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
Hydrogels of conjugated polyelectrolytes for biosensor and biochip applications
Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
2005 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis describes the use of conjugated polyelectrolytes (CPEs) in biosensor devices. The method is based on non-covalent assembly of the biomolecule of interest and the CPE functioning as the reporter, in one case as a transducer, of biomolecular events. Devices of these assemblies on solid supports that can operate in liquid solutions have been the focus. Polythiophenes, both semiconducting and conducting, is the class of materials that has been used in this work. The semiconducting polythiophenes have ionic side chains which makes them water soluble. This ionic side chain is capable of both forming electrostatic and hydrogen bonds, and when paired with the hydrophobic backbone of the polymer a great number of interactions with biomolecules are possible. The highly conducting polythiophene derivative PEDOT -PSS, (PEDOT) doped with ionic and water soluble PSS polyelectrolyte, was used as the conducting material in 3D-electrode. Both the semiconducting and conducting polymers described above forms hydrogels on solid supports if crosslinked with the appropriate ion, biomolecule or polymer. Evaluation of the CPEs, both with and without biomolecules, was performed in liquid, solid and hydrogel state using a number of techniques. This was done to understand how the CPEs behave when exposed to different buffer systems and various biomolecules.

Hydrogels of conjugated polyelectrolytes combined with biomolecules are attractive as biosensors. The advantage with the hydrogel format is the high water content, the porous structure and the large capacity of binding molecules. High water content is important to preserve the biomolecules by providing the correct buffered environment. In this thesis we demonstrated a hydrogel of the highly conducting PEDOT -PSS polymer that was crosslinked on a solid support together with horseradish peroxidase (HRP) enzyme, forming an enzyme-enhanced electrode. Further studies of hydrogels were done using in situ quartz crystal microbalance with dissipation (QCM-D). POWT is a CPE withproperties well suited for biochip applications and readily forms hydrogels when exposed to water-based buffer solutions or biomolecule solutions. Detection ofcomplementary DNA and rejection of non-complementary DNA in a POWT hydrogel was demonstrated. The interaction between POWT and DNAoligonucleotides was also evaluated using fluorescence resonance energy transfer (FRET) in solution. Labeled DNA oligonucleotides with energy accepting or donating fluorophores allowed us to determine distance and binding stoichiometry in the non-covalent POWT-DNA complex.

Patterning and anchoring of biomolecules and non-covalent assembled CPE-biomolecule complexes to a chip surface was studied; in the adsorbed state these complexes are hydrogels. Our novel method is based on the modification of the surface energy of a hydrophilic substrate surface using hydrophobic poly(dimethylsiloxane) (PDMS) elastomer stamp containing a relief pattern. Different conformations in biomolecules could be detected using fluorescence microscopy, where the CPEs acts as reporters and the PDMS modified substrates as discriminator. Also, excellent enzyme activity in patterned CPE/Horseradish peroxidase (HRP) enzyme was shown.

Distances between the individual molecules in solid state devices of conjugated polymers can be small. In luminescence devices, such as light emitting diodes or fluorescence biosensors, there is a chance of interaction between conjugated molecules especially if more than one type of molecule is present. Quenching of the light and fluorescence energy transfer can occur and a simple approach to study this was developed.

Place, publisher, year, edition, pages
Linköping: Linköpings universitet , 2005. , 78 p.
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 982
National Category
Natural Sciences
Identifiers
URN: urn:nbn:se:liu:diva-30215Local ID: 15710ISBN: 91-85457-58-2 (print)OAI: oai:DiVA.org:liu-30215DiVA: diva2:251037
Public defence
2005-12-09, Hörsal Planck, Campus Valla, Linköping, 10:15 (Swedish)
Opponent
Available from: 2009-10-09 Created: 2009-10-09 Last updated: 2012-12-03
List of papers
1. Hydrogels of a conducting conjugated polymer as 3-D enzyme electrode
Open this publication in new window or tab >>Hydrogels of a conducting conjugated polymer as 3-D enzyme electrode
2003 (English)In: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 19, no 3, 199-207 p.Article in journal (Refereed) Published
Abstract [en]

We have utilized the highly conducting poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) aqueous dispersion (PEDOT/PSS) to build a conducting hydrogel matrix. Together with appropriate biomolecules this constitutes a hydrogel bio-electrode. The open hydrogel structure makes diffusion of analytes surrounding the cells into the matrix electrode easier. If enzymes are utilized, osmium is used as mediator between the prosthetic group of the enzyme and the conducting polymer matrix. Osmium also functions as a crosslink point to poly-4-vinylpyridine, which together with the magnesium crosslinked PEDOT/PSS gives a rigid hydrogel. The enzyme Horseradish peroxidase (HRP) was used as a model enzyme to evaluate the enzyme-enhanced electrode. We evaluated the electrode at pH 7, which is the pH choice for many biological systems. From cyclic voltammetry (CV) measurements we deduced that a very low reduction potential was needed to reduce the prosthetic group. Constant potential amperometry were performed to demonstrate the biosensor capabilities. A differential sensitivity of 0.13 A M−1 cm−2 through the 0–30 μM concentration range was achieved. Both the biostability and the influence on conductivity, important aspects when for example making nerve- or cell-electrodes, were investigated.

Keyword
Biomolecule electrode, Conjugated polymer, Horseradish peroxidase, Hydrogel, Osmium, PEDOT/PSS
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-46422 (URN)10.1016/S0956-5663(03)00220-3 (DOI)
Available from: 2009-10-11 Created: 2009-10-11 Last updated: 2017-12-13
2. Hydrogels from a water-soluble Zwitterionic polythiophene: dynamics under pH change and biomolecular interactions observed using quartz crystal microbalance with dissipation monitoring
Open this publication in new window or tab >>Hydrogels from a water-soluble Zwitterionic polythiophene: dynamics under pH change and biomolecular interactions observed using quartz crystal microbalance with dissipation monitoring
2005 (English)In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 21, no 16, 7292-7298 p.Article in journal (Refereed) Published
Abstract [en]

The water-soluble zwitterionic polythiophene, poly(3-((S)-5-amino-5- carboxyl-3-oxapentyl)-2,5-thiophene) hydrochloride (POWT), is a conjugated polyelectrolyte (CPE) with properties well suited for biochip applications. CPEs readily form hydrogels when exposed to water-based buffer solutions or biomolecule solutions. In this work, we used in situ quartz crystal microbalance with dissipation (QCM-D) monitoring to collect information on the interaction between POWT films exposed to buffers with different pH and POWT/DNA chains. Our data show that POWT swells significantly when exposed to low-pH buffers, such as pH 4 acetate, this is seen as an increase in thickness and decrease in viscosity obtained via a Voight-based modeling of combined f and D QCM-D measurements. The magnitude of thickness and viscosity change upon changing from a pH 10 carbonate buffer to pH 4 acetate is 100% increase in thickness and 50% decrease in viscosity. The response of the hydrogel under pH change is well correlated with fluorescence data from POWT films on glass. The state of the hydrogel is important during interaction with biomolecules; illustrated by the observation that a swollen CPE hydrogel adsorbs a higher amount of DNA than a compacted one. In agreement with previous results, the QCM-D data confirmed that the POWT/DNA hydrogel sense complementary DNA specifically and with negligible binding of noncomplementary DNA. These results are important for efficient constructions of biochips in water environments using this class of materials.

National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-12726 (URN)10.1021/la050479e (DOI)
Available from: 2007-12-07 Created: 2007-12-07 Last updated: 2017-12-14
3. Interactions between a zwitterionic polythiophene derivative and oligonucleotides as resolved by fluorescence resonance energy transfer
Open this publication in new window or tab >>Interactions between a zwitterionic polythiophene derivative and oligonucleotides as resolved by fluorescence resonance energy transfer
2005 (English)In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 17, no 16, 4204-4211 p.Article in journal (Refereed) Published
Abstract [en]

The interactions between a zwitterionic polythiophene derivative, POWT, and DNA oligonucleotides in solution have been studied by FRET (fluorescence resonance energy transfer). When POWT and ssDNA are bound alone in a complex, the distance between them is at its smallest. The distance increases when adding complementary DNA, but POWT is still mainly bound to the first DNA strand. We find that two POWT chains bind to one DNA strand, and the two POWT chains seem held together in pairs, unable to separate, as they can only bind to and quench half their own amount of labeled DNA. This POWT−POWT complex appears to dissociate at lower concentrations. ssDNA attached to POWT in a complex can also be substituted by other ssDNA in solution; this occurs to 50% when the free DNA is present in 10-fold concentration compared to the ssDNA bound to POWT. Titration studies at different concentrations show positive cooperativity in the binding of POWT and ssDNA into a complex. The hybridization of complementary DNA to the same complex involves no cooperativity. These observations indicate interesting possibilities for the use of POWT as a DNA sensor.

National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-30356 (URN)10.1021/cm050328x (DOI)15901 (Local ID)15901 (Archive number)15901 (OAI)
Available from: 2009-10-09 Created: 2009-10-09 Last updated: 2017-12-13
4. Fluorescence quenching and excitation transfer between semiconducting and metallic organic layers
Open this publication in new window or tab >>Fluorescence quenching and excitation transfer between semiconducting and metallic organic layers
2004 (English)In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 96, no 6, 3140-3147 p.Article in journal (Refereed) Published
Abstract [en]

Here we present a simple approach to study the interaction of singlet excitons with polarons in conjugated polymers in organic electronic devices. Interlayer quenching constants KIL of 1.5 M−1 between a fluorescent molecule and a doped polymer in a layered sample demonstrates the importance of understanding the quenching of excited states in polymeric devices. A combination of Förster resonance energy transfer and quenching of photoluminescence between a fluorescent molecule and a conjugated polymer in its semiconducting and metallic states were studied. The polymer is a chiral 3-substituted polythiophene (POWT) and the fluorescent molecule is fluorescein bound to dextran (D-FITC). Bilayer samples with fluorescein on top of the POWT were fabricated and studied with absorption spectroscopy, fluorescence microscopy, and electrochemical doping methods. When POWT is electrochemically dedoped it is possible to enhance the photoluminescence in the polymer layer by excitation transfer from the fluorescein layer. Our results demonstrate that PL from the polythiophene disappears rapidly as soon as the layer is doped. As the doping of polymer layer increases the fluorescence from the fluorescein on top of the polymer decreases, due to excitation quenching. Models for excitation transfer and excitation quenching in POWT/FITC bilayer devices have been developed. This model predicts a linear relationship between the PL from the two molecules, in agreement with our experimental findings. These results are relevant for the development of electroluminescent devices or solar cells based on conjugated polymers.

National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-45631 (URN)10.1063/1.1774247 (DOI)
Available from: 2009-10-11 Created: 2009-10-11 Last updated: 2017-12-13
5. Surface energy modified chips for detection of conformational states and enzymatic activity in biomolecules
Open this publication in new window or tab >>Surface energy modified chips for detection of conformational states and enzymatic activity in biomolecules
2006 (English)In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 22, no 5, 2205-2211 p.Article in journal (Refereed) Published
Abstract [en]

A novel patterning method for anchoring biomolecules and noncovalent assembled conjugated polyelectrolyte (CPE)/biomolecule complexes to a chip surface is presented. The surface energy of a hydrophilic substrate is modified using an elastomeric poly(dimethylsiloxane) (PDMS) stamp, containing a relief pattern. Modification takes place on the parts where the PDMS stamp is in conformal contact with the substrate and leaves low molecular weight PDMS residues on the surface resulting in a hydrophobic modification, and then biomolecules and CPE/biomolecule complexes are then adsorbed in a specific pattern. The method constitutes a discrimination system for different conformations in biomolecules using CPEs as reporters and the PDMS modified substrates as the discriminator. Detection of different conformations in two biomacromolecules, a synthetic peptide (JR2E) and a protein (calmodulin), reported by the CPE and resolved by fluorescence was demonstrated. Also, excellent enzyme activity in patterned CPE/horseradish peroxidase (HRP) enzyme was shown, demonstrating that this method can be used to pattern biomolecules with their activity retained. The method presented could be useful in various biochip applications, such as analyzing proteins and peptides in large-scale production, in making metabolic chips, and for making multi-microarrays.

National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-34580 (URN)10.1021/la0527902 (DOI)22009 (Local ID)22009 (Archive number)22009 (OAI)
Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2017-12-13

Open Access in DiVA

No full text

Authority records BETA

Åsberg, Peter

Search in DiVA

By author/editor
Åsberg, Peter
By organisation
Biomolecular and Organic ElectronicsThe Institute of Technology
Natural Sciences

Search outside of DiVA

GoogleGoogle Scholar

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 336 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