Spectroscopy ◽  
Dye Degradation ◽  
Antibacterial Activities ◽  
Bet Analysis ◽  
Modified Zno Nanoparticles ◽  
Grafted Nanoparticles ◽  
Surface Modified

Abstract Surface modification of Zinc oxide nanoparticles (ZnO) with γ-aminopropyltriethoxy silane (APTES) was investigated. Successful surface modification of the nanoparticles was confirmed experimentally by X-ray Photoelectron Spectroscopy (XPS) and Fourier transform infrared spectroscopy (FT-IR). The effect of the surface modifier concentration on the grafting density and surface area was studied by CHN elemental analysis and Brunauer–Emmett–Teller (BET) analysis. The photocatalytic activity and UV shielding ability of the surface-modified particles prepared in water-ethanol solvent in the presence of the surface modifiers were compared to those of non-modified particles. As a case study, It was observed by methylene blue (MB) dye degradation experiment that the photocatalytic activity in the presence of modified nanoparticles was lower than that observed with non-modified ZnO nanoparticles. Dispersion stability tests visually showed that APTES grafted nanoparticles had acquired better stability than non-modified ZnO nanoparticles in aqueous solution.

A ratiometric fluorescence strategy based on polyethyleneimine surface-modified carbon dots and Eosin Y for ultrasensitive determination of protamine and trypsin.

The Analyst ◽  
2022 ◽  
Author(s):  
Wenying Sun ◽  
Feng Zhang ◽  
Mengke Wang ◽  
Nan Wang ◽  
Guannan Wang ◽  
...  
Keyword(s):  
Electrostatic Interaction ◽  
Carbon Dots ◽  
Detection System ◽  
Fluorescence Emission ◽  
Eosin Y ◽  
Ratiometric Fluorescence ◽  
Surface Modified ◽  
Emission Detection ◽  
Positively Charged

In this work, we established a novel and ultrasensitive dual-signal fluorescence emission detection system of protamine and trypsin based on the electrostatic interaction between polyethyleneimine (PEI) surface-modified positively charged carbon...

Human Vascular Endothelial Cells in Primary Cell Culture for the Evaluation of Nanoparticle Bioadhesion

2006 ◽  
Vol 6 (9) ◽  
pp. 3303-3309 ◽  
Author(s):  
Christoph Löhbach ◽  
Dirk Neumann ◽  
Claus-Michael Lehr ◽  
Alf Lamprecht
Keyword(s):  
Drug Delivery ◽  
Cell Culture ◽  
Endothelial Cells ◽  
Covalent Binding ◽  
Particle Diameter ◽  
Fluorescence Emission ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Human Endothelial Cells ◽  
Surface Modified

Nanoparticles (NP) are employed in various therapeutic approaches for innovative drug delivery strategies. Among them, there is drug delivery to the brain and sustained release forms for intravenous drug delivery. In order to optimize drug carriers and to elucidate involved mechanisms such as bioadhesion and cellular uptake, NP were surface modified and analyzed for their interaction with human endothelial cells in cell culture. Fluorescently labeled NP of different diameters (50 to 1000 nm) were surface modified either by simple adsorption of chitosan or by covalent binding to the lectin ulex europaeus agglutinin and thereafter applied to human endothelial cells for different incubation periods. After incubation with NP the binding of NP was quantified directly by the fluorescence emission signals from the cell layers. In order to visualize the binding behaviour, NP were localized three-dimensionally in the cell layer by confocal laser scanning microscopy. Cell binding experiments in phosphate buffer were observed to be particle size dependent with the 50 nm NP showing the highest binding percentage over all experiments. Binding decreased with increasing particle diameter and shorter incubation interval. The adhesion was further enhanced by NP surface modifications in the order blank < chitosan < lectin. The presence of plasma proteins enhanced the adhesiveness of chitosan coated NP, while the binding of lectin coated NP was inhibited. Experiments at 4 °C indicated the involvement of an active process in the binding of NP to endothelial cells.

scholarly journals Surfactant Incorporated Co Nanoparticles Polymer Composites with Uniform Dispersion and Double Percolation

2017 ◽  
Vol 2017 ◽  
pp. 1-6 ◽  
Author(s):  
Tajamal Hussain ◽  
Mirza Nadeem Ahmad ◽  
Aneela Nawaz ◽  
Adnan Mujahid ◽  
Farrukh Bashir ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Polymer Matrix ◽  
Threshold Value ◽  
Filler Concentration ◽  
Physical Interaction ◽  
Uniform Dispersion ◽  
Uv Visible ◽  
Filler Particles ◽  
Lcr Meter ◽  
Co Nanoparticles

Series of Cobalt nanoparticles incorporated polymethylmethacrylate composites in the presence and absence of dodecyl-benzene-sulphonic acid (DBSA-CoNPs/PMMA and CoNPs/PMMA, resp.) were synthesized by solution mixing methodology. UV-visible and FTIR techniques were used to confirm the formation of nanocomposite. UV-visible spectra of the composites showed the incorporation of filler particles in the polymer matrix. On the other hand, FTIR spectra indicated the physical interaction between the two phases of the composite. Moreover, the electrical nature of the composites was studied by plotting graphs between electrical conductivity (measured using LCR meter at 100 kHz) and contents of the filler particles as introduced in the polymer matrix. An increase in electrical conductivity was first observed with increasing filler concentration up to the critical percolation threshold value (0.5% for DBSA-CoNPs/PMMA and 1% for CoNPs/PMMA), which then dropped upon further increments in the filler content. However, at higher concentrations, a second jump in the conductivity was observed in case of DBSA-CoNPs/PMMA composites.

Optical, thermal and combustion properties of self-colored polyamide nanocomposites reinforced with azo dye surface modified ZnO nanoparticles

2017 ◽  
Vol 416 ◽  
pp. 628-638 ◽  
Author(s):  
Mohsen Hajibeygi ◽  
Meisam Shabanian ◽  
Mehrdad Omidi-Ghallemohamadi ◽  
Hossein Ali Khonakdar
Keyword(s):  
Zno Nanoparticles ◽  
Azo Dye ◽  
Combustion Properties ◽  
Modified Zno Nanoparticles ◽  
Surface Modified

Nanomagnetic Poly(vinyl alcohol) Hydrogels

2013 ◽  
Vol 829 ◽  
pp. 539-543 ◽  
Author(s):  
Sima Asa'di ◽  
Masoud Frounchi ◽  
Susan Dadbin
Keyword(s):  
Magnetic Nanoparticles ◽  
Polymer Matrix ◽  
Vinyl Alcohol ◽  
Biomedical Applications ◽  
Nanocomposite Films ◽  
Poly Vinyl Alcohol ◽  
X Ray Diffraction ◽  
Modified Magnetic Nanoparticles ◽  
Gamma Irradiated ◽  
Surface Modified

Surface modified magnetic nanoparticles (M-NPs) were synthetized and stabilized in poly (vinyl-alcohol) solution. The solutions with various magnetic nanoparticles contents were gamma-irradiated and magnetic poly (vinyl-alcohol) (M-PVA) hydrogels were synthesized. The magnetic hydrogels and also the un-irradiated magnetic poly (vinyl alcohol) nanocomposite films were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), Fourier transform infrared spectroscopy (FTIR) and mechanical measurement. The M-NPs were uniformly dispersed in the polymer matrix due to a strong interaction between the surface-modified M-NPs and polymer matrix. Physical properties of the M-PVA hydrogels, including gel fraction and equilibrium water content were measured to evaluate the applicability of these hydrogels for biomedical applications. XRD, FTIR and VSM results indicated that there are important changes in crystalline, chemical and magnetic properties of hydrogels, arising from irradiation.

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