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Asif, Muhammad
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Publikasjoner (10 av 26) Visa alla publikasjoner
ul Hasan, K., Asif, M., Umair Hassan, M., Sandberg, M. O., Nour, O., Willander, M., . . . Strålfors, P. (2015). A Miniature Graphene-based Biosensor for Intracellular Glucose Measurements. Electrochimica Acta, 174, 574-580
Åpne denne publikasjonen i ny fane eller vindu >>A Miniature Graphene-based Biosensor for Intracellular Glucose Measurements
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2015 (engelsk)Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 174, s. 574-580Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

We report on a small and simple graphene-based potentiometric sensor for the measurement of intracellular glucose concentration. A fine borosilicate glass capillary coated with graphene and subsequently immobilized with glucose oxidase (GOD) enzyme is inserted into the intracellular environment of a single human cell. The functional groups on the edge plane of graphene assist the attachment with the free amine terminals of GOD enzyme, resulting in a better immobilization. The sensor exhibits a glucose-dependent electrochemical potential against an Ag/AgCl reference microelectrode which is linear across the whole concentration range of interest (10 - 1000 mu M). Glucose concentration in human fat cell measured by our graphene-based sensor is in good agreement with nuclear magnetic resonance (NMR) spectroscopy.

sted, utgiver, år, opplag, sider
Elsevier, 2015
Emneord
Graphene; Bio-sensors; Glucose-oxidase; Intracellular sensors; Graphene oxide; Glucose Sensor
HSV kategori
Identifikatorer
urn:nbn:se:liu:diva-121309 (URN)10.1016/j.electacta.2015.06.035 (DOI)000359873400073 ()
Tilgjengelig fra: 2015-09-16 Laget: 2015-09-14 Sist oppdatert: 2018-02-13bibliografisk kontrollert
Amin, G., Asif, M., Elsharif Zainelabdin, A., Zaman, S., Nur, O. & Willander, M. (2012). CuO Nanopetals Based Electrochemical Sensor for Selective Ag+ Measurements. SENSOR LETTERS, 10(3-4), 754-759
Åpne denne publikasjonen i ny fane eller vindu >>CuO Nanopetals Based Electrochemical Sensor for Selective Ag+ Measurements
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2012 (engelsk)Inngår i: SENSOR LETTERS, ISSN 1546-198X, Vol. 10, nr 3-4, s. 754-759Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

The electrochemical sensing activity of cupric oxide (CuO) nanopetals was investigated for the detection of silver (I) ions (Ag+). The CuO nanopetals were synthesized on a large area glass substrate by a low-temperature hydrothermal growth process. Structural morphological investigations were carried out using field emission scanning electron microscopy, high resolution transmission electron microscopy, and X-ray diffraction. To check the sensing application of the CuO nanopetals, it was functionalized for selectivity of Ag+. A polymeric membrane with Ag+-selective ionophore was coated on the surface of the CuO nanopetals. CuO nanopetals reveal excellent electrochemical sensing behavior in aqueous solution to selectively detect Ag+. The CuO based sensor exhibits a linear electrochemical response within the concentration range of 1 mu M to 100 mM. The functionalized CuO nanopetal based sensor show stable, fast response and high sensitivity for [Ag+]. This work demonstrates a simple technique for sensitive detection of Ag+ and other biochemical species.

sted, utgiver, år, opplag, sider
American Scientific Publishers, 2012
Emneord
CuO, Nanopetals, Hydrothermal Method, Ag+-Selective Membrane, Electrochemical Sensor
HSV kategori
Identifikatorer
urn:nbn:se:liu:diva-85097 (URN)10.1166/sl.2012.2336 (DOI)000309018700011 ()
Tilgjengelig fra: 2012-11-02 Laget: 2012-11-02 Sist oppdatert: 2018-02-27
ul Hasan, K., Asif, M. H. & Willander, M. (2012). Needle-Type Glucose Sensor Based on Functionalized Graphene. Journal of Biosensors and Bioelectronics, 3(1)
Åpne denne publikasjonen i ny fane eller vindu >>Needle-Type Glucose Sensor Based on Functionalized Graphene
2012 (engelsk)Inngår i: Journal of Biosensors and Bioelectronics, ISSN 2155-6210, Vol. 3, nr 1Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

We demonstrate a novel, highly efficient glucose sensor based on functionalized graphene. Glucose oxidase (GOD) immobilization has been apprehendedbythe direct interaction between carboxyl acid groups of the reduced graphene oxide (RGO) and amines of GOD together with the electrostatic interactions existing between the positively charged polymeric ionic liquid (PIL) and GOD. This combined system can provide a favorable microenvironment for the GOD to retain its good bioactivity. The enzyme-coated graphene biosensor exhibited glucose-dependent electrochemical measurements against an Ag/AgCl reference electrode. The resulting sensor show broad range detection, up to 100 mM glucose concentration, with a sensitivity of 5.59 μA/ decade. It was found that glucose biosensor based on functionalized graphene can be seen as an effective candidate for the detection of sugar concentration in clinical diagnoses.

HSV kategori
Identifikatorer
urn:nbn:se:liu:diva-78677 (URN)10.4172/2155-6210.1000114 (DOI)
Tilgjengelig fra: 2012-06-18 Laget: 2012-06-18 Sist oppdatert: 2014-01-15bibliografisk kontrollert
Asif, M. H., Willander, M., Strålfors, P. & Danielsson, B. (2012). Zinc Oxide Nanorods and their Application to Intracellular Glucose Measurements. In: Lan-Anh Le, Ross J. Hunter, Victor R. Preedy (Ed.), Nanotechnology and Nanomedicine in Diabetes: (pp. 126-146). CRC Press
Åpne denne publikasjonen i ny fane eller vindu >>Zinc Oxide Nanorods and their Application to Intracellular Glucose Measurements
2012 (engelsk)Inngår i: Nanotechnology and Nanomedicine in Diabetes / [ed] Lan-Anh Le, Ross J. Hunter, Victor R. Preedy, CRC Press, 2012, s. 126-146Kapittel i bok, del av antologi (Annet vitenskapelig)
sted, utgiver, år, opplag, sider
CRC Press, 2012
HSV kategori
Identifikatorer
urn:nbn:se:liu:diva-93830 (URN)978-1-57808-729-7 (ISBN)e-978-1-4665-0508-7 (ISBN)
Tilgjengelig fra: 2013-06-10 Laget: 2013-06-10 Sist oppdatert: 2014-01-15bibliografisk kontrollert
Willander, M., Nur, O., Fakhar-e-Alam, M., Jamil Rana, S., Israr Qadir, M., Sultana, K., . . . Asif, M. (2011). Applications of Zinc Oxide Nanowires for Bio-photonics and Bio-electronics. In: Ferechteh Hosseini Teherani, David C. Look, David J. Rogers (Ed.), Proceedings of SPIE Volume 7940. Paper presented at Conference on Oxide-based Materials and Devices II, San Francisco, CA, USA, JAN 23-26, 2011. Bellingham, Washington, USA: SPIE - International Society for Optical Engineering
Åpne denne publikasjonen i ny fane eller vindu >>Applications of Zinc Oxide Nanowires for Bio-photonics and Bio-electronics
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2011 (engelsk)Inngår i: Proceedings of SPIE Volume 7940 / [ed] Ferechteh Hosseini Teherani, David C. Look, David J. Rogers, Bellingham, Washington, USA: SPIE - International Society for Optical Engineering, 2011Konferansepaper, Publicerat paper (Annet vitenskapelig)
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.

sted, utgiver, år, opplag, sider
Bellingham, Washington, USA: SPIE - International Society for Optical Engineering, 2011
Serie
Proceedings of SPIE, ISSN 0277-786X ; 7940
HSV kategori
Identifikatorer
urn:nbn:se:liu:diva-74722 (URN)10.1117/12.879497 (DOI)9780819484772 (ISBN)
Konferanse
Conference on Oxide-based Materials and Devices II, San Francisco, CA, USA, JAN 23-26, 2011
Tilgjengelig fra: 2012-02-06 Laget: 2012-02-06 Sist oppdatert: 2014-01-15bibliografisk kontrollert
Zaman, S., Asif, M., Zainelabdin, A., Amin, G., Nur, O. & Willander, M. (2011). CuO nanoflowers as an electrochemical pH sensor and the effect of pH on the growth. JOURNAL OF ELECTROANALYTICAL CHEMISTRY, 662(2), 421-425
Åpne denne publikasjonen i ny fane eller vindu >>CuO nanoflowers as an electrochemical pH sensor and the effect of pH on the growth
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2011 (engelsk)Inngår i: JOURNAL OF ELECTROANALYTICAL CHEMISTRY, ISSN 1572-6657, Vol. 662, nr 2, s. 421-425Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

Well-crystallized flower-shaped cupric oxide (CuO) nanostructures composed of thin leaves have been synthesized by simple low-temperature chemical bath method and used to fabricate pH sensor. We examined the effect of the pH on the growth of the CuO nanostructures, by changing the pH of the precursor solutions different morphologies of the CuO nanostructures were obtained. CuO nanoflowers have recently become important as a material that provides an effective surface for electrochemical activities with enhanced sensing characteristics. The proposed sensor exhibited a linear electrochemical response within a wide pH range of (2-11). The experimental results (time response, electrochemical activity, reproducibility, absorption spectra, and XRD) indicate that the CuO nanoflowers can be used in pH sensor applications with enhanced properties.

sted, utgiver, år, opplag, sider
Elsevier, 2011
Emneord
CuO nanoflower; Morphological effect; Electrochemical; pH sensor; Repeatability
HSV kategori
Identifikatorer
urn:nbn:se:liu:diva-73334 (URN)10.1016/j.jelechem.2011.09.015 (DOI)000297881200020 ()
Tilgjengelig fra: 2012-01-03 Laget: 2012-01-02 Sist oppdatert: 2014-01-15
Asif, M., Elinder, F. & Willander, M. (2011). Electrochemical Biosensors Based on ZnO Nanostructures to Measure Intracellular Metal Ions and Glucose. Journal of Analytical & Bioanalytical Techniques, S7(003), 1-9
Åpne denne publikasjonen i ny fane eller vindu >>Electrochemical Biosensors Based on ZnO Nanostructures to Measure Intracellular Metal Ions and Glucose
2011 (engelsk)Inngår i: Journal of Analytical & Bioanalytical Techniques, ISSN 2155-9872, Vol. S7, nr 003, s. 1-9Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

Zinc oxide (ZnO) nanostructures have attracted much interest for intracellular electrochemical measurements because of its large surface area, and its biocompatible properties. To design intracellular biosensors for metal ions and glucose, we grew ZnO nanorods on the tip of borosilicate glass capillaries (0.7μm in diameter) and characterized the nano-scale structure with field-emission scanning electron microscopy and high-resolution transmission electron microscopy. The ZnO nanorods were functionalized accordingly for intracellular free metal ions or glucose measurements. Selectivity was achieved by using a metal-ion selective plastic membrane or glucose oxidase enzyme for glucose measurements. These functionalized ZnO nanorods showed high sensitivity and good biocompatibility for intracellular environments. Human adipocytes and frog oocytes were used for determinations of intracellular free metal ions and glucose concentrations. In this review, we discuss the simple and direct approach for intracellular measurements using ZnO nanostructure-based potentiometric biosensors for clinical and non-clinical applications. The performance of ZnO nanostructure-based intracellular sensor can be improved through engineering of morphology, effective surface area, functionality, and adsorption/desorption capability. This study paves the way to find applications in biomedicine by using this simple and miniaturized biosensing device

sted, utgiver, år, opplag, sider
Los Angeles, CA Westlake, United States: Omics Publishing Group, 2011
Emneord
ZnO nanorods; Human adipocytes; Frog oocytes; Potentiometric; Metal ions; Glucose; Membranes; Enzymes; Functionalization
HSV kategori
Identifikatorer
urn:nbn:se:liu:diva-99282 (URN)10.4172/2155-9872.S7-003 (DOI)
Tilgjengelig fra: 2013-10-15 Laget: 2013-10-15 Sist oppdatert: 2018-01-25bibliografisk kontrollert
Amin, G., Asif, M., Zainelabdin, A., Zaman, S., Nur, O. & Willander, M. (2011). Influence of pH, Precursor Concentration, Growth Time, and Temperature on the Morphology of ZnO Nanostructures Grown by the Hydrothermal Method. Journal of Nanomaterials (269692)
Åpne denne publikasjonen i ny fane eller vindu >>Influence of pH, Precursor Concentration, Growth Time, and Temperature on the Morphology of ZnO Nanostructures Grown by the Hydrothermal Method
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2011 (engelsk)Inngår i: Journal of Nanomaterials, ISSN 1687-4110, E-ISSN 1687-4129, nr 269692Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

We investigated the influence of the pH value, precursor concentration (C), growth time and temperature on the morphology of zinc oxide (ZnO) nanostructures. The pH of the starting solution was varied from1.8 to 12.5. It was found that the final pH reaches an inherent value of 6.6 independently of the initial pH solution. Various ZnO structures of nanotetrapod-like, flower-like, and urchin-like morphology were obtained at alkaline pH (8 to 12.5) whereas for pH solution lower than 8 rod-like nanostructures occurred. Moreover, we observed the erosion of the nanorods for a pH value less than 4.6. By changing the concentrations the density and size were also varied. On going from a high (C > 400mM) to lower (C < 25mM) C, the resulted ZnO nanostructures change from a film to nanorods (NRs) and finally nanowires (NWs). It was also found that the length and diameter of ZnO NRs follow a linear relation with time up to 10 hours, above which no further increase was observed. Finally the effect of growth temperature was seen as an influence on the aspect ratio.

sted, utgiver, år, opplag, sider
NY, USA: Hindawi Publishing Corporation, 2011
HSV kategori
Identifikatorer
urn:nbn:se:liu:diva-74729 (URN)10.1155/2011/269692 (DOI)000298424100001 ()
Merknad
funding agencies|advanced Functional Material project Sweden||Tilgjengelig fra: 2012-02-06 Laget: 2012-02-06 Sist oppdatert: 2017-12-08bibliografisk kontrollert
Usman Ali, S., Asif, M., Fulati, A., Nur, O., Willander, M., Brännmark, C., . . . Danielsson, B. (2011). Intracellular K(+) Determination With a Potentiometric Microelectrode Based on ZnO Nanowires. IEEE transactions on nanotechnology, 10(4), 913-919
Åpne denne publikasjonen i ny fane eller vindu >>Intracellular K(+) Determination With a Potentiometric Microelectrode Based on ZnO Nanowires
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2011 (engelsk)Inngår i: IEEE transactions on nanotechnology, ISSN 1536-125X, E-ISSN 1941-0085, Vol. 10, nr 4, s. 913-919Artikkel i tidsskrift (Fagfellevurdert) Published
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.

sted, utgiver, år, opplag, sider
IEEE, 2011
Emneord
Frog oocytes; human adipocytes; intracellular potassium ions; ionophore membrane; nanotechnology; potentiometric nanosensor; ZnO nanowires
HSV kategori
Identifikatorer
urn:nbn:se:liu:diva-69803 (URN)10.1109/TNANO.2010.2089696 (DOI)000292966400038 ()
Merknad

©2011 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 Usman Ali, Muhammad Asif, Alimujiang Fulati, Omer Nur, Magnus Willander, Cecilia Brännmark, Peter Strålfors, Ulrika Englund, Fredrik Elinder and Bengt Danielsson, Intracellular K(+) Determination With a Potentiometric Microelectrode Based on ZnO Nanowires, 2011, IEEE transactions on nanotechnology, (10), 4, 913-919. http://dx.doi.org/10.1109/TNANO.2010.2089696

Tilgjengelig fra: 2011-08-10 Laget: 2011-08-08 Sist oppdatert: 2018-01-25
Börjesson, S. I., Englund, U. H., Asif, M. H., Willander, M. & Elinder, F. (2011). Intracellular potassium (K+) concentration decrease is not obligatory for apoptosis. Journal of Biological Chemistry, 286(46), 39823-39828
Åpne denne publikasjonen i ny fane eller vindu >>Intracellular potassium (K+) concentration decrease is not obligatory for apoptosis
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2011 (engelsk)Inngår i: Journal of Biological Chemistry, ISSN 0021-9258, E-ISSN 1083-351X, Vol. 286, nr 46, s. 39823-39828Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

K+ efflux is observed as an early event in the apoptotic process in various cell types. Loss of intracellular K+ and subsequent reduction in ionic strength is suggested to release the inhibition of proapoptotic caspases. In this work, a new K+-specific microelectrode was used to study possible alterations in intracellular K+ in Xenopus laevis oocytes during chemically induced apoptosis. The accuracy of the microelectrode to detect changes in intracellular K+ was verified with parallel electrophysiological measurements within the same cells. In concordance with previous studies on other cell types, apoptotic stimuli reduced the intracellular K+ concentration in Xenopus oocytes and increased caspase-3 activity. The reduction in intracellular K+ was prevented by dense expression of voltage-gated K (Kv) channels. Despite this, the caspase-3 activity was increased similarly in Kv channel expressing oocytes as in oocytes not expressing Kv channels. Thus, in Xenopus oocytes caspase-3 activity is not dependent on the intracellular concentration of K+.

sted, utgiver, år, opplag, sider
American Society for Biochemistry and Molecular Biology, 2011
Emneord
Caspase-3 activation, Electrophysiology, Intracellular K+ concentrations, K+-selective microelectrode, Xenopus laevis oocytes
HSV kategori
Identifikatorer
urn:nbn:se:liu:diva-68853 (URN)10.1074/jbc.M111.262725 (DOI)000296925700016 ()
Merknad
Funding agencies|Swedish Research Council||Swedish Heart-Lung Foundation||Swedish Brain Foundation||County Council of Ostergotland, King Gustaf V and Queen Victorias Freemasons Foundation||Swedish Society for Medical Research||Tilgjengelig fra: 2011-06-08 Laget: 2011-06-08 Sist oppdatert: 2018-01-25bibliografisk kontrollert
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