| 1. |
- AlSalhi, M S., et al.
(author)
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Growth and characterization of ZnO nanowires for optical applications
- 2013
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In: Laser physics. - : Institute of Physics Publishing (IOPP). - 1054-660X .- 1555-6611. ; 23:6
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Journal article (peer-reviewed)abstract
- In the present work, cerium oxide CeO2 nanoparticles were synthesized by the sol-gel method and used for the growth of ZnO nanorods. The synthesized nanoparticles were studied by x-ray diffraction (XRD) and Raman spectroscopic techniques. Furthermore, these nanoparticles were used as the seed layer for the growth of ZnO nanorods by following the hydrothermal growth method. The structural study of ZnO nanorods was carried out by means of field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM) and XRD techniques. This study demonstrated that the grown ZnO nanorods are well aligned, uniform, of good crystal quality and have diameters of less than 200 nm. Energy dispersive x-ray (EDX) analysis revealed that the ZnO nanorods are composed only of zinc, cerium as the seed atom, and oxygen atoms, with no other impurities in the grown nanorods. Moreover, a photoluminescence (PL) approach was applied for the optical characterization, and it was observed that the near-band-edge (NBE) emission was the same as that of the zinc acetate seed layer, however the green and orange/red emission peaks were slightly raised due to possibly higher levels of defects in the cerium oxide seeded ZnO nanorods. This study provides an alternative approach for the controlled synthesis of ZnO nanorods using cerium oxide nanoparticles as the seed nucleation layer, improving both the morphology of the nanorods and the performance of devices based upon them.
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| 2. |
- Bossi, Alesandra, et al.
(author)
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Ice matrix inreconfigurable microfluidic systems
- 2013
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In: Laser physics. - : Institute of Physics (IOP). - 1054-660X .- 1555-6611. ; 23:7
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Journal article (peer-reviewed)abstract
- Microfluidic devices find many applications in biotechnologies. Here, we introduce a flexible and biocompatible microfluidic ice-based platform with tunable parameters and configuration of microfluidic patterns that can be changed multiple times during experiments. Freezing and melting of cavities, channels and complex relief structures created and maintained in the bulk of ice by continuous scanning of an infrared laser beam are used as a valve action in microfluidic systems. We demonstrate that pre-concentration of samples and transport of ions and dyes through the open channels created can be achieved in ice microfluidic patterns by IR laser-assisted zone melting. The proposed approach can be useful for performing separation and sensing processes in flexible reconfigurable microfluidic devices.
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| 4. |
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| 5. |
- Fakhar-e-Alam, M., et al.
(author)
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Phototoxic effects of zinc oxide nanowires (ZnO NWs) complexed with 5-ALA in RD cell line
- 2011
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In: Laser physics. - : MAIK Nauka/Interperiodica. - 1054-660X .- 1555-6611. ; 21:12, s. 2165-2170
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Journal article (peer-reviewed)abstract
- In this current study, we have manifested the photosensitizing effects of zinc oxide nanowires (ZnO NWs) in dark as well as under ultra violet light exposure with 240 nm of UV region, using human muscle cancer (Rhybdomyosarcoma cells, RD) as in vitro experimental model. We have fabricated ZnO-NWs on the tip of borosilicate glass capillaries (0.5 mu m diameter) and were conjugated using 5-aminolevulinic acid (ALA) for the efficient intracellular drug delivery. When ZnO NWs were applied on tumor localizing drugs with non ionizing illumination, then excited drug liberates reactive oxygen species (ROS), effecting mitochondria and nucleus resulting in cell necrosis within few minutes. During investigations, we observed that when ZnO-NWs grown on intracellular tip was excited by using 240 nm of UV light, as a resultant 625 nm of emitted red light were used as appetizer in the presence of 5-ALA for chemical reaction, which produces singlet oxygen, responsible for cell necrosis. Morphological changes of necrosed cells were examined under microscopy. Moreover, Viability of controlled and treated RD cells with optimum dose of light (UV-Visible) has been assessed by MTT assay as well as reactive oxygen species (ROS) detection.
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| 6. |
- Fakhar-e-Alam, M, et al.
(author)
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Role of ALA sensitivity in HepG2 cell in the presence of diode laser
- 2011
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In: LASER PHYSICS. - : Springer Science Business Media. - 1054-660X. ; 21:5, s. 972-980
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Journal article (peer-reviewed)abstract
- 5-aminolevulinic acid (ALA) being an amazing second generation photosensitizer was studied as photodamaging drug on hepatocellular carcinoma (HepG2) cells. The mentioned photosensitizer is converted to PpIX in HepG2 cells in vitro, inducing haem in the cell causing generation of singlet oxygen leading to cell apoptosis. Cell uptake of 5-ALA was evaluated with different concentrations (ranging from 0-800 mu g/ml) for 0-49 h incubation period. ALA administered in HepG2 cells is converted into Protoporphyrin IX (PpIX) which has a short half life and constitute a good hematoporphyrin derivative (HPD). Cytotoxicity of ALA in dark and cellular viability without ALA in the presence of light was studied, showing minimal toxic effects in dark with no photodamaging effect on mentioned cells in absence of ALA were observed. The optimal uptake of photosensitizer (5-ALA) in HepG2 cells was investigated by means of spectrophotometeric measurements, cellular viability was determined by means of neutral red assay (NRA). It was observed that with different concentrations (0-800 mu g/ml) of ALA or light doses (0-160 J/cm(2)), there were no significant effect on cellular viability when studied independently. The novel of photocytotoxic study indicates that light dose of 120 J/cm(2) produces convincing Photodynamic therapy (PDT) results for HepG2 cells incubated with 262 mu g/ml of 5-ALA deducting that HepG2 cell line is sensitive to ALA mediated PDT. Finally morphological changes in HePG2 cells were determined before and after ALA-mediated PDT by confocal microscopy.
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| 7. |
- Fakhar-e-Alam, M., et al.
(author)
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Tumoricidal Effects of Nanomaterials in HeLa Cell Line
- 2011
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In: Laser physics. - : MAIK Nauka/Interperiodica. - 1054-660X .- 1555-6611. ; 21:11, s. 1978-1988
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Journal article (peer-reviewed)abstract
- The current study exhibits the cellular response of HeLa (cervical cancer) cells to metal oxides ultrafine nanomaterials e.g. manganese dioxide nanowires (MnO(2) NRs), iron oxide nanoparticles (Fe(2)O(3) NPs) and zinc oxide nanorods (ZnO NRs) as bare and as conjugated with photosensitizers. For cytotoxic evaluations, the cellular morphology, (MTT) assay, reactive oxygen species (ROS) production were used for cases with and without photo sensitizer as well illuminated with UV-visible laser exposed conditions. Three different photosensitizers were tested. These are 5-aminolevulinic acid (5-ALA), Photofrin (R), and protoporphyrin dimethyl ester (PPDME). Significant loss in cell viability was noted with 100-500 mu g/ml in bare and conjugated forms of the metal oxides used. The effect was insignificant with lower concentrations (0.05-50 mu g/ml). While notable anticancer effect of 5-ALA under 30 J/cm(2) of diode laser irradiation was noted as compared to other photo sensitizer. By increasing the UV irradiation time of labeled cells, generation of ROS was observed, indicating the possibility of achieving efficient photodynamic therapy (PDT).
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| 8. |
- Svanberg, Sune
(author)
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Optical Analysis of Trapped Gas-Gas in Scattering Media Absorption Spectroscopy
- 2010
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In: Laser Physics. - 1054-660X. ; 20:1, s. 68-77
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Journal article (peer-reviewed)abstract
- An overview of the new field of Gas in Scattering Media Absorption Spectroscopy (GASMAS) is presented. The technique investigates sharp gas spectral signatures, typically 10000 times sharper than those of the host material, in which the gas is trapped in pores or cavities. The presence of pores causes strong multiple scattering. GASMAS combines narrow-band diode-laser spectroscopy, developed for atmospheric gas monitoring, with diffuse media optical propagation, well-known from biomedical optics. Several applications in materials science, food packaging, pharmaceutics and medicine have been demonstrated. So far molecular oxygen and water vapour have been studied around 760 and 935 nm, respectively. Liquid water, an important constituent in many natural materials, such as tissue, has a low absorption at such wavelengths, and this is also true for haemoglobin, making propagation possible in many natural materials. Polystyrene foam, wood, fruits, food-stuffs, pharmaceutical tablets, and human sinus cavities ( frontal, maxillary and mastoideal) have been studied, demonstrating new possibilities for characterization and diagnostics. Transport of gas in porous media ( diffusion) can be studied by first subjecting the material to, e. g., pure nitrogen, and then observing the rate at which normal, oxygen-containing air, reinvades the material. The conductance of the passages connecting a sinus with the nasal cavity can be objectively assessed by observing the oxygen gas dynamics when flushing the nose with nitrogen. Drying of materials, when liquid water is replaced by air and water vapour, is another example of dynamic processes which can be studied. The technique has also been extended to remote-sensing applications (LIDAR-GASMAS or Multiple-Scattering LIDAR).
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