liu.seSearch for publications in DiVA
Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Functionalized zinc oxide nanorod with ionophore-membrane coatingas an intracellular Ca2+ selective sensor
Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology. (physical electronics (Magnus Willander group))
Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.ORCID iD: 0000-0001-6235-7038
Show others and affiliations
2009 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 95, no 2, 23703- p.Article in journal (Refereed) Published
Abstract [en]

The tip of a borosilicate glass capillary with functionalized hexagonal ZnO nanorods was used to make a sensitive electrochemical intracellular Ca2+ sensor. To adjust the sensor for Ca2+ measurements with sufficient selectivity and stability, polyvinyl chloride (PVC) membrane containing Ca2+ ionophores were coated on the surface. The membrane covered ZnO nanorods exhibited a Ca2+-dependent electrochemical potential difference versus an Ag/AgCl reference electrode. The potential difference was linear over a large concentration range (100 nM to 10 mM). The measurements of Ca2+ concentrations using our ZnO nanorods sensor in human fat cells or in frog egg cells were consistent with values of Ca2+ concentrations reported in the literature. This nanoelectrode device paves the way to measurements of intracellular biochemical species in specific locations within single living cells.

Place, publisher, year, edition, pages
EBSCO/American Institute of Physics , 2009. Vol. 95, no 2, 23703- p.
National Category
Natural Sciences
Identifiers
URN: urn:nbn:se:liu:diva-19516DOI: 10.1063/1.3176441OAI: oai:DiVA.org:liu-19516DiVA: diva2:225282
Note
On the day of the defence date the status of this article was Submitted.Available from: 2009-06-25 Created: 2009-06-25 Last updated: 2017-12-13Bibliographically approved
In thesis
1. Electrochemical Biosensors Based on Functionalized Zinc Oxide Nanorods
Open this publication in new window or tab >>Electrochemical Biosensors Based on Functionalized Zinc Oxide Nanorods
2009 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

The semi-conductor zinc oxide (ZnO), a representative of group II-VI has gained substantial interest in the research community due to its novel properties and characteristics. ZnO a direct band gap (3.4eV) semi-conductor has a stable wurtzite structure. Recently ZnO have attracted much interest because of its unique piezoelectric, semiconducting, catalytic properties and being biosafe and biocompatible morphology combined with the easiness of growth. This implies that ZnO has a wide range of applications in optoelectronics, sensors, transducers, energy conversion and medical sciences. This thesis relates specifically to biosensor technology and pertains more particularly to novel biosensors based on multifunctional ZnO nanorods for biological, biochemical and chemical applications.

The nanoscale science and engineering have found great promise in the fabrication of novel nano-biosensors with faster response and higher sensitivity than of planar sensor configurations. This thesis aims to highlight recent developments in materials and techniques for electrochemical biosensing, design, operation and fabrication. Rapid research growths in biomaterials, especially the availability and applications of a vast range of polymers and copolymers associated with new sensing techniques have led to remarkable innovation in the design and fabrication of biosensors. Specially nanowires/nanorods and due to their small dimensions combined with dramatically increased contact surface and strong binding with biological and chemical reagents will have important applications in biological and biochemical research. The diameter of these nanostructures is usually comparable to the size of the biological and chemical species being sensed, which intuitively makes them represent excellent primary transducers for producing electrical signals. ZnO nanostructures have unique advantages including high surface to volume ratio, nontoxicity, chemical stability, electrochemical activity, and high electron communication features. In addition, ZnO can be grown as vertical nanorods and has high ionic bonding (60%), and they are not very soluble at biological pH-values. All these facts open up for possible sensitive extra/intracellular ion measurements. New developments in biosensor design are appearing at a high rate as these devices play increasingly important roles in daily life. In this thesis we have studied calcium ion selectivity of ZnO nanorods sensors using ionophore membrane coatings in two research directions: first, we have adjusted the sensor with sufficient selectivity especially for Ca2+, and the second is to have enough sensitivity for measuring Ca2+ concentrations in extra and intracellular media. The sensor in this study was used to detect and monitor real changes of Ca2+ across human fat cells and frog cells using changes in the electrochemical potential at the interface in the intracellular microenvironment.

The first part of the thesis presents extracellular studies on calcium ions selectively by using ZnO nanorods grown on the surface of a silver wire (250 μm in diameter) with the aim to produce proto-type electrochemical biosensors. The ZnO nanorods exhibited a Ca2+-dependent electrochemical potentiometric behavior in an aqueous solution. The potential difference was found to be linear over a large logarithmic concentration range (1μM to 0.1M) using Ag/AgCl as a reference electrode. To make the sensors selective for calcium ions with sufficient selectivity and stability, plastic membrane coatings containing ionophores were applied. These functionalized ZnO nanorods sensors showed a high sensitivity (26.55 mV/decade) and good stability.

In the second part, the intracellular determination of Ca2+ was performed in two types of cells. For that we have reported functionalized ZnO nanorods grown on the tip of a borosilicate glass capillary (0.7 μm in diameter) used to selectively measure the intracellular free Ca2+ concentration in single human adipocytes and frog oocytes. The sensor exhibited a Ca2+ linear electrochemical potential over a wide Ca2+ concentration range (100 nM to 10 mM). The measurement of the Ca2+ concentration using our ZnO nanorods based sensor in living cells were consistent with values of Ca2+ concentration reported in the literature.

The third and final part, presents the calcium ion detection functionalized ZnO nanorods coupled as an extended gate metal oxide semiconductor field effect transistor (MOSFET). The electrochemical response from the interaction between the ZnO nanorods and Ca2+ in an aqueous solution was coupled directly to the gate of a MOSFET. The sensor exhibited a linear response within the range of interest from 1 μM to 1 mM. Here we demonstrated that ZnO nanorods grown on a silver wire can be combined with conventional electronic component to produce a sensitive and selective biosensor.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2009. 40 p.
Series
Linköping Studies in Science and Technology. Thesis, ISSN 0280-7971 ; 1407
National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-19573 (URN)LIU-TEK-LIC-2009:15 (Local ID)978-91-7393-592-0 (ISBN)LIU-TEK-LIC-2009:15 (Archive number)LIU-TEK-LIC-2009:15 (OAI)
Presentation
2009-08-20, TP1, Täppan, Campus Norrköping, Linköpings universitet, Linköping, 10:15 (English)
Opponent
Supervisors
Available from: 2009-06-29 Created: 2009-06-29 Last updated: 2014-01-15Bibliographically approved
2. Mechanical Characterization and Electrochemical Sensor Applications of Zinc Oxide Nanostructures
Open this publication in new window or tab >>Mechanical Characterization and Electrochemical Sensor Applications of Zinc Oxide Nanostructures
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Nanotechnology is emerging to be one of the most important scientific disciplines that physics, chemistry and biology truly overlap with each other. Over the last two decades science and technology have witnessed tremendous improvement in the hope of unveiling the true secrets of the nature in molecular or atomic level. Today, the regime of nanometer is truly reached.

ZnO is a promising material due to the wide direct band gap (3.37 eV) and the room temperature large exciton binding energy (60 meV). Recent studies have shown considerable attraction towards ZnO nanostructures, particularly on one-dimensional ZnO nanorods, nanowires, and nanotubes due to the fact that, for a large number of applications, shape and size of the ZnO nanostructures play a vital role for the performance of the devices. The noncentrosymmetric property of ZnO makes it an ideal piezoelectric material for nanomechanical devices. Thus, mechanical characterization of one dimensional ZnO nanostructures including strength, toughness, stiffness, hardness, and adhesion to the substrate is very important for the reliability and efficient operation of piezoelectric ZnO nanodevices. Moreover, owing to the large effective surface area with high surface-to-volume ratio, the surface of one dimensional ZnO nanowires, nanorods, and nanotubes is very sensitive to the changes in surface chemistry and hence can be utilized to fabricate highly sensitive ZnO electrochemical sensors.

This thesis studies mechanical properties and electrochemical sensor applications of ZnO nanostructures.

The first part of the thesis deals with mechanical characterization of vertically grown ZnO nanorods and nanotubes including buckling, mechanical instability, and bending flexibility. In paper I, we have investigated mechanical instability and buckling characterization of vertically aligned single-crystal ZnO nanorods grown on Si, SiC, and sapphire substrates by vapor-liquid-solid (VLS) method. The critical loads for the ZnO nanorods grown on Si, SiC, and sapphire were measured and the corresponding buckling and adhesion energies were calculated. It was found that the nanorods grown on SiC substrate have less residual stresses and are more stable than the nanorods grown on Si and sapphire substrates.

Paper II investigates nanomechanical tests of bending flexibility, kinking, and buckling failure characterization of vertically aligned single crystal ZnO nanorods/nanowires grown by VLS and aqueous chemical growth (ACG) methods. We observed that the loading and unloading behaviors during the bending test of the as-grown samples were highly symmetrical and the highest point on the bending curves and the first inflection and critical point were very close. The results also show that the elasticity of the ZnO single crystal is approximately linear up to the first inflection point and is independent of the growth method.

In Paper III, we quantitatively investigated the buckling and the elastic stability of vertically well aligned ZnO nanorods and ZnO nanotubes grown on Si substrate by nanoindentation technique. We found that the critical load for the nanorods was five times larger than the critical load for nanotubes. On the contrary, the flexibility for nanotubes was five times larger than nanorods. The discovery of high flexibility for nanotubes and high elasticity for nanorods can be utilized for designing efficient piezoelectric nanodevices.

The second part of this thesis investigates electrochemical sensor applications of ZnO nanorods, nanotubes , and nanoporous material.

In paper IV, we utilized functionalized ZnO nanorods on the tip of a borosilicate glass capillary coated with ionophore-membrane to construct intracellular Ca2+ selective sensor. The sensor exhibited a Ca2+-dependent electrochemical potential difference and the response was linear over a large dynamic concentration range, which enabled this sensor to measure Ca2+ concentrations in human adipocytes or in frog oocytes. The results were consistent with the values of Ca2+ concentrations reported in the literature.

In paper V, ZnO nanotubes and nanorods were used to create pH sensor devices. The developed ZnO pH sensors display good reproducibility, repeatability, and long-term stability. The ZnO pH sensors exhibited a pH-dependent electrochemical potential difference over a large dynamic pH range. We found that the ZnO nanotubes provide sensitivity as high as twice that of the ZnO nanorods. The possible reasons of enhanced sensitivity were explained.

Paper VI investigates an improved potentiometric intracellular glucose biosensor based on the immobilization of glucose oxidase on the ZnO nanoporous material. We demonstrated that using ZnO nanoporous material as a matrix material for enzyme immobilization improves the sensitivity of the biosensor as compared to using ZnO nanorods. In addition, the fabrication method of the intracellular biosensor was simple and excellent performance in sensitivity, stability, selectivity, reproducibility, and anti-interference was achieved.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2010. 61 p.
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1323
Keyword
Nanotechnology, Zinc Oxide, nanorods, nanotubes, nanoporous, buckling, electrochemical sensor
National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-57297 (URN)978-91-7393-369-8 (ISBN)
Public defence
2010-06-04, K3, Kåkenhus, Campus Norrköping, Linköpings universitet, Norrköping, 10:15
Opponent
Supervisors
Available from: 2010-06-16 Created: 2010-06-16 Last updated: 2014-01-15Bibliographically approved
3. Zinc Oxide Nanostructure Based Electrochemical Sensors and Drug Delivery to Intracellular Environments
Open this publication in new window or tab >>Zinc Oxide Nanostructure Based Electrochemical Sensors and Drug Delivery to Intracellular Environments
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The nanoscale science and nanostructure engineering have well established in the fabrication of novel electrochemical biosensors with faster response and higher sensitivity than of planar sensor configurations. Moreover nanostructures are suggested and used as efficient carrier of photosensitizers for cancerous cell treatment. The semi-conductor zinc oxide (ZnO) nanostructures have attracted much interest because of its unique piezoelectric, polar semiconducting, large surface area, catalytic properties, and being biosafe and biocompatible combined with the easiness of growth. This implies that ZnO nanostructures have a wide range of applications in optoelectronics, sensors, transducers, energy conversion and medical sciences. The aim of this study is to highlight recent developments in materials and techniques for electrochemical biosensing, photodynamic therapy, design, operation, and fabrication. The sensors in this study were used to detect and monitor real changes of metal ions and glucose across human fat cells and frog cells using changes in the electrochemical potential at the interface to the intracellular microenvironments. This thesis relates specifically to “zinc oxide nanostructure based electrochemical sensors and drug delivery to intracellular environments” for biological, biochemical and chemical applications.

The first part of the thesis presents extra and intracellular studies on metal ions such as Ca2+, Mg2+, and Na+…..etc selectively sensed by using ZnO nanorods grown on the tip of a borosilicate glass capillary (0.7 μm in diameter) with the aim to produce proto-type electrochemical extra/intracellular biosensors. The single human adipocyte and frog oocyte cells were used to selectively measure the intracellular free metal ions concentration. To make the sensors selective for metal ions with sufficient selectivity and stability, plastic membrane coatings containing specific ionophores were applied. These functionalized ZnO nanorods sensors showed high sensitivity and good stability with linear electrochemical potential versus a wide metal ion concentration range of interest. The measured intracellular values were consistent with values reported in the literature. Furthermore we have successfully determined that the intracellular potassium (K+) concentration decrease is not obligatory for apoptosis. The aim of this study is to show the possibility of using K+ selective microelectrode to detect and monitor intracellular changes of K+ concentration during injection of various test solution and chemically induced apoptosis in Xenopus laevis oocytes parallel with electrophysiological measurements to verify the accuracy.

The second part, presents the calcium ion (Ca2+) detection using functionalized ZnO nanorods attached as an extended gate metal oxide semiconductor field effect transistor (MOSFET). The electrochemical response was coupled directly to the gate of a commercial MOSFET to study the I-V characterization. Here we verified that ZnO nanorods grown on any thin wire can be combined with conventional electronic component to produce a sensitive and selective biosensor.

In the third part, we have performed the experiment to determine glucose concentration intracellularly and in airway surface liquid (ASL) with functionalized ZnO nanorod-coated microelectrodes. In this study, the GOD enzyme was immobilised electrostatically, drawing on the fact that there is a large difference in the isoelectric points of ZnO and glucose oxidase. Insulin has been found to affect the glucose uptake in human adipocytes and frog Xenopus laevis. The large size of these cells makes it possible to microinject specific reagents that interrupt or activate signal transmission to glucose. The measured glucose concentration in human adipocytes or frog oocytes and ASL using our ZnO nanorod sensor was consistent with values of glucose concentration reported in the literature by using other indirect techniques.

The fourth and final part covers the application of ZnO nanorods to cancer cells for photodynamic therapy. The ZnO nanorods were conjugated with protoporphyrin for local mediated photochemistry and efficient treatment of a single cancer cell. The ZnO nanorods were used as an efficient photosensitizer carrier system and at the same time providing intrinsic white light to achieve necrosis of the cancer cell. Breast cancer cells were used to study the catalytic effect of ZnO for treatment. The grown ZnO nanorods were conjugated with protoporphyrin dimethyl ester (PPDME), which absorbs the light emitted by the ZnO nanorods and cause the cytotoxicity which appears to involve the generation of reactive singlet oxygen inside the cell.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2011. 64 p.
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1376
Keyword
ZnO nanorods, Intracellular electrochemical sensor, Functionalization, Metal ions, Glucose, Human Adipocytes, Frog Oocytes, Airway surface liquid
National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-68856 (URN)978-91-7393-142-7 (ISBN)
Public defence
2011-09-02, K3, Kåkenhus, Campus Norrköping, Linköpings universitet, Norrköping, 10:15 (English)
Opponent
Supervisors
Available from: 2011-06-08 Created: 2011-06-08 Last updated: 2014-01-15Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full textLink to Licentiate Thesis

Authority records BETA

Asif, Muhammad HFulati, AlimujiangNor, OmerWillander, MagnusJohansson, CeciliaStrålfors, PeterBörjesson, Sara I.Elinder, Fredrik

Search in DiVA

By author/editor
Asif, Muhammad HFulati, AlimujiangNor, OmerWillander, MagnusJohansson, CeciliaStrålfors, PeterBörjesson, Sara I.Elinder, Fredrik
By organisation
Department of Science and TechnologyThe Institute of TechnologyCell BiologyFaculty of Health Sciences
In the same journal
Applied Physics Letters
Natural Sciences

Search outside of DiVA

GoogleGoogle Scholar

doi
urn-nbn

Altmetric score

doi
urn-nbn
Total: 639 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf