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Akyüz Ö, Mißun M, Rosenberg R, Scheffner M, Marx A, Cölfen H. Thermostable protein-stabilized gold nanoclusters as a peroxidase mimic. NANOSCALE ADVANCES 2023; 5:6061-6068. [PMID: 37941944 PMCID: PMC10629000 DOI: 10.1039/d3na00566f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Accepted: 09/18/2023] [Indexed: 11/10/2023]
Abstract
Protein-stabilized gold nanoclusters (AuNCs) are fascinating nanostructures with exciting properties owing to their ultra-small sizes and functional shell. However, their applications under extreme conditions are still complicated, waiting for programmable solutions. Therefore, the design of a multi-functional protein stabilizer for specific purposes gains attention to improve the stability and functionality of AuNCs. Herein, we exploited the thermostability of genetically engineered KlenTaq DNA polymerase containing five cysteine residues (KTQ5C) to synthesize heat-stable AuNCs (AuNC@KTQ5C) and characterize optical, structural, and hydrodynamic properties. Besides their excellent photophysical properties, AuNC@KTQ5C also exhibit superior peroxidase-like (POD-like) catalytic activity following typical Michaelis-Menten kinetics together with a high affinity towards the POD substrate 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)-diammonium salt (ABTS). Moreover, FTIR and relative catalytic activity analysis of AuNC@KTQ5C reveal that KTQ5C is resistant to changes in protein secondary structure while the AuNCs conserve 70-80% of their catalytic performance after heat treatments up to more than 80 °C. Our findings show that stabilizing AuNCs with thermostable KTQ5C not only preserves the advantages of protein-stabilized AuNCs but can also promote the resistance of AuNCs against aggregation due to protein denaturation under extreme reaction temperatures, protecting their fluorescent emission or catalytic activity.
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Affiliation(s)
- Özlem Akyüz
- Physical Chemistry, Department of Chemistry, University of Konstanz 78457 Konstanz Germany
| | - Maite Mißun
- Organic Chemistry/Cellular Chemistry, Department of Chemistry, University of Konstanz 78457 Konstanz Germany
| | - Rose Rosenberg
- Physical Chemistry, Department of Chemistry, University of Konstanz 78457 Konstanz Germany
| | - Martin Scheffner
- Department of Biology, University of Konstanz 78457 Konstanz Germany
| | - Andreas Marx
- Organic Chemistry/Cellular Chemistry, Department of Chemistry, University of Konstanz 78457 Konstanz Germany
| | - Helmut Cölfen
- Physical Chemistry, Department of Chemistry, University of Konstanz 78457 Konstanz Germany
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2
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Frank U, Drobek D, Sánchez-Iglesias A, Wawra SE, Nees N, Walter J, Pflug L, Apeleo Zubiri B, Spiecker E, Liz-Marzán LM, Peukert W. Determination of 2D Particle Size Distributions in Plasmonic Nanoparticle Colloids via Analytical Ultracentrifugation: Application to Gold Bipyramids. ACS NANO 2023; 17:5785-5798. [PMID: 36920091 DOI: 10.1021/acsnano.2c12257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Multidimensional particle properties determine the product properties in numerous advanced applications. Accurate and statistically meaningful measurements of complex particles and their multidimensional distributions are highly challenging but strongly needed. 2D particle size distributions of plasmonic nanoparticles of complex regular shape can be obtained from analytical ultracentrifugation experiments via the optical back coupling method. A workflow for the calculation of frictional properties of arbitrarily shaped nanoparticles was developed based on bead shell models and applied to gold bipyramids with a pentagonal cross-section. The obtained 2D particle length-diameter distributions and the reduced cumulative 1D length and diameter distributions were compared to transmission electron microscopy measurements. While we find very good agreement for most measurements, the obtained length and diameter distributions were shifted by a few nanometers for some samples. Transmission electron microscopy, energy-dispersive X-ray spectroscopy, electron tomography, and finite element modeling indicate that the shift originated from a slight mismatch between the assumed shape of the simulated perfect bipyramids and the real particle shape and composition due to the presence of silver in the particles. This study demonstrates the feasibility of the applied techniques for complex shape analysis of nanoparticle ensembles with unmatched particle count numbers.
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Affiliation(s)
- Uwe Frank
- Institute of Particle Technology (LFG), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Cauerstraße 4, 91058 Erlangen, Germany
| | - Dominik Drobek
- Institute of Micro- and Nanostructure Research and Center for Nanoanalysis and Electron Microscopy (CENEM), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Cauerstraße 3, 91058 Erlangen, Germany
| | - Ana Sánchez-Iglesias
- CIC biomaGUNE, Basque Research and Technology Alliance (BRTA), Paseo de Miramon 194, 20014 Donostia-San Sebastián, Spain
- Centro de Investigación en Red de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Paseo de Miramon 194, 20014 Donostia-San Sebastián, Spain
| | - Simon E Wawra
- Institute of Particle Technology (LFG), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Cauerstraße 4, 91058 Erlangen, Germany
| | - Nico Nees
- Department of Mathematics, Chair of Applied Mathematics (Continuous Optimization), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Cauerstraße 11, 91058 Erlangen, Germany
| | - Johannes Walter
- Institute of Particle Technology (LFG), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Cauerstraße 4, 91058 Erlangen, Germany
- Interdisciplinary Center for Functional Particle Systems (FPS), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Haberstraße 9a, 91058 Erlangen, Germany
| | - Lukas Pflug
- Department of Mathematics, Chair of Applied Mathematics (Continuous Optimization), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Cauerstraße 11, 91058 Erlangen, Germany
- Competence Unit for Scientific Computing, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Martensstraße 5a, 91058 Erlangen, Germany
| | - Benjamin Apeleo Zubiri
- Institute of Micro- and Nanostructure Research and Center for Nanoanalysis and Electron Microscopy (CENEM), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Cauerstraße 3, 91058 Erlangen, Germany
- Interdisciplinary Center for Nanostructure Films (IZNF), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Cauerstraße 3, 91058 Erlangen, Germany
| | - Erdmann Spiecker
- Institute of Micro- and Nanostructure Research and Center for Nanoanalysis and Electron Microscopy (CENEM), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Cauerstraße 3, 91058 Erlangen, Germany
- Interdisciplinary Center for Nanostructure Films (IZNF), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Cauerstraße 3, 91058 Erlangen, Germany
| | - Luis M Liz-Marzán
- CIC biomaGUNE, Basque Research and Technology Alliance (BRTA), Paseo de Miramon 194, 20014 Donostia-San Sebastián, Spain
- Ikerbasque, Basque Foundation for Science, 43009 Bilbao, Spain
- Centro de Investigación en Red de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Paseo de Miramon 194, 20014 Donostia-San Sebastián, Spain
| | - Wolfgang Peukert
- Institute of Particle Technology (LFG), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Cauerstraße 4, 91058 Erlangen, Germany
- Interdisciplinary Center for Functional Particle Systems (FPS), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Haberstraße 9a, 91058 Erlangen, Germany
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3
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Henrickson A, Gorbet GE, Savelyev A, Kim M, Hargreaves J, Schultz SK, Kothe U, Demeler B. Multi-wavelength analytical ultracentrifugation of biopolymer mixtures and interactions. Anal Biochem 2022; 652:114728. [PMID: 35609686 PMCID: PMC10276540 DOI: 10.1016/j.ab.2022.114728] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2022] [Revised: 05/07/2022] [Accepted: 05/11/2022] [Indexed: 11/01/2022]
Abstract
Multi-wavelength analytical ultracentrifugation (MW-AUC) is a recent development made possible by new analytical ultracentrifuge optical systems. MW-AUC extends the basic hydrodynamic information content of AUC and provides access to a wide range of new applications for biopolymer characterization, and is poised to become an essential analytical tool to study macromolecular interactions. It adds an orthogonal spectral dimension to the traditional hydrodynamic characterization by exploiting unique chromophores in analyte mixtures that may or may not interact. Here we illustrate the utility of MW-AUC for experimental investigations where the benefit of the added spectral dimension provides critical information that is not accessible, and impossible to resolve with traditional AUC methods. We demonstrate the improvements in resolution and information content obtained by this technique compared to traditional single- or dual-wavelength approaches, and discuss experimental design considerations and limitations of the method. We further address the advantages and disadvantages of the two MW optical systems available today, and the differences in data analysis strategies between the two systems.
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Affiliation(s)
- Amy Henrickson
- University of Lethbridge, Dept. of Chemistry and Biochemistry, Lethbridge, Alberta, Canada
| | | | - Alexey Savelyev
- University of Montana, Dept. of Chemistry, Missoula, MT, USA
| | - Minji Kim
- Carnegie Mellon University, Dept. of Computer Science, Pittsburgh, PA, USA
| | | | - Sarah K Schultz
- University of Lethbridge, Dept. of Chemistry and Biochemistry, Lethbridge, Alberta, Canada
| | - Ute Kothe
- University of Lethbridge, Dept. of Chemistry and Biochemistry, Lethbridge, Alberta, Canada; University of Manitoba, Department of Chemistry, Winnipeg, Manitoba, Canada
| | - Borries Demeler
- University of Lethbridge, Dept. of Chemistry and Biochemistry, Lethbridge, Alberta, Canada; AUC Solutions, LLC, Houston, TX, USA; University of Montana, Dept. of Chemistry, Missoula, MT, USA.
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4
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González-Rubio G, Hilbert H, Rosenberg R, Ni B, Fuhrer L, Cölfen H. Simple Determination of Gold Nanocrystal Dimensions by Analytical Ultracentrifugation via Surface Ligand-Solvent Density Matching. NANOMATERIALS 2021; 11:nano11061427. [PMID: 34071534 PMCID: PMC8228700 DOI: 10.3390/nano11061427] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/18/2021] [Revised: 05/21/2021] [Accepted: 05/25/2021] [Indexed: 11/16/2022]
Abstract
Analytical ultracentrifugation (AUC) is a powerful technique to observe colloidal nanocrystals (NCs) directly in solution and obtain critical information about their physical-chemical properties. Nevertheless, a more comprehensive implementation of AUC for the characterisation of such a class of crystalline colloids has been traditionally impaired by the requirement of having a priori knowledge of the complex, multilayered structure formed by NC in solution. This includes the nature (density and mass) of the surface ligands (SLs) that provide NC colloidal stability and the shell of solvent molecules formed on it. Herein, we propose a methodology to determine the NCs size by using SLs with a density equal to that of the solvent. Thereby, the buoyancy force of the SL shell is neutral, and the density of the NCs is sufficient a priori knowledge to calculate their related mass and size distributions. The simplicity and reliability of the method are evaluated with cetyltrimethylammonium bromide (CTAB) stabilized spherical gold NCs (AuNCs) of dimensions ranging from 1 to 17 nm. The proposed method has great potential to be transferred to any non-crystalline and crystalline colloids of different nature and composition, which have a density that is equal to the bulk and can be stabilized by SLs having a density that matches that of the solvent.
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5
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Henrickson A, Kulkarni JA, Zaifman J, Gorbet GE, Cullis PR, Demeler B. Density Matching Multi-wavelength Analytical Ultracentrifugation to Measure Drug Loading of Lipid Nanoparticle Formulations. ACS NANO 2021; 15:5068-5076. [PMID: 33617224 DOI: 10.1021/acsnano.0c10069] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Previous work suggested that lipid nanoparticle (LNP) formulations, encapsulating nucleic acids, display electron-dense morphology when examined by cryogenic-transmission electron microscopy (cryo-TEM). Critically, the employed cryo-TEM method cannot differentiate between loaded and empty LNP formulations. Clinically relevant formulations contain high lipid-to-nucleic acid ratios (10-25 (w/w)), and for systems that contain mRNA or DNA, it is anticipated that a substantial fraction of the LNP population does not contain a payload. Here, we present a method based on the global analysis of multi-wavelength sedimentation velocity analytical ultracentrifugation, using density matching with heavy water, that not only measures the standard sedimentation and diffusion coefficient distributions of LNP mixtures, but also reports the corresponding partial specific volume distributions and optically separates signal contributions from nucleic acid cargo and lipid shell. This makes it possible to reliably predict molar mass and anisotropy distributions, in particular, for systems that are heterogeneous in partial specific volume and have low to intermediate densities. Our method makes it possible to unambiguously measure the density of nanoparticles and is motivated by the need to characterize the extent to which lipid nanoparticles are loaded with nucleic acid cargoes. Since the densities of nucleic acids and lipids substantially differ, the measured density is directly proportional to the loading of nanoparticles. Hence, different loading levels will produce particles with variable density and partial specific volume. An UltraScan software module was developed to implement this approach for routine analysis.
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Affiliation(s)
- Amy Henrickson
- Department of Chemistry and Biochemistry, The University of Lethbridge, Lethbridge, Alberta, Canada T1K 3M4
| | - Jayesh A Kulkarni
- Department of Biochemistry and Molecular Biology, Faculty of MedicineUniversity of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3
| | - Josh Zaifman
- Department of Biochemistry and Molecular Biology, Faculty of MedicineUniversity of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3
| | | | - Pieter R Cullis
- Department of Biochemistry and Molecular Biology, Faculty of MedicineUniversity of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3
| | - Borries Demeler
- Department of Chemistry and Biochemistry, The University of Lethbridge, Lethbridge, Alberta, Canada T1K 3M4
- AUC Solutions, Houston, Texas 77494, United States
- Department of Chemistry, University of Montana, Missoula, Montana 59812, United States
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6
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Xu X, Cölfen H. Ultracentrifugation Techniques for the Ordering of Nanoparticles. NANOMATERIALS 2021; 11:nano11020333. [PMID: 33513966 PMCID: PMC7912273 DOI: 10.3390/nano11020333] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/13/2020] [Revised: 01/22/2021] [Accepted: 01/22/2021] [Indexed: 01/07/2023]
Abstract
A centrifugal field can provide an external force for the ordering of nanoparticles. Especially with the knowledge from in-situ characterization by analytical (ultra)centrifugation, nanoparticle ordering can be rationally realized in preparative (ultra)centrifugation. This review summarizes the work back to the 1990s, where intuitive use of centrifugation was achieved for the fabrication of colloidal crystals to the very recent work where analytical (ultra)centrifugation is employed to tailor-make concentration gradients for advanced materials. This review is divided into three main parts. In the introduction part, the history of ordering microbeads in gravity is discussed and with the size of particles reduced to nanometers, a centrifugal field is necessary. In the next part, the research on the ordering of nanoparticles in analytical and preparative centrifugation in recent decades is described. In the last part, the applications of the functional materials, fabricated from centrifugation-induced nanoparticle superstructures are briefly discussed.
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Affiliation(s)
- Xufeng Xu
- Laboratory of Physical Chemistry, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, 5612AE Eindhoven, The Netherlands;
| | - Helmut Cölfen
- Physical Chemistry, University of Konstanz, Universitätsstraße 10, Box 714, 78457 Konstanz, Germany
- Correspondence:
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7
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Multi-wavelength analytical ultracentrifugation as a tool to characterise protein-DNA interactions in solution. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2020; 49:819-827. [PMID: 33219833 DOI: 10.1007/s00249-020-01481-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Accepted: 11/09/2020] [Indexed: 10/22/2022]
Abstract
Understanding how proteins interact with DNA, and particularly the stoichiometry of a protein-DNA complex, is key information needed to elucidate the biological role of the interaction, e.g. transcriptional regulation. Here, we present an emerging analytical ultracentrifugation method that features multi-wavelength detection to characterise complex mixtures by deconvoluting the spectral signals of the interaction partners into separate sedimentation profiles. The spectral information obtained in this experiment provides direct access to the molar stoichiometry of the interacting system to complement traditional hydrodynamic information. We demonstrate this approach by characterising a multimeric assembly process between the transcriptional repressor of bacterial sialic acid metabolism, NanR and its DNA-binding sequence. The method introduced in this study can be extended to quantitatively analyse any complex interaction in solution, providing the interaction partners have different optical properties.
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8
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Mitra S, Demeler B. Probing RNA-Protein Interactions and RNA Compaction by Sedimentation Velocity Analytical Ultracentrifugation. Methods Mol Biol 2020; 2113:281-317. [PMID: 32006321 PMCID: PMC10958623 DOI: 10.1007/978-1-0716-0278-2_19] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Recent advances in multi-wavelength analytical ultracentrifugation (MWL-AUC) combine the power of an exquisitely sensitive hydrodynamic-based separation technique with the added dimension of spectral separation. This added dimension has opened up new doors to much improved characterization of multiple, interacting species in solution. When applied to structural investigations of RNA, MWL-AUC can precisely report on the hydrodynamic radius and the overall shape of an RNA molecule by enabling precise measurements of its sedimentation and diffusion coefficients and identify the stoichiometry of interacting components based on spectral decomposition. Information provided in this chapter will allow an investigator to design experiments for probing ion and/or protein-induced global conformational changes of an RNA molecule and exploit spectral differences between proteins and RNA to characterize their interactions in a physiological solution environment.
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Affiliation(s)
- Somdeb Mitra
- Department of Chemistry, New York University, New York, NY, USA.
| | - Borries Demeler
- Department of Chemistry and Biochemistry, University of Lethbridge, Lethbridge, AB, Canada
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9
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Schneidewind J, Krause F, Bocola M, Stadler AM, Davari MD, Schwaneberg U, Jaeger KE, Krauss U. Consensus model of a cyanobacterial light-dependent protochlorophyllide oxidoreductase in its pigment-free apo-form and photoactive ternary complex. Commun Biol 2019; 2:351. [PMID: 31583285 PMCID: PMC6761149 DOI: 10.1038/s42003-019-0590-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Accepted: 08/29/2019] [Indexed: 12/02/2022] Open
Abstract
Photosynthetic organisms employ two different enzymes for the reduction of the C17 = C18 double bond of protochlorophyllide (Pchlide), yielding the chlorophyll precursor chlorophyllide. First, a nitrogenase-like, light-independent (dark-operative) Pchlide oxidoreductase and secondly, a light-dependent Pchlide oxidoreductase (LPOR). For the latter enzyme, despite decades of research, no structural information is available. Here, we use protein structure modelling, molecular dynamics (MD) simulations combined with multi-wavelength analytical ultracentrifugation (MWA-AUC) and small angle X-ray scattering (SAXS) experiments to derive a consensus model of the LPOR apoprotein and the substrate/cofactor/LPOR ternary complex. MWA-AUC and SAXS experiments independently demonstrate that the apoprotein is monomeric, while ternary complex formation induces dimerization. SAXS-guided modelling studies provide a full-length model of the apoprotein and suggest a tentative mode of dimerization for the LPOR ternary complex, supported by published cross-link constraints. Our study provides a first impression of the LPOR structural organization.
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Affiliation(s)
- Judith Schneidewind
- Institut für Molekulare Enzymtechnologie, Heinrich-Heine-Universität Düsseldorf, Forschungszentrum Jülich GmbH, D-52425 Jülich, Germany
| | - Frank Krause
- Nanolytics, Gesellschaft für Kolloidanalytik GmbH, Am Mühlenberg 11, 14476 Potsdam, Germany
| | - Marco Bocola
- Lehrstuhl für Biotechnologie, RWTH Aachen University, Worringerweg 3, 52074 Aachen, Germany
| | - Andreas Maximilian Stadler
- Jülich Centre for Neutron Science (JCNS-1) and Institute for Complex Systems (ICS-1), Forschungszentrum Jülich GmbH, D-52425 Jülich, Germany
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52056 Aachen, Germany
| | - Mehdi D. Davari
- Lehrstuhl für Biotechnologie, RWTH Aachen University, Worringerweg 3, 52074 Aachen, Germany
| | - Ulrich Schwaneberg
- Lehrstuhl für Biotechnologie, RWTH Aachen University, Worringerweg 3, 52074 Aachen, Germany
- DWI-Leibniz Institut für Interaktive Materialien, Forckenbeckstraße 50, 52056 Aachen, Germany
| | - Karl-Erich Jaeger
- Institut für Molekulare Enzymtechnologie, Heinrich-Heine-Universität Düsseldorf, Forschungszentrum Jülich GmbH, D-52425 Jülich, Germany
- IBG-1: Biotechnologie, Forschungszentrum Jülich GmbH, D-52425 Jülich, Germany
| | - Ulrich Krauss
- Institut für Molekulare Enzymtechnologie, Heinrich-Heine-Universität Düsseldorf, Forschungszentrum Jülich GmbH, D-52425 Jülich, Germany
- IBG-1: Biotechnologie, Forschungszentrum Jülich GmbH, D-52425 Jülich, Germany
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Measuring molecular interactions in solution using multi-wavelength analytical ultracentrifugation: combining spectral analysis with hydrodynamics. ACTA ACUST UNITED AC 2019; 41:14-18. [PMID: 32952314 PMCID: PMC7500494 DOI: 10.1042/bio04102014] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
In 1926, the Swedish scientist Theodor Svedberg was awarded the Nobel Prize in Chemistry for his work on a disperse system, and for studying the colloidal properties of proteins. This work was, to a large extent, made possible by his invention of a revolutionary tool, the analytical ultracentrifuge. These days, technological advances in hardware and computing have transformed the field of analytical ultracentrifugation (AUC) by enabling entirely new classes of experiments and modes of measurement unimaginable by Svedberg, making AUC once again an indispensable tool for modern biomedical research. In this article these advances and their impact on studies of interacting molecules will be discussed, with particular emphasis on a new method termed multi-wavelength analytical ultracentrifugation (MWL-AUC). Novel detectors allow us to add a second dimension to the separation of disperse and heterogeneous systems: in addition to the traditional hydrodynamic separation of colloidal mixtures, it is now possible to identify the sedimenting molecules by their spectral absorbance properties. The potential for this advance is significant for the study of a large range of systems. A further advance has occurred in data management and computational capabilities, opening doors to improved analysis methods, as well as direct networking with the instrument, facilitating data acquisition and data handling, and significant increases in data density from faster detectors with higher resolution capability.
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11
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Putting a New Spin of G-Quadruplex Structure and Binding by Analytical Ultracentrifugation. Methods Mol Biol 2019; 2035:87-103. [PMID: 31444745 DOI: 10.1007/978-1-4939-9666-7_5] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Analytical ultracentrifugation is a powerful biophysical tool that provides information about G-quadruplex structure, stability, and binding reactivity. This chapter provides a simplified explanation of the method, along with examples of how it can be used to characterize G4 formation and to monitor small-molecule binding.
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12
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Pearson J, Hofstetter M, Dekorsy T, Totzeck M, Cölfen H. Design concepts in absorbance optical systems for analytical ultracentrifugation. Analyst 2018; 143:4040-4050. [PMID: 29975381 DOI: 10.1039/c8an00706c] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Analytical ultracentrifugation is a powerful technique for analyzing particles in solution, and has proved valuable for a wide range of applications in chemistry, biochemistry and material sciences for many years. The field is presently seeing a resurgence of instrument development from commercial and academic groups. To date, no modern optical modeling techniques have ever been applied to the basic imaging properties of the optical system in analytical ultracentrifugation. In this manuscript we provide a contextual framework for the application of such techniques, including an overview of the essential optical principles. The existing commercial and open source detection systems are evaluated for imaging performance, highlighting the limitations of chromatic aberration for broadband acquisitions. These results are the inspiration for a new mirror-based design, free of chromatic aberration. Our findings present a path forward for continued development in imaging and detector technology, where improved data quality will now push the limits of detection and resolution of analytical ultracentrifugation for years to come.
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Affiliation(s)
- Joseph Pearson
- University of Konstanz, Department of Chemistry, Universitätsstrasse 10, Konstanz 78457, Germany.
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13
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Pearson J, Cölfen H. LED based near infrared spectral acquisition for multiwavelength analytical ultracentrifugation: A case study with gold nanoparticles. Anal Chim Acta 2018; 1043:72-80. [PMID: 30392671 DOI: 10.1016/j.aca.2018.07.022] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Revised: 07/05/2018] [Accepted: 07/10/2018] [Indexed: 11/25/2022]
Abstract
A pulsed light emitting diode, coupled with a properly configured spectrometer is implemented in open source analytical ultracentrifugation detection hardware, allowing for spectral acquisition spanning the visible to near infrared. Details of the challenges arising with the new hardware are described, along with the necessary solutions to overcome them. The system is successfully tested with polystyrene and gold nanoparticles, demonstrating effectiveness for different material and particle geometries. Sedimentation coefficient distributions and analytically extracted spectra are presented for the multiwavelength datasets extending into the near infrared. Additionally, deconvolution algorithms are applied as a further demonstration of tools applicable to these datasets and the resolving power possible. The results of gold nanoparticle analysis presented here show effective near infrared spectral acquisition is now possible for multiwavelength analytical ultracentrifugation, opening the door for analysis of many important samples with spectral properties in this range, including rich classes of metal and semiconductor nanoparticles.
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Affiliation(s)
- Joseph Pearson
- Physical Chemistry, University of Konstanz, Universitätsstraße 10, 78457 Konstanz, Germany
| | - Helmut Cölfen
- Physical Chemistry, University of Konstanz, Universitätsstraße 10, 78457 Konstanz, Germany.
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14
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Gorbet GE, Mohapatra S, Demeler B. Multi-speed sedimentation velocity implementation in UltraScan-III. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2018; 47:825-835. [PMID: 29610996 DOI: 10.1007/s00249-018-1297-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Revised: 03/17/2018] [Accepted: 03/26/2018] [Indexed: 11/28/2022]
Abstract
A framework for the global analysis of multi-speed analytical ultracentrifugation sedimentation velocity experiments is presented. We discuss extensions to the adaptive space-time finite element fitting methods implemented in UltraScan-III to model sedimentation velocity experiments where a single run is performed at multiple rotor speeds, and describe extensions in the optimization routines used for fitting experimental data collected at arbitrary multi-speed profiles. Our implementation considers factors such as speed dependent rotor stretching, the resulting radial shifting of the finite element solution's boundary conditions, and changes in the associated time-invariant noise. We also address the calculation of acceleration rates and acceleration zones from existing radial acceleration and time records, as well as utilization of the time state object available at high temporal resolution from the new Beckman Optima AUC instrument. Analysis methods in UltraScan-III support unconstrained models that extract reliable information for both the sedimentation and the diffusion coefficients. These methods do not rely on any assumptions and allow for arbitrary variations in both sedimentation and diffusion transport. We have adapted these routines for the multi-speed case, and developed optimized and general grid based fitting methods to handle changes in the information content of the simulation matrix for different speed steps. New graphical simulation tools are presented that assist the investigator to estimate suitable grid metrics and evaluate information content based on edit profiles for individual experiments.
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Affiliation(s)
- Gary E Gorbet
- University of Texas Health Science Center, San Antonio, USA
| | | | - Borries Demeler
- University of Texas Health Science Center, San Antonio, USA.
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Walter J, Gorbet G, Akdas T, Segets D, Demeler B, Peukert W. 2D analysis of polydisperse core-shell nanoparticles using analytical ultracentrifugation. Analyst 2018; 142:206-217. [PMID: 27934989 DOI: 10.1039/c6an02236g] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Accurate knowledge of the size, density and composition of nanoparticles (NPs) is of major importance for their applications. In this work the hydrodynamic characterization of polydisperse core-shell NPs by means of analytical ultracentrifugation (AUC) is addressed. AUC is one of the most accurate techniques for the characterization of NPs in the liquid phase because it can resolve particle size distributions (PSDs) with unrivaled resolution and detail. Small NPs have to be considered as core-shell systems when dispersed in a liquid since a solvation layer and a stabilizer shell will significantly contribute to the particle's hydrodynamic diameter and effective density. AUC measures the sedimentation and diffusion transport of the analytes, which are affected by the core-shell compositional properties. This work demonstrates that polydisperse and thus widely distributed NPs pose significant challenges for current state-of-the-art data evaluation methods. The existing methods either have insufficient resolution or do not correctly reproduce the core-shell properties. First, we investigate the performance of different data evaluation models by means of simulated data. Then, we propose a new methodology to address the core-shell properties of NPs. This method is based on the parametrically constrained spectrum analysis and offers complete access to the size and effective density of polydisperse NPs. Our study is complemented using experimental data derived for ZnO and CuInS2 NPs, which do not have a monodisperse PSD. For the first time, the size and effective density of such structures could be resolved with high resolution by means of a two-dimensional AUC analysis approach.
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Affiliation(s)
- Johannes Walter
- Institute of Particle Technology (LFG), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Cauerstr. 4, 91058 Erlangen, Germany. and Interdisciplinary Center for Functional Particle Systems (FPS), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Haberstr. 9a, 91058 Erlangen, Germany
| | - Gary Gorbet
- Department of Biochemistry, The University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, Texas 78229-3901, USA.
| | - Tugce Akdas
- Institute of Particle Technology (LFG), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Cauerstr. 4, 91058 Erlangen, Germany. and Interdisciplinary Center for Functional Particle Systems (FPS), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Haberstr. 9a, 91058 Erlangen, Germany
| | - Doris Segets
- Institute of Particle Technology (LFG), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Cauerstr. 4, 91058 Erlangen, Germany. and Interdisciplinary Center for Functional Particle Systems (FPS), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Haberstr. 9a, 91058 Erlangen, Germany
| | - Borries Demeler
- Department of Biochemistry, The University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, Texas 78229-3901, USA.
| | - Wolfgang Peukert
- Institute of Particle Technology (LFG), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Cauerstr. 4, 91058 Erlangen, Germany. and Interdisciplinary Center for Functional Particle Systems (FPS), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Haberstr. 9a, 91058 Erlangen, Germany
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Pearson J, Walter J, Peukert W, Cölfen H. Advanced Multiwavelength Detection in Analytical Ultracentrifugation. Anal Chem 2017; 90:1280-1291. [PMID: 29214799 DOI: 10.1021/acs.analchem.7b04056] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
This work highlights significant advancements in detector hardware and software for multiwavelength analytical ultracentrifugation (MWL-AUC) experiments, demonstrating improvement in both the spectral performance and UV capabilities of the instrument. The hardware is an extension of the Open AUC MWL detector developed in academia and first introduced in 2006 by Bhattacharya et al. Additional modifications as well as new analytical methods available for MWL data have since been reported. The present work describes new and continuing improvements to the MWL detector, including mirror source and imaging optics, UV sensitive acquisition modes and revised data acquisition software. The marked improvement of experimental data promises to provide access to increasingly complex systems, especially semiconductor nanoparticles, synthetic polymers, biopolymers, and other chromophores absorbing in the UV. Details of the detection system and components are examined to reveal the influences on data quality and to guide further developments. The benchmark comparisons of data quality across platforms will also serve as a reference guide for evaluation of forthcoming commercial absorbance optics.
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Affiliation(s)
- Joseph Pearson
- Physical Chemistry, University of Konstanz , Universitätsstraße 10, 78457 Konstanz, Germany
| | - Johannes Walter
- Institute of Particle Technology (LFG), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) , Cauerstraße 4, 91058 Erlangen, Germany.,Interdisciplinary Center for Functional Particle Systems (FPS), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) , Haberstraße 9a, 91058 Erlangen, Germany
| | - Wolfgang Peukert
- Institute of Particle Technology (LFG), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) , Cauerstraße 4, 91058 Erlangen, Germany.,Interdisciplinary Center for Functional Particle Systems (FPS), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) , Haberstraße 9a, 91058 Erlangen, Germany
| | - Helmut Cölfen
- Physical Chemistry, University of Konstanz , Universitätsstraße 10, 78457 Konstanz, Germany
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Zhang J, Pearson JZ, Gorbet GE, Cölfen H, Germann MW, Brinton MA, Demeler B. Spectral and Hydrodynamic Analysis of West Nile Virus RNA-Protein Interactions by Multiwavelength Sedimentation Velocity in the Analytical Ultracentrifuge. Anal Chem 2017; 89:862-870. [PMID: 27977168 PMCID: PMC5505516 DOI: 10.1021/acs.analchem.6b03926] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Interactions between nucleic acids and proteins are critical for many cellular processes, and their study is of utmost importance to many areas of biochemistry, cellular biology, and virology. Here, we introduce a new analytical method based on sedimentation velocity (SV) analytical ultracentrifugation, in combination with a novel multiwavelength detector to characterize such interactions. We identified the stoichiometry and molar mass of a complex formed during the interaction of a West Nile virus RNA stem loop structure with the human T cell-restricted intracellular antigen-1 related protein. SV has long been proven as a powerful technique for studying dynamic assembly processes under physiological conditions in solution. Here, we demonstrate, for the first time, how the new multiwavelength technology can be exploited to study protein-RNA interactions, and show how the spectral information derived from the new detector complements the traditional hydrodynamic information from analytical ultracentrifugation. Our method allows the protein and nucleic acid signals to be separated by spectral decomposition such that sedimentation information from each individual species, including any complexes, can be clearly identified based on their spectral signatures. The method presented here extends to any interacting system where the interaction partners are spectrally separable.
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Affiliation(s)
- Jin Zhang
- Georgia State University, Department of Chemistry, 50 Decatur St. SE, Atlanta, Georgia 30303, United States
- Georgia State University, Department of Biology, P.O. 4010, Atlanta, Georgia 30303, United States
| | - Joseph Z. Pearson
- University of Konstanz, Department of Chemistry, Physical Chemistry, Universitätsstraße 10, Box 714, D-78457 Konstanz, Germany
| | - Gary E. Gorbet
- The University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, MC 7760, San Antonio, Texas 78229-3901, United States
| | - Helmut Cölfen
- University of Konstanz, Department of Chemistry, Physical Chemistry, Universitätsstraße 10, Box 714, D-78457 Konstanz, Germany
| | - Markus W. Germann
- Georgia State University, Department of Chemistry, 50 Decatur St. SE, Atlanta, Georgia 30303, United States
- Georgia State University, Department of Biology, P.O. 4010, Atlanta, Georgia 30303, United States
| | - Margo A. Brinton
- Georgia State University, Department of Biology, P.O. 4010, Atlanta, Georgia 30303, United States
| | - Borries Demeler
- The University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, MC 7760, San Antonio, Texas 78229-3901, United States
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Karabudak E, Brookes E, Lesnyak V, Gaponik N, Eychmüller A, Walter J, Segets D, Peukert W, Wohlleben W, Demeler B, Cölfen H. Simultaneous Identification of Spectral Properties and Sizes of Multiple Particles in Solution with Subnanometer Resolution. Angew Chem Int Ed Engl 2016; 55:11770-4. [PMID: 27461742 PMCID: PMC5148131 DOI: 10.1002/anie.201603844] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Indexed: 11/11/2022]
Abstract
We report an unsurpassed solution characterization technique based on analytical ultracentrifugation, which demonstrates exceptional potential for resolving particle sizes in solution with sub-nm resolution. We achieve this improvement in resolution by simultaneously measuring UV/Vis spectra while hydrodynamically separating individual components in the mixture. By equipping an analytical ultracentrifuge with a novel multi-wavelength detector, we are adding a new spectral discovery dimension to traditional hydrodynamic characterization, and amplify the information obtained by orders of magnitude. We demonstrate the power of this technique by characterizing unpurified CdTe nanoparticle samples, avoiding tedious and often impossible purification and fractionation of nanoparticles into apparently monodisperse fractions. With this approach, we have for the first time identified the pure spectral properties and band-gap positions of discrete species present in the CdTe mixture.
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Affiliation(s)
- Engin Karabudak
- Max-Planck-Institut für Kolloid- und Grenzflächenforschung, Kolloidchemie, Forschungscampus Golm, Am Mühlenberg, 14424, Potsdam, Germany
- Izmir Institute of Technology, Chemistry Department, 35430, Izmir, Turkey
| | - Emre Brookes
- University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX, 78229-3901, USA
| | - Vladimir Lesnyak
- Physikalische Chemie, TU Dresden, Bergstrasse 66b, 01062, Dresden, Germany
| | - Nikolai Gaponik
- Physikalische Chemie, TU Dresden, Bergstrasse 66b, 01062, Dresden, Germany
| | | | - Johannes Walter
- Institute of Particle Technology (LFG), Friedrich-Alexander Universität Erlangen-Nürnberg (FAU), Cauerstrasse 4, 91058, Erlangen, Germany
- Interdisciplinary Center for Functional Particle Systems (FPS), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Haberstrasse 9a, 91058, Erlangen, Germany
| | - Doris Segets
- Institute of Particle Technology (LFG), Friedrich-Alexander Universität Erlangen-Nürnberg (FAU), Cauerstrasse 4, 91058, Erlangen, Germany
- Interdisciplinary Center for Functional Particle Systems (FPS), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Haberstrasse 9a, 91058, Erlangen, Germany
| | - Wolfgang Peukert
- Institute of Particle Technology (LFG), Friedrich-Alexander Universität Erlangen-Nürnberg (FAU), Cauerstrasse 4, 91058, Erlangen, Germany
- Interdisciplinary Center for Functional Particle Systems (FPS), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Haberstrasse 9a, 91058, Erlangen, Germany
| | | | - Borries Demeler
- University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX, 78229-3901, USA.
| | - Helmut Cölfen
- Max-Planck-Institut für Kolloid- und Grenzflächenforschung, Kolloidchemie, Forschungscampus Golm, Am Mühlenberg, 14424, Potsdam, Germany.
- Universität Konstanz, Physikalische Chemie, Universitätsstrasse 10, 78457, Konstanz, Germany.
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Karabudak E, Brookes E, Lesnyak V, Gaponik N, Eychmüller A, Walter J, Segets D, Peukert W, Wohlleben W, Demeler B, Cölfen H. Simultane Bestimmung spektraler Eigenschaften und Größen von multiplen Partikeln in Lösung mit Subnanometer‐Auflösung. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201603844] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Engin Karabudak
- Max-Planck-Institut für Kolloid- und Grenzflächenforschung, Kolloidchemie, Forschungscampus Golm Am Mühlenberg 14424 Potsdam Deutschland
- Izmir Institute of Technology, Chemistry Department 35430 Izmir Türkei
| | - Emre Brookes
- University of Texas Health Science Center at San Antonio 7703 Floyd Curl Drive San Antonio TX 78229-3901 USA
| | - Vladimir Lesnyak
- Physikalische Chemie, TU Dresden Bergstraße 66b 01062 Dresden Deutschland
| | - Nikolai Gaponik
- Physikalische Chemie, TU Dresden Bergstraße 66b 01062 Dresden Deutschland
| | | | - Johannes Walter
- Lehrstuhl für Feststoff- und Grenzflächenverfahrenstechnik (LFG) Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) Cauerstraße 4 91058 Erlangen Deutschland
- Interdisziplinäres Zentrum für Funktionale Partikelsysteme (FPS) Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) Haberstr. 9a 91058 Erlangen Deutschland
| | - Doris Segets
- Lehrstuhl für Feststoff- und Grenzflächenverfahrenstechnik (LFG) Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) Cauerstraße 4 91058 Erlangen Deutschland
- Interdisziplinäres Zentrum für Funktionale Partikelsysteme (FPS) Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) Haberstr. 9a 91058 Erlangen Deutschland
| | - Wolfgang Peukert
- Lehrstuhl für Feststoff- und Grenzflächenverfahrenstechnik (LFG) Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) Cauerstraße 4 91058 Erlangen Deutschland
- Interdisziplinäres Zentrum für Funktionale Partikelsysteme (FPS) Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) Haberstr. 9a 91058 Erlangen Deutschland
| | | | - Borries Demeler
- University of Texas Health Science Center at San Antonio 7703 Floyd Curl Drive San Antonio TX 78229-3901 USA
| | - Helmut Cölfen
- Max-Planck-Institut für Kolloid- und Grenzflächenforschung, Kolloidchemie, Forschungscampus Golm Am Mühlenberg 14424 Potsdam Deutschland
- Universität Konstanz, Physikalische Chemie Universitätsstraße 10 78457 Konstanz Deutschland
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Yoshihara HAI, Can E, Karlsson M, Lerche MH, Schwitter J, Comment A. High-field dissolution dynamic nuclear polarization of [1-13C]pyruvic acid. Phys Chem Chem Phys 2016; 18:12409-13. [DOI: 10.1039/c6cp00589f] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Greater than 60% solution-state polarization of [1-13C]pyruvic acid polarized at 7 T and 1.0 K can be measured after rapid transfer to an MRI scanner magnet.
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Affiliation(s)
- Hikari A. I. Yoshihara
- Institute of Physics of Biological Systems
- Swiss Federal Institute of Technology
- Lausanne, Switzerland
| | - Emine Can
- Institute of Physics of Biological Systems
- Swiss Federal Institute of Technology
- Lausanne, Switzerland
| | - Magnus Karlsson
- Albeda Research
- ApS
- Copenhagen, Denmark
- Department of Electrical Engineering
- Technical University of Denmark
| | - Mathilde H. Lerche
- Albeda Research
- ApS
- Copenhagen, Denmark
- Department of Electrical Engineering
- Technical University of Denmark
| | - Juerg Schwitter
- Division of Cardiology and Cardiac MR Center
- Lausanne University Hospital
- Lausanne, Switzerland
| | - Arnaud Comment
- Institute of Physics of Biological Systems
- Swiss Federal Institute of Technology
- Lausanne, Switzerland
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