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  • 1.
    Calvo-Rodriguez, Maria
    et al.
    Massachusetts Gen Hosp, MA 02129 USA; Harvard Med Sch, MA 02129 USA.
    Hou, Steven S.
    Massachusetts Gen Hosp, MA 02129 USA; Harvard Med Sch, MA 02129 USA.
    Snyder, Austin C.
    Massachusetts Gen Hosp, MA 02129 USA; Harvard Med Sch, MA 02129 USA.
    Dujardin, Simon
    Massachusetts Gen Hosp, MA 02129 USA; Harvard Med Sch, MA 02129 USA.
    Shirani, Hamid
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
    Nilsson, Peter
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
    Bacskai, Brian J.
    Massachusetts Gen Hosp, MA 02129 USA; Harvard Med Sch, MA 02129 USA.
    In vivo detection of tau fibrils and amyloid beta aggregates with luminescent conjugated oligothiophenes and multiphoton microscopy2019In: Acta neuropathologica communications, E-ISSN 2051-5960, Vol. 7, no 1, article id 171Article in journal (Refereed)
    Abstract [en]

    The detection of amyloid beta deposits and neurofibrillary tangles, both hallmarks of Alzheimers disease (AD), is key to understanding the mechanisms underlying these pathologies. Luminescent conjugated oligothiophenes (LCOs) enable fluorescence imaging of these protein aggregates. Using LCOs and multiphoton microscopy, individual tangles and amyloid beta deposits were labeled in vivo and imaged longitudinally in a mouse model of tauopathy and cerebral amyloidosis, respectively. Importantly, LCO HS-84, whose emission falls in the green region of the spectrum, allowed for the first time longitudinal imaging of tangle dynamics following a single intravenous injection. In addition, LCO HS-169, whose emission falls in the red region of the spectrum, successfully labeled amyloid beta deposits, allowing multiplexing with other reporters whose emission falls in the green region of the spectrum. In conclusion, this method can provide a new approach for longitudinal in vivo imaging using multiphoton microscopy of AD pathologies as well as other neurodegenerative diseases associated with protein aggregation in mouse models.

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  • 2.
    Choong, Ferdinand X.
    et al.
    Karolinska Inst, Sweden.
    Lantz, Linda
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
    Shirani, Hamid
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
    Schulz, Anette
    Karolinska Inst, Sweden.
    Nilsson, Peter
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
    Edlund, Ulrica
    KTH Royal Inst Technol, Sweden.
    Richter-Dahlfors, Agneta
    Karolinska Inst, Sweden.
    Stereochemical identification of glucans by a donor-acceptor-donor conjugated pentamer enables multi-carbohydrate anatomical mapping in plant tissues2019In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 26, no 7, p. 4253-4264Article in journal (Refereed)
    Abstract [en]

    Optotracing is a novel method for analytical imaging of carbohydrates in plant and microbial tissues. This optical method applies structure-responsive oligothiophenes as molecular fluorophores emitting unique optical signatures when bound to polysaccharides. Herein, we apply Carbotrace680, a short length anionic oligothiophene with a central heterocyclic benzodithiazole (BTD) motif, to probe for different glucans. The donor-acceptor-donor type electronic structure of Carbotrace680 provides improved spectral properties compared to oligothiophenes due to the possibility of intramolecular charge-transfer transition to the BTD motif. This enables differentiation of glucans based on the glycosidic linkage stereochemistry. Thus -configured starch is readily differentiated from -configured cellulose. The versatility of optotracing is demonstrated by dynamic monitoring of thermo-induced starch remodelling, shown in parallel by spectrophotometry and microscopy of starch granules. Imaging of Carbotrace680 bound to multiple glucans in plant tissues provided direct identification of their physical locations, revealing the spatial relationship between structural (cellulose) and storage (starch) glucans at sub-cellular scale. Our work forms the basis for the development of superior optotracers for sensitive detection of polysaccharides. Our non-destructive method for anatomical mapping of glucans in biomass will serve as an enabling technology for developments towards efficient use of plant-derived materials and biomass. [GRAPHICS] .

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  • 3.
    Herrmann, Uli S.
    et al.
    University of Zurich Hospital, Switzerland.
    Schuetz, Anne K.
    ETH, Switzerland.
    Shirani, Hamid
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
    Huang, Danzhi
    University of Zurich, Switzerland.
    Saban, Dino
    University of Zurich Hospital, Switzerland.
    Nuvolone, Mario
    University of Zurich Hospital, Switzerland.
    Li, Bei
    University of Zurich Hospital, Switzerland.
    Ballmer, Boris
    University of Zurich Hospital, Switzerland.
    Åslund, Andreas
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Mason, Jeffrey
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Rushing, Elisabeth
    University of Zurich Hospital, Switzerland.
    Budka, Herbert
    University of Zurich Hospital, Switzerland.
    Nyström, Sofie
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
    Hammarström, Per
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
    Boeckmann, Anja
    University of Lyon 1, France.
    Caflisch, Amedeo
    University of Zurich, Switzerland.
    Meier, Beat H.
    ETH, Switzerland.
    Nilsson, Peter
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
    Hornemann, Simone
    University of Zurich Hospital, Switzerland.
    Aguzzi, Adriano
    University of Zurich Hospital, Switzerland.
    Structure-based drug design identifies polythiophenes as antiprion compounds2015In: Science Translational Medicine, ISSN 1946-6234, E-ISSN 1946-6242, Vol. 7, no 299, p. 299ra123-Article in journal (Refereed)
    Abstract [en]

    Prions cause transmissible spongiform encephalopathies for which no treatment exists. Prions consist of PrPSc, a misfolded and aggregated form of the cellular prion protein (PrPC). We explore the antiprion properties of luminescent conjugated polythiophenes (LCPs) that bind and stabilize ordered protein aggregates. By administering a library of structurally diverse LCPs to the brains of prion-infected mice via osmotic minipumps, we found that antiprion activity required a minimum of five thiophene rings bearing regularly spaced carboxyl side groups. Solid-state nuclear magnetic resonance analyses and molecular dynamics simulations revealed that anionic side chains interacted with complementary, regularly spaced cationic amyloid residues of model prions. These findings allowed us to extract structural rules governing the interaction between LCPs and protein aggregates, which we then used to design a new set of LCPs with optimized binding. The new set of LCPs showed robust prophylactic and therapeutic potency in prion-infected mice, with the lead compound extending survival by greater than80% and showing activity against both mouse and hamster prions as well as efficacy upon intraperitoneal administration into mice. These results demonstrate the feasibility of targeted chemical design of compounds that may be useful for treating diseases of aberrant protein aggregation such as prion disease.

  • 4.
    Klingstedt, Therése
    et al.
    Linköping University, Faculty of Science & Engineering. Linköping University, Department of Physics, Chemistry and Biology, Chemistry.
    Shirani, Hamid
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
    Mahler, Jasmin
    University of Tubingen, Germany; German Centre Neurodegenerat Disease, Germany.
    Wegenast-Braun, Bettina M.
    University of Tubingen, Germany; German Centre Neurodegenerat Disease, Germany.
    Nyström, Sofie
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
    Goedert, Michel
    MRC, England.
    Jucker, Mathias
    University of Tubingen, Germany; German Centre Neurodegenerat Disease, Germany.
    Nilsson, Peter
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
    Distinct Spacing Between Anionic Groups: An Essential Chemical Determinant for Achieving Thiophene-Based Ligands to Distinguish Beta-Amyloid or Tau Polymorphic Aggregates2015In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 21, no 25, p. 9072-9082Article in journal (Refereed)
    Abstract [en]

    The accumulation of protein aggregates is associated with many devastating neurodegenerative diseases and the existence of distinct aggregated morphotypes has been suggested to explain the heterogeneous phenotype reported for these diseases. Thus, the development of molecular probes able to distinguish such morphotypes is essential. We report an anionic tetrameric oligothiophene compound that can be utilized for spectral assignment of different morphotypes of -amyloid or tau aggregates present in transgenic mice at distinct ages. The ability of the ligand to spectrally distinguish between the aggregated morphotypes was reduced when the spacing between the anionic substituents along the conjugated thiophene backbone was altered, which verified that specific molecular interactions between the ligand and the protein aggregate are necessary to detect aggregate polymorphism. Our findings provide the structural and functional basis for the development of new fluorescent ligands that can distinguish between different morphotypes of protein aggregates.

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  • 5.
    Klingstedt, Therése
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Shirani, Hamid
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Åslund, Andreas
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Cairns, Nigel J.
    Washington University, MO USA .
    Sigurdson, Christina J.
    University of Calif San Diego, CA USA .
    Goedert, Michel
    MRC, England .
    Nilsson, Peter
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    The Structural Basis for Optimal Performance of Oligothiophene-Based Fluorescent Amyloid Ligands: Conformational Flexibility is Essential for Spectral Assignment of a Diversity of Protein Aggregates2013In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 19, no 31, p. 10179-10192Article in journal (Refereed)
    Abstract [en]

    Protein misfolding diseases are characterized by deposition of protein aggregates, and optical ligands for molecular characterization of these disease-associated structures are important for understanding their potential role in the pathogenesis of the disease. Luminescent conjugated oligothiophenes (LCOs) have proven useful for optical identification of a broader subset of disease-associated protein aggregates than conventional ligands, such as thioflavin T and Congo red. Herein, the molecular requirements for achieving LCOs able to detect nonthioflavinophilic Aβ aggregates or non-congophilic prion aggregates, as well as spectrally discriminate Aβ and tau aggregates, were investigated. An anionic pentameric LCO was subjected to chemical engineering by: 1) replacing thiophene units with selenophene or phenylene moieties, or 2) alternating the anionic substituents along the thiophene backbone. In addition, two asymmetric tetrameric ligands were generated. Overall, the results from this study identified conformational freedom and extended conjugation of the conjugated backbone as crucial determinants for obtaining superior thiophene-based optical ligands for sensitive detection and spectral assignment of disease-associated protein aggregates.

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  • 6.
    Klingstedt, Therése
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Shirani, Hamid
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Åslund, K. O. Andreas
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Cairns, Nigel J.
    Department of Neurology, Alzheimer’s Disease Research Center, Washington University St. Louis, United States.
    Sigurdson, Christina J.
    Department of Pathology, University of California, San Diego, La Jolla, California, United States.
    Goedert, Michel
    MRC Laboratory of Molecular Biology Hills Road, Cambridge, UK.
    Nilsson, K. Peter R.
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    The structural basis for optimal performance of oligothiophene based fluorescent amyloid ligands: Conformational flexibility is essential for spectral assignment of a diversity of protein aggregatesManuscript (preprint) (Other academic)
    Abstract [en]

    Protein misfolding diseases are characterized by deposition of protein aggregates and optical ligands for molecular characterization of these disease-associated structures are important for understanding their potential role in the pathogenesis of the disease. Luminescent conjugated oligothiophenes (LCOs) have proven useful for optical identification of a broader subset of disease-associated protein aggregates than conventional ligands, such as Thioflavin T (ThT) and Congo red. Herein, the molecular requirements for achieving LCOs able to detect non-thioflavinophilic Aβ aggregates or non-congophilic prion aggregates, as well as spectrally discriminate Aβ and tau aggregates, were investigated. An anionic pentameric LCO was subjected to chemical engineering by i) replacing thiophene units with selenophene or phenylene moieties or ii) alternating the anionic substituents along the  thiophene backbone. In addition, two asymmetric tetrameric ligands were  generated. Overall, the results from this study identified conformational  freedom and extended conjugation of the conjugated backbone as crucial  determinants for obtaining superior thiophene-based optical ligands for  sensitive detection and spectral assignment of diseaseassociated protein aggregates.

  • 7.
    Selegård, Robert
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, Faculty of Science & Engineering.
    Rouhbalchsh, Zeinab
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, Faculty of Science & Engineering.
    Shirani, Hamid
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
    Johansson, Leif
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Norman, Patrick
    KTH Royal Institute Technology, Sweden.
    Linares, Mathieu
    KTH Royal Institute Technology, Sweden.
    Aili, Daniel
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, Faculty of Science & Engineering.
    Nilsson, Peter
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
    Distinct Electrostatic Interactions Govern the Chiro-Optical Properties and Architectural Arrangement of Peptide-Oligothiophene Hybrid Materials2017In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 50, no 18, p. 7102-7110Article in journal (Refereed)
    Abstract [en]

    The development of chiral optoelectronic materials is of great interest due to their potential of being utilized in electronic devices, biosensors, and artificial enzymes. Herein, we report the chiral optical properties and architectural arrangement of optoelectronic materials generated from noncovalent self-assembly of a cationic synthetic peptide and five chemically defined anionic pentameric oligothiophenes. The peptide-oligothiophene hybrid materials exhibit a three-dimensional ordered helical structure and optical activity in the pi-pi* transition region that are observed due to a single chain induced chirality of the conjugated thiophene backbone upon interaction with the peptide. The latter property is highly dependent on electrostatic interactions between the peptide and the oligothiophene, verifying that a distinct spacing of the carboxyl groups along the thiophene backbone is a major chemical determinant for having a hybrid material with distinct optoelectronic properties. The necessity of the electrostatic interaction between specific carboxyl functionalities along the thiophene backbone and the lysine residues of the peptide, as well as the induced circular dichroism of the thiophene backbone, was also confirmed by theoretical calculations. We foresee that our findings will aid in designing optoelectronic materials with dynamic architectonical precisions as well as offer the possibility to create the next generation of materials for organic electronics and organic bioelectronics.

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  • 8.
    Shahnawaz, Mohammad
    et al.
    Univ Texas Houston, TX 77004 USA.
    Mukherjee, Abhisek
    Univ Texas Houston, TX 77004 USA.
    Pritzkow, Sandra
    Univ Texas Houston, TX 77004 USA.
    Mendez, Nicolas
    Univ Texas Houston, TX 77004 USA.
    Rabadia, Prakruti
    Univ Texas Houston, TX 77004 USA.
    Liu, Xiangan
    Univ Texas Houston, TX USA.
    Hu, Bo
    Univ Texas Houston, TX USA.
    Schmeichel, Ann
    Mayo Clin, MN USA.
    Singer, Wolfgang
    Mayo Clin, MN USA.
    Wu, Gang
    Univ Texas Houston, TX USA.
    Tsai, Ah-Lim
    Univ Texas Houston, TX USA.
    Shirani, Hamid
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
    Nilsson, Peter
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
    Low, Phillip A.
    Mayo Clin, MN USA.
    Soto, Claudio
    Univ Texas Houston, TX 77004 USA.
    Discriminating alpha-synuclein strains in Parkinsons disease and multiple system atrophy2020In: Nature, ISSN 0028-0836, E-ISSN 1476-4687Article in journal (Refereed)
    Abstract [en]

    Synucleinopathies are neurodegenerative diseases that are associated with the misfolding and aggregation of alpha-synuclein, including Parkinsons disease, dementia with Lewy bodies and multiple system atrophy(1). Clinically, it is challenging to differentiate Parkinsons disease and multiple system atrophy, especially at the early stages of disease(2). Aggregates of alpha-synuclein in distinct synucleinopathies have been proposed to represent different conformational strains of alpha-synuclein that can self-propagate and spread from cell to cell(3-6). Protein misfolding cyclic amplification (PMCA) is a technique that has previously been used to detect alpha-synuclein aggregates in samples of cerebrospinal fluid with high sensitivity and specificity(7,8). Here we show that the alpha-synuclein-PMCA assay can discriminate between samples of cerebrospinal fluid from patients diagnosed with Parkinsons disease and samples from patients with multiple system atrophy, with an overall sensitivity of 95.4%. We used a combination of biochemical, biophysical and biological methods to analyse the product of alpha-synuclein-PMCA, and found that the characteristics of the alpha-synuclein aggregates in the cerebrospinal fluid could be used to readily distinguish between Parkinsons disease and multiple system atrophy. We also found that the properties of aggregates that were amplified from the cerebrospinal fluid were similar to those of aggregates that were amplified from the brain. These findings suggest that alpha-synuclein aggregates that are associated with Parkinsons disease and multiple system atrophy correspond to different conformational strains of alpha-synuclein, which can be amplified and detected by alpha-synuclein-PMCA. Our results may help to improve our understanding of the mechanism of alpha-synuclein misfolding and the structures of the aggregates that are implicated in different synucleinopathies, and may also enable the development of a biochemical assay to discriminate between Parkinsons disease and multiple system atrophy. Protein misfolding cyclic amplification (PMCA) technology can discriminate between patients with Parkinsons disease and patients with multiple system atrophy on the basis of the characteristics of the alpha-synuclein aggregates in the cerebrospinal fluid.

  • 9.
    Shirani, Hamid
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
    Appelqvist, Hanna
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
    Bäck, Marcus
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
    Klingstedt, Therése
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
    Cairns, Nigel J.
    Washington University, MO USA.
    Nilsson, Peter
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
    Synthesis of Thiophene-Based Optical Ligands That Selectively Detect Tau Pathology in Alzheimers Disease2017In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 23, no 67, p. 17127-17135Article in journal (Refereed)
    Abstract [en]

    The accumulation of protein aggregates is associated with many devastating neurodegenerative diseases and the development of molecular ligands able to detect these pathological hallmarks is essential. Here, the synthesis of thiophene based optical ligands, denoted bi-thiophene-vinyl-benzothiazoles (bTVBTs) that can be utilized for selective assignment of tau aggregates in brain tissue with Alzheimers disease (AD) pathology is reported. The ability of the ligands to selectively distinguish tau deposits from the other AD associated pathological hallmark, senile plaques consisting of aggregated amyloid- (A) peptide, was reduced when the chemical composition of the ligands was altered, verifying that specific molecular interactions between the ligands and the aggregates are necessary for the selective detection of tau deposits. Our findings provide the structural and functional basis for the development of new fluorescent ligands that can distinguish between aggregated proteinaceous species consisting of different proteins. In addition, the bTVBT scaffold might be utilized to create powerful practical research tools for studying the underlying molecular events of tau aggregation and for creating novel agents for clinical imaging of tau pathology in AD.

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  • 10.
    Shirani, Hamid
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
    Linares, Mathieu
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Chemistry. Linköping University, Faculty of Science & Engineering.
    Sigurdson, Christina J.
    University of Calif San Diego, CA 92093 USA.
    Lindgren, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
    Norman, Patrick
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Chemistry. Linköping University, Faculty of Science & Engineering.
    Nilsson, Peter
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
    A Palette of Fluorescent Thiophene-Based Ligands for the Identification of Protein Aggregates2015In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 21, no 43, p. 15133-15137Article in journal (Refereed)
    Abstract [en]

    By replacing the central thiophene unit of an anionic pentameric oligothiophene with other heterocyclic moities, a palette of pentameric thiophene-based ligands with distinct fluorescent properties were synthesized. All ligands displayed superior selectivity towards recombinant amyloid fibrils as well as disease-associated protein aggregates in tissue sections.

  • 11.
    Simon, Rozalyn
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Bäck, Marcus
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Shirani, Hamid
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Lindgren, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Nilsson, Peter R
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    pH-dependent optical transitions in anionic pentameric oligothiophenes2014Manuscript (preprint) (Other academic)
    Abstract [en]

    Understanding the photo-physical processes in fluorescent probes are essential as such dyes are widely utilized in molecular biology. Here we report the pH-dependent optical transitions of a library of anionic pentameric luminescent conjugated oligothiophenes (LCOs) that have been used for fluorescent identification of protein aggregates, the pathological hallmark of many devastating diseases. Absorption-, excitation- and emission spectra were recorded for all LCOs in different buffers with a pH range from 3.5 to 7. p-FTAA, a LCO having a central core consisting of a trimeric thiophene  building block with head-to-head acetic acid functionalization as well as terminal carboxyl groups extending the pentameric thiophene backbone, displayed pH/dependent optical characteristics correlating to a non-planar to planar transition of the conjugated backbone as well as aggregation between adjacent thiophene chain upon protonation of the  acetic acid side chains. In contrast, chemically related analogues to p-FTAA lacking the  terminal carboxyl groups extending the pentameric thiophene backbone or the conformational ability to undergo a non/planar to planar transition of the  conjugated backbone, displayed different optical characteristics compared to p-FTAA. Overall these studies highlighted that minor chemical alteration of LCOs can result in major difference in the optical characteristics obtained from the dyes and the results might aid in designing novel LCOs that have  superior optical performance as amyloid ligands.

  • 12.
    Simon, Rozalyn
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Shirani, Hamid
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Åslund, K. O. Andreas
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Bäck, Marcus
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Haroutunian, Vahram
    Department of Psychiatry and Alzheimer’s Disease Research Center, Mount Sinai School of Medicine, New York, USA.
    Gandy, Sam
    Department of Psychiatry and Alzheimer’s Disease Research Center, Mount Sinai School of Medicine, New York, USA.
    Nilsson, Peter R
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Pentameric Thiophene-Based Ligands that Spectrally Discriminate Amyloid-b and Tau Aggregates Display Distinct Solvatochromism and Viscosity-Induced Spectral Shifts2014In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 20, no 39, p. 12537-12543Article in journal (Refereed)
    Abstract [en]

    A wide range of neurodegenerative diseases are characterized by the deposition of multiple protein aggregates. Ligands for molecular characterization and discrimination of these pathological hallmarks are thus important for understanding their potential role in pathogenesis as well as for clinical diagnosis of the disease. In this regard, luminescent conjugated oligothiophenes (LCOs) have proven useful for spectral discrimination of amyloid-beta (Aβ) and tau neurofibrillary tangles (NFTs), two of the pathological hallmarks associated with Alzheimer’s disease. Herein, the solvatochromism of a library of anionic pentameric thiophene-based ligands, as well as their ability to spectrally discriminate Aβ and tau aggregates, were investigated. Overall, the results from this study identified distinct solvatochromic and viscosity-dependent behavior of thiophene-based ligands that can be applied as indices to direct the chemical design of improved LCOs for spectral separation of Aβ and tau aggregates in brain tissue sections. The results also suggest that the observed spectral transitions of the ligands are due to their ability to conform by induced fit to specific microenvironments within the binding interface of each particular protein aggregate. We foresee that these findings might aid in the chemical design of thiophene-based ligands that are increasingly selective for distinct disease-associated protein aggregates.

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  • 13.
    Wahlstrom, Niklas
    et al.
    KTH Royal Inst Technol, Sweden.
    Edlund, Ulrica
    KTH Royal Inst Technol, Sweden.
    Pavia, Henrik
    Univ Gothenburg, Sweden.
    Toth, Gunilla
    Univ Gothenburg, Sweden.
    Jaworski, Aleksander
    Stockholm Univ, Sweden.
    Pell, Andrew J.
    Stockholm Univ, Sweden.
    Choong, Ferdinand X.
    Karolinska Inst, Sweden.
    Shirani, Hamid
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
    Nilsson, Peter
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
    Richter-Dahlfors, Agneta
    Karolinska Inst, Sweden.
    Cellulose from the green macroalgae Ulva lactuca: isolation, characterization, optotracing, and production of cellulose nanofibrils2020In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882XArticle in journal (Refereed)
    Abstract [en]

    We report (1) successful extraction and characterization of cellulose from northern hemisphere green macroalgae Ulva lactuca (Ulva fenestrata) collected along the Swedish west coast and cultivated indoors under controlled conditions, followed by (2) its utilization in the production of lignin-free cellulose nanofibrils (CNF). Cellulose was extracted by sequential treatment with ethanol, hydrogen peroxide, sodium hydroxide, and hydrochloric acid, yielding a cellulose-rich insoluble fraction. The extracted cellulose was disintegrated into CNF using a mechanical homogenization process without any further enzymatic pre-treatments. In addition, regenerated cellulose was prepared. XRD characterization of the CNF showed characteristic peaks for the cellulose I allomorph and confirmed that the nanofibrils were semicrystalline with a crystallinity index of 48%. Regenerated cellulose was mostly amorphous with an XRD pattern indicating the presence of the cellulose II allomorph. The cellulose fractions were essentially free from inorganic substances and thermally stable up to around 260 degrees C. Structural mapping with CP-MAS C-13-NMR sustains the cellulose content of CNF and regenerated cellulose, respectively, yet ion chromatography identified the presence of 10-15% xylose in the fractions. Optotracing was used as a novel and non-disruptive tool to selectively assess the polysaccharide composition of the cellulose fractions and produced CNF aiming to shed light on this hitherto non-resolved origin of xylose in Ulva cell wall matter. Fluorescence excitation and emission spectra of a panel of 4 oligothiophenes identified and verified the presence of cellulose and sustain the conclusion that the isolated fractions consist of cellulose intertwined with a small amount of a xylose-containing glucan copolymer. [GRAPHICS] .

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