| 1. |
- Willander, Magnus, et al.
(författare)
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Applications of Zinc Oxide Nanowires for Bio-photonics and Bio-electronics
- 2011
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Ingår i: Proceedings of SPIE Volume 7940. - Bellingham, Washington, USA : SPIE - International Society for Optical Engineering. - 9780819484772
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Using zinc oxide (ZnO) nanostructures, nanorods (NRs) and nanoparticles (NPs) grown on different substrates (sub-micrometer glass pipettes, thin silver wire and on plastic substrate) different bio-sensors were demonstrated. The demonstrated sensors are based on potentiometric approach and are sensitive to the ionic metals and biological analyte in question. For each case a selective membrane or enzyme was used. The measurements were performed for intracellular environment as well as in some cases (cholesterol and uric acid). The selectivity in each case is tuned according to the element to be sensed. Moreover we also developed photodynamic therapy approach based on the use of ZnO NRs and NPs. Necrosis/apoptosis was possible to achieve for different types of cancerous cell. The results indicate that the ZnO with its UV and white band emissions is beneficial to photodynamic therapy technology.
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| 2. |
- Batool, S S, et al.
(författare)
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Silica nanofibers based impedance type humidity detector prepared on glass substrate
- 2013
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Ingår i: Vacuum. - : Elsevier. - 0042-207X .- 1879-2715. ; 87, s. 1-6
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Tidskriftsartikel (refereegranskat)abstract
- Impedance type relative humidity detector is fabricated by depositing electrospun silica nanofibers on glass substrate. The silica nanofibers with an average diameter similar to 150 nm and length similar to 100 mu m were used. Thermogravimetric and differential scanning calorimetric analysis confirm that the accurate annealing temperature is 500 degrees C for complete removal of PVP. Humidity detecting devices were fabricated by defining titanium electrodes on top of the silica nanofibers. The performance of silica nanofibers humidity detectors was tested by AC electrical measurements at 40-90% relative humidity. The response and the recovery times were 5 s and 3 s, respectively, between 40% and 90% relative humidity. Contribution of dipoles, space charge polarization, relaxation of these dipoles and low frequency dispersion phenomenon were observed during impedance measurements.
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| 3. |
- Gabery, Sanaz, et al.
(författare)
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Characterization of a rat model of Huntington's disease based on targeted expression of mutant huntingtin in the forebrain using adeno-associated viral vectors.
- 2012
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Ingår i: European Journal of Neuroscience. - : Wiley. - 1460-9568 .- 0953-816X. ; 36:6, s. 2789-2800
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Tidskriftsartikel (refereegranskat)abstract
- Huntington's disease (HD) is a fatal neurodegenerative disorder caused by an expanded CAG repeat in the huntingtin (htt) gene. Neuropathology is most severe in the striatum and cerebral cortex. As mutant htt is ubiquitously expressed, it has not been possible to establish clear structure-to-function relationships for the clinical aspects. In the present study, we have injected recombinant adeno-associated viral vectors of serotype 5 (rAAV5) expressing an 853-amino-acid fragment of htt with either 79 (mutant) or 18 (wild-type) glutamines (Q) in the dorsal striatum of neonatal rats to achieve expression of htt in the forebrain. Rats were followed for 6 months and compared with control rats. Neuropathological assessment showed long-term expression of the green fluorescent protein (GFP) transgene (used as a marker protein) and accumulation of htt inclusions in the cerebral cortex with the rAAV5-htt-79Q vectors. We estimated that around 10% of NeuN-positive cells in the cerebral cortex and 2% of DARPP-32 neurons in the striatum were targeted with the GFP-expressing vector. Formation of intracellular htt inclusions was not associated with neuronal loss, gliosis or microglia activation and did not lead to altered motor activity or changes in body weight. However, the same mutant htt vector caused orexin loss in the hypothalamus - another area known to be affected in HD. In conclusion, our results demonstrate that widespread forebrain expression of mutant htt can be achieved using rAAV5-vectors and suggest that this technique can be further explored to study region-specific effects of mutant htt or other disease-causing genes in the brain.
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| 4. |
- Imran, Z., et al.
(författare)
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Excellent humidity sensing properties of cadmium titanate nanofibers
- 2013
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Ingår i: Ceramics International. - : Elsevier. - 0272-8842 .- 1873-3956. ; 39:1, s. 457-462
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Tidskriftsartikel (refereegranskat)abstract
- We report humidity sensing characteristics of CdTiO3 nanofibers prepared by electrospinning. The nanofibers were porous having an average diameter and length of similar to 50-200 nm and similar to 100 mu m, respectively. The nanofiber humidity sensor was fabricated by defining aluminum electrodes using photolithography on top of the nanofibers deposited on glass substrate. The performance of the CdTiO3 nanofiber humidity sensor was evaluated by AC electrical characterization from 40% to 90% relative humidity at 25 degrees C. The frequency of the AC signal was varied from 10(-1) to 10(6) Hz. Fast response time and recovery time of 4 s and 6 s were observed, respectively. The sensor was highly sensitive and exhibited a reversible response with small hysteresis of less than 7%. Long term stability of the sensor was confirmed during 30 day test. The excellent sensing characteristics prove that the CdTiO3 nanofibers are potential candidate for use in high performance humidity sensors.
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| 5. |
- Israr, Muhammad Qadir, et al.
(författare)
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Structural characterization and biocompatible applications of graphene nanosheets for miniaturization of potentiometric cholesterol biosensor
- 2011
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Ingår i: Journal of Biosensors & Bioelectronics. - : OMICS Publishing Group. - 2155-6210. ; 2:3
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Tidskriftsartikel (refereegranskat)abstract
- The potentiometric cholesterol biosensor based on graphene nanosheets has been successfully miniaturized. Cholesterol oxidase (ChOx) has been immobilized onto graphene nanosheets exfoliated on copper wire through the process of physical adsorption,. The presented potentiometric biosensor renders effective selectivity and sensitivity (~82 mV/decade) for the detection of cholesterol biomolecules in 1 × 10−6 M to 1 × 10−3 M logarithmic range and quick output response within ~ 4 sec. The stability and reusability of the biosensor has also been investigated for the above mentioned range of cholesterol concentrations. The enzyme activity measurements on graphene nanosheets are studied using UV-Visible and FTIR spectrophotometers. Additionally, the functioning of the presented biosensor is studied for a range of temperatures (15-70 °C) and pH values (4-9).
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| 6. |
- Israr Qadir, Muhammad, et al.
(författare)
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Cathodoluminescence characterization of ZnO nanorods synthesized by chemical solution and of its conversion to ellipsoidal morphology
- 2014
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Ingår i: Journal of Materials Research. - : Cambridge University Press (CUP): STM Journals. - 0884-2914 .- 2044-5326. ; 29:20, s. 2425-2431
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Tidskriftsartikel (refereegranskat)abstract
- A facile and reproducible low-temperature (80 degrees C) solution route has been introduced to synthesize ZnO ellipsoids on silicon substrate without any pretreatment of the substrate or organic/inorganic additives. Scanning electron microscopy, transmission electron microscopy, and x-ray diffraction spectroscopy are performed to analyze the structural evolution, the single crystalline nature, and growth orientation at different stages of the synthetic process. The sequential formation mechanisms of heterogeneous nucleation in primary and secondary crystal growth behaviors have been discussed in detail. The presented results reveal that the morphology of micro/nanostructures with desired features can be optimized. The optical properties of grown structures at different stages were investigated using cathodoluminescence (CL). The monochromatic CL images were recorded to examine the UV and visible band emission contributions from the different positions of the intermediate and final structures of the individual ZnO ellipsoid. Significant enhancement in the defect level emission intensity at the central position of the structure reveals that the quality of the material improves as the reaction time is extended.
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| 7. |
- Israr Qadir, Muhammad, et al.
(författare)
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Fabrication of ZnO nanodisks from structural transformation of ZnO nanorods through natural oxidation and their emission characteristics
- 2014
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Ingår i: Ceramics International. - : Elsevier. - 0272-8842 .- 1873-3956. ; 40:1, s. 2435-2439
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Tidskriftsartikel (refereegranskat)abstract
- An environmentally benign natural oxidation based synthetic technique has been developed to grow and transform the ZnO nanorods into nanodisks at a very mild temperature of 55 degrees C with excellent features of its novelty and reproducibility. Metallic zinc foil and formamide solution have been utilized as substrate and reacting solution, respectively, for the growth of ZnO nanostructures. The optimized values of temperature, concentration of formamide and the reaction time are achieved to obtain the controlled and desired nanoscale morphologies. Detailed mechanism of the structural transformation of the nanorods into nanodisks has been discussed. Strong ultraviolet emission peak along with the much weaker deep level defects related emission has been realized in the microphotoluminescence spectrum. A visible red-shift and decrease in the intensity of ultraviolet peak are observed with increasing range of temperature from 20 to 300 K.
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| 8. |
- Jamil-Rana, Sadaf, et al.
(författare)
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Naturally oxidized synthesis of ZnO dahlia-flower nanoarchitecture
- 2014
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Ingår i: Ceramics International. - : Elsevier. - 0272-8842 .- 1873-3956. ; 40:8, s. 13667-13671
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Tidskriftsartikel (refereegranskat)abstract
- Three dimensional ZnO dahlia-flowers have been engineered at room temperature relying on natural oxidation based aqueous chemical synthetic approach. Glycine abetted multicomponent isotropic morphology has been synthesized through the conglomeration of thin nanopetals as building blocks with highly large surface area to volume ratio. Highly controllable morphology of thin nanopetals is achieved by stabilizing their polar faces through the adsorption of reactive hydroxyl and amide functions of glycine. Fourier transform infrared conclusions also exemplify good corroboration towards the use of organic additives. Moreover, the synthesized ZnO flowers have been utilized to fabricate cholesterol biosensor and biosensing measurements which have been performed over the cholesterol concentration range of 1 x 10(-6) M to 1 x 10(-3) M.
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| 9. |
- Qadir Israr, Muhammed, et al.
(författare)
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Potentiometric cholesterol biosensor based on ZnO nanorods chemically grown on Ag wire
- 2010
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Ingår i: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 519:3, s. 1106-1109
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Konferensbidrag (refereegranskat)abstract
- An electrochemical biosensor based on ZnO nanorods for potentiometric cholesterol determination is proposed. Hexagon-shaped ZnO nanorods were directly grown on a silver wire having a diameter of 250 mu m using low temperature aqueous chemical approach that produced ZnO nanorods with a diameter of 125250 nm and a length of similar to 1 mu m. Cholesterol oxidase (ChOx) was immobilized by a physical adsorption method onto ZnO nanorods. The electrochemical response of the ChOx/ZnO/Ag biosensor against a standard reference electrode (Ag/AgCl) was investigated as a logarithmic function of the cholesterol concentration (1 x 10(-6)M to 1 x 10(-2)M) showing good linearity with a sensitivity of 35.2 mV per decade and the stable output signal was attained at around 10 s. (C) 2010 Elsevier BM. All rights reserved.
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| 10. |
- Sadaf, Jamal Rana, et al.
(författare)
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White Electroluminescence Using ZnO Nanotubes/GaN Heterostructure Light-Emitting Diode
- 2010
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Ingår i: NANOSCALE RESEARCH LETTERS. - : Springer Science Business Media. - 1931-7573 .- 1556-276X. ; 5:6, s. 957-960
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Tidskriftsartikel (refereegranskat)abstract
- We report the fabrication of heterostructure white light-emitting diode (LED) comprised of n-ZnO nanotubes (NTs) aqueous chemically synthesized on p-GaN substrate. Room temperature electroluminescence (EL) of the LED demonstrates strong broadband white emission spectrum consisting of predominating peak centred at 560 nm and relatively weak violet-blue emission peak at 450 nm under forward bias. The broadband EL emission covering the whole visible spectrum has been attributed to the large surface area and high surface states of ZnO NTs produced during the etching process. In addition, comparison of the EL emission colour quality shows that ZnO nanotubes have much better quality than that of the ZnO nanorods. The colour-rendering index of the white light obtained from the nanotubes was 87, while the nanorods-based LED emit yellowish colour.
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