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Pankratov D, Hidalgo Martinez S, Karman C, Gerzhik A, Gomila G, Trashin S, Boschker HTS, Geelhoed JS, Mayer D, De Wael K, J R Meysman F. The organo-metal-like nature of long-range conduction in cable bacteria. Bioelectrochemistry 2024; 157:108675. [PMID: 38422765 DOI: 10.1016/j.bioelechem.2024.108675] [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] [Received: 10/31/2023] [Revised: 02/22/2024] [Accepted: 02/24/2024] [Indexed: 03/02/2024]
Abstract
Cable bacteria are filamentous, multicellular microorganisms that display an exceptional form of biological electron transport across centimeter-scale distances. Currents are guided through a network of nickel-containing protein fibers within the cell envelope. Still, the mechanism of long-range conduction remains unresolved. Here, we characterize the conductance of the fiber network under dry and wet, physiologically relevant, conditions. Our data reveal that the fiber conductivity is high (median value: 27 S cm-1; range: 2 to 564 S cm-1), does not show any redox signature, has a low thermal activation energy (Ea = 69 ± 23 meV), and is not affected by humidity or the presence of ions. These features set the nickel-based conduction mechanism in cable bacteria apart from other known forms of biological electron transport. As such, conduction resembles that of an organic semi-metal with a high charge carrier density. Our observation that biochemistry can synthesize an organo-metal-like structure opens the way for novel bio-based electronic technologies.
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Affiliation(s)
- Dmitrii Pankratov
- Geobiology Group, Microbial Systems Technology Excellence Centre, Department of Biology, University of Antwerp, Universiteitsplein 1, B-2610 Wilrijk, Belgium; A-Sense Lab, Department of Bioscience Engineering, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerpen, Belgium
| | - Silvia Hidalgo Martinez
- Geobiology Group, Microbial Systems Technology Excellence Centre, Department of Biology, University of Antwerp, Universiteitsplein 1, B-2610 Wilrijk, Belgium
| | - Cheryl Karman
- Geobiology Group, Microbial Systems Technology Excellence Centre, Department of Biology, University of Antwerp, Universiteitsplein 1, B-2610 Wilrijk, Belgium; A-Sense Lab, Department of Bioscience Engineering, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerpen, Belgium
| | - Anastasia Gerzhik
- Institute of Biological Information Processing, Bioelectronics (IBI-3), Forschungszentrum Jülich, 52428 Jülich, Germany
| | - Gabriel Gomila
- Nanoscale Bioelectric Characterization Group, Institute for Bioengineering of Catalunya (IBEC), The Barcelona Institute of Science and Technology, Baldiri i Reixac 15-21, 08028 Barcelona, Spain; Department of Electronics and Biomedical Engineering, Universitat de Barcelona, Martí i Franqués 1, 08028 Barcelona, Spain
| | - Stanislav Trashin
- A-Sense Lab, Department of Bioscience Engineering, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerpen, Belgium
| | - Henricus T S Boschker
- Geobiology Group, Microbial Systems Technology Excellence Centre, Department of Biology, University of Antwerp, Universiteitsplein 1, B-2610 Wilrijk, Belgium; Department of Biotechnology, Delft University of Technology, Van der Maasweg 9, 2629HZ Delft, the Netherlands
| | - Jeanine S Geelhoed
- Geobiology Group, Microbial Systems Technology Excellence Centre, Department of Biology, University of Antwerp, Universiteitsplein 1, B-2610 Wilrijk, Belgium
| | - Dirk Mayer
- Institute of Biological Information Processing, Bioelectronics (IBI-3), Forschungszentrum Jülich, 52428 Jülich, Germany
| | - Karolien De Wael
- A-Sense Lab, Department of Bioscience Engineering, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerpen, Belgium
| | - Filip J R Meysman
- Geobiology Group, Microbial Systems Technology Excellence Centre, Department of Biology, University of Antwerp, Universiteitsplein 1, B-2610 Wilrijk, Belgium; Department of Biotechnology, Delft University of Technology, Van der Maasweg 9, 2629HZ Delft, the Netherlands.
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2
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Tanwar S, Millan-Solsona R, Ruiz-Molina S, Mas-Torrent M, Kyndiah A, Gomila G. Nanoscale Operando Characterization of Electrolyte-Gated Organic Field-Effect Transistors Reveals Charge Transport Bottlenecks. Adv Mater 2023:e2309767. [PMID: 38110297 DOI: 10.1002/adma.202309767] [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] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Revised: 11/21/2023] [Indexed: 12/20/2023]
Abstract
Charge transport in electrolyte-gated organic field-effect transistors (EGOFETs) is governed by the microstructural property of the semiconducting thin film that is in direct contact with the electrolyte. Therefore, a comprehensive nanoscale operando characterization of the active channel is crucial to pinpoint various charge transport bottlenecks for rational and targeted optimization of the devices. Here, the local electrical properties of EGOFETs are systematically probed by in-liquid scanning dielectric microscopy (in-liquid SDM) and a direct picture of their functional mechanism at the nanoscale is provided across all operational regimes, starting from subthreshold, linear to saturation, until the onset of pinch-off. To this end, a robust interpretation framework of in-liquid SDM is introduced that enables quantitative local electric potential mapping directly from raw experimental data without requiring calibration or numerical simulations. Based on this development, a straightforward nanoscale assessment of various charge transport bottlenecks is performed, like contact access resistances, inter- and intradomain charge transport, microstructural inhomogeneities, and conduction anisotropy, which have been inaccessible earlier. Present results contribute to the fundamental understanding of charge transport in electrolyte-gated transistors and promote the development of direct structure-property-function relationships to guide future design rules.
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Affiliation(s)
- Shubham Tanwar
- Nanoscale Bioelectrical Characterization Group, Institut de Bioenginyeria de Catalunya (IBEC), The Barcelona Institute of Science and Technology (BIST), Carrer Baldiri i Reixac 11-15, Barcelona, 08028, Spain
| | - Ruben Millan-Solsona
- Nanoscale Bioelectrical Characterization Group, Institut de Bioenginyeria de Catalunya (IBEC), The Barcelona Institute of Science and Technology (BIST), Carrer Baldiri i Reixac 11-15, Barcelona, 08028, Spain
- Department d'Enginyeria Electrònica i Biomèdica, Universitat de Barcelona, Carrer Martí i Franquès, 1, Barcelona, 08028, Spain
| | - Sara Ruiz-Molina
- Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus UAB Cerdanyola del Vallès, Barcelona, 08193, Spain
| | - Marta Mas-Torrent
- Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus UAB Cerdanyola del Vallès, Barcelona, 08193, Spain
| | - Adrica Kyndiah
- Center for Nano Science and Technology, Istituto Italiano di Tecnologia, Via Rubattino 81, Milano, 20134, Italy
| | - Gabriel Gomila
- Nanoscale Bioelectrical Characterization Group, Institut de Bioenginyeria de Catalunya (IBEC), The Barcelona Institute of Science and Technology (BIST), Carrer Baldiri i Reixac 11-15, Barcelona, 08028, Spain
- Department d'Enginyeria Electrònica i Biomèdica, Universitat de Barcelona, Carrer Martí i Franquès, 1, Barcelona, 08028, Spain
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Huetter L, Kyndiah A, Gomila G. Analytical Physical Model for Electrolyte Gated Organic Field Effect Transistors in the Helmholtz Approximation. Advcd Theory and Sims 2023. [DOI: 10.1002/adts.202200696] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/25/2023]
Affiliation(s)
- Larissa Huetter
- Nanoscale Bioelectric Characterization Group Institute for Bioengineering of Catalunya Baldiri i Reixac 15‐21 Barcelona 08028 Spain
| | - Adrica Kyndiah
- Center for Nano Science and Technology Instituto Italiano di Tecnologia Via Pascoli, 70/3 Milano 20133 Italy
| | - Gabriel Gomila
- Nanoscale Bioelectric Characterization Group Institute for Bioengineering of Catalunya Baldiri i Reixac 15‐21 Barcelona 08028 Spain
- Department of Electronics and Biomedical Engineering University of Barcelona Martí i Franqués 1 Barcelona 08028 Spain
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4
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Dols-Perez A, Fornaguera C, Feiner-Gracia N, Grijalvo S, Solans C, Gomila G. Effect of surface functionalization and loading on the mechanical properties of soft polymeric nanoparticles prepared by nano-emulsion templating. Colloids Surf B Biointerfaces 2023; 222:113019. [PMID: 36435028 DOI: 10.1016/j.colsurfb.2022.113019] [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] [Received: 07/29/2022] [Revised: 11/03/2022] [Accepted: 11/10/2022] [Indexed: 11/13/2022]
Abstract
Drug and gene delivery systems based on polymeric nanoparticles offer a greater efficacy and a reduced toxicity compared to traditional formulations. Recent studies have evidenced that their internalization, biodistribution and efficacy can be affected, among other factors, by their mechanical properties. Here, we analyze by means of Atomic Force Microscopy force spectroscopy how composition, surface functionalization and loading affect the mechanics of nanoparticles. For this purpose, nanoparticles made of Poly(lactic-co-glycolic) (PLGA) and Ethyl cellulose (EC) with different functionalizations and loading were prepared by nano-emulsion templating using the Phase Inversion Composition method (PIC) to form the nano-emulsions. A multiparametric nanomechanical study involving the determination of the Young's modulus, maximum deformation and breakthrough force was carried out. The obtained results showed that composition, surface functionalization and loading affect the nanomechanical properties in a different way, thus requiring, in general, to consider the overall mechanical properties after the addition of a functionalization or loading. A graphical representation method has been proposed enabling to easily identify mechanically equivalent formulations, which is expected to be useful in the development of soft polymeric nanoparticles for pre-clinical and clinical use.
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Affiliation(s)
- Aurora Dols-Perez
- Institute of Advanced Chemistry of Catalonia (IQAC-CSIC), C/Jordi Girona 18-26, 08034 Barcelona, Spain; Biomedical Research Networking Center in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Spain; Institut de Bioenginyeria de Catalunya (IBEC), C/ Balidiri i Reixac 15-21, 08028 Barcelona, Spain; Departament of Electronics and Biomedical Engineering, Universitat de Barcelona, C/ Martí i Franquès 1, 08028 Barcelona, Spain.
| | - Cristina Fornaguera
- Institute of Advanced Chemistry of Catalonia (IQAC-CSIC), C/Jordi Girona 18-26, 08034 Barcelona, Spain; Biomedical Research Networking Center in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Spain; Grup d'Enginyeria de Materials (Gemat) - Institut Químic de Sarrià (IQS) - Universitat Ramon Llull (URL), Barcelona, Spain
| | - Natalia Feiner-Gracia
- Institute of Advanced Chemistry of Catalonia (IQAC-CSIC), C/Jordi Girona 18-26, 08034 Barcelona, Spain; Biomedical Research Networking Center in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Spain
| | - Santiago Grijalvo
- Institute of Advanced Chemistry of Catalonia (IQAC-CSIC), C/Jordi Girona 18-26, 08034 Barcelona, Spain; Biomedical Research Networking Center in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Spain
| | - Conxita Solans
- Institute of Advanced Chemistry of Catalonia (IQAC-CSIC), C/Jordi Girona 18-26, 08034 Barcelona, Spain; Biomedical Research Networking Center in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Spain
| | - Gabriel Gomila
- Institut de Bioenginyeria de Catalunya (IBEC), C/ Balidiri i Reixac 15-21, 08028 Barcelona, Spain; Departament of Electronics and Biomedical Engineering, Universitat de Barcelona, C/ Martí i Franquès 1, 08028 Barcelona, Spain
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5
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Huetter L, Kyndiah A, Gomila G. Analytical Physical Model for Organic Metal‐Electrolyte‐Semiconductor Capacitors. Advcd Theory and Sims 2022. [DOI: 10.1002/adts.202200698] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- Larissa Huetter
- Nanoscale Bioelectric Characterization Group Institute for Bioengineering of Catalunya (IBEC), The Barcelona Institute of Science and Technology (BIST) Baldiri i Reixac 15‐21 Barcelona 08028 Spain
| | - Adrica Kyndiah
- Center for Nano Science and Technology Instituto Italiano di Tecnologia Via Pascoli, 70/3 Milano 20133 Italy
| | - Gabriel Gomila
- Nanoscale Bioelectric Characterization Group Institute for Bioengineering of Catalunya (IBEC), The Barcelona Institute of Science and Technology (BIST) Baldiri i Reixac 15‐21 Barcelona 08028 Spain
- Department of Electronics and Biomedical Engineering Universitat de Barcelona Martí i Franqués, 1 Barcelona 08028 Spain
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Checa M, Jin X, Millan-Solsona R, Neumayer SM, Susner MA, McGuire MA, O'Hara A, Gomila G, Maksymovych P, Pantelides ST, Collins L. Revealing Fast Cu-Ion Transport and Enhanced Conductivity at the CuInP 2S 6-In 4/3P 2S 6 Heterointerface. ACS Nano 2022; 16:15347-15357. [PMID: 35998341 DOI: 10.1021/acsnano.2c06992] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Van der Waals layered ferroelectrics, such as CuInP2S6 (CIPS), offer a versatile platform for miniaturization of ferroelectric device technologies. Control of the targeted composition and kinetics of CIPS synthesis enables the formation of stable self-assembled heterostructures of ferroelectric CIPS and nonferroelectric In4/3P2S6 (IPS). Here, we use quantitative scanning probe microscopy methods combined with density functional theory (DFT) to explore in detail the nanoscale variability in dynamic functional properties of the CIPS-IPS heterostructure. We report evidence of fast ionic transport which mediates an appreciable out-of-plane electromechanical response of the CIPS surface in the paraelectric phase. Further, we map the nanoscale dielectric and ionic conductivity properties as we thermally stimulate the ferroelectric-paraelectric phase transition, recovering the local dielectric behavior during this phase transition. Finally, aided by DFT, we reveal a substantial and tunable conductivity enhancement at the CIPS/IPS interface, indicating the possibility of engineering its interfacial properties for next generation device applications.
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Affiliation(s)
- Marti Checa
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Xin Jin
- Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235, United States
- Institute of Physics and University of the Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100190, China
| | - Ruben Millan-Solsona
- Institut de Bioenginyeria de Catalunya (IBEC), The Barcelona Institute of Science and Technology (BIST), c/Baldiri i Reixac 11-15, 08028 Barcelona, Spain
- Departament d'Enginyeria Electrònica i Biomèdica, Universitat de Barcelona, Martí i Franqués 1, 08028 Barcelona, Spain
| | - Sabine M Neumayer
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Michael A Susner
- Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433, United States
| | - Michael A McGuire
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Andrew O'Hara
- Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Gabriel Gomila
- Institut de Bioenginyeria de Catalunya (IBEC), The Barcelona Institute of Science and Technology (BIST), c/Baldiri i Reixac 11-15, 08028 Barcelona, Spain
- Departament d'Enginyeria Electrònica i Biomèdica, Universitat de Barcelona, Martí i Franqués 1, 08028 Barcelona, Spain
| | - Petro Maksymovych
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Sokrates T Pantelides
- Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235, United States
- Department of Electrical and Computer Engineering, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Liam Collins
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
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7
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Lozano H, Millan-Solsona R, Blanco-Cabra N, Fabregas R, Torrents E, Gomila G. Electrical properties of outer membrane extensions from Shewanella oneidensis MR-1. Nanoscale 2021; 13:18754-18762. [PMID: 34747424 DOI: 10.1039/d1nr04689f] [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] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Shewanella oneidensis MR-1 is a metal-reducing bacterium that is able to exchange electrons with solid-phase minerals outside the cell. These bacterial cells can produce outer membrane extensions (OMEs) that are tens of nanometers wide and several microns long. The capability of these OMEs to transport electrons is currently under investigation. Tubular chemically fixed OMEs from S. oneidensis have shown good dc conducting properties when measured in an air environment. However, no direct demonstration of the conductivity of the more common bubble-like OMEs has been provided yet, due to the inherent difficulties in measuring it. In the present work, we measured the electrical properties of bubble-like OMEs in a dry air environment by Scanning Dielectric Microscopy (SDM) in force detection mode. We found that at the frequency of the measurements (∼2 kHz), OMEs show an insulating behavior, with an equivalent homogeneous dielectric constant εOME = 3.7 ± 0.7 and no dephasing between the applied ac voltage and the measured ac electric force. The dielectric constant measured for the OMEs is comparable to that obtained for insulating supramolecular protein structures (εprotein = 3-4), pointing towards a rich protein composition of the OMEs, probably coming from the periplasm. Based on the detection sensitivity of the measuring instrument, the upper limit for the ac longitudinal conductivity of bubble-like OMEs in a dry air environment has been set to σOME,ac < 10-5 S m-1, a value several orders of magnitude smaller than the dc conductivity measured in tubular chemically fixed OMEs. The lack of conductivity of bubble-like OMEs can be attributed to the relatively large separation between cytochromes in these larger OMEs and to the suppression of cytochrome mobility due to the dry environmental conditions.
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Affiliation(s)
- Helena Lozano
- Nanoscale bioelectric characterization, Institut de Bioenginyeria de Catalunya (IBEC), The Barcelona Institute of Science and Technology (BIST), c/Baldiri i Reixac 11-15, 08028, Barcelona, Spain.
| | - Ruben Millan-Solsona
- Nanoscale bioelectric characterization, Institut de Bioenginyeria de Catalunya (IBEC), The Barcelona Institute of Science and Technology (BIST), c/Baldiri i Reixac 11-15, 08028, Barcelona, Spain.
- Departament d'Enginyeria Electrònica i Biomèdica, Universitat de Barcelona, c/Martí i Franqués 1, 08028, Barcelona, Spain
| | - Nuria Blanco-Cabra
- Bacterial infections and antimicrobial therapies, Institut de Bioenginyeria de Catalunya (IBEC), The Barcelona Institute of Science and Technology (BIST), c/Baldiri i Reixac 11-15, 08028, Barcelona, Spain
| | - Rene Fabregas
- Department of Physics and Astronomy, University of Manchester, Manchester M13 9PL, UK
| | - Eduard Torrents
- Bacterial infections and antimicrobial therapies, Institut de Bioenginyeria de Catalunya (IBEC), The Barcelona Institute of Science and Technology (BIST), c/Baldiri i Reixac 11-15, 08028, Barcelona, Spain
- Departament de Genètica, Microbiologia i Estadística, Universitat de Barcelona, Av. Diagonal 643, 08028, Barcelona, Spain
| | - Gabriel Gomila
- Nanoscale bioelectric characterization, Institut de Bioenginyeria de Catalunya (IBEC), The Barcelona Institute of Science and Technology (BIST), c/Baldiri i Reixac 11-15, 08028, Barcelona, Spain.
- Departament d'Enginyeria Electrònica i Biomèdica, Universitat de Barcelona, c/Martí i Franqués 1, 08028, Barcelona, Spain
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Checa M, Millan-Solsona R, Mares AG, Pujals S, Gomila G. Fast Label-Free Nanoscale Composition Mapping of Eukaryotic Cells Via Scanning Dielectric Force Volume Microscopy and Machine Learning. Small Methods 2021; 5:e2100279. [PMID: 34928004 DOI: 10.1002/smtd.202100279] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Revised: 04/28/2021] [Indexed: 06/14/2023]
Abstract
Mapping the biochemical composition of eukaryotic cells without the use of exogenous labels is a long-sought objective in cell biology. Recently, it has been shown that composition maps on dry single bacterial cells with nanoscale spatial resolution can be inferred from quantitative nanoscale dielectric constant maps obtained with the scanning dielectric microscope. Here, it is shown that this approach can also be applied to the much more challenging case of fixed and dry eukaryotic cells, which are highly heterogeneous and show micrometric topographic variations. More importantly, it is demonstrated that the main bottleneck of the technique (the long computation times required to extract the nanoscale dielectric constant maps) can be shortcut by using supervised neural networks, decreasing them from weeks to seconds in a wokstation computer. This easy-to-use data-driven approach opens the door for in situ and on-the-fly label free nanoscale composition mapping of eukaryotic cells with scanning dielectric microscopy.
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Affiliation(s)
- Martí Checa
- Nanoscale Bioelectrical Characterization Group, Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology (BIST), Carrer Baldiri i Reixac 11-15, Barcelona, 08028, Spain
| | - Ruben Millan-Solsona
- Nanoscale Bioelectrical Characterization Group, Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology (BIST), Carrer Baldiri i Reixac 11-15, Barcelona, 08028, Spain
- Departament d'Enginyeria Electrònica i Biomèdica, Universitat de Barcelona, Carrer Martí i Franquès 1, Barcelona, 08028, Spain
| | - Adrianna Glinkowska Mares
- Nanoscopy for Nanomedicine Group, Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology (BIST), Carrer Baldiri i Reixac 11-15, Barcelona, 08028, Spain
| | - Silvia Pujals
- Departament d'Enginyeria Electrònica i Biomèdica, Universitat de Barcelona, Carrer Martí i Franquès 1, Barcelona, 08028, Spain
- Nanoscopy for Nanomedicine Group, Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology (BIST), Carrer Baldiri i Reixac 11-15, Barcelona, 08028, Spain
| | - Gabriel Gomila
- Nanoscale Bioelectrical Characterization Group, Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology (BIST), Carrer Baldiri i Reixac 11-15, Barcelona, 08028, Spain
- Departament d'Enginyeria Electrònica i Biomèdica, Universitat de Barcelona, Carrer Martí i Franquès 1, Barcelona, 08028, Spain
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9
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Balakrishnan H, Millan-Solsona R, Checa M, Fabregas R, Fumagalli L, Gomila G. Depth mapping of metallic nanowire polymer nanocomposites by scanning dielectric microscopy. Nanoscale 2021; 13:10116-10126. [PMID: 34060583 DOI: 10.1039/d1nr01058a] [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] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Polymer nanocomposite materials based on metallic nanowires are widely investigated as transparent and flexible electrodes or as stretchable conductors and dielectrics for biosensing. Here we show that Scanning Dielectric Microscopy (SDM) can map the depth distribution of metallic nanowires within the nanocomposites in a non-destructive way. This is achieved by a quantitative analysis of sub-surface electrostatic force microscopy measurements with finite-element numerical calculations. As an application we determined the three-dimensional spatial distribution of ∼50 nm diameter silver nanowires in ∼100 nm-250 nm thick gelatin films. The characterization is done both under dry ambient conditions, where gelatin shows a relatively low dielectric constant, εr∼ 5, and under humid ambient conditions, where its dielectric constant increases up to εr∼ 14. The present results show that SDM can be a valuable non-destructive subsurface characterization technique for nanowire-based nanocomposite materials, which can contribute to the optimization of these materials for applications in fields such as wearable electronics, solar cell technologies or printable electronics.
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Affiliation(s)
- Harishankar Balakrishnan
- Institut de Bioenginyeria de Catalunya (IBEC), The Barcelona Institute of Science and Technology (BIST), c/Baldiri i Reixac 11-15, 08028, Barcelona, Spain.
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10
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Di Muzio M, Millan-Solsona R, Dols-Perez A, Borrell JH, Fumagalli L, Gomila G. Dielectric properties and lamellarity of single liposomes measured by in-liquid scanning dielectric microscopy. J Nanobiotechnology 2021; 19:167. [PMID: 34082783 PMCID: PMC8176598 DOI: 10.1186/s12951-021-00912-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [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: 03/05/2021] [Accepted: 05/25/2021] [Indexed: 12/31/2022] Open
Abstract
Liposomes are widely used as drug delivery carriers and as cell model systems. Here, we measure the dielectric properties of individual liposomes adsorbed on a metal electrode by in-liquid scanning dielectric microscopy in force detection mode. From the measurements the lamellarity of the liposomes, the separation between the lamellae and the specific capacitance of the lipid bilayer can be obtained. As application we considered the case of non-extruded DOPC liposomes with radii in the range ~ 100-800 nm. Uni-, bi- and tri-lamellar liposomes have been identified, with the largest population corresponding to bi-lamellar liposomes. The interlamellar separation in the bi-lamellar liposomes is found to be below ~ 10 nm in most instances. The specific capacitance of the DOPC lipid bilayer is found to be ~ 0.75 µF/cm2 in excellent agreement with the value determined on solid supported planar lipid bilayers. The lamellarity of the DOPC liposomes shows the usual correlation with the liposome's size. No correlation is found, instead, with the shape of the adsorbed liposomes. The proposed approach offers a powerful label-free and non-invasive method to determine the lamellarity and dielectric properties of single liposomes.
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Affiliation(s)
- Martina Di Muzio
- Institut de Bioenginyeria de Catalunya (IBEC), The Barcelona Institute of Science and Technology (BIST), c/Baldiri i Reixac 11-15, 08028, Barcelona, Spain
| | - Ruben Millan-Solsona
- Institut de Bioenginyeria de Catalunya (IBEC), The Barcelona Institute of Science and Technology (BIST), c/Baldiri i Reixac 11-15, 08028, Barcelona, Spain.,Departament D'Enginyeria Electrònica I Biomèdica, Universitat de Barcelona, C/Martí i Franqués 1, 08028, Barcelona, Spain
| | - Aurora Dols-Perez
- Institut de Bioenginyeria de Catalunya (IBEC), The Barcelona Institute of Science and Technology (BIST), c/Baldiri i Reixac 11-15, 08028, Barcelona, Spain
| | - Jordi H Borrell
- Secció de Fisicoquímica, Facultat de Farmàcia I Ciències de L'Alimentació, Universitat de Barcelona, Av. Diagonal, 643, 08028, Barcelona, Spain
| | - Laura Fumagalli
- Department of Physics and Astronomy, University of Manchester, Manchester, M13 9PL, UK.,National Graphene Institute, University of Manchester, Manchester, M13 9PL, UK
| | - Gabriel Gomila
- Institut de Bioenginyeria de Catalunya (IBEC), The Barcelona Institute of Science and Technology (BIST), c/Baldiri i Reixac 11-15, 08028, Barcelona, Spain. .,Departament D'Enginyeria Electrònica I Biomèdica, Universitat de Barcelona, C/Martí i Franqués 1, 08028, Barcelona, Spain.
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11
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Checa M, Millan-Solsona R, Glinkowska Mares A, Pujals S, Gomila G. Dielectric Imaging of Fixed HeLa Cells by In-Liquid Scanning Dielectric Force Volume Microscopy. Nanomaterials (Basel) 2021; 11:1402. [PMID: 34070690 PMCID: PMC8226567 DOI: 10.3390/nano11061402] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 05/21/2021] [Accepted: 05/23/2021] [Indexed: 01/16/2023]
Abstract
Mapping the dielectric properties of cells with nanoscale spatial resolution can be an important tool in nanomedicine and nanotoxicity analysis, which can complement structural and mechanical nanoscale measurements. Recently we have shown that dielectric constant maps can be obtained on dried fixed cells in air environment by means of scanning dielectric force volume microscopy. Here, we demonstrate that such measurements can also be performed in the much more challenging case of fixed cells in liquid environment. Performing the measurements in liquid media contributes to preserve better the structure of the fixed cells, while also enabling accessing the local dielectric properties under fully hydrated conditions. The results shown in this work pave the way to address the nanoscale dielectric imaging of living cells, for which still further developments are required, as discussed here.
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Affiliation(s)
- Martí Checa
- Nanoscale Bioelectric Characterization, Institut de Bioenginyeria de Catalunya (IBEC), The Barcelona Institute of Science and Technology (BIST), c/Baldiri I Reixac 11-15, 08028 Barcelona, Spain;
| | - Ruben Millan-Solsona
- Nanoscale Bioelectric Characterization, Institut de Bioenginyeria de Catalunya (IBEC), The Barcelona Institute of Science and Technology (BIST), c/Baldiri I Reixac 11-15, 08028 Barcelona, Spain;
- Departament d’Enginyeria Electrònica i Biomèdica, Universitat de Barcelona, c/Martí i Franquès 1, 08028 Barcelona, Spain;
| | - Adrianna Glinkowska Mares
- Nanoscopy for Nanomedicine, Institut de Bioenginyeria de Catalunya (IBEC), The Barcelona Institute of Science and Technology (BIST), c/Baldiri I Reixac 11-15, 08028 Barcelona, Spain;
| | - Silvia Pujals
- Departament d’Enginyeria Electrònica i Biomèdica, Universitat de Barcelona, c/Martí i Franquès 1, 08028 Barcelona, Spain;
- Nanoscopy for Nanomedicine, Institut de Bioenginyeria de Catalunya (IBEC), The Barcelona Institute of Science and Technology (BIST), c/Baldiri I Reixac 11-15, 08028 Barcelona, Spain;
| | - Gabriel Gomila
- Nanoscale Bioelectric Characterization, Institut de Bioenginyeria de Catalunya (IBEC), The Barcelona Institute of Science and Technology (BIST), c/Baldiri I Reixac 11-15, 08028 Barcelona, Spain;
- Departament d’Enginyeria Electrònica i Biomèdica, Universitat de Barcelona, c/Martí i Franquès 1, 08028 Barcelona, Spain;
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12
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Muzio MD, Millan-Solsona R, Borrell JH, Fumagalli L, Gomila G. Cholesterol Effect on the Specific Capacitance of Submicrometric DOPC Bilayer Patches Measured by in-Liquid Scanning Dielectric Microscopy. Langmuir 2020; 36:12963-12972. [PMID: 33084346 DOI: 10.1021/acs.langmuir.0c02251] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The specific capacitance of biological membranes is a key physical parameter in bioelectricity that also provides valuable physicochemical information on composition, phase, or hydration properties. Cholesterol is known to modulate the physicochemical properties of biomembranes, but its effect on the specific capacitance has not been fully established yet. Here we use the high spatial resolution capabilities of in-liquid scanning dielectric microscopy in force detection mode to directly demonstrate that DOPC bilayer patches at 50% cholesterol concentration show a strong reduction of their specific capacitance with respect to pure DOPC bilayer patches. The reduction observed (∼35%) cannot be explained by the small increase in bilayer thickness (∼16%). We suggest that the reduction of the specific capacitance might be due to the dehydration of the polar head groups caused by the insertion of cholesterol molecules in the bilayer. The results reported confirm the potential of in-liquid SDM to study the electrical and physicochemical properties of lipid bilayers at very small scales (down to ∼200 nm here), with implications in fields such as biophysics, bioelectricity, biochemistry, and biosensing.
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Affiliation(s)
- Martina Di Muzio
- Nanoscale Bioelectrical Characterization, Institut de Bioenginyeria de Catalunya, The Barcelona Institute of Science and Technology, 08028 Barcelona, Spain
| | - Ruben Millan-Solsona
- Nanoscale Bioelectrical Characterization, Institut de Bioenginyeria de Catalunya, The Barcelona Institute of Science and Technology, 08028 Barcelona, Spain
| | | | | | - Gabriel Gomila
- Nanoscale Bioelectrical Characterization, Institut de Bioenginyeria de Catalunya, The Barcelona Institute of Science and Technology, 08028 Barcelona, Spain
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13
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Millan-Solsona R, Checa M, Fumagalli L, Gomila G. Mapping the capacitance of self-assembled monolayers at metal/electrolyte interfaces at the nanoscale by in-liquid scanning dielectric microscopy. Nanoscale 2020; 12:20658-20668. [PMID: 33043923 DOI: 10.1039/d0nr05723a] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Organic self-assembled monolayers (SAMs) at metal/electrolyte interfaces have been thoroughly investigated both from fundamental and applied points of view. A relevant figure of merit of metal/SAM/electrolyte interfaces is the specific capacitance, which determines the charge that can be accumulated at the metal electrode. Here, we show that the specific capacitance of non-uniform alkanethiol SAMs at gold/electrolyte interfaces can be quantitatively measured and mapped at the nanoscale by in-liquid scanning dielectric microscopy in force detection mode. We show that sub-100 nm spatial resolution in ultrathin (<1 nm) SAMs can be achieved, largely improving the performance of current sensing characterization techniques. The present results provide access to study the dielectric properties of metal/SAM/electrolyte interfaces at scales that have remained unexplored until now.
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Affiliation(s)
- Ruben Millan-Solsona
- Institut de Bioenginyeria de Catalunya (IBEC), The Barcelona Institute of Science and Technology, c/Baldiri i Reixac 11-15, 08028, Barcelona, Spain. and Departament d'Enginyeria Electrònica i Biomèdica, Universitat de Barcelona, C/Martí i Franquès 1, 08028, Barcelona, Spain
| | - Martí Checa
- Institut de Bioenginyeria de Catalunya (IBEC), The Barcelona Institute of Science and Technology, c/Baldiri i Reixac 11-15, 08028, Barcelona, Spain.
| | - Laura Fumagalli
- Department of Physics and Astronomy, University of Manchester, Manchester M13 9PL, UK and National Graphene Institute, University of Manchester, Manchester M13 9PL, UK
| | - Gabriel Gomila
- Institut de Bioenginyeria de Catalunya (IBEC), The Barcelona Institute of Science and Technology, c/Baldiri i Reixac 11-15, 08028, Barcelona, Spain. and Departament d'Enginyeria Electrònica i Biomèdica, Universitat de Barcelona, C/Martí i Franquès 1, 08028, Barcelona, Spain
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14
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Kyndiah A, Leonardi F, Tarantino C, Cramer T, Millan-Solsona R, Garreta E, Montserrat N, Mas-Torrent M, Gomila G. Bioelectronic Recordings of Cardiomyocytes with Accumulation Mode Electrolyte Gated Organic Field Effect Transistors. Biosens Bioelectron 2020; 150:111844. [DOI: 10.1016/j.bios.2019.111844] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2019] [Revised: 10/29/2019] [Accepted: 11/01/2019] [Indexed: 10/25/2022]
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15
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Checa M, Millan-Solsona R, Blanco N, Torrents E, Fabregas R, Gomila G. Mapping the dielectric constant of a single bacterial cell at the nanoscale with scanning dielectric force volume microscopy. Nanoscale 2019; 11:20809-20819. [PMID: 31657419 DOI: 10.1039/c9nr07659j] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Mapping the dielectric constant at the nanoscale of samples showing a complex topography, such as non-planar nanocomposite materials or single cells, poses formidable challenges to existing nanoscale dielectric microscopy techniques. Here we overcome these limitations by introducing Scanning Dielectric Force Volume Microscopy. This scanning probe microscopy technique is based on the acquisition of electrostatic force approach curves at every point of a sample and its post-processing and quantification by using a computational model that incorporates the actual measured sample topography. The technique provides quantitative nanoscale images of the local dielectric constant of the sample with unparalleled accuracy, spatial resolution and statistical significance, irrespectively of the complexity of its topography. We illustrate the potential of the technique by presenting a nanoscale dielectric constant map of a single bacterial cell, including its small-scale appendages. The bacterial cell shows three characteristic equivalent dielectric constant values, namely, εr,bac1 = 2.6 ± 0.2, εr,bac2 = 3.6 ± 0.4 and εr,bac3 = 4.9 ± 0.5, which enable identifying different dielectric properties of the cell wall and of the cytoplasmatic region, as well as, the existence of variations in the dielectric constant along the bacterial cell wall itself. Scanning Dielectric Force Volume Microscopy is expected to have an important impact in Materials and Life Sciences where the mapping of the dielectric properties of samples showing complex nanoscale topographies is often needed.
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Affiliation(s)
- Martí Checa
- Nanoscale Bioelectrical Characterization, Institut de Bioenginyeria de Catalunya (IBEC), The Barcelona Institute of Science and Technology, c/Baldiri i Reixac 11-15, 08028, Barcelona, Spain. and Departament d'Enginyeria Electrònica i Biomèdica, Universitat de Barcelona, c/Martí i Franquès 1, 08028, Barcelona, Spain
| | - Ruben Millan-Solsona
- Nanoscale Bioelectrical Characterization, Institut de Bioenginyeria de Catalunya (IBEC), The Barcelona Institute of Science and Technology, c/Baldiri i Reixac 11-15, 08028, Barcelona, Spain. and Departament d'Enginyeria Electrònica i Biomèdica, Universitat de Barcelona, c/Martí i Franquès 1, 08028, Barcelona, Spain
| | - Nuria Blanco
- Bacterial Infections: Antimicrobial Therapies, Institut de Bioenginyeria de Catalunya (IBEC), The Barcelona Institute of Science and Technology, c/Baldiri i Reixac 11-15, 08028, Barcelona
| | - Eduard Torrents
- Bacterial Infections: Antimicrobial Therapies, Institut de Bioenginyeria de Catalunya (IBEC), The Barcelona Institute of Science and Technology, c/Baldiri i Reixac 11-15, 08028, Barcelona
| | - Rene Fabregas
- Departament d'Enginyeria Electrònica i Biomèdica, Universitat de Barcelona, c/Martí i Franquès 1, 08028, Barcelona, Spain
| | - Gabriel Gomila
- Nanoscale Bioelectrical Characterization, Institut de Bioenginyeria de Catalunya (IBEC), The Barcelona Institute of Science and Technology, c/Baldiri i Reixac 11-15, 08028, Barcelona, Spain. and Departament d'Enginyeria Electrònica i Biomèdica, Universitat de Barcelona, c/Martí i Franquès 1, 08028, Barcelona, Spain
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16
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Checa M, Millan-Solsona R, Gomila G. Frequency-dependent force between ac-voltage-biased plates in electrolyte solutions. Phys Rev E 2019; 100:022604. [PMID: 31574759 DOI: 10.1103/physreve.100.022604] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Indexed: 12/26/2022]
Abstract
We analyze the frequency dependence of the force between ac-voltage-biased plates in electrolyte solutions. To this end we solve analytically the Poisson-Nernst-Planck transport model in the dilute concentration and low voltage regime for a 1:1 symmetric electrolyte with blocking electrodes under a dc+ac applied voltage. The total force, which is the resultant of the electric and osmotic forces, shows a complex dependence on plate separation, frequency, ion concentration, and compact layer properties, different from that predicted from electrostatic current models or equivalent circuit models, due to the relevance of the osmotic force contribution in almost the whole range of frequencies. For the total dc force, we show that it decays at fixed ion concentration, linearly with plate separation for separations larger than a few times the Debye screening length. This linear dependence is due to the assumption about the conservation of the number of ions in the system. Moreover, the 1ω and 2ω ac harmonics of the total force show a broad peak at intermediate frequencies; it is centered at about the inverse of the charging time of the double layer capacitance, and covers the frequency range between the inverse of the diffusion time and the inverse of the electrolyte dielectric relaxation time. Finally, the 1ω ac harmonic component attains its high frequency asymptotic value at frequencies much higher than the inverse of the electrolyte dielectric relaxation time due to the very slow relaxation of the osmotic 1ω harmonic component at high frequencies. The derived analytical expressions for the total force remain valid up to voltages of the order of the thermal voltage, as has been assessed by means of numerical calculations. The numerical calculations are also used to explore the onset of higher force harmonics for larger applied voltages. Understanding the frequency dependence of the force acting on voltage-biased plates in electrolyte solutions can be of relevance for electrical actuation strategies in microelectromechanical systems and for the interpretation of some emerging electric scanning probe force microscopy techniques operating in electrolyte solutions.
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Affiliation(s)
- M Checa
- Institut de Bioenginyeria de Catalunya (IBEC), c/ Baldiri i Reixac 11-15, 08028, Barcelona, Spain
| | - R Millan-Solsona
- Institut de Bioenginyeria de Catalunya (IBEC), c/ Baldiri i Reixac 11-15, 08028, Barcelona, Spain
| | - G Gomila
- Institut de Bioenginyeria de Catalunya (IBEC), c/ Baldiri i Reixac 11-15, 08028, Barcelona, Spain.,Departament d'Enginyeria Electrònica i Biomèdica, Universitat de Barcelona, C/ Martí i Franquès 1, 08028, Barcelona, Spain
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17
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Dols-Perez A, Fumagalli L, Gomila G. Interdigitation in spin-coated lipid layers in air. Colloids Surf B Biointerfaces 2018; 172:400-406. [PMID: 30195157 DOI: 10.1016/j.colsurfb.2018.08.041] [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] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Revised: 08/14/2018] [Accepted: 08/19/2018] [Indexed: 10/28/2022]
Abstract
In this study, we show that dry saturated phospholipid layers prepared by the spin-coating technique could present thinner regions associated to interdigitated phases under some conditions. The morphological characteristics of lipid layers of saturated phosphocholines, such as dilauroylphosphatidylcholine (DLPC), dimyristoylphosphatidylcholine (DMPC), dipalmitoylphosphatidylcholine (DPPC) and distearoylphosphatidylcholine (DSPC), have been measured by Atomic Force Microscopy and revealed that the presence of interdigitated regions is not induced by the same parameters that induce them in hydrated samples. To achieve these results the effect of the lipid hidrocabonated chain length, the presence of alcohol in the coating solution, the spinning velocity and the presence of cholesterol were tested. We showed that DPPC and DSPC bilayers, on the one side, can show structures with similar height than interdigitated regions observed in hydrated samples, while, on the other side, DLPC and DMPC tend to show no evidence of interdigitation. Results indicate that the presence of interdigitated areas is due to the presence of lateral tensions and, hence, that they can be eliminated by releasing these tensions by, for instance, the addition of cholesterol. These results demonstrate that interdigitation in lipid layers is a rather general phenomena and can be observed in lipid bilayers in dry conditions.
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Affiliation(s)
- Aurora Dols-Perez
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Van der Maasweg 9, 2629 HZ, Delft, Netherlands.
| | - Laura Fumagalli
- School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester, M13 9PL, United Kingdom
| | - Gabriel Gomila
- Institut de Bioenginyeria de Catalunya (IBEC), C/ Baldiri i Reixac 15-21, 08028, Barcelona, Spain; Departament d'Enginyeria Electrònica i Biomèdica, Universitat de Barcelona, C/ Martí i Franquès 1, 08028, Barcelona, Spain
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18
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Lozano H, Fabregas R, Blanco-Cabra N, Millán-Solsona R, Torrents E, Fumagalli L, Gomila G. Dielectric constant of flagellin proteins measured by scanning dielectric microscopy. Nanoscale 2018; 10:19188-19194. [PMID: 30302472 DOI: 10.1039/c8nr06190d] [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] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The dielectric constant of flagellin proteins in flagellar bacterial filaments ∼10-20 nm in diameter is measured using scanning dielectric microscopy. We obtained for two different bacterial species (Shewanella oneidensis MR-1 and Pseudomonas aeruginosa PAO1) similar relative dielectric constant values εSo = 4.3 ± 0.6 and εPa = 4.5 ± 0.7, respectively, despite their different structure and amino acid sequence. The present results show the applicability of scanning dielectric microscopy to nanoscale filamentous protein complexes and to general 3D macromolecular protein geometries, thus opening new avenues to study the relationship between the dielectric response and protein structure and function.
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Affiliation(s)
- Helena Lozano
- Nanoscale Bioelectrical Characterization, Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology (BIST), c/ Baldiri i Reixac 11-15, 08028, Barcelona, Spain.
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19
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Fumagalli L, Esfandiar A, Fabregas R, Hu S, Ares P, Janardanan A, Yang Q, Radha B, Taniguchi T, Watanabe K, Gomila G, Novoselov KS, Geim AK. Anomalously low dielectric constant of confined water. Science 2018; 360:1339-1342. [PMID: 29930134 DOI: 10.1126/science.aat4191] [Citation(s) in RCA: 416] [Impact Index Per Article: 69.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2018] [Accepted: 05/03/2018] [Indexed: 01/02/2023]
Abstract
The dielectric constant ε of interfacial water has been predicted to be smaller than that of bulk water (ε ≈ 80) because the rotational freedom of water dipoles is expected to decrease near surfaces, yet experimental evidence is lacking. We report local capacitance measurements for water confined between two atomically flat walls separated by various distances down to 1 nanometer. Our experiments reveal the presence of an interfacial layer with vanishingly small polarization such that its out-of-plane ε is only ~2. The electrically dead layer is found to be two to three molecules thick. These results provide much-needed feedback for theories describing water-mediated surface interactions and the behavior of interfacial water, and show a way to investigate the dielectric properties of other fluids and solids under extreme confinement.
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Affiliation(s)
- L Fumagalli
- School of Physics and Astronomy, University of Manchester, Manchester M13 9PL, UK. .,National Graphene Institute, University of Manchester, Manchester M13 9PL, UK
| | - A Esfandiar
- Department of Physics, Sharif University of Technology, P.O. Box 11155-9161, Tehran, Iran
| | - R Fabregas
- Departament d'Electrònica, Universitat de Barcelona, C/ Martí i Franquès 1, 08028 Barcelona, Spain.,Institut de Bioenginyeria de Catalunya, Barcelona Institute of Science and Technology, C/ Baldiri i Reixac 15-21, 08028 Barcelona, Spain
| | - S Hu
- School of Physics and Astronomy, University of Manchester, Manchester M13 9PL, UK.,National Graphene Institute, University of Manchester, Manchester M13 9PL, UK
| | - P Ares
- School of Physics and Astronomy, University of Manchester, Manchester M13 9PL, UK.,National Graphene Institute, University of Manchester, Manchester M13 9PL, UK
| | - A Janardanan
- School of Physics and Astronomy, University of Manchester, Manchester M13 9PL, UK.,National Graphene Institute, University of Manchester, Manchester M13 9PL, UK
| | - Q Yang
- School of Physics and Astronomy, University of Manchester, Manchester M13 9PL, UK.,National Graphene Institute, University of Manchester, Manchester M13 9PL, UK
| | - B Radha
- School of Physics and Astronomy, University of Manchester, Manchester M13 9PL, UK.,National Graphene Institute, University of Manchester, Manchester M13 9PL, UK
| | - T Taniguchi
- National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - K Watanabe
- National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - G Gomila
- Departament d'Electrònica, Universitat de Barcelona, C/ Martí i Franquès 1, 08028 Barcelona, Spain.,Institut de Bioenginyeria de Catalunya, Barcelona Institute of Science and Technology, C/ Baldiri i Reixac 15-21, 08028 Barcelona, Spain
| | - K S Novoselov
- School of Physics and Astronomy, University of Manchester, Manchester M13 9PL, UK.,National Graphene Institute, University of Manchester, Manchester M13 9PL, UK
| | - A K Geim
- School of Physics and Astronomy, University of Manchester, Manchester M13 9PL, UK. .,National Graphene Institute, University of Manchester, Manchester M13 9PL, UK
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20
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Biagi MC, Badino G, Fabregas R, Gramse G, Fumagalli L, Gomila G. Direct mapping of the electric permittivity of heterogeneous non-planar thin films at gigahertz frequencies by scanning microwave microscopy. Phys Chem Chem Phys 2018; 19:3884-3893. [PMID: 28106185 DOI: 10.1039/c6cp08215g] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We obtained maps of electric permittivity at ∼19 GHz frequencies on non-planar thin film heterogeneous samples by means of combined atomic force-scanning microwave microscopy (AFM-SMM). We show that the electric permittivity maps can be obtained directly from the capacitance images acquired in contact mode, after removing the topographic cross-talk effects. This result demonstrates the possibility of identifying the electric permittivity of different materials in a thin film sample irrespectively of their thickness by just direct imaging and processing. We show, in addition, that quantitative maps of the electric permittivity can be obtained with no need for any theoretical calculation or complex quantification procedures when the electric permittivity of one of the materials is known. To achieve these results the use of contact mode imaging is a key factor. For non-contact imaging modes the effects of local sample thickness and of the imaging distance make the interpretation of the capacitance images in terms of the electric permittivity properties of the materials much more complex. The present results represent a substantial contribution to the field of nanoscale microwave dielectric characterization of thin film materials with important implications for the characterization of novel 3D electronic devices and 3D nanomaterials.
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Affiliation(s)
- Maria Chiara Biagi
- Institut de Bioenginyeria de Catalunya (IBEC), c/Baldiri i Reixac 11-15, 08028, Barcelona, Spain.
| | - Giorgio Badino
- Keysight Technologies Austria GmbH, Keysight Lab, Gruberst. 40, 4020-Linz, Austria
| | - Rene Fabregas
- Institut de Bioenginyeria de Catalunya (IBEC), c/Baldiri i Reixac 11-15, 08028, Barcelona, Spain. and Departament d'Enginyeries: Electrònica, Universitat de Barcelona, C/Martí i Franqués 1, 08028, Barcelona, Spain
| | - Georg Gramse
- Johannes Kepler University Linz, Institute for Biophysics, Gruberst. 40, 4020-Linz, Austria
| | - Laura Fumagalli
- School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Gabriel Gomila
- Institut de Bioenginyeria de Catalunya (IBEC), c/Baldiri i Reixac 11-15, 08028, Barcelona, Spain. and Departament d'Enginyeries: Electrònica, Universitat de Barcelona, C/Martí i Franqués 1, 08028, Barcelona, Spain
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21
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Van Der Hofstadt M, Fabregas R, Millan-Solsona R, Juarez A, Fumagalli L, Gomila G. Internal Hydration Properties of Single Bacterial Endospores Probed by Electrostatic Force Microscopy. ACS Nano 2016; 10:11327-11336. [PMID: 28024372 DOI: 10.1021/acsnano.6b06578] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [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: 05/14/2023]
Abstract
We show that the internal hydration properties of single Bacillus cereus endospores in air under different relative humidity (RH) conditions can be determined through the measurement of its electric permittivity by means of quantitative electrostatic force microscopy (EFM). We show that an increase in the RH from 0% to 80% induces a large increase in the equivalent homogeneous relative electric permittivity of the bacterial endospores, from ∼4 up to ∼17, accompanied only by a small increase in the endospore height, of just a few nanometers. These results correlate the increase of the moisture content of the endospore with the corresponding increase of environmental RH. Three-dimensional finite element numerical calculations, which include the internal structure of the endospores, indicate that the moisture is mainly accumulated in the external layers of the endospore, hence preserving the core of the endospore at low hydration levels. This mechanism is different from what we observe for vegetative bacterial cells of the same species, in which the cell wall at high humid atmospheric conditions is not able to preserve the cytoplasmic region at low hydration levels. These results show the potential of quantitative EFM under environmental humidity control to study the hygroscopic properties of small-scale biological (and nonbiological) entities and to determine its internal hydration state. A better understanding of nanohygroscopic properties can be of relevance in the study of essential biological processes and in the design of bionanotechnological applications.
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Affiliation(s)
- Marc Van Der Hofstadt
- Institut de Bioenginyeria de Catalunya (IBEC) , c/Baldiri i Reixac 11-15, Barcelona 08028, Spain
- Departament d'Enginyeries: Electrònica, Universitat de Barcelona , C/Martí i Franqués 1, Barcelona 08028, Spain
| | - Rene Fabregas
- Institut de Bioenginyeria de Catalunya (IBEC) , c/Baldiri i Reixac 11-15, Barcelona 08028, Spain
- Departament d'Enginyeries: Electrònica, Universitat de Barcelona , C/Martí i Franqués 1, Barcelona 08028, Spain
| | - Ruben Millan-Solsona
- Institut de Bioenginyeria de Catalunya (IBEC) , c/Baldiri i Reixac 11-15, Barcelona 08028, Spain
| | - Antonio Juarez
- Institut de Bioenginyeria de Catalunya (IBEC) , c/Baldiri i Reixac 11-15, Barcelona 08028, Spain
- Departament de Microbiologia, Universitat de Barcelona , Av. Diagonal 643, Barcelona 08028, Spain
| | - Laura Fumagalli
- School of Physics and Astronomy, University of Manchester , Oxford Road, Manchester M13 9PL, United Kingdom
| | - Gabriel Gomila
- Institut de Bioenginyeria de Catalunya (IBEC) , c/Baldiri i Reixac 11-15, Barcelona 08028, Spain
- Departament d'Enginyeries: Electrònica, Universitat de Barcelona , C/Martí i Franqués 1, Barcelona 08028, Spain
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22
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Van Der Hofstadt M, Fabregas R, Biagi MC, Fumagalli L, Gomila G. Nanoscale dielectric microscopy of non-planar samples by lift-mode electrostatic force microscopy. Nanotechnology 2016; 27:405706. [PMID: 27597315 DOI: 10.1088/0957-4484/27/40/405706] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Lift-mode electrostatic force microscopy (EFM) is one of the most convenient imaging modes to study the local dielectric properties of non-planar samples. Here we present the quantitative analysis of this imaging mode. We introduce a method to quantify and subtract the topographic crosstalk from the lift-mode EFM images, and a 3D numerical approach that allows for extracting the local dielectric constant with nanoscale spatial resolution free from topographic artifacts. We demonstrate this procedure by measuring the dielectric properties of micropatterned SiO2 pillars and of single bacteria cells, thus illustrating the wide applicability of our approach from materials science to biology.
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Affiliation(s)
- M Van Der Hofstadt
- Institut de Bioenginyeria de Catalunya (IBEC), C/Baldiri i Reixac 11-15, E-08028, Barcelona, Spain. Departament d'Enginyeries: Electrònica, Universitat de Barcelona, C/Martí i Franqués 1, E-08028, Barcelona, Spain
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Biagi MC, Fabregas R, Gramse G, Van Der Hofstadt M, Juárez A, Kienberger F, Fumagalli L, Gomila G. Nanoscale Electric Permittivity of Single Bacterial Cells at Gigahertz Frequencies by Scanning Microwave Microscopy. ACS Nano 2016; 10:280-8. [PMID: 26643251 DOI: 10.1021/acsnano.5b04279] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [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: 05/22/2023]
Abstract
We quantified the electric permittivity of single bacterial cells at microwave frequencies and nanoscale spatial resolution by means of near-field scanning microwave microscopy. To this end, calibrated complex admittance images have been obtained at ∼19 GHz and analyzed with a methodology that removes the nonlocal topographic cross-talk contributions and thus provides quantifiable intrinsic dielectric images of the bacterial cells. Results for single Escherichia coli cells provide a relative electric permittivity of ∼4 in dry conditions and ∼20 in humid conditions, with no significant loss contributions. Present findings, together with the ability of microwaves to penetrate the cell membrane, open an important avenue in the microwave label-free imaging of single cells with nanoscale spatial resolution.
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Affiliation(s)
- Maria Chiara Biagi
- Institut de Bioenginyeria de Catalunya (IBEC), c/Baldiri i Reixac 11-15, 08028 Barcelona, Spain
| | - Rene Fabregas
- Institut de Bioenginyeria de Catalunya (IBEC), c/Baldiri i Reixac 11-15, 08028 Barcelona, Spain
| | - Georg Gramse
- Institute for Biophysics, Johannes Kepler University Linz , Gruberst. 40, 4020 Linz, Austria
| | - Marc Van Der Hofstadt
- Institut de Bioenginyeria de Catalunya (IBEC), c/Baldiri i Reixac 11-15, 08028 Barcelona, Spain
| | - Antonio Juárez
- Institut de Bioenginyeria de Catalunya (IBEC), c/Baldiri i Reixac 11-15, 08028 Barcelona, Spain
- Departament de Microbiologia, Universitat de Barcelona , Av. Diagonal 643, 08028 Barcelona, Spain
| | - Ferry Kienberger
- Keysight Lab, Keysight Technologies Austria GmbH , Gruberst. 40, 4020 Linz, Austria
| | - Laura Fumagalli
- School of Physics and Astronomy, University of Manchester , Oxford Road, Manchester M13 9PL, United Kingdom
| | - Gabriel Gomila
- Institut de Bioenginyeria de Catalunya (IBEC), c/Baldiri i Reixac 11-15, 08028 Barcelona, Spain
- Departament d'Electrònica, Universitat de Barcelona , C/Martí i Franqués 1, 08028 Barcelona, Spain
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Dols-Perez A, Gramse G, Calò A, Gomila G, Fumagalli L. Nanoscale electric polarizability of ultrathin biolayers on insulating substrates by electrostatic force microscopy. Nanoscale 2015; 7:18327-18336. [PMID: 26488226 DOI: 10.1039/c5nr04983k] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We measured and quantified the local electric polarization properties of ultrathin (∼5 nm) biolayers on mm-thick mica substrates. We achieved it by scanning a sharp conductive tip (<10 nm radius) of an electrostatic force microscope over the biolayers and quantifying sub-picoNewton electric polarization forces with a sharp-tip model implemented using finite-element numerical calculations. We obtained relative dielectric constants εr = 3.3, 2.4 and 1.9 for bacteriorhodopsin, dioleoylphosphatidylcholine (DOPC) and cholesterol layers, chosen as representative of the main cell membrane components, with an error below 10% and a spatial resolution down to ∼50 nm. The ability of using insulating substrates common in biophysics research, such as mica or glass, instead of metallic substrates, offers both a general platform to determine the dielectric properties of biolayers and a wider compatibility with other characterization techniques, such as optical microscopy. This opens up new possibilities for biolayer research at the nanoscale, including nanoscale label-free composition mapping.
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Affiliation(s)
- A Dols-Perez
- Institut de Química Avançada de Catalunya (IQAC-CSIC), C/Jordi Girona 18-26, 08034, Barcelona, Spain and CIBER of Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Barcelona, Spain
| | - G Gramse
- Johannes Kepler University Linz, Institute for Biophysics, Gruberst. 40, 4020-Linz, Austria
| | - A Calò
- CIC NanoGUNE Consolider, E-20018 Donostia San Sebastian, Spain
| | - G Gomila
- Nanobioelec group, Institut de Bioenginyeria de Catalunya (IBEC), Baldiri i Reixac 15-21, 08028-Barcelona, Spain and Departament d'Electrònica, Universitat de Barcelona, C/Martí i Franquès 1, 08028 Barcelona, Spain
| | - L Fumagalli
- School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester, M13 9PL, UK.
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Van Der Hofstadt M, Hüttener M, Juárez A, Gomila G. Nanoscale imaging of the growth and division of bacterial cells on planar substrates with the atomic force microscope. Ultramicroscopy 2015; 154:29-36. [PMID: 25791909 DOI: 10.1016/j.ultramic.2015.02.018] [Citation(s) in RCA: 9] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Revised: 02/27/2015] [Accepted: 02/28/2015] [Indexed: 02/05/2023]
Abstract
With the use of the atomic force microscope (AFM), the Nanomicrobiology field has advanced drastically. Due to the complexity of imaging living bacterial processes in their natural growing environments, improvements have come to a standstill. Here we show the in situ nanoscale imaging of the growth and division of single bacterial cells on planar substrates with the atomic force microscope. To achieve this, we minimized the lateral shear forces responsible for the detachment of weakly adsorbed bacteria on planar substrates with the use of the so called dynamic jumping mode with very soft cantilever probes. With this approach, gentle imaging conditions can be maintained for long periods of time, enabling the continuous imaging of the bacterial cell growth and division, even on planar substrates. Present results offer the possibility to observe living processes of untrapped bacteria weakly attached to planar substrates.
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Affiliation(s)
- M Van Der Hofstadt
- Institut de Bioenginyeria de Catalunya (IBEC), C/ Baldiri i Reixac 11-15, 08028 Barcelona, Spain
| | - M Hüttener
- Institut de Bioenginyeria de Catalunya (IBEC), C/ Baldiri i Reixac 11-15, 08028 Barcelona, Spain; Departament de Microbiologia, Universitat de Barcelona, Avinguda Diagonal 645, 08028 Barcelona, Spain
| | - A Juárez
- Institut de Bioenginyeria de Catalunya (IBEC), C/ Baldiri i Reixac 11-15, 08028 Barcelona, Spain; Departament de Microbiologia, Universitat de Barcelona, Avinguda Diagonal 645, 08028 Barcelona, Spain
| | - G Gomila
- Institut de Bioenginyeria de Catalunya (IBEC), C/ Baldiri i Reixac 11-15, 08028 Barcelona, Spain; Departament d'Electronica, Universitat de Barcelona, C/ Marti i Franqués 1, 08028 Barcelona, Spain.
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Abstract
Electrostatic force microscopy (EFM) probes are typically coated in either metal (radius ∼ 30 nm) or highly-doped diamond (radius ∼ 100 nm). Highly-doped silicon probes, which offer a sharpened and stable tip apex (radius ∼ 1-10 nm) and are usually used only in standard atomic force microscopy, have been recently shown to allow enhanced lateral resolution in quantitative EFM and its application for dielectric constant measurement. Here we present the theoretical modelling required to quantitatively interpret the electrostatic force between these sharpened tips and samples. In contrast to a sphere-capped cone geometry used to describe metal/diamond-coated tips, modelling a sharpened silicon tip requires a geometry comprised of a cone with two different angles. Theoretical results are supported by experimental measurements of metallic substrates and ∼10 nm radius dielectric nanoparticles. This work is equally applicable to EFM and other electrical scanned probe techniques, where it allows quantifying electrical properties of nanomaterials and 3D nano-objects with higher resolution.
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Affiliation(s)
- L Fumagalli
- Nanobioelec Group, Institut de Bioenginyeria de Catalunya (IBEC), Universitat de Barcelona, C/Martí i Franquès 1, E-08028 Barcelona, Spain. Departament d'Electrònica, Universitat de Barcelona, C/Martí i Franquès 1, E-08028 Barcelona, Spain.
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Esteban-Ferrer D, Edwards MA, Fumagalli L, Juárez A, Gomila G. Electric polarization properties of single bacteria measured with electrostatic force microscopy. ACS Nano 2014; 8:9843-9. [PMID: 25184827 DOI: 10.1021/nn5041476] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [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: 05/06/2023]
Abstract
We quantified the electrical polarization properties of single bacterial cells using electrostatic force microscopy. We found that the effective dielectric constant, ε(r,eff), for the four bacterial types investigated (Salmonella typhimurium, Escherchia coli, Lactobacilus sakei, and Listeria innocua) is around 3-5 under dry air conditions. Under ambient humidity, it increases to ε(r,eff) ∼ 6-7 for the Gram-negative bacterial types (S. typhimurium and E. coli) and to ε(r,eff) ∼ 15-20 for the Gram-positive ones (L. sakei and L. innocua). We show that the measured effective dielectric constants can be consistently interpreted in terms of the electric polarization properties of the biochemical components of the bacterial cell compartments and of their hydration state. These results demonstrate the potential of electrical studies of single bacterial cells.
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Affiliation(s)
- Daniel Esteban-Ferrer
- Institut de Bioenginyeria de Catalunya (IBEC) , C/Baldiri i Reixac 11-15, 08028 Barcelona, Spain
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Gomila G, Gramse G, Fumagalli L. Finite-size effects and analytical modeling of electrostatic force microscopy applied to dielectric films. Nanotechnology 2014; 25:255702. [PMID: 24897410 DOI: 10.1088/0957-4484/25/25/255702] [Citation(s) in RCA: 9] [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] [Indexed: 05/06/2023]
Abstract
A numerical analysis of the polarization force between a sharp conducting probe and a dielectric film of finite lateral dimensions on a metallic substrate is presented with the double objective of (i) determining the conditions under which the film can be approximated by a laterally infinite film and (ii) proposing an analytical model valid in this limit. We show that, for a given dielectric film, the critical diameter above which the film can be modeled as laterally infinite depends not only on the probe geometry, as expected, but mainly on the film thickness. In particular, for films with intermediate to large thicknesses (>100 nm), the critical diameter is nearly independent from the probe geometry and essentially depends on the film thickness and dielectric constant following a relatively simple phenomenological expression. For films that can be considered as laterally infinite, we propose a generalized analytical model valid in the thin-ultrathin limit (<20-50 nm) that reproduces the numerical calculations and the experimental data. Present results provide a general framework under which accurate quantification of electrostatic force microscopy measurements on dielectric films on metallic substrates can be achieved.
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Affiliation(s)
- G Gomila
- Institut de Bioenginyeria de Catalunya (IBEC), C/Balidiri i Reixac 15-21, 08028 Barcelona, Spain. Departament d'Electrònica, Universitat de Barcelona, C/Martí i Franquès 1, 08028 Barcelona, Spain
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Gramse G, Kasper M, Fumagalli L, Gomila G, Hinterdorfer P, Kienberger F. Calibrated complex impedance and permittivity measurements with scanning microwave microscopy. Nanotechnology 2014; 25:145703. [PMID: 24633347 DOI: 10.1088/0957-4484/25/14/145703] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We present a procedure for calibrated complex impedance measurements and dielectric quantification with scanning microwave microscopy. The calibration procedure works in situ directly on the substrate with the specimen of interest and does not require any specific calibration sample. In the workflow tip-sample approach curves are used to extract calibrated complex impedance values and to convert measured S11 reflection signals into sample capacitance and resistance images. The dielectric constant of thin dielectric SiO2 films were determined from the capacitance images and approach curves using appropriate electrical tip-sample models and the εr value extracted at f = 19.81 GHz is in good agreement with the nominal value of εr ∼ 4. The capacitive and resistive material properties of a doped Si semiconductor sample were studied at different doping densities and tip-sample bias voltages. Following a simple serial model the capacitance-voltage spectroscopy curves are clearly related to the semiconductor depletion zone while the resistivity is rising with falling dopant density from 20 Ω to 20 kΩ. The proposed procedure of calibrated complex impedance measurements is simple and fast and the accuracy of the results is not affected by varying stray capacitances. It works for nanoscale samples on either fully dielectric or highly conductive substrates at frequencies between 1 and 20 GHz.
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Affiliation(s)
- G Gramse
- Johannes Kepler University of Linz, Institute for Biophysics, Gruberstrasse 40, A-4020 Linz, Austria
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Dols-Perez A, Fumagalli L, Gomila G. Structural and nanomechanical effects of cholesterol in binary and ternary spin-coated single lipid bilayers in dry conditions. Colloids Surf B Biointerfaces 2014; 116:295-302. [DOI: 10.1016/j.colsurfb.2013.12.049] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2013] [Revised: 11/26/2013] [Accepted: 12/21/2013] [Indexed: 12/24/2022]
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Calò A, Reguera D, Oncins G, Persuy MA, Sanz G, Lobasso S, Corcelli A, Pajot-Augy E, Gomila G. Force measurements on natural membrane nanovesicles reveal a composition-independent, high Young's modulus. Nanoscale 2014; 6:2275-2285. [PMID: 24407152 DOI: 10.1039/c3nr05107b] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Mechanical properties of nano-sized vesicles made up of natural membranes are crucial to the development of stable, biocompatible nanocontainers with enhanced functional, recognition and sensing capabilities. Here we measure and compare the mechanical properties of plasma and inner membrane nanovesicles ∼80 nm in diameter obtained from disrupted yeast Saccharomyces cerevisiae cells. We provide evidence of a highly deformable behaviour for these vesicles, able to support repeated wall-to-wall compressions without irreversible deformations, accompanied by a noticeably high Young's modulus (∼300 MPa) compared to that obtained for reconstituted artificial liposomes of similar size and approaching that of some virus particles. Surprisingly enough, the results are approximately similar for plasma and inner membrane nanovesicles, in spite of their different lipid compositions, especially on what concerns the ergosterol content. These results point towards an important structural role of membrane proteins in the mechanical response of natural membrane vesicles and open the perspective to their potential use as robust nanocontainers for bioapplications.
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Affiliation(s)
- Annalisa Calò
- IBEC Institute for Bioengineering of Catalonia, C/Baldiri Reixac 10-12, 08028, Barcelona, Spain.
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Gramse G, Dols-Pérez A, Edwards MA, Fumagalli L, Gomila G. Quantitative Dielectric Measurements of Biomembranes and Oxides in Electrolyte Solutions at High Frequencies. Biophys J 2014. [DOI: 10.1016/j.bpj.2013.11.2861] [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: 10/23/2022] Open
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Gomila G, Esteban-Ferrer D, Fumagalli L. Quantification of the dielectric constant of single non-spherical nanoparticles from polarization forces: eccentricity effects. Nanotechnology 2013; 24:505713. [PMID: 24284953 DOI: 10.1088/0957-4484/24/50/505713] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We analyze by means of finite-element numerical calculations the polarization force between a sharp conducting tip and a non-spherical uncharged dielectric nanoparticle with the objective of quantifying its dielectric constant from electrostatic force microscopy (EFM) measurements. We show that for an oblate spheroid nanoparticle of given height the strength of the polarization force acting on the tip depends linearly on the eccentricity, e, of the nanoparticle in the small eccentricity and low dielectric constant regimes (1 < e < 2 and 1 < ε(r) < 10), while for higher eccentricities (e > 2) the dependence is sub-linear and finally becomes independent of e for very large eccentricities (e > 30). These results imply that a precise account of the nanoparticle shape is required to quantify EFM data and obtain the dielectric constants of non-spherical dielectric nanoparticles. Experimental results obtained on polystyrene, silicon dioxide and aluminum oxide nanoparticles and on single viruses are used to illustrate the main findings.
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Affiliation(s)
- G Gomila
- Institut de Bioenginyeria de Catalunya (IBEC) , C/Balidiri i Reixac 15-21, E-08028 Barcelona, Spain. Departament d'Electrònica, Universitat de Barcelona, C/Martí i Franquès 1, E-08028 Barcelona, Spain
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Gramse G, Edwards MA, Fumagalli L, Gomila G. Theory of amplitude modulated electrostatic force microscopy for dielectric measurements in liquids at MHz frequencies. Nanotechnology 2013; 24:415709. [PMID: 24061045 DOI: 10.1088/0957-4484/24/41/415709] [Citation(s) in RCA: 3] [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: 05/07/2023]
Abstract
A theoretical analysis of amplitude modulated electrostatic force microscopy (AM-EFM) in liquid media at MHz frequencies, based on a simple tip-sample parallel plate model, is presented. The model qualitatively explains the main features of AM-EFM in liquid media and provides a simple explanation of how the measured electric forces are affected by: the frequency of the applied voltage, the tip-sample distance, the ionic concentration, the relative dielectric constant of the solution, and the relative dielectric constant and thickness of the sample. These results provide a simple framework for the design of AM-EFM measurements for localized dielectric characterization in liquid media.
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Affiliation(s)
- G Gramse
- Institut de Bioenginyeria de Catalunya (IBEC), C/Baldiri i Reixac 15-21, E-08028 Barcelona, Spain. Departament d'Electrònica, Universitat de Barcelona, C/Martí i Franquès 1, E-08028 Barcelona, Spain
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Dols-Perez A, Sisquella X, Fumagalli L, Gomila G. Optical visualization of ultrathin mica flakes on semitransparent gold substrates. Nanoscale Res Lett 2013; 8:305. [PMID: 23819688 PMCID: PMC3716790 DOI: 10.1186/1556-276x-8-305] [Citation(s) in RCA: 3] [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] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Accepted: 06/26/2013] [Indexed: 05/22/2023]
Abstract
We show that optical visualization of ultrathin mica flakes on metallic substrates is viable using semitransparent gold as substrates. This enables to easily localize mica flakes and rapidly estimate their thickness directly on gold substrates by conventional optical reflection microscopy. We experimentally demonstrate it by comparing optical images with atomic force microscopy images of mica flakes on semitransparent gold. Present results open the possibility for simple and rapid characterization of thin mica flakes as well as other thin sheets directly on metallic substrates.
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Affiliation(s)
- Aurora Dols-Perez
- Nanobioelec Group, Institute for BioEngineering of Catalonia (IBEC), c/Baldiri i Reixac 15-21, Barcelona 08028, Spain
- Departament d’Electrònica, Universitat de Barcelona, c/Martí i Franquès 1, Barcelona 08028, Spain
| | - Xavier Sisquella
- Nanotechnology Platform, Barcelona Science Park, c/Josep Samitier 1-5, Barcelona 08028, Spain
- Current address: The Walter and Eliza Hall Institute of Medical Research, Parkville, Melbourne 3052, Australia
| | - Laura Fumagalli
- Nanobioelec Group, Institute for BioEngineering of Catalonia (IBEC), c/Baldiri i Reixac 15-21, Barcelona 08028, Spain
- Departament d’Electrònica, Universitat de Barcelona, c/Martí i Franquès 1, Barcelona 08028, Spain
| | - Gabriel Gomila
- Nanobioelec Group, Institute for BioEngineering of Catalonia (IBEC), c/Baldiri i Reixac 15-21, Barcelona 08028, Spain
- Departament d’Electrònica, Universitat de Barcelona, c/Martí i Franquès 1, Barcelona 08028, Spain
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Fumagalli L, Esteban-Ferrer D, Cuervo A, Carrascosa JL, Gomila G. Label-free identification of single dielectric nanoparticles and viruses with ultraweak polarization forces. Nat Mater 2012; 11:808-16. [PMID: 22772654 DOI: 10.1038/nmat3369] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2012] [Accepted: 05/28/2012] [Indexed: 05/26/2023]
Abstract
Label-free detection of the material composition of nanoparticles could be enabled by the quantification of the nanoparticles' inherent dielectric response to an applied electric field. However, the sensitivity of dielectric nanoscale objects to geometric and non-local effects makes the dielectric response extremely weak. Here we show that electrostatic force microscopy with sub-piconewton resolution can resolve the dielectric constants of single dielectric nanoparticles without the need for any reference material, as well as distinguish nanoparticles that have an identical surface but different inner composition. We unambiguously identified unlabelled ~10 nm nanoparticles of similar morphology but different low-polarizable materials, and discriminated empty from DNA-containing virus capsids. Our approach should make the in situ characterization of nanoscale dielectrics and biological macromolecules possible.
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Affiliation(s)
- Laura Fumagalli
- Institut de Bioenginyeria de Catalunya, c/ Baldiri i Reixac 15-21, 08028 Barcelona, Spain.
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Gramse G, Gomila G, Fumagalli L. Quantifying the dielectric constant of thick insulators by electrostatic force microscopy: effects of the microscopic parts of the probe. Nanotechnology 2012; 23:205703. [PMID: 22543516 DOI: 10.1088/0957-4484/23/20/205703] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We present a systematic analysis of the effects that the microscopic parts of electrostatic force microscopy probes (the cone and cantilever) have on the electrostatic interaction between the tip apex and thick insulating substrates (thickness > 100 μm). We discuss how these effects can influence the measurement and quantification of the local dielectric constant of the substrates. We propose and experimentally validate a general methodology that takes into account the influence of the cone and the cantilever, thus enabling us to obtain very accurate values of the dielectric constants of thick insulators.
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Affiliation(s)
- G Gramse
- Institut de Bioenginyeria de Catalunya, C/ Balidiri i Reixac 15-21, 08028 Barcelona, Spain.
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Dols-Perez A, Fumagalli L, Simonsen AC, Gomila G. Ultrathin spin-coated dioleoylphosphatidylcholine lipid layers in dry conditions: a combined atomic force microscopy and nanomechanical study. Langmuir 2011; 27:13165-13172. [PMID: 21936555 DOI: 10.1021/la202942j] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Atomic force microscopy (AFM) has been used to study the structural and mechanical properties of low concentrated spin-coated dioleoylphosphatidylcholine (DOPC) layers in dry environment (RH ≈ 0%) at the nanoscale. It is shown that for concentrations in the 0.1-1 mM range the structure of the DOPC spin-coated samples consists of an homogeneous lipid monolayer ∼1.3 nm thick covering the whole substrate on top of which lipid bilayer (or multilayer) micro- and nanometric patches and rims are formed. The thickness of the bilayer structures is found to be ∼4.5 nm (or multiples of this value for multilayer structures), while the lateral dimensions range from micrometers to tens of nanometer depending on the lipid concentration. The force required to break a bilayer (breakthrough force) is found to be ∼0.24 nN. No dependence of the mechanical values on the lateral dimensions of the bilayer structures is evidenced. Remarkably, the thickness and breakthrough force values of the bilayers measured in dry environment are very similar to values reported in the literature for supported DOPC bilayers in pure water.
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Affiliation(s)
- Aurora Dols-Perez
- Nanobioelec group, Institut de Bioenginyeria de Catalunya (IBEC), Baldiri i Reixac 15-21, 08028 Barcelona, Spain.
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Sanmartí M, Iavicoli P, Pajot-Augy E, Gomila G, Samitier J. Human olfactory receptors immobilization on a mixed self assembled monolayer for the development of a bioelectronic nose. ACTA ACUST UNITED AC 2010. [DOI: 10.1016/j.proeng.2010.09.226] [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: 11/30/2022]
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Gramse G, Casuso I, Toset J, Fumagalli L, Gomila G. Quantitative dielectric constant measurement of thin films by DC electrostatic force microscopy. Nanotechnology 2009; 20:395702. [PMID: 19724109 DOI: 10.1088/0957-4484/20/39/395702] [Citation(s) in RCA: 16] [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] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
A simple method to measure the static dielectric constant of thin films with nanometric spatial resolution is presented. The dielectric constant is extracted from DC electrostatic force measurements with the use of an accurate analytical model. The method is validated here on thin silicon dioxide films (8 nm thick, dielectric constant approximately 4) and purple membrane monolayers (6 nm thick, dielectric constant approximately 2), providing results in excellent agreement with those recently obtained by nanoscale capacitance microscopy using a current-sensing approach. The main advantage of the force detection approach resides in its simplicity and direct application on any commercial atomic force microscope with no need of additional sophisticated electronics, thus being easily available to researchers in materials science, biophysics and semiconductor technology.
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Affiliation(s)
- G Gramse
- Institut de Bioenginyeria de Catalunya (IBEC) and Departament d'Electrònica-Universitat de Barcelona, C/Martí i Franquès 1, E-08028 Barcelona, Spain
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Fumagalli L, Ferrari G, Sampietro M, Gomila G. Quantitative nanoscale dielectric microscopy of single-layer supported biomembranes. Nano Lett 2009; 9:1604-8. [PMID: 19271767 DOI: 10.1021/nl803851u] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
We present the experimental demonstration of low-frequency dielectric constant imaging of single-layer supported biomembranes at the nanoscale. The dielectric constant image has been quantitatively reconstructed by combining the thickness and local capacitance obtained using a scanning force microscope equipped with a sub-attofarad low-frequency capacitance detector. This work opens new possibilities for studying bioelectric phenomena and the dielectric properties of biological membranes at the nanoscale.
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Affiliation(s)
- Laura Fumagalli
- Departament d'Electronica, Institut de Bioenginyeria de Catalunya, Universitat de Barcelona, Barcelona, Spain.
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Casuso I, Pla-Roca M, Gomila G, Samitier J, Minic J, Persuy MA, Salesse R, Pajot-Augy E. Immobilization of olfactory receptors onto gold electrodes for electrical biosensor. Materials Science and Engineering: C 2008. [DOI: 10.1016/j.msec.2007.10.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Mills CA, Martinez E, Errachid A, Engel E, Funes M, Moormann C, Wahlbrink T, Gomila G, Planell J, Samitier J. Nanoembossed polymer substrates for biomedical surface interaction studies. J Nanosci Nanotechnol 2007; 7:4588-4594. [PMID: 18283849] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Biomedical devices are moving towards the incorporation of nanostructures to investigate the interactions of biological species with such topological surfaces found in nature. Good optical transparency and sealing properties, low fabrication cost, fast design realization times, and biocompatibility make polymers excellent candidates for the production of surfaces containing such nanometric structures. In this work, a method for the production of nanostructures in free-standing sheets of different thermoplastic polymers is presented, with a view to using these substrates in biomedical cell-surface applications where optical microscopy techniques are required. The process conditions for the production of these structures in poly(methyl methacrylate), poly(ethylene naphthalate), poly(lactic acid), poly(styrene), and poly(ethyl ether ketone) are given. The fabrication method used is based on a modified nanoimprint lithography (NIL) technique using silicon based moulds, fabricated via reactive ion etching or focused ion beam lithography, to emboss nanostructures into the surface of the biologically compatible thermoplastic polymers. The method presented here is designed to faithfully replicate the nanostructures in the mould while maximising the mould lifetime. Examples of polymer replicas with nanostructures of different topographies are presented in poly(methyl methacrylate), including nanostructures for use in cell-surface interactions and nanostructure-containing microfluidic devices.
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Affiliation(s)
- Christopher A Mills
- Laboratori de Recerca en Nanobioenginyeria (CREBEC), Parc Cientific de Barcelona, Josep Samitier 1-5, 08028 Barcelona, Spain
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Casuso I, Fumagalli L, Samitier J, Padrós E, Reggiani L, Akimov V, Gomila G. Electron transport through supported biomembranes at the nanoscale by conductive atomic force microscopy. Nanotechnology 2007; 18:465503. [PMID: 21730477 DOI: 10.1088/0957-4484/18/46/465503] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [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
We present a reliable methodology to perform electron transport measurements at the nanoscale on supported biomembranes by conductive atomic force microscopy (C-AFM). It allows measurement of both (a) non-destructive conductive maps and (b) force controlled current-voltage characteristics in wide voltage bias range in a reproducible way. Tests experiments were performed on purple membrane monolayers, a two-dimensional (2D) crystal lattice of the transmembrane protein bacteriorhodopsin. Non-destructive conductive images show uniform conductivity of the membrane with isolated nanometric conduction defects. Current-voltage characteristics under different compression conditions show non-resonant tunneling electron transport properties, with two different conduction regimes as a function of the applied bias, in excellent agreement with theoretical predictions. This methodology opens the possibility for a detailed study of electron transport properties of supported biological membranes, and of soft materials in general.
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Affiliation(s)
- I Casuso
- Department Electrònica, Universitat de Barcelona and Laboratori de Nanobioenginyeria-IBEC, Parc Científic de Barcelona, Barcelona, Spain
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Casuso I, Fumagalli L, Samitier J, Padrós E, Reggiani L, Akimov V, Gomila G. Nanoscale electrical conductivity of the purple membrane monolayer. Phys Rev E Stat Nonlin Soft Matter Phys 2007; 76:041919. [PMID: 17995038 DOI: 10.1103/physreve.76.041919] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2006] [Revised: 09/27/2007] [Indexed: 05/25/2023]
Abstract
Nanoscale electron transport through the purple membrane monolayer, a two-dimensional crystal lattice of the transmembrane protein bacteriorhodopsin, is studied by conductive atomic force microscopy. We demonstrate that the purple membrane exhibits nonresonant tunneling transport, with two characteristic tunneling regimes depending on the applied voltage (direct and Fowler-Nordheim). Our results show that the purple membrane can carry significant current density at the nanometer scale, several orders of magnitude larger than previously estimated by macroscale measurements.
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Affiliation(s)
- I Casuso
- Department Electrònica, Universitat de Barcelona and Laboratori de Nanobioenginyeria-IBEC, Parc Científic de Barcelona, Barcelona, Spain
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Hou Y, Jaffrezic-Renault N, Martelet C, Zhang A, Minic-Vidic J, Gorojankina T, Persuy MA, Pajot-Augy E, Salesse R, Akimov V, Reggiani L, Pennetta C, Alfinito E, Ruiz O, Gomila G, Samitier J, Errachid A. A novel detection strategy for odorant molecules based on controlled bioengineering of rat olfactory receptor I7. Biosens Bioelectron 2007; 22:1550-5. [PMID: 16884902 DOI: 10.1016/j.bios.2006.06.018] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [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: 02/22/2006] [Revised: 06/13/2006] [Accepted: 06/20/2006] [Indexed: 11/26/2022]
Abstract
In this study, we report a dose-dependent detection of odorant molecules in solution by rat olfactory receptor I7 (OR I7) in its membrane fraction. The OR I7 is immobilized on a gold electrode by multilayer bioengineering based on a mixed self-assembled monolayer and biotin/avidin system, which allows for a well-controlled immobilization of the bioreceptor within its lipid environment. The odorant detection is electronically performed in a quantitative manner by electrochemical impedance spectroscopy (EIS) measurements on samples and controls.
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Affiliation(s)
- Yanxia Hou
- Centre de Génie Electrique de Lyon (CEGELY), Ecole Centrale de Lyon, 69134 Ecully Cedex, France.
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Fumagalli L, Ferrari G, Sampietro M, Casuso I, Martínez E, Samitier J, Gomila G. Nanoscale capacitance imaging with attofarad resolution using ac current sensing atomic force microscopy. Nanotechnology 2006; 17:4581-4587. [PMID: 21727580 DOI: 10.1088/0957-4484/17/18/009] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [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
Nanoscale capacitance imaging with attofarad resolution (∼1 aF) of a nano-structured oxide thin film, using ac current sensing atomic force microscopy, is reported. Capacitance images are shown to follow the topographic profile of the oxide closely, with nanometre vertical resolution. A comparison between experimental data and theoretical models shows that the capacitance variations observed in the measurements can be mainly associated with the capacitance probed by the tip apex and not with positional changes of stray capacitance contributions. Capacitance versus distance measurements further support this conclusion. The application of this technique to the characterization of samples with non-voltage-dependent capacitance, such as very thin dielectric films, self-assembled monolayers and biological membranes, can provide new insight into the dielectric properties at the nanoscale.
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Affiliation(s)
- L Fumagalli
- Dipartimento di Elettronica e Informazione, Politecnico di Milano, Piazza Leonardo da Vinci 32, I-20133 Milano, Italy
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Minic J, Grosclaude J, Aioun J, Persuy MA, Gorojankina T, Salesse R, Pajot-Augy E, Hou Y, Helali S, Jaffrezic-Renault N, Bessueille F, Errachid A, Gomila G, Ruiz O, Samitier J. Immobilization of native membrane-bound rhodopsin on biosensor surfaces. Biochim Biophys Acta Gen Subj 2005; 1724:324-32. [PMID: 15927400 DOI: 10.1016/j.bbagen.2005.04.017] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [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: 02/23/2005] [Revised: 04/12/2005] [Accepted: 04/13/2005] [Indexed: 11/16/2022]
Abstract
In this paper, we evaluated the grafting of G-protein-coupled receptors (GPCRs) onto functionalized surfaces, which is a primary requirement to elaborate receptor-based biosensors, or to develop novel GPCR assays. Bovine rhodopsin, a prototypical GPCR, was used in the form of receptor-enriched membrane fraction. Quantitative immobilization of the membrane-bound rhodopsin either non-specifically on a carboxylated dextran surface grafted with long alkyl groups, or specifically on a surface coated with anti-rhodopsin antibody was demonstrated by surface plasmon resonance. In addition, a new substrate based on mixed self-assembled multilayer that anchors specific anti-receptor antibodies was developed. Electrochemical impedance spectroscopy performed upon deposition of membrane-bound rhodopsin of increasing concentration exhibited a significant change, until a saturation level was reached, indicating optimum receptor immobilization on the substrate. The structures obtained with this new immobilization procedure of the rhodopsin in its native membrane environment are stable, with a controlled density of specific anchoring sites. Therefore, such receptor immobilization method is attractive for a range of applications, especially in the field of GPCR biosensors.
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Affiliation(s)
- Jasmina Minic
- INRA, Neurobiologie de l'Olfaction et de la Prise Alimentaire, Equipe Récepteurs et Communication Chimique, Domaine de Vilvert, 78352 Jouy-en-Josas Cedex, France
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Hou Y, Jaffrezic-Renault N, Martelet C, Tlili C, Zhang A, Pernollet JC, Briand L, Gomila G, Errachid A, Samitier J, Salvagnac L, Torbiéro B, Temple-Boyer P. Study of Langmuir and Langmuir-Blodgett films of odorant-binding protein/amphiphile for odorant biosensors. Langmuir 2005; 21:4058-4065. [PMID: 15835974 DOI: 10.1021/la0471801] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
To make ultrathin films for the fabrication of artificial olfactory systems, odorant biosensors, we have investigated mixed Langmuir and Langmuir-Blodgett films of odorant-binding protein/amphiphile. Under optimized experimental conditions (phosphate buffer solution, pH 7.5, OBP-1F concentration of 4 mg L(-1), target pressure 35 mN m(-1)), the mixed monolayer at the air/water interface is very stable and has been efficiently transferred onto gold supports, which were previously functionalized by self-assembled monolayers (SAMs) with 1-octadecanethiol (ODT). Atomic force microscopy and electrochemical impedance spectroscopy were used to characterize mixed Langmuir-Blodgett (LB) films before and after contact with a specific odorant molecule, isoamyl acetate. AFM phase images show a higher contrast after contact with the odorant molecule due to the new structure of the OBP-1F/ODA LB film. Non-Faradaic electrochemical spectroscopy (EIS) is used to quantify the effect of the odorant based on the electrical properties of the OBP-1F/ODA LB film, as its resistance strongly decreases from 1.18 MOmega (before contact) to 25 kOmega (after contact).
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Affiliation(s)
- Yanxia Hou
- Centre de Génie Electrique de Lyon (CEGELY), Ecole Centrale de Lyon, 69134 ECULLY Cedex, France.
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Gomila G, Pennetta C, Reggiani L, Sampietro M, Ferrari G, Bertuccio G. Shot noise in linear macroscopic resistors. Phys Rev Lett 2004; 92:226601. [PMID: 15245247 DOI: 10.1103/physrevlett.92.226601] [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] [Received: 05/15/2003] [Indexed: 05/24/2023]
Abstract
We report on direct experimental evidence of shot noise in a linear macroscopic resistor. The origin of the shot noise comes from the fluctuation of the total number of charge carriers inside the resistor associated with their diffusive motion under the condition that the dielectric relaxation time becomes longer than the dynamic transit time. The present results show that neither potential barriers nor the absence of inelastic scattering are necessary to observe shot noise in electronic devices.
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Affiliation(s)
- G Gomila
- Department d'Electronica and Research Centre for Bioelectronics and Nanobioscience, Universitat de Barcelona, Edifici Modulari, Josep Samitier 1-5, 08028 Barcelona, Spain
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