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Sobek J, Li J, Combes BF, Gerez JA, Henrich MT, Geibl FF, Nilsson PR, Shi K, Rominger A, Oertel WH, Nitsch RM, Nordberg A, Ågren H, Ni R. Efficient characterization of multiple binding sites of small molecule imaging ligands on amyloid-beta, tau and alpha-synuclein. Eur J Nucl Med Mol Imaging 2024:10.1007/s00259-024-06806-7. [PMID: 38953933 DOI: 10.1007/s00259-024-06806-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2024] [Accepted: 06/17/2024] [Indexed: 07/04/2024]
Abstract
PURPOSE There is an unmet need for compounds to detect fibrillar forms of alpha-synuclein (αSyn) and 4-repeat tau, which are critical in many neurodegenerative diseases. Here, we aim to develop an efficient surface plasmon resonance (SPR)-based assay to facilitate the characterization of small molecules that can bind these fibrils. METHODS SPR measurements were conducted to characterize the binding properties of fluorescent ligands/compounds toward recombinant amyloid-beta (Aβ)42, K18-tau, full-length 2N4R-tau and αSyn fibrils. In silico modeling was performed to examine the binding pockets of ligands on αSyn fibrils. Immunofluorescence staining of postmortem brain tissue slices from Parkinson's disease patients and mouse models was performed with fluorescence ligands and specific antibodies. RESULTS We optimized the protocol for the immobilization of Aβ42, K18-tau, full-length 2N4R-tau and αSyn fibrils in a controlled aggregation state on SPR-sensor chips and for assessing their binding to ligands. The SPR results from the analysis of binding kinetics suggested the presence of at least two binding sites for all fibrils, including luminescent conjugated oligothiophenes, benzothiazole derivatives, nonfluorescent methylene blue and lansoprazole. In silico modeling studies for αSyn (6H6B) revealed four binding sites with a preference for one site on the surface. Immunofluorescence staining validated the detection of pS129-αSyn positivity in the brains of Parkinson's disease patients and αSyn preformed-fibril injected mice, 6E10-positive Aβ in arcAβ mice, and AT-8/AT-100-positivity in pR5 mice. CONCLUSION SPR measurements of small molecules binding to Aβ42, K18/full-length 2N4R-tau and αSyn fibrils suggested the existence of multiple binding sites. This approach may provide efficient characterization of compounds for neurodegenerative disease-relevant proteinopathies.
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Affiliation(s)
- Jens Sobek
- Functional Genomics Center, University of Zurich & ETH Zurich, Zürich, Switzerland
| | - Junhao Li
- Department of Physics and Astronomy, Uppsala University, Uppsala, Sweden
| | - Benjamin F Combes
- Institute for Regenerative Medicine, University of Zurich, Wagistrasse 12, 8952, Zürich, Switzerland
| | - Juan A Gerez
- Laboratory of Physical Chemistry, Department of Chemistry and Applied Biosciences, ETH Zurich, Zürich, Switzerland
| | - Martin T Henrich
- Department of Psychiatry and Psychotherapy, Philipps-University Marburg, Marburg, Germany
- Department of Neurology, Philipps-University Marburg, Marburg, Germany
| | - Fanni F Geibl
- Department of Psychiatry and Psychotherapy, Philipps-University Marburg, Marburg, Germany
- Department of Neurology, Philipps-University Marburg, Marburg, Germany
| | - Peter R Nilsson
- Divison of Chemistry, Department of Physics, Chemistry and Biology, Linköping University, Linköping, Sweden
| | - Kuangyu Shi
- Department of Nuclear Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Axel Rominger
- Department of Nuclear Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Wolfgang H Oertel
- Department of Psychiatry and Psychotherapy, Philipps-University Marburg, Marburg, Germany
- Department of Neurology, Philipps-University Marburg, Marburg, Germany
| | - Roger M Nitsch
- Institute for Regenerative Medicine, University of Zurich, Wagistrasse 12, 8952, Zürich, Switzerland
| | - Agneta Nordberg
- Divison of Clinical Geriatrics, Center for Alzheimer Research, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Stockholm, Sweden
| | - Hans Ågren
- Department of Physics and Astronomy, Uppsala University, Uppsala, Sweden
| | - Ruiqing Ni
- Institute for Regenerative Medicine, University of Zurich, Wagistrasse 12, 8952, Zürich, Switzerland.
- Department of Nuclear Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland.
- Institute for Biomedical Engineering, University of Zurich & ETH Zurich, Zürich, Switzerland.
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Mahmudin L, Wulandani R, Riswan M, Kurnia Sari E, Dwi Jayanti P, Syahrul Ulum M, Arifin M, Suharyadi E. Silver nanoparticles-based localized surface plasmon resonance biosensor for Escherichia coli detection. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2024; 311:123985. [PMID: 38316074 DOI: 10.1016/j.saa.2024.123985] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2023] [Revised: 01/28/2024] [Accepted: 01/29/2024] [Indexed: 02/07/2024]
Abstract
Escherichia coli (E. coli) bacteria with varying solution concentrations have been successfully detected using silver nanoparticles (Ag NPs)-based localized surface plasmon resonance (LSPR) biosensors. The Ag NPs were effectively synthesized by a chemical method using trisodium citrate with L-Histidine (L-His) and deposited on the surface of Au thin film-coated half-cylinder BK-7 prisms. He-Ne laser with a wavelength of 632.8 nm was used to generate LSPR phenomena in Kretschmann configuration with prism/Au thin film/His-Ag NPs/E. coli bacteria/air structure arrangements. The variation of E. coli bacteria concentration was carried out to determine the effect of E. coli bacteria concentration on the LSPR curve characteristics. The characterization results showed that the size of Ag NPs was 18.7 nm, and that of His-Ag NPs was 17.9 nm. Selected area electron diffraction results indicated the formation of diffraction rings with the presence of lattice planes (111), (200), (220), and (311), proving the face-centered cubic crystal structure of silver. The absorbance peak of Ag NPs shifted from a wavelength of 421-414 nm with an increase in band gap energy from 2.94 eV to 2.99 eV, along with a decreased average particle size. The functional groups observed in His-Ag NPs showed wavenumbers at 3320 to 3318 cm-1, 2106 to 2129 cm-1, and 1635 cm-1, showing the OH, CH, and C CO bonds, respectively. The SPR angle of the prism/Au thin film/air structure is 44.80°. Meanwhile, the LSPR angle for the prism/Au thin film/His-Ag NPs/air structure is 44.92°. There is an increase in the LSPR angle by 0.12°. Moreover, the minimum reflectance increases by 0.02. After detecting E. coli bacteria, the LSPR angle shifted by 0.26°, 0.38°, and 0.49° for concentrations of 6.0 × 108 CFU/mL, 6.0 × 107 CFU/mL and 6.0 × 106 CFU/mL respectively. However, the minimum reflectance rose from 0.09° to 0.14°, 0.20°, and 0.22°. Moreover, SPR testing with the structure of the prism/Au thin film/E. coli bacteria/air was carried out to determine the contribution of His-Ag NPs for detecting E. coli bacteria. The results showed that no angular shift occurs. These results indicate that using Ag NPs encapsulated with L-His is essential in amplifying the SPR signal and detecting E. coli bacteria. There was a notable alteration in both the LSPR angle and minimum reflectance indicating that adding His-Ag NPs facilitated the interaction between the E. coli and the sensor surface, thereby enhancing the performance of LSPR-based sensors for E. coli detection for low limit of detection value at 0.47 CFU/mL.
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Affiliation(s)
- Lufsyi Mahmudin
- Department of Physics, Universitas Tadulako, Palu, Indonesia.
| | | | - Muhammad Riswan
- Department of Physics, Universitas Gadjah Mada, Yogyakarta, Indonesia
| | - Emi Kurnia Sari
- Department of Physics, Universitas Gadjah Mada, Yogyakarta, Indonesia
| | - Putri Dwi Jayanti
- Department of Physics, Universitas Gadjah Mada, Yogyakarta, Indonesia
| | - M Syahrul Ulum
- Department of Physics, Universitas Tadulako, Palu, Indonesia
| | - Muhammad Arifin
- Department of Physics, Universitas Gadjah Mada, Yogyakarta, Indonesia
| | - Edi Suharyadi
- Department of Physics, Universitas Gadjah Mada, Yogyakarta, Indonesia.
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