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Asymmetric Oligothiophenes: Chemical Evolution of Multimodal Amyloid Ligands
Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Luminescent conjugated polymers (LCPs) and luminescent conjugated oligothiophenes (LCOs) can be used as molecular probes to study diseases associated with protein aggregation. The conventionally used dyes to study and detect protein aggregates, denoted amyloid, have been Congo red (CR) and Thioflavin T (ThT). In contrast to these amyloid ligands, LCOs offer the possibility to detect aggregated proteinaceous species occurring at earlier stages of amyloid formation as well as to distinguish different morphotypes of protein aggregates. The interaction between the LCOs and the protein deposits can be studied by fluorescence spectroscopy and microscopy both in vitro and ex vivo. In this thesis we report the development of multimodal asymmetric LCOs that can be utilized with two novel techniques, Surface Plasmon Resonance (SPR) and Positron Emission Tomography (PET), to study the interaction between LCO and amyloid fibrils in real time. With SPR, we have been able to determine binding affinities between LCO and amyloid, and with PET we have shown that radiolabelled LCOs can be used as a non-invasive method to study amyloid deposits in vivo. In addition, by alteration of the backbone (change of thiophene units), and of adding different side chains functionalities, we have shown that the properties of the amyloid ligands have a huge impact of the binding to different stages or forms of protein aggregates. By making asymmetrical LCOs, which can be attached to a surface, we also foresee a methodology that will offer the possibility to create a sensitive and selective detection method, and maybe lead to a lab-on-a-chip-application.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2015. , 67 p.
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1692
National Category
Chemical Sciences
Identifiers
URN: urn:nbn:se:liu:diva-122278DOI: 10.3384/diss.diva-122278ISBN: 978-91-7685-987-2 (print)OAI: oai:DiVA.org:liu-122278DiVA: diva2:865189
Public defence
2015-11-20, Planck, Fysikhuset, Campus Valla, Linköping, 10:15 (Swedish)
Opponent
Supervisors
Available from: 2015-10-27 Created: 2015-10-27 Last updated: 2015-11-02Bibliographically approved
List of papers
1. Synthesis of a library of oligothiophenes and their utilization as fluorescent ligands for spectral assignment of protein aggregates
Open this publication in new window or tab >>Synthesis of a library of oligothiophenes and their utilization as fluorescent ligands for spectral assignment of protein aggregates
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2011 (English)In: Organic and biomolecular chemistry, ISSN 1477-0520, E-ISSN 1477-0539, Vol. 9, no 24, 8356-8370 p.Article in journal (Refereed) Published
Abstract [en]

Molecular probes for selective identification of protein aggregates are important to advance our understanding of the molecular pathogenesis underlying protein aggregation diseases. Here we report the chemical design of a library of anionic luminescent conjugated oligothiophenes (LCOs), which can be utilized as ligands for detection of protein aggregates. Certain molecular requirements were shown to be necessary for detecting (i) early non-thioflavinophilic protein assemblies of A beta 1-42 and insulin preceding the formation of amyloid fibrils and (ii) for obtaining distinct spectral signatures of the two main pathological hallmarks observed in human Alzheimers diease brain tissue (A beta plaques and neurofibrillary tangles). Our findings suggest that a superior anionic LCO-based ligand should have a backbone consisting of five to seven thiophene units and carboxyl groups extending the conjugated thiophene backbone. Such LCOs will be highly useful for studying the underlying molecular events of protein aggregation diseases and could also be utilized for the development of novel diagnostic tools for these diseases.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2011
National Category
Organic Chemistry
Identifiers
urn:nbn:se:liu:diva-73487 (URN)10.1039/c1ob05637a (DOI)000297354100019 ()
Available from: 2012-01-04 Created: 2012-01-04 Last updated: 2017-12-08
2. An azide functionalized oligothiophene ligand - A versatile tool for multimodal detection of disease associated protein aggregates
Open this publication in new window or tab >>An azide functionalized oligothiophene ligand - A versatile tool for multimodal detection of disease associated protein aggregates
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2015 (English)In: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 63, 204-211 p.Article in journal (Refereed) Published
Abstract [en]

Ligands for identifying protein aggregates are of great interest as such deposits are the pathological hallmark of a wide range of severe diseases including Alzheimers and Parkinsons disease. Here we report the synthesis of an azide functionalized fluorescent pentameric oligothiophene that can be utilized as a ligand for multimodal detection of disease-associated protein aggregates. The azide functionalization allows for attachment of the ligand to a surface by conventional click chemistry without disturbing selective interaction with protein aggregates and the oligothiophene-aggregate interaction can be detected by fluorescence or surface plasmon resonance. In addition, a methodology where the oligothiophene ligand is employed as a capturing molecule selective for aggregated proteins in combination with an antibody detecting a distinct peptide/protein is also presented. We foresee that this methodology will offer the possibility to create a variety of multiplex sensing systems for sensitive and selective detection of protein aggregates, the pathological hallmarks of several neurodegenerative diseases.

Place, publisher, year, edition, pages
Elsevier, 2015
Keyword
Protein aggregates; Oligothiophene; Fluorescence; Surface plasmon resonance; Click chemistry
National Category
Chemical Sciences Biological Sciences
Identifiers
urn:nbn:se:liu:diva-112169 (URN)10.1016/j.bios.2014.07.042 (DOI)000343337000030 ()25089818 (PubMedID)
Note

Funding Agencies|Swedish Foundation for Strategic Research; Ehrling Persson Foundation; ERC Starting Independent Researcher grant (Project: MUMID)

Available from: 2014-11-18 Created: 2014-11-18 Last updated: 2017-12-05
3.
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4. A variety of thiophene based ligands for detection of protein aggregates by surface plasmon resonance
Open this publication in new window or tab >>A variety of thiophene based ligands for detection of protein aggregates by surface plasmon resonance
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(English)Manuscript (preprint) (Other academic)
Abstract [en]

By attaching an azide functional group via a tetraethylene glycol linker to the α-terminal position of a variety of oligothiophenes, thiophene-based ligands that can be utilized for detection of protein aggregates with surface plasmon resonance have been developed. All ligands displayed selectivity towards recombinant amyloid fibrils and the LCO/protein aggregate interaction could be detected by fluorescence as well as by surface plasmon resonance.

National Category
Chemical Sciences
Identifiers
urn:nbn:se:liu:diva-122274 (URN)
Available from: 2015-10-27 Created: 2015-10-27 Last updated: 2015-10-27Bibliographically approved

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