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  • 1.
    Ali, Syed M. Usman
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Fabrication and characterization of ZnO nanostructures for sensing and photonic device applications2012Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Nanotechnology is an emerging inter-disciplinary paradigm which encompasses diverse fields of science and engineering converge at the nanoscale. This nanoscale science and nanostructure engineering have well demonstrated in the fabrication of sensors/transducers devices with faster response time and better sensitivity then the planer version of the sensor’s configurations. Nanotechnology is not just to grow/fabricate nanostructures by just mixing nanoscale materials together but it requires the ability to understand and to precisely manipulate and control of the developed nanomaterials in a useful way. Nanotechnology is aiding to substantially improve, even revolutionize, many technology and industry sectors like information technology, energy, environmental science, medicine/medical instrumentation, homeland security, food safety, and transportation, among many others. Such applications of nanotechnology are delivering in both expected and unexpected ways on nanotechnology’s promise to benefit the society.

    The semiconductor ZnO with wide band gap (~ 3.37 eV) is a distinguish and unique material and its nanostructures have attracted great attention among the researchers due to its peculiar properties such as large exciton binding energy (60 meV) at room temperature, the high electron mobility, high thermal conductivity, good transparency and easiness of fabricating it in the different type of nanostructures. Based on all these fascinating properties, ZnO have been chosen as a suitable material for the fabrication of photonic, transducers/sensors, piezoelectric, transparent and spin electronics devices etc. The objective of the current study is to highlight the recent developments in materials and techniques for electrochemical sensing and hetrostructure light emitting diodes (LEDs) luminescence properties based on the different ZnO nanostructures. The sensor devices fabricated and characterized in the work were applied to determine and monitor the real changes of the chemical or biochemical species. We have successfully demonstrated the application of our fabricated devices as primary transducers/sensors for the determination of extracellular glucose and the glucose inside the human fat cells and frog cells using the potentiometric technique. Moreover, the fabricated ZnO based nanosensors have also been applied for the selective determination of uric acid, urea and metal ions successfully. This thesis relates specifically to zinc oxide nanostructure based electrochemical sensors and photonic device (LED) applications.

    List of papers
    1. A fast and sensitive potentiometric glucose microsensor based on glucose oxidase coated ZnO nanowires grown on a thin silver wire
    Open this publication in new window or tab >>A fast and sensitive potentiometric glucose microsensor based on glucose oxidase coated ZnO nanowires grown on a thin silver wire
    2010 (English)In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 145, no 2, p. 869-874Article in journal (Refereed) Published
    Abstract [en]

    In this study, a potentiometric glucose biosensor was fabricated by immobilization of glucose oxidase on to zinc oxide nanowires. Zinc oxide nanowires with 250-300 nm diameters and approximately 1.2 mu m lengths were grown on the surface of silver wires with a diameter of 250 mu m. Glucose oxidase (GOD) was electrostatically immobilized on the surface of the well aligned zinc oxide nanowires resulting in sensitive, selective, stable and reproducible glucose biosensors. The potentiometric response vs. Ag/AgCl reference electrode was found to be linear over a relatively wide logarithmic concentration range (0.5-1000 mu M) suitable for intracellular glucose detection. By applying a membrane on the sensor the linear range could be extended to 0.5 mu M to 10 mM, which increased the response time from less than 1 to 4s. On the other hand the membrane increased the sensor durability considerably. The sensor response was unaffected by normal concentrations of common interferents with glucose sensing such as uric acid and ascorbic acid.

    Place, publisher, year, edition, pages
    Elsevier Science B.V., Amsterdam., 2010
    Keywords
    Glucose oxidase (GOD), Nafion membrane, Potentiometric biosensor, Electrochemical nanodevices, ZnO nanowires, Fast response
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-55508 (URN)10.1016/j.snb.2009.12.072 (DOI)000276589900039 ()
    Available from: 2010-04-30 Created: 2010-04-30 Last updated: 2017-12-12Bibliographically approved
    2. Glocuse detection with a commercial MOSFET using ZnO nanowires extended gate
    Open this publication in new window or tab >>Glocuse detection with a commercial MOSFET using ZnO nanowires extended gate
    2009 (English)In: IEEE Transaction on Nanotechnology, Vol. 8, no 6, p. 678-683Article in journal (Refereed) Published
    Abstract [en]

    Zinc oxide (ZnO) nanowires were grown on a silver (Ag) wire with a diameter of approximately 250 $mu$m and used in an electrochemical sensor. The enzyme glucose oxidase (GOD) was immobilized on the ZnO nanowires and the silver wire was connected directly to the gate of a MOSFET. Upon exposure to glucose (1-100 $mu$M) the electrochemical response from the glucose oxidase induced a stable measurable voltage change on the gate leading to a strong modulation of the current through the MOSFET. For a sensor with uniform ZnO nanowires functionalized with GOD a fast response time of less than 100 ms, was demonstrated. The effect of the uniformity of the ZnO nanowires on the sensing property was also investigated. The extended gate arrangement facilitated glucose detection in small sample volumes and made it possible to demonstrate the present sensor concept using a standard low threshold MOSFET. The extended gate MOSFET sensor approach demonstrates the possibility and potential of the use of nano-structures coupled to standard electronic components for biosensing applications.

    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-50566 (URN)10.1109/TNANO.2009.2019958 (DOI)
    Note
    ©2009 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE. Syed M. Usman Ali, Omer Nour, Magnus Willander and Bengt Danielsson, Glocuse detection with a commercial MOSFET using ZnO nanowires extended gate, 2009, IEEE Transaction on Nanotechnology, (8), 6, 678-683. http://dx.doi.org/10.1109/TNANO.2009.2019958 Available from: 2009-10-12 Created: 2009-10-12 Last updated: 2014-01-15
    3. Functionalised ZnO-nanorod-based selective electrochemical sensor for intracellular glucose
    Open this publication in new window or tab >>Functionalised ZnO-nanorod-based selective electrochemical sensor for intracellular glucose
    Show others...
    2010 (English)In: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 25, no 10, p. 2205-2211Article in journal (Refereed) Published
    Abstract [en]

    In this article, we report a functionalised ZnO-nanorod-based selective electrochemical sensor for intracellular glucose. To adjust the sensor for intracellular glucose measurements, we grew hexagonal ZnO nanorods on the tip of a silver-covered borosilicate glass capillary (0.7 mu m diameter) and coated them with the enzyme glucose oxidase. The enzyme-coated ZnO nanorods exhibited a glucose-dependent electrochemical potential difference versus an Ag/AgCl reference microelectrode. The potential difference was linear over the concentration range of interest (0.5-1000 mu M). The measured glucose concentration in human adipocytes or frog oocytes using our ZnO-nanorod sensor was consistent with values of glucose concentration reported in the literature; furthermore, the sensor was able to show that insulin increased the intracellular glucose concentration. This nanoelectrode device demonstrates a simple technique to measure intracellular glucose concentration.

    Place, publisher, year, edition, pages
    Elsevier Science B.V., Amsterdam., 2010
    Keywords
    ZnO nanorods; Functionalisation; Intracellular glucose; Electrochemical sensor
    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-58381 (URN)10.1016/j.bios.2010.02.025 (DOI)000278702600004 ()
    Note
    Original Publication: Muhammad Asif, Syed Usman Ali, Omer Nour, Magnus Willander, Cecilia Brännmark, Peter Strålfors, Ulrika Englund, Fredrik Elinder and Bengt Danielsson, Functionalised ZnO-nanorod-based selective electrochemical sensor for intracellular glucose, 2010, Biosensors & bioelectronics, (25), 10, 2205-2211. http://dx.doi.org/10.1016/j.bios.2010.02.025 Copyright: Elsevier Science B.V., Amsterdam. http://www.elsevier.com/ Available from: 2010-08-13 Created: 2010-08-11 Last updated: 2018-01-25
    4. Wireless Remote Monitoring of Glucose Using a Functionalized ZnO Nanowire Arrays Based Sensor
    Open this publication in new window or tab >>Wireless Remote Monitoring of Glucose Using a Functionalized ZnO Nanowire Arrays Based Sensor
    Show others...
    2011 (English)In: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 11, no 9, p. 8485-8496Article in journal (Refereed) Published
    Abstract [en]

    This paper presents a prototype wireless remote glucose monitoring system interfaced with a ZnO nanowire arrays-based glucose sensor, glucose oxidase enzyme immobilized onto ZnO nanowires in conjunction with a Nafion (R) membrane coating, which can be effectively applied for the monitoring of glucose levels in diabetics. Global System for Mobile Communications (GSM) services like General Packet Radio Service (GPRS) and Short Message Service (SMS) have been proven to be logical and cost effective methods for gathering data from remote locations. A communication protocol that facilitates remote data collection using SMS has been utilized for monitoring a patients sugar levels. In this study, we demonstrate the remote monitoring of the glucose levels with existing GPRS/GSM network infra-structures using our proposed functionalized ZnO nanowire arrays sensors integrated with standard readily available mobile phones. The data can be used for centralized monitoring and other purposes. Such applications can reduce health care costs and allow caregivers to monitor and support to their patients remotely, especially those located in rural areas.

    Place, publisher, year, edition, pages
    MDPI, 2011
    Keywords
    electrochemical nanosensor, ZnO nanowires, glucose oxidase, Nafion (R) membrane, remote monitoring, data acquisition, Global System for Mobile Communications (GSM)
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-71798 (URN)10.3390/s110908485 (DOI)000295211700017 ()
    Available from: 2011-11-04 Created: 2011-11-04 Last updated: 2017-12-08
    5. Selective potentiometric determination of uric acid with uricase immobilized on ZnO nanowires
    Open this publication in new window or tab >>Selective potentiometric determination of uric acid with uricase immobilized on ZnO nanowires
    Show others...
    2011 (English)In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 152, no 2, p. 241-247Article in journal (Refereed) Published
    Abstract [en]

    In this study, a potentiometric uric acid biosensor was fabricated by immobilization of uricase onto zinc oxide (ZnO) nanowires. Zinc oxide nanowires with 80-150 nm in diameter and 900 nm to 1.5 mu m in lengths were grown on the surface of a gold coated flexible plastic substrate. Uricase was electrostatically immobilized on the surface of well aligned ZnO nanowires resulting in a sensitive, selective, stable and reproducible uric acid biosensor. The potentiometric response of the ZnO sensor vs Ag/AgCl reference electrode was found to be linear over a relatively wide logarithmic concentration range (1-650 mu M) suitable for human blood serum. By applying a Nafion (R) membrane on the sensor the linear range could be extended to 1-1000 mu M at the expense of an increased response time from 6.25 s to less than 9 s. On the other hand the membrane increased the sensor durability considerably. The sensor response was unaffected by normal concentrations of common interferents such as ascorbic acid, glucose, and urea.

    Place, publisher, year, edition, pages
    Elsevier Science B.V., Amsterdam., 2011
    Keywords
    ZnO nanowires, Potentiometric nanosensor, Uricase, Uric acid, Nafion (R), Membrane, Electrochemical nanodevices
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-67542 (URN)10.1016/j.snb.2010.12.015 (DOI)000288877700015 ()
    Note
    Original Publication: Syed Usman Ali, Naveed Ul Hassan Alvi, Zafar Hussain Ibupoto, Omer Nur, Magnus Willander and Bengt Danielsson, Selective potentiometric determination of uric acid with uricase immobilized on ZnO nanowires, 2011, SENSORS AND ACTUATORS B-CHEMICAL, (152), 2, 241-247. http://dx.doi.org/10.1016/j.snb.2010.12.015 Copyright: Elsevier Science B.V., Amsterdam. http://www.elsevier.com/ Available from: 2011-04-18 Created: 2011-04-18 Last updated: 2017-12-11Bibliographically approved
    6. Fabrication and comparative optical characterization of n-ZnO nanostructures (nanowalls, nanorods, nanoflowers and nanotubes)/p-GaN white-light-emitting diodes
    Open this publication in new window or tab >>Fabrication and comparative optical characterization of n-ZnO nanostructures (nanowalls, nanorods, nanoflowers and nanotubes)/p-GaN white-light-emitting diodes
    Show others...
    2011 (English)In: Scripta Materialia, ISSN 1359-6462, E-ISSN 1872-8456, Vol. 64, no 8, p. 697-700Article in journal (Refereed) Published
    Abstract [en]

    White light-emitting diodes (LED) based on ZnO (nanowalls, nanorods, nanoflowers and nanotubes)/p-GaN were fabricated and their electrical, optical and electro-optical characteristics were comparatively characterized. All the LED showed rectifying behavior. The nanowalls and nanorods structures have the highest photoluminescence emission intensity in the visible and UV (at 3.29 eV) regions, respectively. The nanowalls have the highest color rendering index, with a value of 95, and the highest electroluminescence intensity with peaks approximately centered at 420, 450 nm and broad peak covering the visible region.

    Place, publisher, year, edition, pages
    Elsevier Science B.V., Amsterdam., 2011
    Keywords
    Zinc oxide, Nanostructure, Aqueous chemical growth, Optical properties, Heterojunctions
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-66849 (URN)10.1016/j.scriptamat.2010.11.046 (DOI)000287908300002 ()
    Available from: 2011-03-22 Created: 2011-03-21 Last updated: 2017-12-11Bibliographically approved
  • 2.
    Asif, Muhammad H
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Usman Ali, Syed M
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Nur, Omer
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Willander, Magnus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Brännmark, Cecilia
    Linköping University, Department of Clinical and Experimental Medicine, Cell Biology. Linköping University, Faculty of Health Sciences.
    Strålfors, Peter
    Linköping University, Department of Clinical and Experimental Medicine, Cell Biology. Linköping University, Faculty of Health Sciences.
    Englund H, Ulrika
    Linköping University, Department of Clinical and Experimental Medicine, Cell Biology. Linköping University, Faculty of Health Sciences.
    Elinder, Fredrik
    Linköping University, Department of Clinical and Experimental Medicine, Cell Biology. Linköping University, Faculty of Health Sciences.
    Danielsson, Bengt
    Pure and Applied Biochemistry, Lund University, Box 124, SE-221 00 Lund, Sweden.
    Functionalised ZnO-nanorod-based selective electrochemical sensor for intracellular glucose2010In: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 25, no 10, p. 2205-2211Article in journal (Refereed)
    Abstract [en]

    In this article, we report a functionalised ZnO-nanorod-based selective electrochemical sensor for intracellular glucose. To adjust the sensor for intracellular glucose measurements, we grew hexagonal ZnO nanorods on the tip of a silver-covered borosilicate glass capillary (0.7 mu m diameter) and coated them with the enzyme glucose oxidase. The enzyme-coated ZnO nanorods exhibited a glucose-dependent electrochemical potential difference versus an Ag/AgCl reference microelectrode. The potential difference was linear over the concentration range of interest (0.5-1000 mu M). The measured glucose concentration in human adipocytes or frog oocytes using our ZnO-nanorod sensor was consistent with values of glucose concentration reported in the literature; furthermore, the sensor was able to show that insulin increased the intracellular glucose concentration. This nanoelectrode device demonstrates a simple technique to measure intracellular glucose concentration.

  • 3.
    Asif, Muhammad
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Usman Ali, Syed
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Nour, Omer
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Willander, Magnus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Englund, Ulrika
    Linköping University, Department of Clinical and Experimental Medicine, Cell Biology. Linköping University, Faculty of Health Sciences.
    Elinder, Fredrik
    Linköping University, Department of Clinical and Experimental Medicine, Cell Biology. Linköping University, Faculty of Health Sciences.
    Functionalized ZnO nanorod-based selective magnesium ion sensor for intracellular measurements2010In: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 26, no 3, p. 1118-1123Article in journal (Refereed)
    Abstract [en]

    ZnO nanorods were grown on a silver-coated tip of a borosilicate glass capillary (0.7 mu m in tip diameter) and used as selective potentiometric sensor of intracellular free Mg2+. To functionalize the ZnO nanorods for selectivity of Mg2+, a polymeric membrane with Mg2+-selective ionophores were coated on the surface of the ZnO nanorods. These functionalized ZnO nanorods exhibited a Mg2+-dependent electrochemical potential difference versus an Ag/AgCl reference microelectrode within the concentration range from 500 nM to 100 mM. Two types of cells, human adipocytes and frog oocytes, were used for the intracellular Mg2+ measurements. The intracellular concentration of free Mg2+ in human adipocytes and frog oocytes were 0.4-0.5 and 0.8-0.9 mM, respectively. Such type of nanoelectrode device paves the way to enable analytical measurements in single living cells and to sense other bio-chemical species at the intracellular level.

  • 4.
    Chey, Chan Oeurn
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Usman Ali, Syed M.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Ibupoto, Zafar H.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Khun, Kimleang
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Nur, Omer
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Potentiometric creatinine biosensor based on ZnO nanowires2012In: Journal of Nanoscience Letters, ISSN 2231-4008, Vol. 2, no 4, p. 24-24Article in journal (Refereed)
    Abstract [en]

    In the present work, we have grown well-aligned zinc oxide (ZnO) nanowires (NWs) on the surface of gold coated glass substrates by a low temperature aqueous chemical growth (ACG) approach and utilized it as a potentiometric creatinine biosensor. This was achieved by electrostatic immobilization of creatinine deiminase (CD) on the surface of the ZnO NWs followed by applying a chitosan membrane in conjunction with glutaraldehyde. This immobilization resulted in a sensitive, selective, stable, reproducible and fast creatinine biosensor. The potentiometric response of the ZnO sensor vs. Ag/AgCl reference electrode was found to be linear over a wide logarithmic concentration of creatinine electrolyte solution ranging from 1-1000 µM. The sensor illustrates good linear sensitivity slope curve of ~33.9 mV/decade along with a rapid response time of ~7 s. Furthermore, the sensor response was unaffected by normal concentrations of common interferences such as potassium, calcium, magnesium, sodium, copper ions and glucose.

  • 5.
    Fakhar-e-Alam, M
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology. Pakistan Institute of Engineering and Applied Sciences, Pakistan.
    Usman Ali, Syed
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology. , NED University of Engineering and Technology, Pakistan.
    Hussain Ibupoto, Zafar
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Atif, M
    Pakistan Institute of Engineering and Applied Sciences, Pakistan;Physics and Astronomy Department, College of Science, King Saud University, Saudi Arabia.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Erratum: “Phototoxic effects of zinc oxide nanowires (ZnO NWs) complexed with 5-ALA in RD cell line” (Laser Physics 21, 2165 (2011))2012In: Laser physics, ISSN 1054-660X, E-ISSN 1555-6611, Vol. 22, no 2, p. 476-476Article in journal (Other academic)
    Abstract [en]

    n/a

  • 6.
    Fakhar-e-Alam, M.
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Usman Ali, Syed
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Hussain Ibupoto, Zafar
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Atif, M.
    Pakistan Institute for Engineering and Applied Science.
    Willander, Magnus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Phototoxic effects of zinc oxide nanowires (ZnO NWs) complexed with 5-ALA in RD cell line2011In: Laser physics, ISSN 1054-660X, E-ISSN 1555-6611, Vol. 21, no 12, p. 2165-2170Article in journal (Refereed)
    Abstract [en]

    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.

  • 7.
    Fakhar-e-Alam, M
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology. Pakistan Institute of Engineering and Applied Sciences, Nilore, Islamabad, Pakistan.
    Usman Ali, Syed
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology. Department of Electronic Engineering, NED University of Engineering and Technology, Karachi, Pakistan.
    Ibupoto, Zafar Hussain
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Atif, M
    Pakistan Institute of Engineering and Applied Sciences, Nilore, Islamabad, Pakistan; Physics and Astronomy Department, College of Science, King Saud University, Riyadh, Saudi Arabia.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Erratum: “Phototoxic Effects of Zinc Oxide Nanowires (ZnO NWs) Complexed with 5-ALA in RD Cell Line” (Laser Physics 21, 2165 (2011))2012In: Laser physics, ISSN 1054-660X, E-ISSN 1555-6611, Vol. 22, no 1, p. 338-338Article in journal (Other academic)
    Abstract [en]

    n/a

  • 8.
    Fakhar-e-Alam, Muhammad
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology. Pakistan Institute of Engineering and Applied Sciences, Pakistan.
    Usman Ali, Syed
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology. , NED University of Engineering and Technology, Pakistan.
    Ibupoto, Zafar Hussain
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Khun, Kimleang
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Atif, M.
    King Saud University, Saudi Arabia; National Institute of Laser and Optronics, Pakistan.
    Kashif, Muhammad
    University Malaysia Perlis, Kangar, Malaysia.
    Kai Loong, Foo
    University Malaysia Perlis, Kangar, Malaysia.
    Hashim, Uda
    University Malaysia Perlis, Kangar, Malaysia.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Sensitivity of A-549 human lung cancer cells to nanoporous zinc oxide conjugated with Photofrin2012In: Lasers in Medical Science, ISSN 0268-8921, E-ISSN 1435-604X, Vol. 27, no 3, p. 607-614Article in journal (Refereed)
    Abstract [en]

    In the present study, we demonstrated the use of nanoporous zinc oxide (ZnO NPs) in photodynamic therapy. The ZnO NPs structure possesses a high surface to volume ratio due to its porosity and ZnO NPs can be used as an efficient photosensitizer carrier system. We were able to grow ZnO NPs on the tip of borosilicate glass capillaries (0.5 mu m diameter) and conjugated this with Photofrin for efficient intracellular drug delivery. The ZnO NPs on the capillary tip could be excited intracellularly with 240 nm UV light, and the resultant 625 nm red light emitted in the presence of Photofrin activated a chemical reaction that produced reactive oxygen species (ROS). The procedure was tested in A-549 cells and led to cell death within a few minutes. The morphological changes in necrosed cells were examined by microscopy. The viability of control and treated A-549 cells with the optimum dose of UV/visible light was assessed using the MTT assay, and ROS were detected using a fluorescence microscopy procedure.

  • 9.
    Fulati, Alimujiang
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Usman Ali, Syed M.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Asif, Muhammad H.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology. Pakistan.
    Hassan Alvi, Naveed Ul
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Willander, Magnus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Brännmark, Cecilia
    Linköping University, Department of Clinical and Experimental Medicine, Cell Biology. Linköping University, Faculty of Health Sciences.
    Strålfors, Peter
    Linköping University, Department of Clinical and Experimental Medicine, Cell Biology. Linköping University, Faculty of Health Sciences.
    Börjesson, Sara I.
    Linköping University, Department of Clinical and Experimental Medicine, Cell Biology. Linköping University, Faculty of Health Sciences.
    Elinder, Fredrik
    Linköping University, Department of Clinical and Experimental Medicine, Cell Biology. Linköping University, Faculty of Health Sciences.
    Danielsson, Bengt
    Lund University, Sweden.
    An intracellular glucose biosensor based on nanoflake ZnO2010In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 150, no 2, p. 673-680Article in journal (Other academic)
    Abstract [en]

    In this study, an improved potentiometric intracellular glucose biosensor was fabricated with immobilization of glucose oxidase on a ZnO nanoporous material. The ZnO nanoporous material with a wall thickness around 200 nm was grown on the tip of a borosilicate glass capillary and used as a selective intracellular glucose sensor for the measurement of glucose concentrations in human adipocytes and frog oocytes. The results showed a fast response within 4 s and a linear glucosedependent electrochemical response over a wide range of glucose concentration (500 nM-10 mM). The measurements of intracellular glucose concentrations with our biosensor were consistent with the values of intracellular glucose concentrations reported in the literature. The sensor also demonstrated its capability by detecting an increase in the intracellular glucose concentration induced by insulin. We found that the ZnO nanoporous material provides sensitivity as high as 1.8 times higher than that obtained using ZnO nanorods under the same conditions. Moreover, the fabrication method in our experiment is simple and the excellent performance of the developed nanosensor in sensitivity, stability, selectivity, reproducibility and anti-interference was achieved. All these advantageous features of this intracellular glucose biosensor based on functionalised ZnO nanoporous material compared to ZnO nanorods demonstrate a promising way of enhancing glucose biosensor performance to measure reliable intracellular glucose concentrations within single living cells.

  • 10.
    Fulati, Alimujiang
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Usman Ali, Syed M
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Riaz, Muhammad
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Amin, Gul
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Nour, Omer
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Willander, Magnus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Miniaturized pH Sensors Based on Zinc Oxide Nanotubes/Nanorods2009In: SENSORS, ISSN 1424-8220, Vol. 9, no 11, p. 8911-8923Article in journal (Refereed)
    Abstract [en]

    ZnO nanotubes and nanorods grown on gold thin film were used to create pH sensor devices. The developed ZnO nanotube and nanorod pH sensors display good reproducibility, repeatability and long-term stability and exhibit a pH-dependent electrochemical potential difference versus an Ag/AgCl reference electrode over a large dynamic pH range. We found the ZnO nanotubes provide sensitivity as high as twice that of the ZnO nanorods, which can be ascribed to the fact that small dimensional ZnO nanotubes have a higher level of surface and subsurface oxygen vacancies and provide a larger effective surface area with higher surface-to-volume ratio as compared to ZnO nanorods, thus affording the ZnO nanotube pH sensor a higher sensitivity. Experimental results indicate ZnO nanotubes can be used in pH sensor applications with improved performance. Moreover, the ZnO nanotube arrays may find potential application as a novel material for measurements of intracellular biochemical species within single living cells.

  • 11.
    Hussain Ibupoto, Zafar
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Usman Ali, Syed
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Chey, C O
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Khun, K
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Nur, Omer
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Willander, Magnus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Selective zinc ion detection by functionalised ZnO nanorods with ionophore2011In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 110, no 10, p. 104702-Article in journal (Refereed)
    Abstract [en]

    In this paper, highly dense and well aligned single-crystal zinc oxide nanorods were grown along the c-axis on a gold coated glass substrate using a low temperature aqueous chemical growth approach. The prepared ZnO nanorods were functionalized with plastic membrane coatings containing specific ionophore (12-crown-4) which is highly selective to zinc ions (Zn(+2)). The electrochemical response of the sensor was found to be linear over a relatively wide logarithmic concentration range from 1 mu M to 100mM. The proposed sensor showed a good linearity with a high sensitivity of similar to 35 mV/decade for sensing Zn(+2) ions. A fast response time of less than 5 s with a good selectivity, repeatability, reproducibility, and negligible response to common interferents ions such as calcium (Ca(2+)), magnesium (Mg(2+)), or potassium (K(+)), and iron (Fe(+3)) and copper (Cu(+2)) was also demonstrated. Moreover, the proposed sensor showed good stoichiometric results for potentiometric titration.

  • 12.
    Ibupoto, Zafar Hussain
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Ali, Syed M. Usman
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Khun, Kimleang
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Selective Thallium (I) Ion Sensor Based on Functionalised ZnO Nanorods2012In: Journal of Nanotechnology, ISSN 1687-9503Article in journal (Refereed)
    Abstract [en]

    Well controlled in length and highly aligned ZnO nanorods were grown on the gold-coated glass substrate by hydrothermal growth method. ZnO nanorods were functionalised with selective thallium (I) ion ionophore dibenzyldiaza-18-crown- 6 (DBzDA18C6). The thallium ion sensor showed wide linear potentiometric response to thallium (I) ion concentrations (1 × 10 - 7 M to 5 × 10 - 2 M) with high sensitivity of 36.87 ± 1.49 mV/decade. Moreover, thallium (I) ion demonstrated fast response time of less than 5 s, high selectivity, reproducibility, storage stability, and negligible response to common interferents. The proposed thallium (I) ion-sensor electrode was also used as an indicator electrode in the potentiometric titration, and it has shown good stoichiometric response for the determination of thallium (I) ion. © 2012 Z. H. Ibupoto et al.

  • 13.
    Ibupoto, Zafar Hussain
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Usman Ali, Syed
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Khun, Kimleang
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Electrochemical L-Lactic Acid Sensor Based on Immobilized ZnO Nanorods with Lactate Oxidase2012In: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 12, no 3, p. 2456-2466Article in journal (Refereed)
    Abstract [en]

    In this work, fabrication of gold coated glass substrate, growth of ZnO nanorods and potentiometric response of lactic acid are explained. The biosensor was developed by immobilizing the lactate oxidase on the ZnO nanorods in combination with glutaraldehyde as a cross linker for lactate oxidase enzyme. The potentiometric technique was applied for the measuring the output (EMF) response of L-lactic acid biosensor. We noticed that the present biosensor has wide linear detection range of concentration from 1 x 10(-4)-1 x 10(0) mM with acceptable sensitivity about 41.33 +/- 1.58 mV/decade. In addition, the proposed biosensor showed fast response time less than 10 s, a good selectivity towards L-lactic acid in presence of common interfering substances such as ascorbic acid, urea, glucose, galactose, magnesium ions and calcium ions. The present biosensor based on immobilized ZnO nanorods with lactate oxidase sustained its stability for more than three weeks.

  • 14.
    Kashif, M
    et al.
    University of Malaysia Perlis, Malaysia.
    Al-Douri, Y
    University of Malaysia Perlis, Malaysia.
    Hashim, U
    University of Malaysia Perlis, Malaysia.
    Ali, M E
    University of Malaysia Perlis, Malaysia.
    Usman Ali, Syed
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology. NED University of Engineering and Technology, Pakistan.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Characterisation, analysis and optical properties of nanostructure ZnO using the sol-gel method2012In: Micro & Nano Letters, ISSN 1750-0443, E-ISSN 1750-0443, Vol. 7, no 2, p. 163-167Article in journal (Refereed)
    Abstract [en]

    Nanostructure ZnO was grown on thin aluminium layer, deposited on silicon substrate using the sol-gel method. The surface morphologies of nanostructure ZnO at different precursor concentrations were studied using scanning electron microscopy. Raman spectroscopy suggested that nanorods started to grow along with nanoflakes at a precursor concentration of 50 mM and the density of the nanorods significantly increases when the concentration was raised to 75 mM. Raman spectra were intensified and red shifted with the increment of precursor concentration. Optical properties of refractive index and optical dielectric constant are investigated. The structural defects at lower level of precursor were probably due to the hypoxic environment, whereas the red shift of Raman spectra was due to the structural change of ZnO nanocrystals.

  • 15.
    Kashif, M.
    et al.
    University of Malaysia Perlis, Malaysia .
    Usman Ali, Syed
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Ali, M.E.
    University of Malaysia Perlis, Malaysia .
    Abdulgafour, H.I.
    University of Sains Malaysia, Malaysia .
    Hashim, U.
    University of Malaysia Perlis, Malaysia .
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Hassan, Z.
    University of Sains Malaysia, Malaysia .
    Morphological, optical, and Raman characteristics of ZnO nanoflakes prepared via a sol-gel method2012In: PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE, ISSN 1862-6300, Vol. 209, no 1, p. 143-147Article in journal (Refereed)
    Abstract [en]

    Two-dimensional (2D) ZnO nanoflakes were grown on thin aluminum layer, deposited on silicon substrate, using a sol-gel method. The surface morphologies of ZnO nanoflakes at different precursor concentrations were studied using scanning electron microscopy (SEM). Combined studies of SEM, photoluminescence (PL), and Raman spectroscopy suggested that nanorods started to grow along with nanoflakes at a precursor concentration of 0.05 M and the density of the nanorods significantly increased when the concentration was raised to 0.075 M. Both the UV-luminescence and Raman spectra were intensified and redshifted with the increment of precursor concentration. Spectral intensification suggests improvement in crystal qualities and better optical properties of the fabricated ZnO nanostructures. The structural defects at lower levels of precursor were probably due to the hypoxic environment, whereas, the redshift of PL and Raman spectra was due to the local heating of ZnO nanocrystals.

  • 16.
    Kashif, Muhammad
    et al.
    University of Malaysia Perlis, Malaysia .
    Hashim, Uda
    University of Malaysia Perlis, Malaysia .
    Eaqub Ali, Md
    University of Malaysia Perlis, Malaysia .
    Saif, Alaeddin A
    University of Malaysia Perlis, Malaysia .
    Usman Ali, Syed
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Structural and impedance spectroscopy study of Al-doped ZnO nanorods grown by sol-gel method2012In: Microelectronics international, ISSN 1356-5362, E-ISSN 1758-812X, Vol. 29, no 3, p. 131-135Article in journal (Refereed)
    Abstract [en]

    Purpose - The purpose of this paper is to investigate the electrical transport mechanism of the Al-doped ZnO nanorods at different temperatures by employing impedance spectroscopy. less thanbrgreater than less thanbrgreater thanDesign/methodology/approach - Al-doped ZnO nanorods were grown on silicon substrate using step sol-gel method. For the seed solution preparation Zinc acetate dihydrate, 2-methoxyethanol, monoethanolannine and aluminum nitrite nano-hydrate were used as a solute, solvent, stabilizer and dopant, respectively. Prior to the deposition, P-type Si (100) wafer was cut into pieces of 1 cm x 2 cm. The samples were then cleaned in an ultrasonic bath with acetone, ethanol, and de-ionized (DI) water for 5 min. The prepared seed solution was coated on silicon substrate using spin coater at spinning speed of 3000 rpm for 30s and then dried at 250 degrees C for 10 min followed by annealing at 550 degrees C for 1 h. The hydrothermal growth was carried out in a solution of zinc nitrate hexahydrate (0.025M), Hexamethyltetramine (0.025M) in DI water. less thanbrgreater than less thanbrgreater thanFindings - Al-doped ZnO nanorods were characterized using scanning electron microscope (SEM), X-ray diffraction (XRD) and impedance spectroscopy. The impedance measurements were carried out at various temperatures (100 degrees C-325 degrees C). The impedance results showed that temperature has great influence on the impedance; the impedance value decreased as the temperature increased. This decrement is attributed to the increase of the mobility of the defects, especially the oxygen vacancies. The surface morphology of the samples was measured by SEM and X-ray diffraction. The SEM images show that the high density of Al-doped ZnO nanorods covers the silicon substrate, whereas the XRD pattern shows the (002) crystal orientation. less thanbrgreater than less thanbrgreater thanOriginality/value - This paper demonstrates the electron transport mechanism of Al-doped ZnO nanorods, at different temperatures, to understand the charge transport model.

  • 17.
    Khun, Kimleang
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Ibupoto, Zafar Hussain
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Usman Ali, Syed
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Ouern Chey, Chan
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Nur, Omer
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Iron Ion Sensor Based on Functionalized ZnO Nanorods2012In: Electroanalysis, ISSN 1040-0397, E-ISSN 1521-4109, Vol. 24, no 3, p. 521-528Article in journal (Refereed)
    Abstract [en]

    In this work, we are presenting an iron ion (Fe3+) potentiometric sensor based on functionalized ZnO nanorods with selective ionophore (18 crown 6). Zinc oxide nanorods with a diameter of about 100 to 150 nm and 1 mu m in length were grown on gold coated glass. The selective Fe3+ ionophore sensor with highly aligned ZnO nanorods showed high sensitivity, acceptable selectivity, reproducibility and a stable signal response for detecting Fe3+. The potentiometric response of the Fe3+ sensor with functionalized ZnO nanorods versus a Ag/AgCl reference electrode was observed to be linear over a logarithmic concentration range from 10-5 M to 10-2 M. The detection limit of the proposed sensor was about 5 mu M, which is lower than the normal blood concentration of Fe3+ which is about 10 mu M and can be up to 30 +/- M. The sensitivity of the proposed Fe3+ sensor was found to be 70.2 +/- 2.81 mV/decade with a regression coefficient R2=0.99 and a response time less than 5 s. The functionalized ZnO nanorods sensor with selective iron ionophore has a life time greater than one month and has shown insignificant interference with other ions usually present in the human blood serum. The proposed sensor was used as an indicator electrode for potentiometric titration.

  • 18.
    Ul Hassan Alvi, Naveed
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Usman Ali, Syed
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Hussain, S
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Nour, Omer
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Willander, Magnus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Fabrication and comparative optical characterization of n-ZnO nanostructures (nanowalls, nanorods, nanoflowers and nanotubes)/p-GaN white-light-emitting diodes2011In: Scripta Materialia, ISSN 1359-6462, E-ISSN 1872-8456, Vol. 64, no 8, p. 697-700Article in journal (Refereed)
    Abstract [en]

    White light-emitting diodes (LED) based on ZnO (nanowalls, nanorods, nanoflowers and nanotubes)/p-GaN were fabricated and their electrical, optical and electro-optical characteristics were comparatively characterized. All the LED showed rectifying behavior. The nanowalls and nanorods structures have the highest photoluminescence emission intensity in the visible and UV (at 3.29 eV) regions, respectively. The nanowalls have the highest color rendering index, with a value of 95, and the highest electroluminescence intensity with peaks approximately centered at 420, 450 nm and broad peak covering the visible region.

  • 19.
    Usman Ali, Syed
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Aijazi, Tasuif
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Axelsson, Kent
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Nur, Omer
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Willander, Magnus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Wireless Remote Monitoring of Glucose Using a Functionalized ZnO Nanowire Arrays Based Sensor2011In: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 11, no 9, p. 8485-8496Article in journal (Refereed)
    Abstract [en]

    This paper presents a prototype wireless remote glucose monitoring system interfaced with a ZnO nanowire arrays-based glucose sensor, glucose oxidase enzyme immobilized onto ZnO nanowires in conjunction with a Nafion (R) membrane coating, which can be effectively applied for the monitoring of glucose levels in diabetics. Global System for Mobile Communications (GSM) services like General Packet Radio Service (GPRS) and Short Message Service (SMS) have been proven to be logical and cost effective methods for gathering data from remote locations. A communication protocol that facilitates remote data collection using SMS has been utilized for monitoring a patients sugar levels. In this study, we demonstrate the remote monitoring of the glucose levels with existing GPRS/GSM network infra-structures using our proposed functionalized ZnO nanowire arrays sensors integrated with standard readily available mobile phones. The data can be used for centralized monitoring and other purposes. Such applications can reduce health care costs and allow caregivers to monitor and support to their patients remotely, especially those located in rural areas.

  • 20.
    Usman Ali, Syed
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Asif, Muhammad
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology. Pakistan.
    Fulati, Alimujiang
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Nur, Omer
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Willander, Magnus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Brännmark, Cecilia
    Linköping University, Department of Clinical and Experimental Medicine, Cell Biology. Linköping University, Faculty of Health Sciences.
    Strålfors, Peter
    Linköping University, Department of Clinical and Experimental Medicine, Cell Biology. Linköping University, Faculty of Health Sciences.
    Englund, Ulrika
    Linköping University, Department of Clinical and Experimental Medicine, Cell Biology. Linköping University, Faculty of Health Sciences.
    Elinder, Fredrik
    Linköping University, Department of Clinical and Experimental Medicine, Cell Biology. Linköping University, Faculty of Health Sciences.
    Danielsson, Bengt
    Lund University.
    Intracellular K(+) Determination With a Potentiometric Microelectrode Based on ZnO Nanowires2011In: IEEE transactions on nanotechnology, ISSN 1536-125X, E-ISSN 1941-0085, Vol. 10, no 4, p. 913-919Article in journal (Refereed)
    Abstract [en]

    The fabrication and application of an intracellular K(+)-selective microelectrode is demonstrated. ZnO nanowires with a diameter of 100-180 nm and a length of approximately 1.5. m are grown on a borosilicate glass microcapillary. The ZnO nanowires were coated by a K(+)-ionophore-containing membrane. The K(+)-selective microelectrode exhibited a K(+)-dependent potentiometric response versus an Ag/AgCl reference microelectrode that was linear over a large concentration range (25 . M-125 mM) with a minimum detection limit of 1 . M. The measured K(+) concentrations in human adipocytes and in frog oocytes were consistent with values of K(+) concentrations reported in the literature. The sensor has several advantages including ease of fabrication, ease of insertion into the cells, low cost, and high selectivity features that make this type of sensor suitable to characterize physiologically relevant ions within single living cells.

  • 21.
    Usman Ali, Syed
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology. NED University of Engineering and Technology, Pakistan.
    Ibupoto, Zafar Hussain
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Kashif, Muhammad
    University of Malaysia Perlis, Malaysia.
    Hashim, Uda
    University of Malaysia Perlis, Malaysia.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    A Potentiometric Indirect Uric Acid Sensor Based on ZnO Nanoflakes and Immobilized Uricase2012In: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 12, no 3, p. 2787-2797Article in journal (Refereed)
    Abstract [en]

    In the present work zinc oxide nanoflakes (ZnO-NF) structures with a wall thickness around 50 to 100 nm were synthesized on a gold coated glass substrate using a low temperature hydrothermal method. The enzyme uricase was electrostatically immobilized in conjunction with Nafion membrane on the surface of well oriented ZnO-NFs, resulting in a sensitive, selective, stable and reproducible uric acid sensor. The electrochemical response of the ZnO-NF-based sensor vs. a Ag/AgCl reference electrode was found to be linear over a relatively wide logarithmic concentration range (500 nM to 1.5 mM). In addition, the ZnO-NF structures demonstrate vast surface area that allow high enzyme loading which results provided a higher sensitivity. The proposed ZnO-NF array-based sensor exhibited a high sensitivity of similar to 66 mV/ decade in test electrolyte solutions of uric acid, with fast response time. The sensor response was unaffected by normal concentrations of common interferents such as ascorbic acid, glucose, and urea.

  • 22.
    Usman Ali, Syed
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Ibupoto, Zafar Hussain
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Salman, Salah
    Acromed Invest AB, SE-22643 Lund, Sweden .
    Nur, Omer
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Willander, Magnus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Danielsson, Bengt
    Acromed Invest AB.
    Selective determination of urea using urease immobilized on ZnO nanowires2011In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 160, no 1, p. 637-643Article in journal (Refereed)
    Abstract [en]

    Well-aligned zinc oxide (ZnO) nanowire arrays were fabricated on gold-coated plastic substrates using a low-temperature aqueous chemical growth (ACG) method. The ZnO nanowire arrays with 50-130 nm diameters and similar to 1 mu m in lengths were used in an enzyme-based urea sensor through immobilization of the enzyme urease that was found to be sensitive to urea concentrations from 0.1 mM to 100 mM. Two linear sensitivity regions were observed when the electrochemical responses (EMF) of the sensors were plotted vs. the logarithmic concentration range of urea from 0.1 mM to 100 mM. The proposed sensor showed a sensitivity of 52.8 mV/decade for 0.1-40 mM urea and a fast response time less than 4s was achieved with good selectivity, reproducibility and negligible response to common interferents such as ascorbic acid and uric acid, glucose. K(+) and Na(+) ions.

  • 23.
    Usman Ali, Syed M.
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Kashif, M
    Nano Biochip Research Group, Institute of Nano Electronic Engineering (INEE), University Malaysia Perlis (UniMAP), Perlis, Malaysia.
    Hussain Ibupoto, Zafar
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Fakhar-e-Alam, M
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Hashim, U
    Nano Biochip Research Group, Institute of Nano Electronic Engineering (INEE), University Malaysia Perlis (UniMAP), Perlis, Malaysia.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Functionalised zinc oxide nanotube arrays as electrochemical sensors for the selective determination of glucose2011In: Micro & Nano Letters, ISSN 1750-0443, E-ISSN 1750-0443, Vol. 6, no 8, p. 609-613Article in journal (Refereed)
    Abstract [en]

    In the present study, highly oriented single-crystal zinc oxide nanotube (ZnO-NT) arrays were prepared by a trimming of ZnO nanorods along the c-axis on the gold-coated glass substrate having a diameter of 100-200 nm and a length of similar to 1 mu m using a low-temperature aqueous chemical growth process. The prepared (ZnO-NT) arrays were further used as electrochemical enzyme-based glucose sensors through immobilisation of glucose oxidase by the physical adsorption method in conjunction with a Nafion coating. The electrochemical response of the sensor was found to be linear over a relatively wide logarithmic concentration range from 0.5 x 10(-6) to 12 x 10(-3) M. The proposed sensor showed a high sensitivity of 69.12 mV/decade with R = 0.9934 for sensing of glucose. A fast-response time less than 4 s with good selectivity, reproducibility and negligible response to common interferents such as ascorbic acid and uric acid prevailed.

  • 24.
    Usman Ali, Syed M
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Nour, Omer
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Willander, Magnus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Danielsson, B.
    Lund University.
    A fast and sensitive potentiometric glucose microsensor based on glucose oxidase coated ZnO nanowires grown on a thin silver wire2010In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 145, no 2, p. 869-874Article in journal (Refereed)
    Abstract [en]

    In this study, a potentiometric glucose biosensor was fabricated by immobilization of glucose oxidase on to zinc oxide nanowires. Zinc oxide nanowires with 250-300 nm diameters and approximately 1.2 mu m lengths were grown on the surface of silver wires with a diameter of 250 mu m. Glucose oxidase (GOD) was electrostatically immobilized on the surface of the well aligned zinc oxide nanowires resulting in sensitive, selective, stable and reproducible glucose biosensors. The potentiometric response vs. Ag/AgCl reference electrode was found to be linear over a relatively wide logarithmic concentration range (0.5-1000 mu M) suitable for intracellular glucose detection. By applying a membrane on the sensor the linear range could be extended to 0.5 mu M to 10 mM, which increased the response time from less than 1 to 4s. On the other hand the membrane increased the sensor durability considerably. The sensor response was unaffected by normal concentrations of common interferents with glucose sensing such as uric acid and ascorbic acid.

  • 25.
    Usman Ali, Syed M.
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Nour, Omer
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Willander, Magnus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Danielsson, Bengt
    Lund University.
    Glocuse detection with a commercial MOSFET using ZnO nanowires extended gate2009In: IEEE Transaction on Nanotechnology, Vol. 8, no 6, p. 678-683Article in journal (Refereed)
    Abstract [en]

    Zinc oxide (ZnO) nanowires were grown on a silver (Ag) wire with a diameter of approximately 250 $mu$m and used in an electrochemical sensor. The enzyme glucose oxidase (GOD) was immobilized on the ZnO nanowires and the silver wire was connected directly to the gate of a MOSFET. Upon exposure to glucose (1-100 $mu$M) the electrochemical response from the glucose oxidase induced a stable measurable voltage change on the gate leading to a strong modulation of the current through the MOSFET. For a sensor with uniform ZnO nanowires functionalized with GOD a fast response time of less than 100 ms, was demonstrated. The effect of the uniformity of the ZnO nanowires on the sensing property was also investigated. The extended gate arrangement facilitated glucose detection in small sample volumes and made it possible to demonstrate the present sensor concept using a standard low threshold MOSFET. The extended gate MOSFET sensor approach demonstrates the possibility and potential of the use of nano-structures coupled to standard electronic components for biosensing applications.

  • 26.
    Usman Ali, Syed
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Ul Hassan Alvi, Naveed
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Hussain Ibupoto, Zafar
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Nur, Omer
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Willander, Magnus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Danielsson, Bengt
    Acromed Invest AB.
    Selective potentiometric determination of uric acid with uricase immobilized on ZnO nanowires2011In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 152, no 2, p. 241-247Article in journal (Refereed)
    Abstract [en]

    In this study, a potentiometric uric acid biosensor was fabricated by immobilization of uricase onto zinc oxide (ZnO) nanowires. Zinc oxide nanowires with 80-150 nm in diameter and 900 nm to 1.5 mu m in lengths were grown on the surface of a gold coated flexible plastic substrate. Uricase was electrostatically immobilized on the surface of well aligned ZnO nanowires resulting in a sensitive, selective, stable and reproducible uric acid biosensor. The potentiometric response of the ZnO sensor vs Ag/AgCl reference electrode was found to be linear over a relatively wide logarithmic concentration range (1-650 mu M) suitable for human blood serum. By applying a Nafion (R) membrane on the sensor the linear range could be extended to 1-1000 mu M at the expense of an increased response time from 6.25 s to less than 9 s. On the other hand the membrane increased the sensor durability considerably. The sensor response was unaffected by normal concentrations of common interferents such as ascorbic acid, glucose, and urea.

  • 27.
    Willander, Magnus
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Nour, Omer
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Ali, Sayed Usman
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Zinc oxide nanostrucutres based bio and chemical extra- and intracellular sensors2011In: Portable chemical sensors: weapons against terrorism / [ed] D. P. Nikolelis, Springer, 2011, p. 305-322Chapter in book (Other academic)
    Abstract [en]

    In this chapter we present sensors based on ZnO nanostructures suitable for sensing in small volumes and can be used for intracellular as well as extracellular environments. The principle of the measurement is based on the potentiometric effect. The measurement electrodes were constructed by growing ZnO nanostructures on the tip of sub-micrometer glass pipettes and were used versus Ag/AgCl reference electrodes. By functionalizing the ZnO nanostructures based electrodes, the selectivity of the sensors can be tuned to detect the ion or the analyte in question. The developed sensors were used to measure the concentration of most of the common ions like calcium, potassium, sodium and magnesium. In addition different biological analytes were also measured. These include glucose, urine, uric acid and cholesterol. The developed sensors showed good sensitivity and a wide dynamic range and represent a step towards developing efficient sensor of interest for human health diagnostic.

  • 28.
    Willander, Magnus
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Nur, Omer
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Fakhar-e-Alam, M.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Jamil Rana, Sadaf
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Israr Qadir, Muhammad
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Sultana, Kishwar
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Ali, Syed M. Usman
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Asif, Muhammad
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Applications of Zinc Oxide Nanowires for Bio-photonics and Bio-electronics2011In: Proceedings of SPIE Volume 7940 / [ed] Ferechteh Hosseini Teherani, David C. Look, David J. Rogers, Bellingham, Washington, USA: SPIE - International Society for Optical Engineering, 2011Conference paper (Other academic)
    Abstract [en]

    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.

  • 29.
    Willander, Magnus
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Yang, Lili
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Wadeasa, A.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Ali, S.U.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Asif, M.H.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Zhao, Q.X.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Nour, Omer
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Zinc oxide nanowires: controlled low temperature growth and electrochemical and optical devices2009In: Journal of Materials Chemsitry, Vol. 19, no 7, p. 1006-1018Article in journal (Refereed)
    Abstract [en]

    In this paper we present our new findings on the growth, characterization and nano-devices based on ZnO nanowires. We will limit the scope of this article to low temperature grown ZnO nanowires, due to the fact that low temperature growth is suitable for many applications. On growth and size control we will present our methodology for the growth of ZnO nanowires on Si substrates using low temperature techniques. The effect of the annealing on these low temperature grown ZnO nanowires is investigated and discussed. We then present our results on the surface recombination velocity of ZnO nanowires. This will be followed by the demonstration of new prototype nano-devices. These nano-devices include the demonstration of two new electrochemical nano-sensors. These are the extended gate glucose sensor and the calcium ion selective sensor using ionophore membrane coating on ZnO nanowires. Finally we will present results from light emitting diodes (LEDs) based on our ZnO nanowires grown on p-type organic semiconductors. The effect of the interlayer design of this hybrid organic–inorganic LED on the emission properties is highlighted.

1 - 29 of 29
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