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Mortelmans T, Marty B, Kazazis D, Padeste C, Li X, Ekinci Y. Three-Dimensional Microfluidic Capillary Device for Rapid and Multiplexed Immunoassays in Whole Blood. ACS Sens 2024; 9:2455-2464. [PMID: 38687557 DOI: 10.1021/acssensors.4c00153] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/02/2024]
Abstract
In this study, we demonstrate whole blood immunoassays using a microfluidic device optimized for conducting rapid and multiplexed fluorescence-linked immunoassays. The device is capable of handling whole blood samples without any preparatory treatment. The three-dimensional channels in poly(methyl methacrylate) are designed to passively load bodily fluids and, due to their linearly tapered profile, facilitate size-dependent immobilization of biofunctionalized particles. The channel geometry is optimized to allow for the unimpeded flow of cellular constituents such as red blood cells (RBCs). Additionally, to make the device easier to operate, the biofunctionalized particles are pretrapped in a first step, and the channel is dried under vacuum, after which it can be loaded with the biological sample. This novel approach and design eliminated the need for traditionally laborious steps such as filtering, incubation, and washing steps, thereby substantially simplifying the immunoassay procedures. Moreover, by leveraging the shallow device dimensions, we show that sample loading to read-out is possible within 5 min. Our results also show that the presence of RBCs does not compromise the sensitivity of the assays when compared to those performed in a pure buffer solution. This highlights the practical adaptability of the device for simple and rapid whole-blood assays. Lastly, we demonstrate the device's multiplexing capability by pretrapping particles of different sizes, each functionalized with a different antigen, thus enabling the performance of multiplexed on-chip whole-blood immunoassays, showcasing the device's versatility and effectiveness toward low-cost, simple, and multiplexed sensing of biomarkers and pathogens directly in whole blood.
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Affiliation(s)
- Thomas Mortelmans
- Laboratory for X-ray Nanoscience and Technologies, 5232 Villigen, Switzerland
- Swiss Nanoscience Institute, University of Basel, 4056 Basel, Switzerland
| | - Balz Marty
- Laboratory for X-ray Nanoscience and Technologies, 5232 Villigen, Switzerland
| | - Dimitrios Kazazis
- Laboratory for X-ray Nanoscience and Technologies, 5232 Villigen, Switzerland
| | - Celestino Padeste
- Laboratory of Nanoscale Biology, Paul Scherrer Institute, 5232 Villigen, Switzerland
| | - Xiaodan Li
- Laboratory of Biomolecular Research, Paul Scherrer Institute, 5232 Villigen, Switzerland
| | - Yasin Ekinci
- Laboratory for X-ray Nanoscience and Technologies, 5232 Villigen, Switzerland
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2
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Carrillo M, Mason TJ, Karpik A, Martiel I, Kepa MW, McAuley KE, Beale JH, Padeste C. Micro-structured polymer fixed targets for serial crystallography at synchrotrons and XFELs. IUCrJ 2023; 10:678-693. [PMID: 37727961 PMCID: PMC10619457 DOI: 10.1107/s2052252523007595] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2023] [Accepted: 08/31/2023] [Indexed: 09/21/2023]
Abstract
Fixed targets are a popular form of sample-delivery system used in serial crystallography at synchrotron and X-ray free-electron laser sources. They offer a wide range of sample-preparation options and are generally easy to use. The supports are typically made from silicon, quartz or polymer. Of these, currently, only silicon offers the ability to perform an aperture-aligned data collection where crystals are loaded into cavities in precise locations and sequentially rastered through, in step with the X-ray pulses. The polymer-based fixed targets have lacked the precision fabrication to enable this data-collection strategy and have been limited to directed-raster scans with crystals randomly distributed across the polymer surface. Here, the fabrication and first results from a new polymer-based fixed target, the micro-structured polymer fixed targets (MISP chips), are presented. MISP chips, like those made from silicon, have a precise array of cavities and fiducial markers. They consist of a structured polymer membrane and a stabilization frame. Crystals can be loaded into the cavities and the excess crystallization solution removed through apertures at their base. The fiducial markers allow for a rapid calculation of the aperture locations. The chips have a low X-ray background and, since they are optically transparent, also allow for an a priori analysis of crystal locations. This location mapping could, ultimately, optimize hit rates towards 100%. A black version of the MISP chip was produced to reduce light contamination for optical-pump/X-ray probe experiments. A study of the loading properties of the chips reveals that these types of fixed targets are best optimized for crystals of the order of 25 µm, but quality data can be collected from crystals as small as 5 µm. With the development of these chips, it has been proved that polymer-based fixed targets can be made with the precision required for aperture-alignment-based data-collection strategies. Further work can now be directed towards more cost-effective mass fabrication to make their use more sustainable for serial crystallography facilities and users.
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Affiliation(s)
- Melissa Carrillo
- Paul Scherrer Institut, Forschungsstrasse 111, 5232 Villigen, Switzerland
- Department of Chemistry, University of Basel, Mattenstrasse 24a, 4002 Basel, Switzerland
- Swiss Nanoscience Institute, Klingelbergstrasse 82, 4056 Basel, Switzerland
| | - Thomas J. Mason
- Paul Scherrer Institut, Forschungsstrasse 111, 5232 Villigen, Switzerland
| | - Agnieszka Karpik
- Paul Scherrer Institut, Forschungsstrasse 111, 5232 Villigen, Switzerland
- Institute of Polymer Nanotechnology (INKA), FHNW University of Applied Sciences and Arts Northwestern Switzerland, School of Engineering, Klosterzelgstrasse 2, 5210 Windisch, Switzerland
| | - Isabelle Martiel
- Paul Scherrer Institut, Forschungsstrasse 111, 5232 Villigen, Switzerland
| | - Michal W. Kepa
- Paul Scherrer Institut, Forschungsstrasse 111, 5232 Villigen, Switzerland
| | | | - John H. Beale
- Paul Scherrer Institut, Forschungsstrasse 111, 5232 Villigen, Switzerland
| | - Celestino Padeste
- Paul Scherrer Institut, Forschungsstrasse 111, 5232 Villigen, Switzerland
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Carrillo M, Beale J, Padeste C. Fixed targets for serial protein crystallography at SwissFEL. Acta Crystallogr A Found Adv 2022. [DOI: 10.1107/s2053273322097200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Alpert PA, Boucly A, Yang S, Yang H, Kilchhofer K, Luo Z, Padeste C, Finizio S, Ammann M, Watts B. Ice nucleation imaged with X-ray spectro-microscopy. Environ Sci : Atmos 2022; 2:335-351. [PMID: 35694137 PMCID: PMC9119033 DOI: 10.1039/d1ea00077b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Accepted: 02/07/2022] [Indexed: 11/21/2022]
Abstract
Ice nucleation is one of the most uncertain microphysical processes, as it occurs in various ways and on many types of particles. To overcome this challenge, we present a heterogeneous ice nucleation study on deposition ice nucleation and immersion freezing in a novel cryogenic X-ray experiment with the capability to spectroscopically probe individual ice nucleating and non-ice nucleating particles. Mineral dust type particles composed of either ferrihydrite or feldspar were used and mixed with organic matter of either citric acid or xanthan gum. We observed in situ ice nucleation using scanning transmission X-ray microscopy (STXM) and identified unique organic carbon functionalities and iron oxidation state using near-edge X-ray absorption fine structure (NEXAFS) spectroscopy in the new in situ environmental ice cell, termed the ice nucleation X-ray cell (INXCell). Deposition ice nucleation of ferrihydrite occurred at a relative humidity with respect to ice, RHi, between ∼120–138% and temperatures, T ∼ 232 K. However, we also observed water uptake on ferrihydrite at the same T when deposition ice nucleation did not occur. Although, immersion freezing of ferrihydrite both in pure water droplets and in aqueous citric acid occurred at or slightly below conditions for homogeneous freezing, i.e. the effect of ferrihydrite particles acting as a heterogeneous ice nucleus for immersion freezing was small. Microcline K-rich feldspar mixed with xanthan gum was also used in INXCell experiments. Deposition ice nucleation occurred at conditions when xanthan gum was expected to be highly viscous (glassy). At less viscous conditions, immersion freezing was observed. We extended a model for heterogeneous and homogeneous ice nucleation, named the stochastic freezing model (SFM). It was used to quantify heterogeneous ice nucleation rate coefficients, mimic the competition between homogeneous ice nucleation; water uptake; deposition ice nucleation and immersion freezing, and predict the T and RHi at which ice was observed. The importance of ferrihydrite to act as a heterogeneous ice nucleating particle in the atmosphere using the SFM is discussed. Ice nucleation can now be imaged in situ using X-ray spectro-microscopy in a new experiment, which is applied to mineral aerosol particles composed of ferrihydrite or feldspar and associated organic matter.![]()
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Affiliation(s)
- Peter A. Alpert
- Laboratory of Environmental Chemistry, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
| | - Anthony Boucly
- Laboratory of Environmental Chemistry, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
- Electrochemistry Laboratory, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
| | - Shuo Yang
- Laboratory of Environmental Chemistry, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, State Environmental Protection Key Laboratory of Sources and Control of Air Pollution Complex, Beijing Key Laboratory of Indoor Air Quality Evaluation and Control, Tsinghua University, Beijing 100084, China
| | - Huanyu Yang
- Laboratory of Environmental Chemistry, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
| | - Kevin Kilchhofer
- Laboratory of Environmental Chemistry, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
| | - Zhaochu Luo
- Laboratory for Multiscale Materials Experiments, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
- Laboratory for Mesoscopic Systems, Department of Materials, ETH Zürich, Zürich, Switzerland
| | - Celestino Padeste
- Laboratory of Nanoscale Biology, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
| | - Simone Finizio
- Swiss Light Source, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
| | - Markus Ammann
- Laboratory of Environmental Chemistry, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
| | - Benjamin Watts
- Swiss Light Source, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
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Tran HT, Lucas MS, Ishikawa T, Shahmoradian SH, Padeste C. A Compartmentalized Neuronal Cell-Culture Platform Compatible With Cryo-Fixation by High-Pressure Freezing for Ultrastructural Imaging. Front Neurosci 2021; 15:726763. [PMID: 34566569 PMCID: PMC8455873 DOI: 10.3389/fnins.2021.726763] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Accepted: 08/17/2021] [Indexed: 12/29/2022] Open
Abstract
The human brain contains a wide array of billions of neurons and interconnections, which are often simplified for analysis in vitro using compartmentalized microfluidic devices for neuronal cell culturing, to better understand neuronal development and disease. However, such devices are traditionally incompatible for high-pressure freezing and high-resolution nanoscale imaging and analysis of their sub-cellular processes by methods including electron microscopy. Here we develop a novel compartmentalized neuronal co-culture platform allowing reconstruction of neuronal networks with high variable spatial control, which is uniquely compatible for high-pressure freezing. This cryo-fixation method is well-established to enable high-fidelity preservation of the reconstructed neuronal networks and their sub-cellular processes in a near-native vitreous state without requiring chemical fixatives. To direct the outgrowth of neurites originating from two distinct groups of neurons growing in the two different compartments, polymer microstructures akin to microchannels are fabricated atop of sapphire disks. Two populations of neurons expressing either enhanced green fluorescent protein (EGFP) or mCherry were grown in either compartment, facilitating the analysis of the specific interactions between the two separate groups of cells. Neuronally differentiated PC12 cells, murine hippocampal and striatal neurons were successfully used in this context. The design of this device permits direct observation of entire neuritic processes within microchannels by optical microscopy with high spatial and temporal resolution, prior to processing for high-pressure freezing and electron microscopy. Following freeze substitution, we demonstrate that it is possible to process the neuronal networks for ultrastructural imaging by electron microscopy. Several key features of the embedded neuronal networks, including mitochondria, synaptic vesicles, axonal terminals, microtubules, with well-preserved ultrastructures were observed at high resolution using focused ion beam - scanning electron microscopy (FIB-SEM) and serial sectioning - transmission electron microscopy (TEM). These results demonstrate the compatibility of the platform with optical microscopy, high-pressure freezing and electron microscopy. The platform can be extended to neuronal models of brain disease or development in future studies, enabling the investigation of subcellular processes at the nanoscale within two distinct groups of neurons in a functional neuronal pathway, as well as pharmacological testing and drug screening.
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Affiliation(s)
- Hung Tri Tran
- Laboratory of Nanoscale Biology, Paul Scherrer Institute, Villigen, Switzerland
| | - Miriam S. Lucas
- Scientific Center for Optical and Electron Microscopy ScopeM, ETH Zürich, Zurich, Switzerland
| | - Takashi Ishikawa
- Laboratory of Nanoscale Biology, Paul Scherrer Institute, Villigen, Switzerland
| | | | - Celestino Padeste
- Laboratory of Nanoscale Biology, Paul Scherrer Institute, Villigen, Switzerland
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Martiel I, Beale JH, Karpik A, Huang CY, Vera L, Olieric N, Wranik M, Tsai CJ, Mühle J, Aurelius O, John J, Högbom M, Wang M, Marsh M, Padeste C. Versatile microporous polymer-based supports for serial macromolecular crystallography. Acta Crystallogr D Struct Biol 2021; 77:1153-1167. [PMID: 34473086 PMCID: PMC8411977 DOI: 10.1107/s2059798321007324] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Accepted: 07/15/2021] [Indexed: 11/10/2022] Open
Abstract
Serial data collection has emerged as a major tool for data collection at state-of-the-art light sources, such as microfocus beamlines at synchrotrons and X-ray free-electron lasers. Challenging targets, characterized by small crystal sizes, weak diffraction and stringent dose limits, benefit most from these methods. Here, the use of a thin support made of a polymer-based membrane for performing serial data collection or screening experiments is demonstrated. It is shown that these supports are suitable for a wide range of protein crystals suspended in liquids. The supports have also proved to be applicable to challenging cases such as membrane proteins growing in the sponge phase. The sample-deposition method is simple and robust, as well as flexible and adaptable to a variety of cases. It results in an optimally thin specimen providing low background while maintaining minute amounts of mother liquor around the crystals. The 2 × 2 mm area enables the deposition of up to several microlitres of liquid. Imaging and visualization of the crystals are straightforward on the highly transparent membrane. Thanks to their affordable fabrication, these supports have the potential to become an attractive option for serial experiments at synchrotrons and free-electron lasers.
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Affiliation(s)
- Isabelle Martiel
- Paul Scherrer Institute, Forschungsstrasse 111, 5232 Villigen, Switzerland
| | - John H. Beale
- Paul Scherrer Institute, Forschungsstrasse 111, 5232 Villigen, Switzerland
| | - Agnieszka Karpik
- Paul Scherrer Institute, Forschungsstrasse 111, 5232 Villigen, Switzerland
- Institute of Polymer Nanotechnology (INKA), FHNW University of Applied Sciences and Arts Northwestern Switzerland, 5210 Windisch, Switzerland
| | - Chia-Ying Huang
- Paul Scherrer Institute, Forschungsstrasse 111, 5232 Villigen, Switzerland
| | - Laura Vera
- Paul Scherrer Institute, Forschungsstrasse 111, 5232 Villigen, Switzerland
| | - Natacha Olieric
- Paul Scherrer Institute, Forschungsstrasse 111, 5232 Villigen, Switzerland
| | - Maximilian Wranik
- Paul Scherrer Institute, Forschungsstrasse 111, 5232 Villigen, Switzerland
| | - Ching-Ju Tsai
- Paul Scherrer Institute, Forschungsstrasse 111, 5232 Villigen, Switzerland
| | - Jonas Mühle
- Paul Scherrer Institute, Forschungsstrasse 111, 5232 Villigen, Switzerland
| | - Oskar Aurelius
- Department of Biochemistry and Biophysics, Stockholm University, 106 91 Stockholm, Sweden
- MAX IV Laboratory, Lund University, Fotongatan 2, 224 84 Lund, Sweden
| | - Juliane John
- Department of Biochemistry and Biophysics, Stockholm University, 106 91 Stockholm, Sweden
| | - Martin Högbom
- Department of Biochemistry and Biophysics, Stockholm University, 106 91 Stockholm, Sweden
| | - Meitian Wang
- Paul Scherrer Institute, Forschungsstrasse 111, 5232 Villigen, Switzerland
| | - May Marsh
- Paul Scherrer Institute, Forschungsstrasse 111, 5232 Villigen, Switzerland
| | - Celestino Padeste
- Paul Scherrer Institute, Forschungsstrasse 111, 5232 Villigen, Switzerland
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Karpik A, Martiel I, Kristiansen PM, Padeste C. Fabrication of ultrathin suspended polymer membranes as supports for serial protein crystallography. Micro and Nano Engineering 2020. [DOI: 10.1016/j.mne.2020.100053] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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8
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Martiel I, Mozzanica A, Opara NL, Panepucci E, Leonarski F, Redford S, Mohacsi I, Guzenko V, Ozerov D, Padeste C, Schmitt B, Pedrini B, Wang M. X-ray fluorescence detection for serial macromolecular crystallography using a JUNGFRAU pixel detector. J Synchrotron Radiat 2020; 27:329-339. [PMID: 32153271 PMCID: PMC7064105 DOI: 10.1107/s1600577519016758] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Accepted: 12/14/2019] [Indexed: 05/06/2023]
Abstract
Detection of heavy elements, such as metals, in macromolecular crystallography (MX) samples by X-ray fluorescence is a function traditionally covered at synchrotron MX beamlines by silicon drift detectors, which cannot be used at X-ray free-electron lasers because of the very short duration of the X-ray pulses. Here it is shown that the hybrid pixel charge-integrating detector JUNGFRAU can fulfill this function when operating in a low-flux regime. The feasibility of precise position determination of micrometre-sized metal marks is also demonstrated, to be used as fiducials for offline prelocation in serial crystallography experiments, based on the specific fluorescence signal measured with JUNGFRAU, both at the synchrotron and at SwissFEL. Finally, the measurement of elemental absorption edges at a synchrotron beamline using JUNGFRAU is also demonstrated.
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Affiliation(s)
- Isabelle Martiel
- Paul Scherrer Institute, Forschungsstrasse 111, Villigen 5232, Switzerland
| | - Aldo Mozzanica
- Paul Scherrer Institute, Forschungsstrasse 111, Villigen 5232, Switzerland
| | - Nadia L. Opara
- Paul Scherrer Institute, Forschungsstrasse 111, Villigen 5232, Switzerland
- Center for Cellular Imaging and NanoAnalytics (C-CINA), Biozentrum, University of Basel, Basel 4058, Switzerland
- SwissNanoscience Institute, University of Basel, Basel 4056, Switzerland
| | - Ezequiel Panepucci
- Paul Scherrer Institute, Forschungsstrasse 111, Villigen 5232, Switzerland
| | - Filip Leonarski
- Paul Scherrer Institute, Forschungsstrasse 111, Villigen 5232, Switzerland
| | - Sophie Redford
- Paul Scherrer Institute, Forschungsstrasse 111, Villigen 5232, Switzerland
| | - Istvan Mohacsi
- Paul Scherrer Institute, Forschungsstrasse 111, Villigen 5232, Switzerland
| | - Vitaliy Guzenko
- Paul Scherrer Institute, Forschungsstrasse 111, Villigen 5232, Switzerland
| | - Dmitry Ozerov
- Paul Scherrer Institute, Forschungsstrasse 111, Villigen 5232, Switzerland
| | - Celestino Padeste
- Paul Scherrer Institute, Forschungsstrasse 111, Villigen 5232, Switzerland
| | - Bernd Schmitt
- Paul Scherrer Institute, Forschungsstrasse 111, Villigen 5232, Switzerland
| | - Bill Pedrini
- Paul Scherrer Institute, Forschungsstrasse 111, Villigen 5232, Switzerland
| | - Meitian Wang
- Paul Scherrer Institute, Forschungsstrasse 111, Villigen 5232, Switzerland
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9
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Opara N, Martiel I, Arnold SA, Braun T, Stahlberg H, Makita M, David C, Padeste C. Direct protein crystallization on ultrathin membranes for diffraction measurements at X-ray free-electron lasers. Corrigendum. J Appl Crystallogr 2019. [DOI: 10.1107/s1600576719013918] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Errors in the article by Opara, Martiel, Arnold, Braun, Stahlberg, Makita, David & Padeste [J. Appl. Cryst. (2017), 50, 909–918] are corrected.
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10
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Górzny M, Opara N, Guzenko V, Cadarso V, Schift H, Li X, Padeste C. Microfabricated silicon chip as lipid membrane sample holder for serial protein crystallography. Micro and Nano Engineering 2019. [DOI: 10.1016/j.mne.2019.03.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Moradi M, Opara NL, Tulli LG, Wäckerlin C, Dalgarno SJ, Teat SJ, Baljozovic M, Popova O, van Genderen E, Kleibert A, Stahlberg H, Abrahams JP, Padeste C, Corvini PFX, Jung TA, Shahgaldian P. Supramolecular architectures of molecularly thin yet robust free-standing layers. Sci Adv 2019; 5:eaav4489. [PMID: 30801017 PMCID: PMC6386556 DOI: 10.1126/sciadv.aav4489] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Accepted: 01/11/2019] [Indexed: 06/09/2023]
Abstract
Stable, single-nanometer thin, and free-standing two-dimensional layers with controlled molecular architectures are desired for several applications ranging from (opto-)electronic devices to nanoparticle and single-biomolecule characterization. It is, however, challenging to construct these stable single molecular layers via self-assembly, as the cohesion of those systems is ensured only by in-plane bonds. We herein demonstrate that relatively weak noncovalent bonds of limited directionality such as dipole-dipole (-CN⋅⋅⋅NC-) interactions act in a synergistic fashion to stabilize crystalline monomolecular layers of tetrafunctional calixarenes. The monolayers produced, demonstrated to be free-standing, display a well-defined atomic structure on the single-nanometer scale and are robust under a wide range of conditions including photon and electron radiation. This work opens up new avenues for the fabrication of robust, single-component, and free-standing layers via bottom-up self-assembly.
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Affiliation(s)
- Mina Moradi
- Institute of Chemistry and Bioanalytics, School of Life Sciences, University of Applied Sciences and Arts Northwestern Switzerland, Hofackerstrasse 35, CH-4132 Muttenz, Switzerland
- Laboratory for Micro- and Nano-technology, Paul Scherrer Institute, Villigen CH-5232, Switzerland
| | - Nadia L. Opara
- Laboratory for Micro- and Nano-technology, Paul Scherrer Institute, Villigen CH-5232, Switzerland
- Center for Cellular Imaging and NanoAnalytics (C-CINA), Biozentrum, University of Basel, Mattenstrasse 26, CH-4058 Basel, Switzerland
| | - Ludovico G. Tulli
- Institute of Chemistry and Bioanalytics, School of Life Sciences, University of Applied Sciences and Arts Northwestern Switzerland, Hofackerstrasse 35, CH-4132 Muttenz, Switzerland
| | - Christian Wäckerlin
- Empa–Swiss Federal Laboratories for Materials Science and Technology, CH-8600 Dübendorf, Switzerland
| | - Scott J. Dalgarno
- Institute of Chemical Sciences, Heriot-Watt University, Riccarton, Edinburgh, Scotland EH14 4AS, UK
| | - Simon J. Teat
- Advanced Light Source, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, MS6R2100, Berkeley, CA 94720, USA
| | - Milos Baljozovic
- Laboratory for Micro- and Nano-technology, Paul Scherrer Institute, Villigen CH-5232, Switzerland
| | - Olha Popova
- Department of Physics, University of Basel, Klingelbergstrasse 82, 4056 Basel, Switzerland
| | - Eric van Genderen
- Laboratory for Micro- and Nano-technology, Paul Scherrer Institute, Villigen CH-5232, Switzerland
| | - Armin Kleibert
- Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen, Switzerland
| | - Henning Stahlberg
- Center for Cellular Imaging and NanoAnalytics (C-CINA), Biozentrum, University of Basel, Mattenstrasse 26, CH-4058 Basel, Switzerland
| | - Jan Pieter Abrahams
- Biozentrum, University of Basel, Switzerland and Laboratory of Biomolecular Research, Paul Scherrer Institute, Villigen, Switzerland
- Institute of Biology Leiden, Leiden University, Sylviusweg 72, 2333 BE Leiden, Netherlands
| | - Celestino Padeste
- Laboratory for Micro- and Nano-technology, Paul Scherrer Institute, Villigen CH-5232, Switzerland
| | - Philippe F.-X. Corvini
- Institute of Chemistry and Bioanalytics, School of Life Sciences, University of Applied Sciences and Arts Northwestern Switzerland, Hofackerstrasse 35, CH-4132 Muttenz, Switzerland
| | - Thomas A. Jung
- Laboratory for Micro- and Nano-technology, Paul Scherrer Institute, Villigen CH-5232, Switzerland
| | - Patrick Shahgaldian
- Institute of Chemistry and Bioanalytics, School of Life Sciences, University of Applied Sciences and Arts Northwestern Switzerland, Hofackerstrasse 35, CH-4132 Muttenz, Switzerland
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Makita M, Vartiainen I, Mohacsi I, Caleman C, Diaz A, Jönsson HO, Juranić P, Medvedev N, Meents A, Mozzanica A, Opara NL, Padeste C, Panneels V, Saxena V, Sikorski M, Song S, Vera L, Willmott PR, Beaud P, Milne CJ, Ziaja-Motyka B, David C. Femtosecond phase-transition in hard x-ray excited bismuth. Sci Rep 2019; 9:602. [PMID: 30679456 PMCID: PMC6345934 DOI: 10.1038/s41598-018-36216-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Accepted: 11/14/2018] [Indexed: 11/26/2022] Open
Abstract
The evolution of bismuth crystal structure upon excitation of its A1g phonon has been intensely studied with short pulse optical lasers. Here we present the first-time observation of a hard x-ray induced ultrafast phase transition in a bismuth single crystal at high intensities (~1014 W/cm2). The lattice evolution was followed using a recently demonstrated x-ray single-shot probing setup. The time evolution of the (111) Bragg peak intensity showed strong dependence on the excitation fluence. After exposure to a sufficiently intense x-ray pulse, the peak intensity dropped to zero within 300 fs, i.e. faster than one oscillation period of the A1g mode at room temperature. Our analysis indicates a nonthermal origin of a lattice disordering process, and excludes interpretations based on electron-ion equilibration process, or on thermodynamic heating process leading to plasma formation.
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Affiliation(s)
- M Makita
- Paul Scherrer Institut, CH-5232, Villigen PSI, Switzerland.
| | - I Vartiainen
- Paul Scherrer Institut, CH-5232, Villigen PSI, Switzerland
| | - I Mohacsi
- Paul Scherrer Institut, CH-5232, Villigen PSI, Switzerland.,Synchrotron SOLEIL, L'Orme des Merisiers, 91190, Saint-Aubin, France
| | - C Caleman
- CFEL, Deutsches Elektronen-Synchrotron DESY, 22607, Hamburg, Germany.,Department of Physics and Astronomy, Uppsala University, SE-751 24, Uppsala, Sweden
| | - A Diaz
- Paul Scherrer Institut, CH-5232, Villigen PSI, Switzerland
| | - H O Jönsson
- Department of Physics and Astronomy, Uppsala University, SE-751 24, Uppsala, Sweden.,Department of Applied physics, KTH Royal Institute of Technology, SE-106 91, Stockholm, Sweden
| | - P Juranić
- Paul Scherrer Institut, CH-5232, Villigen PSI, Switzerland
| | - N Medvedev
- Institute of Physics, Czech Academy of Sciences, 182 21, Prague 8, Czech Republic.,Institute of Plasma Physics, Czech Academy of Sciences, 182 00, Prague 8, Czech Republic
| | - A Meents
- CFEL, Deutsches Elektronen-Synchrotron DESY, 22607, Hamburg, Germany
| | - A Mozzanica
- Paul Scherrer Institut, CH-5232, Villigen PSI, Switzerland
| | - N L Opara
- Paul Scherrer Institut, CH-5232, Villigen PSI, Switzerland.,C-CINA Biozentrum, University of Basel, CH-4058, Basel, Switzerland
| | - C Padeste
- Paul Scherrer Institut, CH-5232, Villigen PSI, Switzerland
| | - V Panneels
- Paul Scherrer Institut, CH-5232, Villigen PSI, Switzerland
| | - V Saxena
- CFEL, Deutsches Elektronen-Synchrotron DESY, 22607, Hamburg, Germany.,Institute for Plasma Research, Bhat, Gandhinagar, 382428, India
| | - M Sikorski
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, California, 94025, USA
| | - S Song
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, California, 94025, USA
| | - L Vera
- Paul Scherrer Institut, CH-5232, Villigen PSI, Switzerland
| | - P R Willmott
- Paul Scherrer Institut, CH-5232, Villigen PSI, Switzerland
| | - P Beaud
- Paul Scherrer Institut, CH-5232, Villigen PSI, Switzerland
| | - C J Milne
- Paul Scherrer Institut, CH-5232, Villigen PSI, Switzerland
| | - B Ziaja-Motyka
- CFEL, Deutsches Elektronen-Synchrotron DESY, 22607, Hamburg, Germany.,Institute of Nuclear Physics, Polish Academy of Sciences, 31-342, Krakow, Poland
| | - C David
- Paul Scherrer Institut, CH-5232, Villigen PSI, Switzerland
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13
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Casadei CM, Nass K, Barty A, Hunter MS, Padeste C, Tsai CJ, Boutet S, Messerschmidt M, Sala L, Williams GJ, Ozerov D, Coleman M, Li XD, Frank M, Pedrini B. Structure-factor amplitude reconstruction from serial femtosecond crystallography of two-dimensional membrane-protein crystals. IUCrJ 2019; 6:34-45. [PMID: 30713701 PMCID: PMC6327180 DOI: 10.1107/s2052252518014641] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Accepted: 10/16/2018] [Indexed: 06/09/2023]
Abstract
Serial femtosecond crystallography of two-dimensional membrane-protein crystals at X-ray free-electron lasers has the potential to address the dynamics of functionally relevant large-scale motions, which can be sterically hindered in three-dimensional crystals and suppressed in cryocooled samples. In previous work, diffraction data limited to a two-dimensional reciprocal-space slice were evaluated and it was demonstrated that the low intensity of the diffraction signal can be overcome by collecting highly redundant data, thus enhancing the achievable resolution. Here, the application of a newly developed method to analyze diffraction data covering three reciprocal-space dimensions, extracting the reciprocal-space map of the structure-factor amplitudes, is presented. Despite the low resolution and completeness of the data set, it is shown by molecular replacement that the reconstructed amplitudes carry meaningful structural information. Therefore, it appears that these intrinsic limitations in resolution and completeness from two-dimensional crystal diffraction may be overcome by collecting highly redundant data along the three reciprocal-space axes, thus allowing the measurement of large-scale dynamics in pump-probe experiments.
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Affiliation(s)
| | - Karol Nass
- Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
| | - Anton Barty
- Center for Free-Electron Laser Science, DESY, Notkestrasse 85, 22607 Hamburg, Germany
| | - Mark S. Hunter
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550, USA
| | | | - Ching-Ju Tsai
- Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
| | - Sébastien Boutet
- Linac Coherent Light Source, 2575 Sand Hill Road, Menlo Park, CA 94025, USA
| | - Marc Messerschmidt
- Linac Coherent Light Source, 2575 Sand Hill Road, Menlo Park, CA 94025, USA
- National Science Foundation BioXFEL Science and Technology Center, 700 Ellicott Street, Buffalo, NY 14203, USA
| | - Leonardo Sala
- Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
| | - Garth J. Williams
- Linac Coherent Light Source, 2575 Sand Hill Road, Menlo Park, CA 94025, USA
- NSLS-II, Brookhaven National Laboratory, PO Box 5000, Upton, NY 11973, USA
| | - Dmitry Ozerov
- Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
| | - Matthew Coleman
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550, USA
| | - Xiao-Dan Li
- Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
| | - Matthias Frank
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550, USA
| | - Bill Pedrini
- Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
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14
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Opara NL, Mohacsi I, Makita M, Castano-Diez D, Diaz A, Juranić P, Marsh M, Meents A, Milne CJ, Mozzanica A, Padeste C, Panneels V, Sikorski M, Song S, Stahlberg H, Vartiainen I, Vera L, Wang M, Willmott PR, David C. Demonstration of femtosecond X-ray pump X-ray probe diffraction on protein crystals. Struct Dyn 2018; 5:054303. [PMID: 30364211 PMCID: PMC6192410 DOI: 10.1063/1.5050618] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Accepted: 09/12/2018] [Indexed: 05/24/2023]
Abstract
The development of X-ray free-electron lasers (XFELs) has opened the possibility to investigate the ultrafast dynamics of biomacromolecules using X-ray diffraction. Whereas an increasing number of structures solved by means of serial femtosecond crystallography at XFELs is available, the effect of radiation damage on protein crystals during ultrafast exposures has remained an open question. We used a split-and-delay line based on diffractive X-ray optics at the Linac Coherent Light Source XFEL to investigate the time dependence of X-ray radiation damage to lysozyme crystals. For these tests, crystals were delivered to the X-ray beam using a fixed-target approach. The presented experiments provide probe signals at eight different delay times between 19 and 213 femtoseconds after a single pump event, thereby covering the time-scales relevant for femtosecond serial crystallography. Even though significant impact on the crystals was observed at long time scales after exposure with a single X-ray pulse, the collected diffraction data did not show significant signal reduction that could be assigned to beam damage on the crystals in the sampled time window and resolution range. This observation is in agreement with estimations of the applied radiation dose, which in our experiment was clearly below the values expected to cause damage on the femtosecond time scale. The experiments presented here demonstrate the feasibility of time-resolved pump-multiprobe X-ray diffraction experiments on protein crystals.
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Affiliation(s)
| | | | | | | | - Ana Diaz
- Paul Scherrer Institut, CH-5232 Villigen-PSI, Switzerland
| | - Pavle Juranić
- Paul Scherrer Institut, CH-5232 Villigen-PSI, Switzerland
| | - May Marsh
- Paul Scherrer Institut, CH-5232 Villigen-PSI, Switzerland
| | - Alke Meents
- Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, D-22607 Hamburg, Germany
| | | | - Aldo Mozzanica
- Paul Scherrer Institut, CH-5232 Villigen-PSI, Switzerland
| | | | | | - Marcin Sikorski
- LCLS, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
| | - Sanghoon Song
- LCLS, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
| | | | | | - Laura Vera
- Paul Scherrer Institut, CH-5232 Villigen-PSI, Switzerland
| | - Meitian Wang
- Paul Scherrer Institut, CH-5232 Villigen-PSI, Switzerland
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15
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Casadei CM, Tsai CJ, Barty A, Hunter MS, Zatsepin NA, Padeste C, Capitani G, Benner WH, Boutet S, Hau-Riege SP, Kupitz C, Messerschmidt M, Ogren JI, Pardini T, Rothschild KJ, Sala L, Segelke B, Williams GJ, Evans JE, Li XD, Coleman M, Pedrini B, Frank M. Resolution extension by image summing in serial femtosecond crystallography of two-dimensional membrane-protein crystals. IUCrJ 2018; 5:103-117. [PMID: 29354276 PMCID: PMC5755582 DOI: 10.1107/s2052252517017043] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Accepted: 11/27/2017] [Indexed: 05/08/2023]
Abstract
Previous proof-of-concept measurements on single-layer two-dimensional membrane-protein crystals performed at X-ray free-electron lasers (FELs) have demonstrated that the collection of meaningful diffraction patterns, which is not possible at synchrotrons because of radiation-damage issues, is feasible. Here, the results obtained from the analysis of a thousand single-shot, room-temperature X-ray FEL diffraction images from two-dimensional crystals of a bacteriorhodopsin mutant are reported in detail. The high redundancy in the measurements boosts the intensity signal-to-noise ratio, so that the values of the diffracted intensities can be reliably determined down to the detector-edge resolution of 4 Å. The results show that two-dimensional serial crystallography at X-ray FELs is a suitable method to study membrane proteins to near-atomic length scales at ambient temperature. The method presented here can be extended to pump-probe studies of optically triggered structural changes on submillisecond timescales in two-dimensional crystals, which allow functionally relevant large-scale motions that may be quenched in three-dimensional crystals.
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Affiliation(s)
| | - Ching-Ju Tsai
- Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
| | - Anton Barty
- Center for Free-Electron Laser Science, DESY, Notkestrasse 85, 22607 Hamburg, Germany
| | - Mark S. Hunter
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550, USA
| | - Nadia A. Zatsepin
- Arizona State University, 300 East University Drive, Tempe, AZ 85287, USA
| | | | | | - W. Henry Benner
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550, USA
| | - Sébastien Boutet
- Linac Coherent Light Source, 2575 Sand Hill Road, Menlo Park, CA 94025, USA
| | - Stefan P. Hau-Riege
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550, USA
| | - Christopher Kupitz
- Arizona State University, 300 East University Drive, Tempe, AZ 85287, USA
| | - Marc Messerschmidt
- Linac Coherent Light Source, 2575 Sand Hill Road, Menlo Park, CA 94025, USA
- National Science Foundation BioXFEL Science and Technology Center, 700 Ellicott Street, Buffalo, NY 14203, USA
| | - John I. Ogren
- Physics Departement, Boston University, 590 Commonwealth Avenue, Boston, MA 02215, USA
| | - Tom Pardini
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550, USA
| | - Kenneth J. Rothschild
- Physics Departement, Boston University, 590 Commonwealth Avenue, Boston, MA 02215, USA
| | - Leonardo Sala
- Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
| | - Brent Segelke
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550, USA
| | - Garth J. Williams
- Linac Coherent Light Source, 2575 Sand Hill Road, Menlo Park, CA 94025, USA
| | - James E. Evans
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, 3335 Innovation Boulevard, Richland, WA 99354, USA
| | - Xiao-Dan Li
- Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
| | - Matthew Coleman
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550, USA
| | - Bill Pedrini
- Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
- Correspondence e-mail:
| | - Matthias Frank
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550, USA
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16
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Opara N, Martiel I, Arnold SA, Braun T, Stahlberg H, Makita M, David C, Padeste C. Direct protein crystallization on ultrathin membranes for diffraction measurements at X-ray free-electron lasers. J Appl Crystallogr 2017. [DOI: 10.1107/s1600576717005799] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
A new era of protein crystallography started when X-ray free-electron lasers (XFELs) came into operation, as these provide an intense source of X-rays that facilitates data collection in the `diffract-before-destroy' regime. In typical experiments, crystals sequentially delivered to the beam are exposed to X-rays and destroyed. Therefore, the novel approach of serial crystallography requires thousands of nearly identical samples. Currently applied sample-delivery methods, in particular liquid jets or drop-on-demand systems, suffer from significant sample consumption of the precious crystalline material. Direct protein microcrystal growth by the vapour diffusion technique inside arrays of nanolitre-sized wells is a method specifically tailored to crystallography at XFELs. The wells, with X-ray transparent Si3N4windows as bottoms, are fabricated in silicon chips. Their reduced dimensions can significantly decrease protein specimen consumption. Arrays provide crystalline samples positioned in an ordered way without the need to handle fragile crystals. The nucleation process inside these microfabricated cavities was optimized to provide high membrane coverage and a quasi-random crystal distribution. Tight sealing of the chips and protection of the crystals from dehydration were achieved, as confirmed by diffraction experiments at a protein crystallography beamline. Finally, the test samples were shown to be suitable for time-resolved measurements at an XFEL at femtosecond resolution.
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17
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Dübner M, Cadarso VJ, Gevrek TN, Sanyal A, Spencer ND, Padeste C. Reversible Light-Switching of Enzymatic Activity on Orthogonally Functionalized Polymer Brushes. ACS Appl Mater Interfaces 2017; 9:9245-9249. [PMID: 28266210 DOI: 10.1021/acsami.7b01154] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Copolymer brushes, composed of glycidyl methacrylate and a furan-protected maleimide-containing monomer, were grafted from radical initiators at the surface of irradiation-activated fluoropolymer foils. After postpolymerization modification with enzymatically active microperoxidase-11 and photochromic spiropyran moieties, the polymer brushes catalyzed the oxidation of 3,3'5,5'-tetramethylbenzidine. Exposure to either UV or visible-light allowed switching the turnover by more than 1 order of magnitude, as consequence of the reversible, light-induced spiropyran-merocyanine transition. The modified samples were integrated into an optofluidic device that allowed the reversible switching of enzymatic activity for several cycles under flow, validating the potential for application in smart lab-on-a-chip systems.
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Affiliation(s)
- Matthias Dübner
- Laboratory for Micro- and Nanotechnology, Paul Scherrer Institute , 5232 Villigen PSI, Switzerland
- Laboratory for Surface Science and Technology, Department of Materials, ETH Zürich , 8093 Zurich, Switzerland
| | - Victor J Cadarso
- Laboratory for Micro- and Nanotechnology, Paul Scherrer Institute , 5232 Villigen PSI, Switzerland
| | - Tugce N Gevrek
- Department of Chemistry, Bogazici University , 34342 Bebek, Istanbul, Turkey
| | - Amitav Sanyal
- Department of Chemistry, Bogazici University , 34342 Bebek, Istanbul, Turkey
| | - Nicholas D Spencer
- Laboratory for Surface Science and Technology, Department of Materials, ETH Zürich , 8093 Zurich, Switzerland
| | - Celestino Padeste
- Laboratory for Micro- and Nanotechnology, Paul Scherrer Institute , 5232 Villigen PSI, Switzerland
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18
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Dübner M, Naoum ME, Spencer ND, Padeste C. From pH- to Light-Response: Postpolymerization Modification of Polymer Brushes Grafted onto Microporous Polymeric Membranes. ACS Omega 2017; 2:455-461. [PMID: 31457450 PMCID: PMC6641005 DOI: 10.1021/acsomega.6b00394] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Accepted: 01/25/2017] [Indexed: 06/06/2023]
Abstract
A microporous pH- and light-responsive membrane that enables remote control over its interfacial properties has been fabricated. pH-Responsiveness was imparted to a porous polypropylene film via grafting of poly(methacrylic acid) brushes from the substrate using argon-plasma-induced free-radical graft polymerization. Morphological changes as a function of grafting level were analyzed using atomic force microscopy. Conversion into a light-responsive membrane was performed via postpolymerization modification to covalently attach photochromic spiropyran moieties to the grafted polymer brushes. Reversible switches in wettability and permeability were determined upon changing from acidic to basic pH or upon alternating UV- and visible-light irradiation. Additionally, light-responsive membranes show a switch in color upon UV exposure.
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Affiliation(s)
- Matthias Dübner
- Laboratory
for Micro- and Nanotechnology, Paul Scherrer
Institute (PSI), ODRA/105, 5232 Villigen, Switzerland
- Laboratory
for Surface Science and Technology, Department of Materials, ETH Zürich, Vladimir-Prelog-Weg 5, 8093 Zürich, Switzerland
| | - Maria-Eleni Naoum
- Laboratory
for Micro- and Nanotechnology, Paul Scherrer
Institute (PSI), ODRA/105, 5232 Villigen, Switzerland
| | - Nicholas D. Spencer
- Laboratory
for Surface Science and Technology, Department of Materials, ETH Zürich, Vladimir-Prelog-Weg 5, 8093 Zürich, Switzerland
| | - Celestino Padeste
- Laboratory
for Micro- and Nanotechnology, Paul Scherrer
Institute (PSI), ODRA/105, 5232 Villigen, Switzerland
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19
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Gajos K, Guzenko VA, Dübner M, Haberko J, Budkowski A, Padeste C. Electron-Beam Lithographic Grafting of Functional Polymer Structures from Fluoropolymer Substrates. Langmuir 2016; 32:10641-10650. [PMID: 27673344 DOI: 10.1021/acs.langmuir.6b02808] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Well-defined submicrometer structures of poly(dimethylaminoethyl methacrylate) (PDMAEMA) were grafted from 100 μm thick films of poly(ethene-alt-tetrafluoroethene) after electron-beam lithographic exposure. To explore the possibilities and limits of the method under different exposure conditions, two different acceleration voltages (2.5 and 100 keV) were employed. First, the influence of electron energy and dose on the extent of grafting and on the structure's morphology was determined via atomic force microscopy. The surface grafting with PDMAEMA was confirmed by advanced surface analytical techniques such as time-of-flight secondary ion mass spectrometry and X-ray photoelectron spectroscopy. Additionally, the possibility of effective postpolymerization modification of grafted structures was demonstrated by quaternization of the grafted PDMAEMA to the polycationic QPDMAEMA form and by exploiting electrostatic interactions to bind charged organic dyes and functional proteins.
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Affiliation(s)
- Katarzyna Gajos
- M. Smoluchowski Institute of Physics, Jagiellonian University , Łojasiewicza 11, 30-348 Kraków, Poland
- Laboratory of Micro- and Nanotechnology, Paul Scherrer Institute , CH-5232 Villigen, Switzerland
| | - Vitaliy A Guzenko
- Laboratory of Micro- and Nanotechnology, Paul Scherrer Institute , CH-5232 Villigen, Switzerland
| | - Matthias Dübner
- Laboratory of Micro- and Nanotechnology, Paul Scherrer Institute , CH-5232 Villigen, Switzerland
| | - Jakub Haberko
- Faculty of Physics and Applied Computer Science, AGH University of Science and Technology , Mickiewicza 30, 30-059 Kraków, Poland
| | - Andrzej Budkowski
- M. Smoluchowski Institute of Physics, Jagiellonian University , Łojasiewicza 11, 30-348 Kraków, Poland
| | - Celestino Padeste
- Laboratory of Micro- and Nanotechnology, Paul Scherrer Institute , CH-5232 Villigen, Switzerland
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20
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Opara N, Arnold S, Braun T, Stahlberg H, Padeste C. Ultrathin membrane chips as X-ray transparent supports for serial crystallography. Acta Crystallogr A Found Adv 2016. [DOI: 10.1107/s2053273316097266] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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21
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Arnold SA, Albiez S, Opara N, Chami M, Schmidli C, Bieri A, Padeste C, Stahlberg H, Braun T. Total Sample Conditioning and Preparation of Nanoliter Volumes for Electron Microscopy. ACS Nano 2016; 10:4981-4988. [PMID: 27074622 DOI: 10.1021/acsnano.6b01328] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Electron microscopy (EM) entered a new era with the emergence of direct electron detectors and new nanocrystal electron diffraction methods. However, sample preparation techniques have not progressed and still suffer from extensive blotting steps leading to a massive loss of sample. Here, we present a simple but versatile method for the almost lossless sample conditioning and preparation of nanoliter volumes of biological samples for EM, keeping the sample under close to physiological condition. A microcapillary is used to aspirate 3-5 nL of sample. The microcapillary tip is immersed into a reservoir of negative stain or trehalose, where the sample becomes conditioned by diffusive exchange of salt and heavy metal ions or sugar molecules, respectively, before it is deposited as a small spot onto an EM grid. We demonstrate the use of the method to prepare protein particles for imaging by transmission EM and nanocrystals for analysis by electron diffraction. Furthermore, the minute sample volume required for this method enables alternative strategies for biological experiments, such as the analysis of the content of a single cell by visual proteomics, fully exploiting the single molecule detection limit of EM.
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Affiliation(s)
| | | | - Nadia Opara
- Paul Scherrer Institute (PSI) , 5232 Villigen, Switzerland
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22
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Panneels V, Wu W, Tsai CJ, Nogly P, Rheinberger J, Jaeger K, Cicchetti G, Gati C, Kick LM, Sala L, Capitani G, Milne C, Padeste C, Pedrini B, Li XD, Standfuss J, Abela R, Schertler G. Time-resolved structural studies with serial crystallography: A new light on retinal proteins. Struct Dyn 2015; 2:041718. [PMID: 26798817 PMCID: PMC4711639 DOI: 10.1063/1.4922774] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Accepted: 06/03/2015] [Indexed: 05/19/2023]
Abstract
Structural information of the different conformational states of the two prototypical light-sensitive membrane proteins, bacteriorhodopsin and rhodopsin, has been obtained in the past by X-ray cryo-crystallography and cryo-electron microscopy. However, these methods do not allow for the structure determination of most intermediate conformations. Recently, the potential of X-Ray Free Electron Lasers (X-FELs) for tracking the dynamics of light-triggered processes by pump-probe serial femtosecond crystallography has been demonstrated using 3D-micron-sized crystals. In addition, X-FELs provide new opportunities for protein 2D-crystal diffraction, which would allow to observe the course of conformational changes of membrane proteins in a close-to-physiological lipid bilayer environment. Here, we describe the strategies towards structural dynamic studies of retinal proteins at room temperature, using injector or fixed-target based serial femtosecond crystallography at X-FELs. Thanks to recent progress especially in sample delivery methods, serial crystallography is now also feasible at synchrotron X-ray sources, thus expanding the possibilities for time-resolved structure determination.
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Affiliation(s)
- Valérie Panneels
- Laboratory of Biomolecular Research, Paul Scherrer Institute , 5232 Villigen PSI, Switzerland
| | - Wenting Wu
- Laboratory of Biomolecular Research, Paul Scherrer Institute , 5232 Villigen PSI, Switzerland
| | - Ching-Ju Tsai
- Laboratory of Biomolecular Research, Paul Scherrer Institute , 5232 Villigen PSI, Switzerland
| | - Przemek Nogly
- Laboratory of Biomolecular Research, Paul Scherrer Institute , 5232 Villigen PSI, Switzerland
| | - Jan Rheinberger
- Laboratory of Biomolecular Research, Paul Scherrer Institute , 5232 Villigen PSI, Switzerland
| | - Kathrin Jaeger
- Laboratory of Biomolecular Research, Paul Scherrer Institute , 5232 Villigen PSI, Switzerland
| | - Gregor Cicchetti
- Laboratory of Biomolecular Research, Paul Scherrer Institute , 5232 Villigen PSI, Switzerland
| | | | - Leonhard M Kick
- Laboratory of Biomolecular Research, Paul Scherrer Institute , 5232 Villigen PSI, Switzerland
| | - Leonardo Sala
- Scientific Computing, Paul Scherrer Institute , 5232 Villigen PSI, Switzerland
| | - Guido Capitani
- Laboratory of Biomolecular Research, Paul Scherrer Institute , 5232 Villigen PSI, Switzerland
| | - Chris Milne
- SwissFEL Paul Scherrer Institute , 5232 Villigen PSI, Switzerland
| | - Celestino Padeste
- Lab for Micro- and Nanotechnology, Paul Scherrer Institute , 5232 Villigen PSI, Switzerland
| | - Bill Pedrini
- SwissFEL Paul Scherrer Institute , 5232 Villigen PSI, Switzerland
| | - Xiao-Dan Li
- Laboratory of Biomolecular Research, Paul Scherrer Institute , 5232 Villigen PSI, Switzerland
| | - Jörg Standfuss
- Laboratory of Biomolecular Research, Paul Scherrer Institute , 5232 Villigen PSI, Switzerland
| | - Rafael Abela
- SwissFEL Paul Scherrer Institute , 5232 Villigen PSI, Switzerland
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23
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Dübner M, Gevrek TN, Sanyal A, Spencer ND, Padeste C. Fabrication of Thiol-Ene "Clickable" Copolymer-Brush Nanostructures on Polymeric Substrates via Extreme Ultraviolet Interference Lithography. ACS Appl Mater Interfaces 2015; 7:11337-11345. [PMID: 25978723 DOI: 10.1021/acsami.5b01804] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We demonstrate a new approach to grafting thiol-reactive nanopatterned copolymer-brush structures on polymeric substrates by means of extreme ultraviolet (EUV) interference lithography. The copolymer brushes were designed to contain maleimide functional groups as thiol-reactive centers. Fluoropolymer films were exposed to EUV radiation at the X-ray interference lithography beamline (XIL-II) at the Swiss Light Source, in order to create radical patterns on their surfaces. The radicals served as initiators for the copolymerization of thiol-ene "clickable" brushes, composed of a furan-protected maleimide monomer (FuMaMA) and different methacrylates, namely, methyl methacrylate (MMA), ethylene glycol methyl ether methacrylate (EGMA), or poly(ethylene glycol) methyl ether methacrylate (PEGMA). Copolymerization with ethylene-glycol-containing monomers provides antibiofouling properties to these surfaces. The number of reactive centers on the grafted brush structures can be tailored by varying the monomer ratios in the feed. Grafted copolymers were characterized by using attenuated total reflection infrared (ATR-IR) spectroscopy. The reactive maleimide methacrylate (MaMA) units were utilized to conjugate thiol-containing moieties using the nucleophilic Michael-addition reaction, which proceeds at room temperature without the need for any metal-based catalyst. Using this approach, a variety of functionalities was introduced to yield polyelectrolytes, as well as fluorescent and light-responsive polymer-brush structures. Functionalization of the brush structures was demonstrated via ATR-IR and UV-vis spectroscopy and fluorescence microscopy, and was also indicated by a color switch. Furthermore, grafted surfaces were generated via plasma activation, showing a strongly increased wettability for polyelectrolytes and a reversible switch in static water contact angle (CA) of up to 18° for P(EGMA-co-MaMA-SP) brushes, upon exposure to alternating visible and UV-light irradiation.
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Affiliation(s)
- Matthias Dübner
- †Laboratory for Micro- and Nanotechnology, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
- ‡Laboratory for Surface Science and Technology, Department of Materials, ETH Zürich, CH-8093 Zürich, Switzerland
| | - Tugce N Gevrek
- §Department of Chemistry, Bogazici University, Bebek, 34342 Istanbul, Turkey
| | - Amitav Sanyal
- §Department of Chemistry, Bogazici University, Bebek, 34342 Istanbul, Turkey
| | - Nicholas D Spencer
- ‡Laboratory for Surface Science and Technology, Department of Materials, ETH Zürich, CH-8093 Zürich, Switzerland
| | - Celestino Padeste
- †Laboratory for Micro- and Nanotechnology, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
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Pedrini B, Tsai CJ, Capitani G, Padeste C, Hunter MS, Zatsepin NA, Barty A, Benner WH, Boutet S, Feld GK, Hau-Riege SP, Kirian RA, Kupitz C, Messerschmitt M, Ogren JI, Pardini T, Segelke B, Williams GJ, Spence JCH, Abela R, Coleman M, Evans JE, Schertler GFX, Frank M, Li XD. 7 Å resolution in protein two-dimensional-crystal X-ray diffraction at Linac Coherent Light Source. Philos Trans R Soc Lond B Biol Sci 2015; 369:20130500. [PMID: 24914166 DOI: 10.1098/rstb.2013.0500] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Membrane proteins arranged as two-dimensional crystals in the lipid environment provide close-to-physiological structural information, which is essential for understanding the molecular mechanisms of protein function. Previously, X-ray diffraction from individual two-dimensional crystals did not represent a suitable investigational tool because of radiation damage. The recent availability of ultrashort pulses from X-ray free-electron lasers (XFELs) has now provided a means to outrun the damage. Here, we report on measurements performed at the Linac Coherent Light Source XFEL on bacteriorhodopsin two-dimensional crystals mounted on a solid support and kept at room temperature. By merging data from about a dozen single crystal diffraction images, we unambiguously identified the diffraction peaks to a resolution of 7 Å, thus improving the observable resolution with respect to that achievable from a single pattern alone. This indicates that a larger dataset will allow for reliable quantification of peak intensities, and in turn a corresponding increase in the resolution. The presented results pave the way for further XFEL studies on two-dimensional crystals, which may include pump-probe experiments at subpicosecond time resolution.
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Affiliation(s)
- Bill Pedrini
- Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
| | - Ching-Ju Tsai
- Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
| | | | | | - Mark S Hunter
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550, USA
| | - Nadia A Zatsepin
- Department of Physics, Arizona State University, 300 E. University Drive, Tempe, AZ 85287, USA
| | - Anton Barty
- Center for Free-Electron Laser Science, DESY, Notkestrasse 85, 22607 Hamburg, Germany
| | - W Henry Benner
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550, USA
| | - Sébastien Boutet
- Linac Coherent Light Source, 2575 Sand Hill Road, Menlo Park, CA 94025, USA
| | - Geoffrey K Feld
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550, USA
| | - Stefan P Hau-Riege
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550, USA
| | - Richard A Kirian
- Center for Free-Electron Laser Science, DESY, Notkestrasse 85, 22607 Hamburg, Germany
| | - Christopher Kupitz
- Department of Physics, Arizona State University, 300 E. University Drive, Tempe, AZ 85287, USA
| | - Marc Messerschmitt
- Linac Coherent Light Source, 2575 Sand Hill Road, Menlo Park, CA 94025, USA
| | - John I Ogren
- Physics Department, Boston University, 590 Commonwealth Avenue, Boston, MA 02215, USA
| | - Tommaso Pardini
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550, USA
| | - Brent Segelke
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550, USA
| | - Garth J Williams
- Linac Coherent Light Source, 2575 Sand Hill Road, Menlo Park, CA 94025, USA
| | - John C H Spence
- Department of Physics, Arizona State University, 300 E. University Drive, Tempe, AZ 85287, USA
| | - Rafael Abela
- Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
| | - Matthew Coleman
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550, USA
| | - James E Evans
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, 3335 Innovation Boulevard, Richland, WA 99354, USA
| | | | - Matthias Frank
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550, USA
| | - Xiao-Dan Li
- Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
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Dübner M, Spencer ND, Padeste C. Light-responsive polymer surfaces via postpolymerization modification of grafted polymer-brush structures. Langmuir 2014; 30:14971-14981. [PMID: 25419582 DOI: 10.1021/la503388j] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Light-induced, spatially well-defined, reversible switching of surface properties enables the creation of remote-controlled smart surfaces. We have taken advantage of the unique high-resolution structuring capabilities of extreme ultraviolet (EUV) interference lithography to produce nanostructured photoresponsive polymer brushes. Patterns of poly(glycidyl methacrylate) (PGMA) and poly(methacrylic acid) (PMAA) were grafted from two different 100 μm thick fluoropolymer substrates by means of a radiation-initiated, grafting-from approach based on free-radical polymerization (FRP). Photochromic properties were introduced via novel one- or two-step postpolymerization modifications with spiropyran (SP) derivatives, which allowed us to control the number of photochromic groups on the polymer brushes. Depending on the degree of functionalization and the local chemical environment, the SP moieties can open upon UV-light exposure to form zwitterionic, deeply colored, and fluorescent merocyanines (MCs) and reclose to the colorless SP configuration via thermal or visible light-induced relaxation. Switching kinetics were studied by means of time-resolved fluorescence microscopy and compared with kinetic measurements of the SP moiety in solution. The results indicated the importance, for the intensity of the switching, of the local chemical environment provided by both the polymer brush and added solvents, and showed the predominant influence on the ring-closing kinetics of polar solvents, which stabilize the MC form. To allow further characterization of the polymer-brush arrangements on a macroscopic scale, similar, but unstructured brush systems were grafted from fluoropolymers after large-area activation using EUV radiation or argon plasma. All steps of the postpolymerization modification were characterized in detail using attenuated total reflection infrared (ATR-IR) spectroscopy. Furthermore, a light-induced reversible static-contact-angle switch with a range of up to 15° for PGMA-SP brushes and up to 30° for PMA-SP brushes was demonstrated upon alternating UV- and visible-light irradiation.
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Affiliation(s)
- Matthias Dübner
- Laboratory for Micro- and Nanotechnology, Paul Scherrer Institut , CH-5232 Villigen PSI, Switzerland
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Özçelik H, Padeste C, Hasirci V. Systematically organized nanopillar arrays reveal differences in adhesion and alignment properties of BMSC and Saos-2 cells. Colloids Surf B Biointerfaces 2014; 119:71-81. [DOI: 10.1016/j.colsurfb.2014.03.019] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2013] [Revised: 03/06/2014] [Accepted: 03/10/2014] [Indexed: 10/25/2022]
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Frank M, Carlson DB, Hunter MS, Williams GJ, Messerschmidt M, Zatsepin NA, Barty A, Benner WH, Chu K, Graf AT, Hau-Riege SP, Kirian RA, Padeste C, Pardini T, Pedrini B, Segelke B, Seibert MM, Spence JCH, Tsai CJ, Lane SM, Li XD, Schertler G, Boutet S, Coleman M, Evans JE. Femtosecond X-ray diffraction from two-dimensional protein crystals. IUCrJ 2014; 1:95-100. [PMID: 25075325 PMCID: PMC4062087 DOI: 10.1107/s2052252514001444] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2013] [Accepted: 01/21/2014] [Indexed: 05/19/2023]
Abstract
X-ray diffraction patterns from two-dimensional (2-D) protein crystals obtained using femtosecond X-ray pulses from an X-ray free-electron laser (XFEL) are presented. To date, it has not been possible to acquire transmission X-ray diffraction patterns from individual 2-D protein crystals due to radiation damage. However, the intense and ultrafast pulses generated by an XFEL permit a new method of collecting diffraction data before the sample is destroyed. Utilizing a diffract-before-destroy approach at the Linac Coherent Light Source, Bragg diffraction was acquired to better than 8.5 Å resolution for two different 2-D protein crystal samples each less than 10 nm thick and maintained at room temperature. These proof-of-principle results show promise for structural analysis of both soluble and membrane proteins arranged as 2-D crystals without requiring cryogenic conditions or the formation of three-dimensional crystals.
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Affiliation(s)
- Matthias Frank
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550, USA
| | - David B. Carlson
- Department of Molecular and Cellular Biology, University of California, Davis, 1 Shields Avenue, Davis, CA 95616, USA
| | - Mark S. Hunter
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550, USA
| | - Garth J. Williams
- Linac Coherent Light Source, 2575 Sand Hill Road, Menlo Park, CA 94025, USA
| | - Marc Messerschmidt
- Linac Coherent Light Source, 2575 Sand Hill Road, Menlo Park, CA 94025, USA
| | - Nadia A. Zatsepin
- Arizona State University, 300 East University Drive, Tempe, AZ 85287, USA
| | - Anton Barty
- Center for Free-Electron Laser Science, University of Hamburg, Luruper Chaussee 149, Hamburg 22761, Germany
| | - W. Henry Benner
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550, USA
| | - Kaiqin Chu
- Center for Biophotonics, 2700 Stockton Boulevard, Sacramento, CA 95817, USA
| | - Alexander T. Graf
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550, USA
| | - Stefan P. Hau-Riege
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550, USA
| | - Richard A. Kirian
- Center for Free-Electron Laser Science, University of Hamburg, Luruper Chaussee 149, Hamburg 22761, Germany
| | | | - Tommaso Pardini
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550, USA
| | - Bill Pedrini
- Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
| | - Brent Segelke
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550, USA
| | - M. Marvin Seibert
- Linac Coherent Light Source, 2575 Sand Hill Road, Menlo Park, CA 94025, USA
| | - John C. H. Spence
- Arizona State University, 300 East University Drive, Tempe, AZ 85287, USA
| | - Ching-Ju Tsai
- Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
| | - Stephen M. Lane
- Center for Biophotonics, 2700 Stockton Boulevard, Sacramento, CA 95817, USA
| | - Xiao-Dan Li
- Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
| | | | - Sebastien Boutet
- Linac Coherent Light Source, 2575 Sand Hill Road, Menlo Park, CA 94025, USA
| | - Matthew Coleman
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550, USA
| | - James E. Evans
- Department of Molecular and Cellular Biology, University of California, Davis, 1 Shields Avenue, Davis, CA 95616, USA
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, 3335 Innovation Boulevard, Richland, WA 99354, USA
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Waser-Althaus J, Salamon A, Waser M, Padeste C, Kreutzer M, Pieles U, Müller B, Peters K. Differentiation of human mesenchymal stem cells on plasma-treated polyetheretherketone. J Mater Sci Mater Med 2014; 25:515-525. [PMID: 24202913 DOI: 10.1007/s10856-013-5072-5] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2013] [Accepted: 10/10/2013] [Indexed: 06/02/2023]
Abstract
Polyetheretherketone (PEEK) generally exhibits physical and chemical characteristics that prevent osseointegration. To activate the PEEK surface, we applied oxygen and ammonia plasma treatments. These treatments resulted in surface modifications, leading to changes in nanostructure, contact angle, electrochemical properties and protein adhesion in a plasma power and process gas dependent way. To evaluate the effect of the plasma-induced PEEK modifications on stem cell adhesion and differentiation, adipose tissue-derived mesenchymal stem cells (adMSC) were seeded on PEEK specimens. We demonstrated an increased adhesion, proliferation, and osteogenic differentiation of adMSC in contact to plasma-treated PEEK. In dependency on the process gas (oxygen or ammonia) and plasma power (between 10 and 200 W for 5 min), varying degrees of osteogenic differentiation were induced. When adMSC were grown on 10 and 50 W oxygen and ammonia plasma-treated PEEK substrates they exhibited a doubled mineralization degree relative to the original PEEK. Thus plasma treatment of PEEK specimens induced changes in surface chemistry and topography and supported osteogenic differentiation of adMSC in vitro. Therefore plasma treated PEEK holds perspective for contributing to osseointegration of dental and orthopedic load-bearing PEEK implants in vivo.
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Affiliation(s)
- Jasmin Waser-Althaus
- Department of Cell Biology, Rostock University Medical Center, Schillingallee 69, 18057, Rostock, Germany
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Abstract
Structured poly(glycidyl methracrylate) (poly-GMA) brushes have been grafted onto flexible fluoro-polymer films using a radiation grafting process. The reactive epoxide of poly-GMA provides the basis for a versatile biofunctionalization of the grafted brushes. Structure definition by extreme ultraviolet (EUV) exposure allowed nanometer-scale resolution of periodic patterns. By variation of the exposure dose the height of the grafted structures can be adapted in a wide range. Derivatization of the grafted brushes included reaction with various amines with different side chains, hydrolysis of the epoxide to diols to increase protein resistance and introduction of ionic groups to yield poly-electrolytes. As an example for biofunctionalization, biotin was linked to the grafted brush and biofunctionality was demonstrated in a competitive biotin-streptavidin assay. In this article we also present a brief review of other approaches to obtain structured biofunctional polymer brushes.
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Affiliation(s)
- Celestino Padeste
- Laboratory for Micro- and Nanotechnology, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland.
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Neuhaus S, Spencer ND, Padeste C. Anisotropic wetting of microstructured surfaces as a function of surface chemistry. ACS Appl Mater Interfaces 2012; 4:123-130. [PMID: 22148671 DOI: 10.1021/am201104q] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
In order to study the influence of surface chemistry on the wetting of structured surfaces, microstructures consisting of grooves or squares were produced via hot embossing of poly(ethylene-alt-tetrafluoroethylene) ETFE substrates. The structured substrates were modified with polymer brushes, thereby changing their surface functionality and wettability. Water droplets were most strongly pinned to the structure when the surface was moderately hydrophilic, as in the case of poly(4-vinylpyridine) (P4VP) or poly(vinyl(N-methyl-2-pyridone) (PVMP) brush-modified substrates. As a result, the droplet shape was determined by the features of the microstructure. The water contact angles (CA) were considerably higher than on flat surfaces and differed, in the most extreme case, by 37° when measured on grooved substrates, parallel and perpendicular to the grooves. On hydrophobic substrates (pristine ETFE), the same effects were observed but were much less pronounced. On very hydrophilic sampes (those modified with poly(N-methyl-vinylpyridinium) (QP4VP)), the microstructure had no influence on the drop shape. These findings are explained by significant differences in apparent and real contact angles at the relatively smooth edges of the embossed structures. Finally, the highly anisotropic grooved microstructure was combined with a gradient in polymer brush composition and wettability. In the case of a parallel alignment of the gradient direction to the grooves, the directed spreading of water droplets could be observed.
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Affiliation(s)
- Sonja Neuhaus
- Laboratory for Micro- and Nanotechnology, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland
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Althaus J, Padeste C, Köser J, Pieles U, Peters K, Müller B. Nanostructuring polyetheretherketone for medical implants. European Journal of Nanomedicine 2012. [DOI: 10.1515/ejnm-2011-0001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Neuhaus S, Padeste C, Spencer ND. Versatile wettability gradients prepared by chemical modification of polymer brushes on polymer foils. Langmuir 2011; 27:6855-6861. [PMID: 21568351 DOI: 10.1021/la2005908] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
A method to create a wettability gradient by variation of the chemical functionality in a polymer brush is presented. A poly(N-methyl-vinylpyridinium) (QP4VP) brush was created on a poly(ethylene-alt-tetrafluoroethylene) (ETFE) foil by the grafting of 4-vinylpyridine and subsequent quaternization. The instability of QP4VP, a strong polyelectrolyte, in alkaline media was exploited to transform it to the neutral poly(vinyl(N-methyl-2-pyridone)) (PVMP), as confirmed with ATR-IR spectroscopy. The slow transformation resulted in a substantial, time-dependent decrease in wettability. A nearly linear gradient in water contact angle (CA) was created by immersion of a QP4VP brush modified sample into a sodium hydroxide solution, resulting in CAs ranging from 10° to 60°. The concurrent decrease in the number of charged functional groups along the gradient was characterized by loading an anionic dye into the polymer brush and measuring the UV transmittance of the sample. The versatility of the wettability gradient was demonstrated by exchanging the counterions of the N-methyl-vinylpyridinium groups, whereby a reversal of gradient direction was reproducibly achieved.
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Affiliation(s)
- Sonja Neuhaus
- Laboratory for Micro- and Nanotechnology, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland
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Herzen J, Donath T, Pfeiffer F, Bunk O, Padeste C, Beckmann F, Schreyer A, David C. Quantitative phase-contrast tomography of a liquid phantom using a conventional x-ray tube source. Opt Express 2009; 17:10010-8. [PMID: 19506651 DOI: 10.1364/oe.17.010010] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Over the last few years, differential phase-contrast x-ray computed tomography (PC-CT) using a hard x-ray grating interferometer and polychromatic x-ray tube sources has been developed. The method allows for simultaneous determination of the attenuation coefficient and the refractive index decrement distribution inside an object in three dimensions. Here we report experimental results of our investigation on the quantitativeness and accuracy of this method. For this study, a phantom consisting of several tubes filled with chemically well-defined liquids was built and measured in PC-CT. We find, that the measured attenuation coefficients and refractive index decrements closely match calculated, theoretical values. Moreover, the study demonstrates, how substances with similar attenuation coefficient or refractive index decrement, can be uniquely distinguished by the simultaneous, quantitative measurement of both quantities.
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Bunk O, Satapathy DK, Pfeiffera F, Diaza A, David C, Nygård K, Perret E, Padeste C, Willmott PR, Patterson BD, Schmitt B, van der Veen FJ. Concentration Profiles of Colloidal Fluids in One-Dimensional Confinement. Chimia (Aarau) 2008. [DOI: 10.2533/chimia.2008.789] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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Farquet P, Padeste C, Solak HH, Gürsel SA, Scherer GG, Wokaun A. Extreme UV Radiation Grafting of Glycidyl Methacrylate Nanostructures onto Fluoropolymer Foils by RAFT-Mediated Polymerization. Macromolecules 2008. [DOI: 10.1021/ma800202b] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Patrick Farquet
- Laboratory of Micro- and Nanotechnology and Laboratory of Electrochemistry, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland
| | - Celestino Padeste
- Laboratory of Micro- and Nanotechnology and Laboratory of Electrochemistry, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland
| | - Harun H. Solak
- Laboratory of Micro- and Nanotechnology and Laboratory of Electrochemistry, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland
| | - Selmiye Alkan Gürsel
- Laboratory of Micro- and Nanotechnology and Laboratory of Electrochemistry, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland
| | - Günther G. Scherer
- Laboratory of Micro- and Nanotechnology and Laboratory of Electrochemistry, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland
| | - Alexander Wokaun
- Laboratory of Micro- and Nanotechnology and Laboratory of Electrochemistry, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland
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Bunk O, Diaz A, Pfeiffer F, David C, Padeste C, Keymeulen H, Willmott PR, Patterson BD, Schmitt B, Satapathy DK, van der Veen JF, Guo H, Wegdam GH. Confinement-induced liquid ordering investigated by x-ray phase retrieval. Phys Rev E Stat Nonlin Soft Matter Phys 2007; 75:021501. [PMID: 17358342 DOI: 10.1103/physreve.75.021501] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2006] [Revised: 10/30/2006] [Indexed: 05/14/2023]
Abstract
Using synchrotron x-ray diffraction, we have determined the ensemble-averaged density profile of colloidal fluids within confining channels of different widths. We observe an oscillatory ordering-disordering behavior of the colloidal particles as a function of the channel width, while the colloidal solution remains in the liquid state. This phenomenon has been suggested by surface force studies of hard-sphere fluids and also theoretically predicted, but here we see it by direct measurements of the structure for comparable systems.
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Affiliation(s)
- Oliver Bunk
- Research Department Synchrotron Radiation and Nanotechnology, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland.
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Park S, Padeste C, Schift H, Gobrecht J, Scharf T. Chemical Nanopatterns via Nanoimprint Lithography for Simultaneous Control over Azimuthal and Polar Alignment of Liquid Crystals. Adv Mater 2005; 17:1398-1401. [PMID: 34412443 DOI: 10.1002/adma.200400989] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2004] [Accepted: 03/09/2005] [Indexed: 06/13/2023]
Abstract
Chemical nanopatterns down to 50 nm in feature size have been fabricated via nanoimprint lithography and used to simultaneously control azimuthal and polar orientation of liquid crystals (LCs). The polar orientation depends on the ratio of the homeotropic/planar surface potential areas, while the LC azimuthally orients along the direction of the silane patterns.
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Affiliation(s)
- S Park
- Laboratory for Micro- and Nanotechnology, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
- Present address: Mechanical Engineering Department, Louisiana State University Baton Rouge, LA 70803, USA
| | - C Padeste
- Laboratory for Micro- and Nanotechnology, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - H Schift
- Laboratory for Micro- and Nanotechnology, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - J Gobrecht
- Laboratory for Micro- and Nanotechnology, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - T Scharf
- Institute for Microtechnology, Rue A.-L. Breguet 2, CH-2000 Neuchâtel, Switzerland
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Padeste C, Steiger B, Grubelnik A, Tiefenauer L. Molecular assembly of redox-conductive ferrocene–streptavidin conjugates — towards bio-electrochemical devices. Biosens Bioelectron 2004; 20:545-52. [PMID: 15494238 DOI: 10.1016/j.bios.2004.03.004] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2004] [Revised: 03/02/2004] [Accepted: 03/04/2004] [Indexed: 11/15/2022]
Abstract
Peptidic spacers, 0.4 and 2 nm in length, were used to couple ferrocene moieties to streptavidin. The resulting conjugates were immobilised on electrode surfaces using biotin binding. The electron transfer through multilayers of the conjugates is strongly dependent on the length of the spacer between the protein and the attached ferrocene. A monolayer of the long-linker conjugate immobilised on interdigitated microelectrode arrays was found to electrochemically bridge the 2 microm wide non-conductive gap between the electrodes. The redox current through the layer is dependent on external parameters such as the applied voltage difference between the two electrode arrays or the temperature. The long-range electrochemical conductivity in combination with the biotin binding capability is a prerequisite for the application of the conjugates in future bio-electrochemical devices.
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Affiliation(s)
- Celestino Padeste
- Laboratory for Micro- and Nanotechnology, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland.
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Stamou D, Musil C, Ulrich WP, Leufgen K, Padeste C, David C, Gobrecht J, Duschl C, Vogel H. Site-directed molecular assembly on templates structured with electron-beam lithography. Langmuir 2004; 20:3495-7. [PMID: 15875370 DOI: 10.1021/la049954j] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
We describe a simple method for patterning biomolecular films on surfaces with high resolution. A conventional polymeric resist is structured by electron-beam lithography. The exposed and developed patterns are then used for the directed self-assembly (SA) of a first molecule from solution. Removal of the remaining resist allows the SA of a second species. We illustrate the potential of the approach by assembling on gold (Au) substrates two alkanethiols of contrasting terminal functionality. The patterns have dimensions from the micrometer range down to 40 nm and an edge resolution of 3.5 nm.
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Affiliation(s)
- D Stamou
- Institut de Science Biomoléculaire, ISB-VO, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland.
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Brack HP, Padeste C, Slaski M, Alkan S, Solak HH. Preparation of Micro- and Nanopatterns of Polymer Chains Grafted onto Flexible Polymer Substrates. J Am Chem Soc 2004; 126:1004-5. [PMID: 14746452 DOI: 10.1021/ja0379870] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In this work a simple novel method for preparing micro- and nanoscale patterns of polymer chains grafted onto flexible polymer substrates is described. A combination of the two techniques of radiation grafting and "grafting-from" has been made. This combination makes it possible to prepare grafted structures having micro- or nanoscale lateral dimensions that are determined by the electron beam or X-ray irradiation patterns used. The height of the grafted features can be controlled by the irradiation dose or such grafting reaction conditions as time, temperature, or monomer concentration. Our first results for nanopatterned samples demonstrate resolution comparable to those of other polymer-based lithography processes.
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Affiliation(s)
- Hans-Peter Brack
- Electrochemistry Laboratory, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland.
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Abstract
Conjugates of avidin with ferrocene and with microperoxidase 8 have been used as electrochemically active molecular building blocks. Assemblies of the conjugates with biotinylated glucose oxidase or lactate oxidase on gold electrodes were tested as enzyme sensors for glucose and lactate. The electrochemical detection is based either on ferrocene-mediated oxidation of the substrate in oxygen-free solution, or on microperoxidase-catalysed reduction of H2O2 which is enzymatically produced from the substrate and molecular oxygen. Glucose and lactate were detectable with both detection principles in concentrations down to 1 or 0.1 mM, respectively. The molecular architecture concept allows quick adaptation of the sensors to other analytes, and it provides a platform for arrays of sensors with different selectivity.
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Affiliation(s)
- Celestino Padeste
- Laboratory for Micro- and Nanotechnology, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland.
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Steiger B, Padeste C, Grubelnik A, Tiefenauer L. Charge transport effects in ferrocene–streptavidin multilayers immobilized on electrode surfaces. Electrochim Acta 2003. [DOI: 10.1016/s0013-4686(02)00746-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Abstract
Standard positive photoresist techniques were adapted to generate micropatterns of proteins on glass and oxide surfaces. Both lift-off and plasma-etching techniques were used to transfer the photoresist pattern into a layer of covalently immobilised protein. The surface properties of the areas adjacent to the patterns were altered by chemical surface modification. Using a combination of the lift-off and the etching process complementary patterns of two different proteins were generated. The biochemical and biological functionality of the protein patterns were assessed by immunostaining and by investigating the outgrowth of neurites from neurons plated on the patterned substrates. The investigated patterning processes are compatible with microstructuring and thin film processes, and may be used to generate functional surfaces for sensor and neuron culture applications.
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Affiliation(s)
- Helga Sorribas
- Laboratory for Micro- and Nanotechnology, Paul Scherrer Institut, Villigen, Switzerland
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Abstract
Coupling of ferrocene moieties to avidin via a flexible spacer molecule yields a conjugate which combines the unique biotin-binding properties of avidin with the reversible redox characteristics of ferrocenes. Synthesis of the conjugate has been optimised and the conjugates were characterised bio- and electrochemically. Covalent immobilisation of the conjugate on gold electrodes in a dense monolayer results in electrodes with a high binding capacity for biotinylated molecules as well as good electron transfer properties. The application potential of such electrodes for bioelectrochemical systems is demonstrated by electrochemical reduction of hydrogen peroxide under mild conditions catalysed by a bound biotin-microperoxidase MP11 conjugate.
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Affiliation(s)
- C Padeste
- Laboratory for Micro- and Nanotechnology, Paul Scherrer Institut, Villigen PSI, Switzerland.
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Sorribas H, Padeste C, Mezzacasa T, Tiefenauer L, Leder L, Fitzli D, Sonderegger P. Neurite outgrowth on microstructured surfaces functionalized by a neural adhesion protein. J Mater Sci Mater Med 1999; 10:787-791. [PMID: 15347952 DOI: 10.1023/a:1008955101492] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Designed networks of neurons are potentially very useful to investigate neural activities. Using photolithography microgrooves suited in size for single neurons have been produced on glass chips. Two conducting gold lanes ending in each microgroove allow extracelluar stimulation of the neurons and recording of their activity. A cell adhesive surface was created by functionalization of glass with the adhesion peptide RGDC. In addition, in order to optimize the contact of the neuronal cell membrane to the electrode surface axonin-1, a specific neural adhesion protein was used. A recombinant form of axonin-1 was produced and immobilized in a correct orientation on protected gold surfaces through a C-terminal cysteine residue. Neurite outgrowth of neurons cultured on chips derivatized with RGDC or axonin-1 were compared. The developed materials and methods represent a first step towards establishing designed functionalized glass surfaces for neurophysiological investigations.
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Affiliation(s)
- H Sorribas
- Micro- and Nanotechnology, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
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Tiefenauer L, Padeste C. Micro- and Nanotechnology in Biosensor Research. Chimia (Aarau) 1999. [DOI: 10.2533/chimia.1999.62] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Biosensor research is strongly interdisciplinary as it requires experience in chemistry, biochemistry, biology, material science, electronics and engineering. The recent progress in micro- and nanotechnology allows to miniaturize complex systems as well as to address problems at a molecular level. The architecture and even the function of single molecules on a sensor surface have been investigated and can to some extent even be predetermined. At present, microtechnology is well established in the production of micro-fluid transport systems and has a high potential for cell-culturing and monitoring devices in the future.Three different running projects are presented which illustrate the usefulness of micro- and nanotechnology for biosensor research: 1) Investigations on amperometric immunosensor devices, 2) the measurement of binding forces of individual antigen-antibody pairs, and 3) the fabrication of microchannels suitable for neuron-cell growth and recording. Big efforts, however, will be required to integrate the recognition element of a sensor into a device for an intended application
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Abstract
In contrast to optical immunosensors, the electrochemical detection of an immunanalytical reaction does require a labeling, but allows an easier discrimination of specific and non-specific binding. We present a concept and first results for a multivalent amperometric immunosensor system which is based on silicon technology. The capture molecule streptavidin, covalently immobilized on silica, allows the immobilization of biotinylated antigens at a defined density. A nanostructured gold electrode serving as a stable network of nanowires is expected to be beneficial for the electrochemical detection of bound ferrocene-labeled antibody molecules. The results presented focus on site-specific immobilization of streptavidin on silica and reduction of non-specific binding of proteins.
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Affiliation(s)
- L X Tiefenauer
- Paul Scherrer Institut, Micro- and Nanostructures Laboratory, Villigen, Switzerland.
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