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  • 1.
    Atif, M.
    et al.
    King Saud University, Saudi Arabia; National Institute Laser and Optron, Pakistan .
    Alsalhi, M. S.
    King Saud University, Saudi Arabia .
    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.
    The synthesis and optical characterization of well aligned ZnO nanorods using seed layer of Mn3O4 nanoparticles2014In: Optoelectronics and Advanced Materials Rapid Communications, ISSN 1842-6573, E-ISSN 2065-3824, Vol. 8, no 7-8, p. 643-646Article in journal (Refereed)
    Abstract [en]

    In this study, vertically aligned ZnO nanorods were fabricated by hydrothermal growth method using manganese oxide Mn3O4 nanoparticles as a seed layer. X-ray diffraction and Raman studies have shown the nano meter size of Mn3O4 nanoparticles. ZnO nanorods were characterized by field emission scanning electron microscopy and X-ray diffraction techniques. The prepared ZnO nanorods are highly dense, uniform and verily aligned and possess good crystal quality. Photoluminescence analysis has demonstrated that the ZnO nanorods exhibit deep level emission in green region due to oxygen vacancy related emission and the orange/red region is resulted due to interstitial oxygen defects related emission. This method for the fabrication of well aligned ZnO nanorods can be adapted for the development of optoelectronic devices.

  • 2.
    Chey, Chan Oeurn
    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.
    Khun, Kimleang
    Linköping University, Department of Science and Technology. 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.
    Indirect Determination of Mercury Ion by Inhibition of a Glucose Biosensor Based on ZnO Nanorods2012In: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 12, no 11, p. 15063-15077Article in journal (Refereed)
    Abstract [en]

    A potentiometric glucose biosensor based on immobilization of glucose oxidase (GOD) on ZnO nanorods (ZnO-NRs) has been developed for the indirect determination of environmental mercury ions. The ZnO-NRs were grown on a gold coated glass substrate by using the low temperature aqueous chemical growth (ACG) approach. Glucose oxidase in conjunction with a chitosan membrane and a glutaraldehyde (GA) were immobilized on the surface of the ZnO-NRs using a simple physical adsorption method and then used as a potentiometric working electrode. The potential response of the biosensor between the working electrode and an Ag/AgCl reference electrode was measured in a 1mM phosphate buffer solution (PBS). The detection limit of the mercury ion sensor was found to be 0.5 nM. The experimental results provide two linear ranges of the inhibition from 0.5 x 10(-6) mM to 0.5 x 10(-4) mM, and from 0.5 x 10(-4) mM to 20 mM of mercury ion for fixed 1 mM of glucose concentration in the solution. The linear range of the inhibition from 10(-3) mM to 6 mM of mercury ion was also acquired for a fixed 10 mM of glucose concentration. The working electrode can be reactivated by more than 70% after inhibition by simply dipping the used electrode in a 10 mM PBS solution for 7 min. The electrodes retained their original enzyme activity by about 90% for more than three weeks. The response to mercury ions was highly sensitive, selective, stable, reproducible, and interference resistant, and exhibits a fast response time. The developed glucose biosensor has a great potential for detection of mercury with several advantages such as being inexpensive, requiring minimum hardware and being suitable for unskilled users.

  • 3.
    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.

  • 4.
    Elhag, Sami
    et al.
    Linköping University, Department of Science and Technology. Linköping University, Faculty of Science & Engineering.
    Khun, Kimleang
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Khranovskyy, Volodymyr
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Nour, Omer
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Efficient Donor Impurities in ZnO Nanorods by Polyethylene Glycol for Enhanced Optical and Glutamate Sensing Properties2016In: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 16, no 2Article in journal (Refereed)
    Abstract [en]

    In this paper, we show that the possibility of using polyethylene glycol (EG) as a hydrogen source and it is used to assist the hydrothermal synthesis of ZnO nanorods (ZNRs). EG doping in ZNRs has been found to significantly improve their optical and chemical sensing characteristics toward glutamate. The EG was found to have no role on the structural properties of the ZNRs. However, the x-ray photoelectron spectroscopy (XPS) suggests that the EG could induce donor impurities effect in ZnO. Photoluminescence (PL) and UV-Vis. spectra demonstrated this doping effect. Mott-Schottky analysis at the ZNRs/electrolyte interface was used to investigate the charge density for the doped ZNRs and showed comparable dependence on the used amount of EG. Moreover, the doped ZNRs were used in potentiometric measurements for glutamate for a range from 10(-6) M to 10(-3) M and the potential response of the sensor electrode was linear with a slope of 91.15 mV/decade. The wide range and high sensitivity of the modified ZNRs based glutamate biosensor is attributed to the doping effect on the ZNRs that is dictated by the EG along with the high surface area-to-volume ratio. The findings in the present study suggest new avenues to control the growth of n-ZnO nanostructures and enhance the performance of their sensing devices.

  • 5.
    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.

  • 6.
    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.

  • 7.
    Ibupoto, Zafar Hussain
    et al.
    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.
    Beni, Valerio
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, The Institute of Technology.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Synthesis of Novel CuO Nanosheets and Their Non-Enzymatic Glucose Sensing Applications2013In: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 13, no 6, p. 7926-7938Article in journal (Refereed)
    Abstract [en]

    Abstract: In this study, we have developed a sensitive and selective glucose sensor using novel CuO nanosheets which were grown on a gold coated glass substrate by a low temperature growth method. X-ray differaction (XRD) and scanning electron microscopy (SEM) techniques were used for the structural characterization of CuO nanostructures. CuO nanosheets are highly dense, uniform, and exhibited good crystalline array structure. X-ray photoelectron spectroscopy (XPS) technique was applied for the study of chemical composition of CuO nanosheets and the obtained information demonstrated pure phase CuO nanosheets. The novel CuO nanosheets were employed for the development of a sensitive and selective non-enzymatic glucose sensor. The measured sensitivity and a correlation coefficient are in order 5.20 × 102 µA/mMcm2 and 0.998, respectively. The proposed sensor is associated with several advantages such as low cost, simplicity, high stability, reproducibility and selectivity for the quick detection of glucose.

  • 8.
    Ibupoto, Zafar Hussain
    et al.
    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.
    Eriksson, Martin
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    AlSalhi, Mohammad
    King Saud University, Riyadh, Saudi Arabia .
    Atif, Muhammad
    King Saud University, Riyadh, Saudi Arabia .
    Ansari, Anees
    King Saud University, Riyadh, Saudi Arabia .
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology. King Saud University, Riyadh, Saudi Arabia .
    Hydrothermal Growth of Vertically Aligned ZnO Nanorods Using a Biocomposite Seed Layer of ZnO Nanoparticles2013In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 6, no 8, p. 3584-3597Article in journal (Refereed)
    Abstract [en]

    Well aligned ZnO nanorods have been prepared by a low temperature aqueous chemical growth method, using a biocomposite seed layer of ZnO nanoparticles prepared in starch and cellulose bio polymers. The effect of different concentrations of biocomposite seed layer on the alignment of ZnO nanorods has been investigated. ZnO nanorods grown on a gold-coated glass substrate have been characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) techniques. These techniques have shown that the ZnO nanorods are well aligned and perpendicular to the substrate, and grown with a high density and uniformity on the substrate. Moreover, ZnO nanorods can be grown with an orientation along the c-axis of the substrate and exhibit a wurtzite crystal structure with a dominant (002) peak in an XRD spectrum and possessed a high crystal quality. A photoluminescence (PL) spectroscopy study of the ZnO nanorods has revealed a conventional near band edge ultraviolet emission, along with emission in the visible part of the electromagnetic spectrum due to defect emission. This study provides an alternative method for the fabrication of well aligned ZnO nanorods. This method can be helpful in improving the performance of devices where alignment plays a significant role.

  • 9.
    Ibupoto, Zafar Hussain
    et al.
    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.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    A Potentiometric Biosensor for the Detection of Notch 3 Using Functionalized ZnO Nanorods2014In: Journal of Nanoscience and Nanotechnology, ISSN 1533-4880, E-ISSN 1533-4899, Vol. 14, no 9, p. 6704-6710Article in journal (Refereed)
    Abstract [en]

    The notch signalling plays a vital and radical role for the activity of cellular proliferation, differentiation and apoptosis. In this study, for the first time a particular biosensor is developed for the detection of notch 3. ZnO nanorods were fabricated on the gold coated glass substrate by hydrothermal method and afterwards were decorated with the gold nanoparticles by electrodepositing technique. Scanning electron microscopy (SEM) has shown the perpendicular to the substrate growth pattern of ZnO nanorods. X-ray diffraction (XRD) studies showed the c-axis oriented growth direction with wurtzite crystal structure of ZnO nanorods. X-ray Photoelectron Spectroscopy (XPS) and energy dispersive X-ray (EDX) techniques have shown the presence of Zn, O and Au atoms in the prepared functional material. Furthermore, the anti-notch 3 was physically adsorbed on the gold nanoparticles functionalized ZnO nanorods. The developed potentiometric immunosensor has shown response to the wide range of notch 3 molecules. The detected range included 1.00 x 10(-5)-1.50 x 10(0) mu g/mL with a sensitivity of 23.15 +/- 0.31 mV/decade. The analytical parameters including reproducibility, stability, and selectivity were also investigated and the observed results indicate the acceptable performance of the notch 3 biosensor. Moreover, the proposed notch 3 biosensor exhibited a fast response time of 10 s.

  • 10.
    Ibupoto, Zafar Hussain
    et al.
    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.
    Development of a pH Sensor Using Nanoporous Nanostructures of NiO2014In: Journal of Nanoscience and Nanotechnology, ISSN 1533-4880, E-ISSN 1533-4899, Vol. 14, no 9, p. 6699-6703Article in journal (Refereed)
    Abstract [en]

    Glass is the conventional material used in pH electrodes to monitor pH in various applications. However, the glass-based pH electrode has some limitations for particular applications. The glass sensor is limited in the use of in vivo biomedical, clinical or food applications because of the brittleness of glass, its large size, the difficulty in measuring small volumes and the absence of deformation (inflexibility). Nanostructure-based pH sensors are very sensitive, reliable, fast and applicable towards in vivo measurements. In this study, nanoporous NiO nanostructures are synthesized on a gold-coated glass substrate by a hydrothermal route using poly(vinyl alcohol) (PVA) as a stabilizer. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques were used for the morphological and crystalline studies. The grown NiO nanostructures are uniform and dense, and they possess good crystallinity. A pH sensor based on these NiO nanostructures was developed by testing the different pH values from 2-12 of phosphate buffered saline solution. The proposed pH sensor showed robust sensitivity of -43.74 +/- 0.80 mV/pH and a quick response time of less than 10 s. Moreover, the repeatability, reproducibility and stability of the presented pH sensor were also studied.

  • 11.
    Ibupoto, Zafar Hussain
    et al.
    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.
    Hydrothermal Growth of CuO Nanoleaf Structures, and Their Mercuric Ion Detection Application2014In: Journal of Nanoscience and Nanotechnology, ISSN 1533-4880, E-ISSN 1533-4899, Vol. 14, no 9, p. 6711-6717Article in journal (Refereed)
    Abstract [en]

    Mercury is the hazardous heavy metal ion for the environment and the humanbeing therefore its determination is very important and herein we describe the development of mercury ion sensor on the CuO nanoleaf like nanostructures using cetyltrimethylammonium bromide (CTAB) surfactant as template for the growth by hydrothermal growth method. Scanning electron microscopy and X-ray diffraction study has shown high density and good crystal quality of the fabricated CuO nanostructures respectively. The presented mercury ion sensor has detected the wide range of 1.0 x 10(-7) to 1.0 x 10(-1) M mercury ion concentrations with an acceptable Nernstian behaviour and a sensitivity of 30.1 +/- 0.6 mV/decade. The proposed mercury ion sensor exhibited low detection limit of 1.0 x 10(-8) M and also a fast response time of less than 5 s. In addition, the presented mercury ion sensor has shown an excellent repeatability, reproducibility, stability and selectivity. Moreover, the mercury ion selective electrode based on CuO nanoleaves was tested as an indicator electrode in the potentiometric titration.

  • 12.
    Ibupoto, Zafar Hussain
    et al.
    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.
    Selective Lead Ion Sensor Based on the CuO Nanoshuttles2013In: Sensor Letters, ISSN 1546-198X, E-ISSN 1546-1971, Vol. 11, no 11, p. 2049-2054Article in journal (Refereed)
    Abstract [en]

    In this research work, CuO nanoshuttles like nanostructures are synthesized by hydrothermal method using polyvinyl alcohol surfactant and the structural characterisation was carried out using scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. The structural studies showed the high yield of the CuO nanostructures on the substrate and also exhibit good crystal quality. Moreover, CuO nanoshuttles like nanostructures were utilized for the development of lead ion sensor electrode and the sensor electrode has shown the linear potentiometric response for the lead ions over the wide range of 5 x 10(-6) M-1 x 10(-1) M with a Nernstian slope of 31 mV/decade. The advantageous features of the proposed sensor electrode include high selectivity, repeatability, low limit of detection (1 x 10(-7) M) and a fast response time of less than 10 s, good stability, and the reproducibility. The CuO nanoshuttles based lead ion sensor electrode was used as an indicator electrode for the potentiometric titration of lead ions against the etthylenediaminetetraacetic acid (EDTA). All the obtained results indicate that the presented lead ion sensor may have a good potential for its utilization in the real sample analysis.

  • 13.
    Ibupoto, Zafar
    et al.
    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.
    Beni, Valerio
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, The Institute of Technology.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Non-Enzymatic Glucose Sensor Based on the Novel Flower Like Morphology of Nickel Oxide2013In: Soft Nanoscience Letters, ISSN 2160-0600, E-ISSN 2160-0740, Vol. 3, p. 46-50Article in journal (Refereed)
    Abstract [en]

    In this study, novel nickel oxide (NiO) flowers like nanostructures were fabricated onto gold coated glass substrate by hydrothermal method using high alkaline pH medium. The structural study of nickel oxide nanostructures was per-formed by scanning electron microscopy (SEM) and X-ray differaction (XRD) techniques. Nickel oxide nanostructures are highly dense, uniform and possess good crystalline quality. The so prepared structures were investigated for their electrochemical properties by cyclic voltammetry and amperometric techniques. The nickel oxide flower like morphol-ogy has shown good electrochemical performances for the oxidation of glucose. The presented sensing material was able to detected glucose in a wide range of concentration of 0.001 mM to 8 mM with a high sensitivity (123 μmA/mM) and regression coefficient of 0.99. Moreover, the NiO nanostructures based sensor is highly reproducible, stable, exhib-iting a fast response time and selective in the response. All the obtained results indicate the potential use of this material in the development of enzyme free sensors for the detection of glucose.

  • 14.
    Khun, Kimleang
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Synthesising Metal Oxide Materials and Their Composite Nanostructures for Sensing and Optoelectronic Device Applications2014Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Research on nanomaterials has been revolutionized in the last few years because of the attractive properties they have in comparison to the bulk phase of similar materials. These properties are physical, chemical, catalytic and optical. Among these nanomaterials, the metal oxide nanostructures have become of particular interest to scientists for the development of different optical, biochemical and biomedical nanodevices. In the present research work using the advantageous features of nanotechnology, high performance nanodevices for optoelectronics with a wide band gap compound nanostructure and highly sensitive sensor devices have been demonstrated. The nanotechnology is used to fabricate sensitive and precise nanodevices based on nanomaterials for the application of sensing.

    Among metal oxide nanostructures, ZnO, CuO and NiO are attractive materials because of their unique properties; their high surface area to volume ratio, their energy band gap of 3.37 eV, 1.2 eV and 3.7 eV, respectively, biocompatibility, high electron mobility, fast electron transfer rate and they are environmental-friendly in many applications. When used in sensor devices, nanomaterials have indicated high selectivity for possible use to detect the various analytes even in small volumes. Metal oxide nanostructures have shown to be good for optoelectronic nanodevices because of their electrical characteristics, high optical absorption and low-processing temperature.

    In this thesis, the synthesis of different morphologies of metal oxide semiconductor nanostructures and their composite using the hydrothermal method are demonstrated for various applications. This thesis is divided into three parts:

    In the first part of this research work, the fabrication of well-aligned ZnO nanorods using different concentrations of composite seed layer of inorganic and organic materials when using the hydrothermal growth method is presented. The effect of the composite seed layer on the alignment, density and optical properties of the grown ZnO nanorods is investigated (paper I). Utilizing the advantage of ZnO nanostructure, a comparative study of ZnO nanorods and thin films for chemical and biosensing application was carried out. The ZnO nanorods and thin films were functionalized with strontium ionophore membrane, immobilized the galactose oxidase and lactate oxidase for determining the strontium ions, D-galactose and L-lactic acid, respectively (paper II).

    In the second part, the effects of different urea concentrations on the morphology of CuO nanostructures is studied as described in paper III. Moreover, CuO nanoflowers were functionalized with cadmium ion ionophore for the detection of Cd ions, while CuO nanosheets were grown by the low temperature growth method and were used for the development of a nonenzymatic glucose sensor, respectively (Paper IV).

    In the last part of this thesis, composite nanostructures of CuO/ZnO and NiO/ZnO were applied to develop dopamine sensor and fast sensitive UV photodetector, respectively. A nanohybrid of CuO/ZnO nanostructure was used as a non-enzymatic electrode to detect dopamine by cyclic voltammetry (CV) and amperometric techniques (Paper V). In paper VI, we have demonstrated a strong UV absorption from ZnO nano-sheets achieved by the supramoleculesassisted growth solution using the hydrothermal method. The synthesized nanomaterial was used in the fabrication of UV photodetector based on p-NiO/ n-ZnO heterostructures.

    List of papers
    1. Fabrication of Well-Aligned ZnO Nanorods Using a Composite Seed Layer of ZnO Nanoparticles and Chitosan Polymer
    Open this publication in new window or tab >>Fabrication of Well-Aligned ZnO Nanorods Using a Composite Seed Layer of ZnO Nanoparticles and Chitosan Polymer
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    2013 (English)In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 6, no 10, p. 4361-4374Article in journal (Refereed) Published
    Abstract [en]

    In this study, by taking the advantage of both inorganic ZnO nanoparticles and the organic material chitosan as a composite seed layer, we have fabricated well-aligned ZnO nanorods on a gold-coated glass substrate using the hydrothermal growth method. The ZnO nanoparticles were characterized by the Raman spectroscopic techniques, which showed the nanocrystalline phase of the ZnO nanoparticles. Different composites of ZnO nanoparticles and chitosan were prepared and used as a seed layer for the fabrication of well-aligned ZnO nanorods. Field emission scanning electron microscopy, energy dispersive X-ray, high-resolution transmission electron microscopy, X-ray diffraction, and infrared reflection absorption spectroscopic techniques were utilized for the structural characterization of the ZnO nanoparticles/chitosan seed layer-coated ZnO nanorods on a gold-coated glass substrate. This study has shown that the ZnO nanorods are well-aligned, uniform, and dense, exhibit the wurtzite hexagonal structure, and are perpendicularly oriented to the substrate. Moreover, the ZnO nanorods are only composed of Zn and O atoms. An optical study was also carried out for the ZnO nanoparticles/chitosan seed layer-coated ZnO nanorods, and the obtained results have shown that the fabricated ZnO nanorods exhibit good crystal quality. This study has provided a cheap fabrication method for the controlled morphology and good alignment of ZnO nanorods, which is of high demand for enhancing the working performance of optoelectronic devices.

    Place, publisher, year, edition, pages
    MDPI, 2013
    Keywords
    ZnO nanoparticles; chitosan; ZnO nanorods; well-aligned; low-temperature growth
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-104420 (URN)10.3390/ma6104361 (DOI)000330295600005 ()
    Available from: 2014-02-17 Created: 2014-02-17 Last updated: 2017-12-06Bibliographically approved
    2. Comparative study of ZnO nanorods and thin films for chemical and biosensing applications and the development of ZnO nanorods based potentiometric strontium ion sensor
    Open this publication in new window or tab >>Comparative study of ZnO nanorods and thin films for chemical and biosensing applications and the development of ZnO nanorods based potentiometric strontium ion sensor
    Show others...
    2013 (English)In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 268, p. 37-43Article in journal (Refereed) Published
    Abstract [en]

    In this study, the comparative study of ZnO nanorods and ZnO thin films were performed regarding the chemical and biosensing properties and also ZnO nanorods based strontium ion sensor is proposed. ZnO nanorods were grown on gold coated glass substrates by the hydrothermal growth method and the ZnO thin films were deposited by electro deposition technique. ZnO nanorods and thin films were characterised by field emission electron microscopy [FESEM] and X-ray diffraction [XRD] techniques and this study has shown that the grown nanostructures are highly dense, uniform and exhibited good crystal quality. Moreover, transmission electron microscopy [TEM] was used to investigate the quality of ZnO thin film and we observed that ZnO thin film was comprised of nano clusters. ZnO nanorods and thin films were functionalised with selective strontium ionophore salicylaldehyde thiosemicarbazone [ST] membrane, galactose oxidase, and lactate oxidase for the detection of strontium ion, galactose and l-lactic acid, respectively. The electrochemical response of both ZnO nanorods and thin films sensor devices was measured by using the potentiometric method. The strontium ion sensor has exhibited good characteristics with a sensitivity of 28.65 +/- 0.52 mV/decade, for a wide range of concentrations from 1.00 x 10(-6) to 5.00 x 10(-2) M, selectivity, reproducibility, stability and fast response time of 10.00 s. The proposed strontium ion sensor was used as indicator electrode in the potentiometric titration of strontium ion versus ethylenediamine tetra acetic acid [EDTA]. This comparative study has shown that ZnO nanorods possessed better performance with high sensitivity and low limit of detection due to high surface area to volume ratio as compared to the flat surface of ZnO thin films.

    Place, publisher, year, edition, pages
    Elsevier, 2013
    Keywords
    ZnO nanorods, ZnO thin film, Immobilisation, Galactose oxidase, Lactate oxidase, Strontium ionophore, Potentiometric technique
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-90674 (URN)10.1016/j.apsusc.2012.11.141 (DOI)000315330300007 ()
    Available from: 2013-04-03 Created: 2013-04-03 Last updated: 2018-02-27
    3. Urea Assisted Synthesis of Flower Like CuO Nanostructures and Their Chemical Sensing Application for the Determination of Cadmium Ions
    Open this publication in new window or tab >>Urea Assisted Synthesis of Flower Like CuO Nanostructures and Their Chemical Sensing Application for the Determination of Cadmium Ions
    2013 (English)In: Electroanalysis, ISSN 1040-0397, E-ISSN 1521-4109, Vol. 25, no 6, p. 1425-1432Article in journal (Refereed) Published
    Abstract [en]

    The novel nanostructures of CuO with improved morphology are strongly required for the development of devices with enhanced performance. In this study flower like nanostructures of CuO are synthesized by hydrothermal method using urea as tuning material for the morphology of CuO during the growth process. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques were used for the characterization of these nanostructures. The nanostructures are highly dense, uniform and well aligned on the gold coated glass substrate. Moreover, CuO nanostructures exhibited pure phase of CuO. These novel CuO nanostructures were potentially used for the construction of cadmium ion sensor by functionalizing with tetrathia-12-crown-4 a selective cadmium ion ionophore. The proposed cadmium ion sensor has detected the wide range of cadmium ion concentrations from 1.0x10-9-1.0x10-1M with a sensitivity of 29.3 +/- 0.3mV/decade and also a fast response time of less than 10.0s is demonstrated. CuO nanostructures based cadmium ion selective electrode has also shown excellent reproducibility, repeatability, selectivity, and stability. The sensor electrode was also used as indicator electrode for the confirmation of practical utility and the obtained result describes the good behavior of the sensor in the potentiometric titration for the determination of cadmium ions.

    Place, publisher, year, edition, pages
    Wiley-VCH Verlag, 2013
    Keywords
    Urea; Flower like morphology of CuO; Potentiometric response; Cadmium ions; Output response; Nanostructures
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-96119 (URN)10.1002/elan.201200660 (DOI)000320193100013 ()
    Available from: 2013-08-14 Created: 2013-08-14 Last updated: 2017-12-06
    4. Synthesis of Novel CuO Nanosheets and Their Non-Enzymatic Glucose Sensing Applications
    Open this publication in new window or tab >>Synthesis of Novel CuO Nanosheets and Their Non-Enzymatic Glucose Sensing Applications
    Show others...
    2013 (English)In: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 13, no 6, p. 7926-7938Article in journal (Refereed) Published
    Abstract [en]

    Abstract: In this study, we have developed a sensitive and selective glucose sensor using novel CuO nanosheets which were grown on a gold coated glass substrate by a low temperature growth method. X-ray differaction (XRD) and scanning electron microscopy (SEM) techniques were used for the structural characterization of CuO nanostructures. CuO nanosheets are highly dense, uniform, and exhibited good crystalline array structure. X-ray photoelectron spectroscopy (XPS) technique was applied for the study of chemical composition of CuO nanosheets and the obtained information demonstrated pure phase CuO nanosheets. The novel CuO nanosheets were employed for the development of a sensitive and selective non-enzymatic glucose sensor. The measured sensitivity and a correlation coefficient are in order 5.20 × 102 µA/mMcm2 and 0.998, respectively. The proposed sensor is associated with several advantages such as low cost, simplicity, high stability, reproducibility and selectivity for the quick detection of glucose.

    Place, publisher, year, edition, pages
    Basel, Switzerland: MDPI, 2013
    Keywords
    CuO nanosheets; hydrothermal growth method; non-enzymatic glucose sensor; selectivity; reproducibility
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-96478 (URN)10.3390/s130607926 (DOI)000320767600059 ()
    Available from: 2013-08-23 Created: 2013-08-20 Last updated: 2017-12-06Bibliographically approved
    5. An Electrochemical Dopamine Sensor Based on the ZnO/CuO Nanohybrid Structures
    Open this publication in new window or tab >>An Electrochemical Dopamine Sensor Based on the ZnO/CuO Nanohybrid Structures
    Show others...
    2014 (English)In: Journal of Nanoscience and Nanotechnology, ISSN 1533-4880, E-ISSN 1533-4899, Vol. 14, no 9, p. 6646-6652Article in journal (Refereed) Published
    Abstract [en]

    The selective detection of dopamine (DA) is of great importance in the modern medicine because dopamine is one of the main regulators in human behaviour. In this study, ZnO/CuO nanohybrid structures, grown on the gold coated glass substrate, have been investigated as a novel electrode material for the electrochemical detection of dopamine. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) techniques were used for the material characterization and the obtained results are in good agreement. The selective determination of dopamine was demonstrated by cyclic voltammetry (CV) and amperometric experiments. The amperometric response was linear for dopamine concentrations between 1.0 x 10(-3) and 8.0 mM with a sensitivity of 90.9 mu A mM(-1) cm(-2). The proposed dopamine biosensor is very stable, selective over common interferents as glucose, uric acid and ascorbic acid, and also good reproducibility was observed for seven electrodes. Moreover, the dopamine sensor exhibited a fast response time of less than 10 s. The wide range and acceptable sensitivity of the presented dopamine sensor provide the possible application in analysing the dopamine from the real samples.

    Place, publisher, year, edition, pages
    American Scientific Publishers, 2014
    Keywords
    Dopamine; ZnO/CuO Nanohybrid Structures; Cyclic Voltammetry; Amperometry
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-107432 (URN)10.1166/jnn.2014.9367 (DOI)000335873900020 ()
    Available from: 2014-06-12 Created: 2014-06-12 Last updated: 2017-12-05Bibliographically approved
    6. Supramolecules-assisted ZnO nanostructures growth and their UV photodetector application
    Open this publication in new window or tab >>Supramolecules-assisted ZnO nanostructures growth and their UV photodetector application
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    2015 (English)In: Solid State Sciences, ISSN 1293-2558, E-ISSN 1873-3085, Vol. 41, p. 14-18Article in journal (Refereed) Published
    Abstract [en]

    Zinc oxide (ZnO) nanosheets, nickel oxide (NiO) nanoflowers and their nanocomposite were grown on the fluorine doped tin oxide (FTO) substrate. The supramolecules-assisted ZnO growth by a hydrothermal method used to tune the morphology of the grown ZnO nanostructures to nanosheets morphology. The synthesis, purity and the optical properties of the grown material were characterized by scanning electron microscopy (SEM), x-ray diffraction (XRD), UV-visible spectrometry and photoluminescence (PL) analysis. The current-voltage (I-V) characterization of the ZnO/NiO heterojunction was performed at room temperature and showed an obvious nonlinear and rectifying response. A strong UV absorption with fast switching was observed from the ZnO/NiO composite heterojunction. The proposed UV photodetector based on this nano-composite is more stable, possesses fast rising and decaying time response approximately 100 ms and low leakage current was investigated. The findings indicate that the importance of the use of controlled nanostructures morphology for developing efficient nanodevices for various applications

    Place, publisher, year, edition, pages
    Elsevier, 2015
    Keywords
    ZnO/NiO nano-composite; UV absorption ZnO; nano-heterojunction; UV photodetector
    National Category
    Physical Sciences Electrical Engineering, Electronic Engineering, Information Engineering
    Identifiers
    urn:nbn:se:liu:diva-112863 (URN)10.1016/j.solidstatesciences.2015.01.011 (DOI)000350888800003 ()
    Note

    On the day of the defence date the status of this article was Manuscript.

    Available from: 2014-12-18 Created: 2014-12-18 Last updated: 2017-12-05Bibliographically approved
  • 15.
    Khun, Kimleang
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Elhag, Sami
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Ibupoto, Zafar Hussain
    Dr. M. A. Kazi Institute of Chemistry, University of Sindh, Jamshoro, Sindh, Pakistan.
    Khranovskyy, Volodymyr
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. 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.
    Supramolecules-assisted ZnO nanostructures growth and their UV photodetector application2015In: Solid State Sciences, ISSN 1293-2558, E-ISSN 1873-3085, Vol. 41, p. 14-18Article in journal (Refereed)
    Abstract [en]

    Zinc oxide (ZnO) nanosheets, nickel oxide (NiO) nanoflowers and their nanocomposite were grown on the fluorine doped tin oxide (FTO) substrate. The supramolecules-assisted ZnO growth by a hydrothermal method used to tune the morphology of the grown ZnO nanostructures to nanosheets morphology. The synthesis, purity and the optical properties of the grown material were characterized by scanning electron microscopy (SEM), x-ray diffraction (XRD), UV-visible spectrometry and photoluminescence (PL) analysis. The current-voltage (I-V) characterization of the ZnO/NiO heterojunction was performed at room temperature and showed an obvious nonlinear and rectifying response. A strong UV absorption with fast switching was observed from the ZnO/NiO composite heterojunction. The proposed UV photodetector based on this nano-composite is more stable, possesses fast rising and decaying time response approximately 100 ms and low leakage current was investigated. The findings indicate that the importance of the use of controlled nanostructures morphology for developing efficient nanodevices for various applications

  • 16.
    Khun, Kimleang
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Ibupoto, Z. H.
    University of Sindh Jamshoro, Pakistan.
    Liu, X.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Beni, Valerio
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, The Institute of Technology.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    The ethylene glycol template assisted hydrothermal synthesis of Co3O4 nanowires; structural characterization and their application as glucose non-enzymatic sensor2015In: Materials Science & Engineering: B. Solid-state Materials for Advanced Technology, ISSN 0921-5107, E-ISSN 1873-4944, Vol. 194, p. 94-100Article in journal (Refereed)
    Abstract [en]

    In the work reported herein the ethylene glycol template assisted hydrothermal synthesis, onto Au substrate, of thin and highly dense cobalt oxide (Co3O4) nanowires and their characterization and their application for non-enzymatic glucose sensing are reported. The structure and composition of Co3O4 nanowires have been fully characterized using scanning electron microscopy, X-ray diffraction, high resolution transmission electron microscopy and X-ray photoelectron spectroscopy. The synthesized Co3O4 nanowires resulted to have high purity and showed diameter of approximately 10 nm. The prepared Co3O4 nanowires coated gold electrodes were applied to the non-enzymatic detection of glucose. The developed sensor showed high sensitivity (4.58 x 10(1) mu A mM(-1) cm(-2)), a wide linear range of concentration (1.00 x 10(-4)-1.2 x 10(1) mM) and a detection limit of 2.65 x 10(-5) mM. The developed glucose sensor has also shown to be very stable and selective over interferents such as uric acid and ascorbic acid. Furthermore, the proposed fabrication process was shown to be highly reproducible response (over nine electrodes).

  • 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.
    AlSalhi, Mohammad
    Physics and Astronomy Department, College of Science, King Saud University, Riyadh, Saudi Arabia.
    Atif, Muhammad
    Physics and Astronomy Department, College of Science, King Saud University, Riyadh, Saudi Arabia.
    Ansari, Anees
    King Abdullah Institute for Nanotechnology, King Saud University, Riyadh, Saudi Arabia.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology. King Saud University, Riyadh, Saudi Arabia .
    Fabrication of Well-Aligned ZnO Nanorods Using a Composite Seed Layer of ZnO Nanoparticles and Chitosan Polymer2013In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 6, no 10, p. 4361-4374Article in journal (Refereed)
    Abstract [en]

    In this study, by taking the advantage of both inorganic ZnO nanoparticles and the organic material chitosan as a composite seed layer, we have fabricated well-aligned ZnO nanorods on a gold-coated glass substrate using the hydrothermal growth method. The ZnO nanoparticles were characterized by the Raman spectroscopic techniques, which showed the nanocrystalline phase of the ZnO nanoparticles. Different composites of ZnO nanoparticles and chitosan were prepared and used as a seed layer for the fabrication of well-aligned ZnO nanorods. Field emission scanning electron microscopy, energy dispersive X-ray, high-resolution transmission electron microscopy, X-ray diffraction, and infrared reflection absorption spectroscopic techniques were utilized for the structural characterization of the ZnO nanoparticles/chitosan seed layer-coated ZnO nanorods on a gold-coated glass substrate. This study has shown that the ZnO nanorods are well-aligned, uniform, and dense, exhibit the wurtzite hexagonal structure, and are perpendicularly oriented to the substrate. Moreover, the ZnO nanorods are only composed of Zn and O atoms. An optical study was also carried out for the ZnO nanoparticles/chitosan seed layer-coated ZnO nanorods, and the obtained results have shown that the fabricated ZnO nanorods exhibit good crystal quality. This study has provided a cheap fabrication method for the controlled morphology and good alignment of ZnO nanorods, which is of high demand for enhancing the working performance of optoelectronic devices.

  • 18.
    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.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Mansor, N. A.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Turner, Anthony
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, The Institute of Technology.
    Beni, Valerio
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, The Institute of Technology.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    An Electrochemical Dopamine Sensor Based on the ZnO/CuO Nanohybrid Structures2014In: Journal of Nanoscience and Nanotechnology, ISSN 1533-4880, E-ISSN 1533-4899, Vol. 14, no 9, p. 6646-6652Article in journal (Refereed)
    Abstract [en]

    The selective detection of dopamine (DA) is of great importance in the modern medicine because dopamine is one of the main regulators in human behaviour. In this study, ZnO/CuO nanohybrid structures, grown on the gold coated glass substrate, have been investigated as a novel electrode material for the electrochemical detection of dopamine. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) techniques were used for the material characterization and the obtained results are in good agreement. The selective determination of dopamine was demonstrated by cyclic voltammetry (CV) and amperometric experiments. The amperometric response was linear for dopamine concentrations between 1.0 x 10(-3) and 8.0 mM with a sensitivity of 90.9 mu A mM(-1) cm(-2). The proposed dopamine biosensor is very stable, selective over common interferents as glucose, uric acid and ascorbic acid, and also good reproducibility was observed for seven electrodes. Moreover, the dopamine sensor exhibited a fast response time of less than 10 s. The wide range and acceptable sensitivity of the presented dopamine sensor provide the possible application in analysing the dopamine from the real samples.

  • 19.
    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.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. 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.
    Danielsson, Bengt
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    A Selective Potentiometric Copper (II) Ion Sensor Based on the Functionalized ZnO Nanorods2014In: Journal of Nanoscience and Nanotechnology, ISSN 1533-4880, E-ISSN 1533-4899, Vol. 14, no 9, p. 6723-6731Article in journal (Refereed)
    Abstract [en]

    In this work, ZnO nanorods were hydrothermally grown on the gold-coated glass substrate and characterized by field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD) techniques. The ZnO nanorods were functionalized by two different approaches and performance of the sensor electrode was monitored. Fourier transform infrared spectroscopy (FTIR) was carried out for the confirmation of interaction between the ionophore molecules and ZnO nanorods. In addition to this, the surface of the electrode was characterized by X-ray photoelectron spectroscopy (XPS) showing the chemical and electronic state of the ionophore and ZnO nanorod components. The ionophore solution was prepared in the stabilizer, poly vinyl chloride (PVC) and additives, and then functionalized on the ZnO nanorods that have shown the Nernstian response with the slope of 31 mV/decade. However, the Cu2+ ion sensor was fabricated only by immobilizing the selective copper ion ionophore membrane without the use of PVC, plasticizers, additives and stabilizers and the sensor electrode showed a linear potentiometric response with a slope of 56.4 mV/decade within a large dynamic concentration range (from 1.0 x 10(-6) to 1.0 x 10(-1) M) of copper (II) nitrate solutions. The sensor showed excellent repeatability and reproducibility with response time of less than 10 s. The negligible response to potentially interfering metal ions such as calcium (Ca2+), magnesium (Mg2+), potassium (K+), iron (Fe3+), zinc (Zn2+), and sodium (Na+) allows this sensor to be used in biological studies. It may also be used as an indicator electrode in the potentiometric titration.

  • 20.
    Khun, Kimleang
    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.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    AlSalhi, M. S.
    King Saud University, Saudi Arabia King Saud University, Saudi Arabia .
    Atif, M.
    King Saud University, Saudi Arabia .
    Ansari, Anees A.
    King Saud University, Saudi Arabia .
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Potentiometric glucose sensor based on the glucose oxidase immobilized iron ferrite magnetic particle/chitosan composite modified gold coated glass electrode2012In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 173, p. 698-703Article in journal (Refereed)
    Abstract [en]

    A potentiometric glucose sensor based on the glucose oxidase immobilized on iron ferrite (Fe3O4) nanoparticles/chitosan composite modified gold coated glass substrate was fabricated. The electrode has advantages of both the inorganic Fe3O4 magnetic nanoparticles and the organic substance chitosan. The freshly prepared iron ferrite magnetic nanoparticles were characterized by X-ray diffraction (xRD) and transmission electron microscopy (TEM) technique was used for the analysis of dispersed iron ferrite magnetic nanoparticles in the mixture of glucose oxidase and chitosan. The electrostatic interaction of Fe3O4 nanoparticles with chitosan and the glucose oxidase molecules was investigated by the infra-red reflection absorption spectroscopy (IRAS) study. The glucose oxidase enzyme was immobilized on the surface of iron ferrite/chitosan composite without the use of Nafion or cross linker molecules. The fabricated glucose sensor has shown acceptable potentiometric response for the wide range of glucose concentrations from 1.0 x 10(-6) to 3.0 x 10(-2) M. The sensor electrode showed a sensitivity of 27.3 +/- 0.8 mV/decade and also fast response time of 7.0s. Moreover, the present glucose sensor has demonstrated good reproducibility, repeatability, selectivity and the storage stability. All the obtained results indicated that the glucose sensor based on the glucose oxidase immobilized iron ferrite/chitosan composite modified gold coated glass electrode can be used for the monitoring of glucose concentrations in human serum, drugs and may be applicable to detect glucose in the presence of other analytes.

  • 21.
    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.
    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.
    Development of Galactose Biosensor Based on Functionalized ZnO Nanorods with Galactose Oxidase2012In: Journal of Sensors, ISSN 1687-725X, E-ISSN 1687-7268, no 696247Article in journal (Refereed)
    Abstract [en]

    The fabrication of galactose biosensor based on functionalised ZnO nanorods is described. The galactose biosensor was developed by immobilizing galactose oxidase on ZnO nanorods in conjunction with glutaraldehyde as a cross-linker molecule. The IRAS study provided evidence for the interaction of galactose oxidase with the surface of ZnO nanorods. The electromotive force (EMF) response of the galactose biosensor was measured by potentiometric method. We observed that the proposed biosensor has a linear detection range over a concentration range from 10 mM to 200 mM with good sensitivity of 89.10 +/- 1.23 mV/decade. In addition, the proposed biosensor has shown fast time response of less than 10 s and a good selectivity towards galactose in the presence of common interferents such as ascorbic acid, uric acid, glucose, and magnesium ions. The galactose biosensor based on galactose oxidase immobilized ZnO nanorods has a shelf life more than four weeks.

  • 22.
    Willander, Magnus
    et al.
    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.
    Ibupoto, Zafar Hussain
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Metal Oxide Nanosensors Using Polymeric Membranes, Enzymes and Antibody Receptors as Ion and Molecular Recognition Elements2014In: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 14, no 5, p. 8605-8632Article, review/survey (Refereed)
    Abstract [en]

    The concept of recognition and biofunctionality has attracted increasing interest in the fields of chemistry and material sciences. Advances in the field of nanotechnology for the synthesis of desired metal oxide nanostructures have provided a solid platform for the integration of nanoelectronic devices. These nanoelectronics-based devices have the ability to recognize molecular species of living organisms, and they have created the possibility for advanced chemical sensing functionalities with low limits of detection in the nanomolar range. In this review, various metal oxides, such as ZnO-, CuO-, and NiO-based nanosensors, are described using different methods (receptors) of functionalization for molecular and ion recognition. These functionalized metal oxide surfaces with a specific receptor involve either a complex formation between the receptor and the analyte or an electrostatic interaction during the chemical sensing of analytes. Metal oxide nanostructures are considered revolutionary nanomaterials that have a specific surface for the immobilization of biomolecules with much needed orientation, good conformation and enhanced biological activity which further improve the sensing properties of nanosensors. Metal oxide nanostructures are associated with certain unique optical, electrical and molecular characteristics in addition to unique functionalities and surface charge features which shows attractive platforms for interfacing biorecognition elements with effective transducing properties for signal amplification. There is a great opportunity in the near future for metal oxide nanostructure-based miniaturization and the development of engineering sensor devices.

  • 23.
    Willander, Magnus
    et al.
    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.
    Ibupoto, Zafar Hussain
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    ZnO Based Potentiometric and Amperometric Nanosensors2014In: Journal of Nanoscience and Nanotechnology, ISSN 1533-4880, E-ISSN 1533-4899, Vol. 14, no 9, p. 6497-6508Article, review/survey (Refereed)
    Abstract [en]

    The existence of nanomaterials provides the solid platform for sensing applications due to owing of high sensitivity and a low concentration limit of detection. More likely used nanomaterials for sensing applications includes gold nanoparticles, carbon nanotubes, magnetic nanoparticles such as Fe3O4, quantum dots and metal oxides etc. Recently nanomaterial and biological detection becomes an interdisciplinary field and is very much focussed by the researchers. Among metal oxides ZnO is largely considered due to its less toxic nature, biocompatible, cheap and easy to synthesis. ZnO nanomaterial is highly used for the chemical sensing, especially electrochemical sensing due to its fascinating properties such as high surface to volume ratio, atoxic, biosafe and biocompatible. Moreover, ZnO nanostructures exhibit unique features which could expose a suitable nanoenviroment for the immobilization of proteineous material such as enzymes, DNA, antibodies, etc. and in doing so it retains the biological efficiency of the immobilized bio sensitive material. The following review describes the two different coatings (i.e., ionophore and enzyme) on the surface of ZnO nanorods for the chemical sensing of zinc ion detection, thallium (I) ion detection, and L-lactic acid and the measurement of galactose molecules. ZnO nanorods provide the excellent transducing properties in the generation of strong electrical signals. Moreover, this review is very much focused on the applications of ZnO nanostructures in the sensing field.

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