1
|
Exertier F, Tegg L, Taylor A, Cairney JM, Fu J, Marceau RKW. Nanoscale Analysis of Frozen Water by Atom Probe Tomography Using Graphene Encapsulation and Cryo-Workflows. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2024:ozae054. [PMID: 38905154 DOI: 10.1093/mam/ozae054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Revised: 04/24/2024] [Accepted: 05/28/2024] [Indexed: 06/23/2024]
Abstract
There has been an increasing interest in atom probe tomography (APT) to characterize hydrated and biological materials. A major benefit of APT compared to microscopy techniques more commonly used in biology is its combination of outstanding three-dimensional (3D) spatial resolution and mass sensitivity. APT has already been successfully used to characterize biominerals, revealing key structural information at the atomic scale, however there are many challenges inherent to the analysis of soft hydrated materials. New preparation protocols, often involving specimen preparation and transfer at cryogenic temperature, enable APT analysis of hydrated materials and have the potential to enable 3D atomic scale characterization of biological materials in the near-native hydrated state. In this study, samples of pure water at the tips of tungsten needle specimens were prepared at room temperature by graphene encapsulation. A comparative study was conducted where specimens were transferred at either room temperature or cryo-temperature and analyzed by APT by varying the flight path and pulsing mode. The differences between the analysis workflows are presented along with recommendations for future studies, and the compatibility between graphene coating and cryogenic workflows is demonstrated.
Collapse
Affiliation(s)
- Florant Exertier
- Institute for Frontier Materials, Deakin University, Geelong, VIC 3216, Australia
| | - Levi Tegg
- School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, Sydney, NSW 2006, Australia
- Australian Centre for Microscopy and Microanalysis, The University of Sydney, Sydney, NSW 2006, Australia
| | - Adam Taylor
- Institute for Frontier Materials, Deakin University, Geelong, VIC 3216, Australia
| | - Julie M Cairney
- School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, Sydney, NSW 2006, Australia
- Australian Centre for Microscopy and Microanalysis, The University of Sydney, Sydney, NSW 2006, Australia
| | - Jing Fu
- Department of Mechanical and Aerospace Engineering, Monash University, Clayton, VIC 3800, Australia
| | - Ross K W Marceau
- Institute for Frontier Materials, Deakin University, Geelong, VIC 3216, Australia
| |
Collapse
|
2
|
Schwarz TM, Woods E, Singh MP, Chen X, Jung C, Aota LS, Jang K, Krämer M, Kim SH, McCarroll I, Gault B. In Situ Metallic Coating of Atom Probe Specimen for Enhanced Yield, Performance, and Increased Field-of-View. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2024:ozae006. [PMID: 38366381 DOI: 10.1093/mam/ozae006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2023] [Revised: 01/09/2024] [Accepted: 01/16/2024] [Indexed: 02/18/2024]
Abstract
Atom probe tomography requires needle-shaped specimens with a diameter typically below 100 nm, making them both very fragile and reactive, and defects (notches at grain boundaries or precipitates) are known to affect the yield and data quality. The use of a conformal coating directly on the sharpened specimen has been proposed to increase yield and reduce background. However, to date, these coatings have been applied ex situ and mostly are not uniform. Here, we report on the controlled focused-ion beam in situ deposition of a thin metal film on specimens immediately after specimen preparation. Different metallic targets e.g. Cr were attached to a micromanipulator via a conventional lift-out method and sputtered using Ga or Xe ions. We showcase the many advantages of coating specimens from metallic to nonmetallic materials. We have identified an increase in data quality and yield, an improvement of the mass resolution, as well as an increase in the effective field-of-view. This wider field-of-view enables visualization of the entire original specimen, allowing to detect the complete surface oxide layer around the specimen. The ease of implementation of the approach makes it very attractive for generalizing its use across a very wide range of atom probe analyses.
Collapse
Affiliation(s)
- Tim M Schwarz
- Department of Microstructure Physics and Alloy Design, Max-Planck-Institut für Eisenforschung, Max-Planck-Str. 1, Düsseldorf 40237, Germany
| | - Eric Woods
- Department of Microstructure Physics and Alloy Design, Max-Planck-Institut für Eisenforschung, Max-Planck-Str. 1, Düsseldorf 40237, Germany
| | - Mahander P Singh
- Department of Microstructure Physics and Alloy Design, Max-Planck-Institut für Eisenforschung, Max-Planck-Str. 1, Düsseldorf 40237, Germany
| | - Xinren Chen
- Department of Microstructure Physics and Alloy Design, Max-Planck-Institut für Eisenforschung, Max-Planck-Str. 1, Düsseldorf 40237, Germany
| | - Chanwon Jung
- Department of Microstructure Physics and Alloy Design, Max-Planck-Institut für Eisenforschung, Max-Planck-Str. 1, Düsseldorf 40237, Germany
| | - Leonardo S Aota
- Department of Microstructure Physics and Alloy Design, Max-Planck-Institut für Eisenforschung, Max-Planck-Str. 1, Düsseldorf 40237, Germany
| | - Kyuseon Jang
- Department of Microstructure Physics and Alloy Design, Max-Planck-Institut für Eisenforschung, Max-Planck-Str. 1, Düsseldorf 40237, Germany
- Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
| | - Mathias Krämer
- Department of Microstructure Physics and Alloy Design, Max-Planck-Institut für Eisenforschung, Max-Planck-Str. 1, Düsseldorf 40237, Germany
| | - Se-Ho Kim
- Department of Microstructure Physics and Alloy Design, Max-Planck-Institut für Eisenforschung, Max-Planck-Str. 1, Düsseldorf 40237, Germany
| | - Ingrid McCarroll
- Department of Microstructure Physics and Alloy Design, Max-Planck-Institut für Eisenforschung, Max-Planck-Str. 1, Düsseldorf 40237, Germany
| | - Baptiste Gault
- Department of Microstructure Physics and Alloy Design, Max-Planck-Institut für Eisenforschung, Max-Planck-Str. 1, Düsseldorf 40237, Germany
- Department of Materials, Imperial College London, London SW7 2AZ, UK
| |
Collapse
|
3
|
Wang R, Li R, Zheng P, Yang Z, Qian C, Wang Z, Qian S. Silver Nanoparticles Modified with Polygonatum sibiricum Polysaccharide Improve Biocompatibility and Infected Wound Bacteriostasis. J Microbiol 2023:10.1007/s12275-023-00042-8. [PMID: 37052796 DOI: 10.1007/s12275-023-00042-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 03/13/2023] [Accepted: 03/14/2023] [Indexed: 04/14/2023]
Abstract
Silver nanoparticles (AgNPs) exhibit strong antibacterial activity and do not easily induce drug resistance; however, the poor stability and biocompatibility in solution limit their widespread application. In this study, AgNPs were modified with Polygonatum sibiricum Polysaccharide (PSP) to synthesize PSP@AgNPs with good stability, biocompatibility, and antibacterial activity. When PSP@AgNP synthesis was performed under a reaction time of 70 min, a reaction temperature of 35 °C, and an AgNO3-to-PSP volume ratio of 1:1, the synthesized PSP@AgNPs were more regular and uniform than AgNPs, and their particle size was around 10 nm. PSP@AgNPs exhibited lower cytotoxicity and hemolysis, and stronger bacteriostatic activity. PSP@AgNPs damage the integrity and internal structure of cells, resulting in the leakage of intracellular nucleic acids and proteins. The rate of cell membrane damage in Escherichia coli and Staphylococcus aureus treated with PSP@AgNPs increased by 38.52% and 43.75%, respectively, compared with that of AgNPs. PSP@AgNPs inhibit the activities of key enzymes related to antioxidant, energy and substance metabolism in cells. The inhibitory effects on the activities of superoxide dismutase (SOD), catalase (CAT), adenosine triphosphate enzyme (ATPase), malate dehydrogenase (MDH), and succinate dehydrogenase (SDH) in E. coli and S. aureus cells were significantly higher than those of AgNPs. In addition, compared with AgNPs, PSP@AgNPs promote faster healing of infected wounds. Therefore, PSP@AgNPs represent potential antibacterial agents against wound infections.
Collapse
Affiliation(s)
- Ruonan Wang
- College of Biological and Food Engineering, Anhui Polytechnic University, Wuhu, 241000, People's Republic of China
| | - Rongyu Li
- School of Basic Medical Sciences, Wannan Medical College, Wuhu, 241002, People's Republic of China
| | - Peng Zheng
- College of Biological and Food Engineering, Anhui Polytechnic University, Wuhu, 241000, People's Republic of China
| | - Zicheng Yang
- College of Biological and Food Engineering, Anhui Polytechnic University, Wuhu, 241000, People's Republic of China
| | - Cheng Qian
- College of Biological and Food Engineering, Anhui Polytechnic University, Wuhu, 241000, People's Republic of China
| | - Zhou Wang
- College of Biological and Food Engineering, Anhui Polytechnic University, Wuhu, 241000, People's Republic of China
| | - Senhe Qian
- College of Biological and Food Engineering, Anhui Polytechnic University, Wuhu, 241000, People's Republic of China.
| |
Collapse
|
4
|
Schwarz TM, Ott J, Solodenko H, Schmitz G, Stender P. Nanoscale analysis of frozen honey by atom probe tomography. Sci Rep 2022; 12:17786. [PMID: 36273026 PMCID: PMC9587987 DOI: 10.1038/s41598-022-22717-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Accepted: 10/18/2022] [Indexed: 01/19/2023] Open
Abstract
Three-dimensional reconstruction of the analysed volume is one of the main goals of atom probe tomography (APT) and can deliver nearly atomic resolution (~ 0.2 nm spatial resolution) and chemical information with a mass sensitivity down to the ppm range. Extending this technique to frozen biological systems would have an enormous impact on the structural analysis of biomolecules. In previous works, we have shown that it is possible to measure frozen liquids with APT. In this paper, we demonstrate the ability of APT to trace nanoscale precipitation in frozen natural honey. While the mass signals of the common sugar fragments CxHy and CxOyHz overlap with (H2O)nH from water, we achieved correct stoichiometric values via different interpretation approaches for the peaks and thus determined the water content reliably. Next, we use honey to investigate the spatial resolution capabilities as a step toward the measurement of biological molecules in solution in 3D with sub-nanometer resolution. This may take analytical techniques to a new level, since methods of chemical characterization for cryogenic samples, especially biological samples, are still limited.
Collapse
Affiliation(s)
- Tim M. Schwarz
- grid.5719.a0000 0004 1936 9713Institute for Materials Science, Chair of Materials Physics, University of Stuttgart, Heisenbergstr. 3, 70569 Stuttgart, Germany
| | - Jonas Ott
- grid.5719.a0000 0004 1936 9713Institute for Materials Science, Chair of Materials Physics, University of Stuttgart, Heisenbergstr. 3, 70569 Stuttgart, Germany
| | - Helena Solodenko
- grid.5719.a0000 0004 1936 9713Institute for Materials Science, Chair of Materials Physics, University of Stuttgart, Heisenbergstr. 3, 70569 Stuttgart, Germany
| | - Guido Schmitz
- grid.5719.a0000 0004 1936 9713Institute for Materials Science, Chair of Materials Physics, University of Stuttgart, Heisenbergstr. 3, 70569 Stuttgart, Germany
| | - Patrick Stender
- grid.5719.a0000 0004 1936 9713Institute for Materials Science, Chair of Materials Physics, University of Stuttgart, Heisenbergstr. 3, 70569 Stuttgart, Germany
| |
Collapse
|
5
|
Grandfield K, Micheletti C, Deering J, Arcuri G, Tang T, Langelier B. Atom Probe Tomography for Biomaterials and Biomineralization. Acta Biomater 2022; 148:44-60. [DOI: 10.1016/j.actbio.2022.06.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 05/18/2022] [Accepted: 06/06/2022] [Indexed: 01/27/2023]
|
6
|
Schwarz TM, Dietrich CA, Ott J, Weikum EM, Lawitzki R, Solodenko H, Hadjixenophontos E, Gault B, Kästner J, Schmitz G, Stender P. 3D sub-nanometer analysis of glucose in an aqueous solution by cryo-atom probe tomography. Sci Rep 2021; 11:11607. [PMID: 34078953 PMCID: PMC8172843 DOI: 10.1038/s41598-021-90862-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Accepted: 05/18/2021] [Indexed: 11/23/2022] Open
Abstract
Atom Probe Tomography (APT) is currently a well-established technique to analyse the composition of solid materials including metals, semiconductors and ceramics with up to near-atomic resolution. Using an aqueous glucose solution, we now extended the technique to frozen solutions. While the mass signals of the common glucose fragments CxHy and CxOyHz overlap with (H2O)nH from water, we achieved stoichiometrically correct values via signal deconvolution. Density functional theory (DFT) calculations were performed to investigate the stability of the detected pyranose fragments. This paper demonstrates APT’s capabilities to achieve sub-nanometre resolution in tracing whole glucose molecules in a frozen solution by using cryogenic workflows. We use a solution of defined concentration to investigate the chemical resolution capabilities as a step toward the measurement of biological molecules. Due to the evaporation of nearly intact glucose molecules, their position within the measured 3D volume of the solution can be determined with sub-nanometre resolution. Our analyses take analytical techniques to a new level, since chemical characterization methods for cryogenically-frozen solutions or biological materials are limited.
Collapse
Affiliation(s)
- T M Schwarz
- Chair of Materials Physics, Institute for Materials Science, University of Stuttgart, Heisenbergstr. 3, 70569, Stuttgart, Germany
| | - C A Dietrich
- Institute for Theoretical Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569, Stuttgart, Germany
| | - J Ott
- Chair of Materials Physics, Institute for Materials Science, University of Stuttgart, Heisenbergstr. 3, 70569, Stuttgart, Germany
| | - E M Weikum
- Chair of Materials Physics, Institute for Materials Science, University of Stuttgart, Heisenbergstr. 3, 70569, Stuttgart, Germany
| | - R Lawitzki
- Chair of Materials Physics, Institute for Materials Science, University of Stuttgart, Heisenbergstr. 3, 70569, Stuttgart, Germany
| | - H Solodenko
- Chair of Materials Physics, Institute for Materials Science, University of Stuttgart, Heisenbergstr. 3, 70569, Stuttgart, Germany
| | - E Hadjixenophontos
- Chair of Materials Physics, Institute for Materials Science, University of Stuttgart, Heisenbergstr. 3, 70569, Stuttgart, Germany
| | - B Gault
- Max-Planck-Institut Für Eisenforschung, Max-Planck-Str. 1, 40237, Düsseldorf, Germany.,Department of Materials, Royal School of Mines, Imperial College, Prince Consort Road, London, SW7 2BP, UK
| | - J Kästner
- Institute for Theoretical Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569, Stuttgart, Germany
| | - G Schmitz
- Chair of Materials Physics, Institute for Materials Science, University of Stuttgart, Heisenbergstr. 3, 70569, Stuttgart, Germany
| | - P Stender
- Chair of Materials Physics, Institute for Materials Science, University of Stuttgart, Heisenbergstr. 3, 70569, Stuttgart, Germany.
| |
Collapse
|
7
|
Mosiman DS, Chen YS, Yang L, Hawkett B, Ringer SP, Mariñas BJ, Cairney JM. Atom Probe Tomography of Encapsulated Hydroxyapatite Nanoparticles. SMALL METHODS 2021; 5:e2000692. [PMID: 34927889 DOI: 10.1002/smtd.202000692] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Revised: 10/19/2020] [Indexed: 06/14/2023]
Abstract
Hydroxyapatite nanoparticles (HAP NPs) are important for medicine, bioengineering, catalysis, and water treatment. However, current understanding of the nanoscale phenomena that confer HAP NPs their many useful properties is limited by a lack of information about the distribution of the atoms within the particles. Atom probe tomography (APT) has the spatial resolution and chemical sensitivity for HAP NP characterization, but difficulties in preparing the required needle-shaped samples make the design of these experiments challenging. Herein, two techniques are developed to encapsulate HAP NPs and prepare them into APT tips. By sputter-coating gold or the atomic layer deposition of alumina for encapsulation, partially fluoridated HAP NPs are successfully characterized by voltage- or laser-pulsing APT, respectively. Analyses reveal that significant tradeoffs exist between encapsulant methods/materials for HAP characterization and that selection of a more robust approach will require additional technique development. This work serves as an essential starting point for advancing knowledge about the nanoscale spatiochemistry of HAP NPs.
Collapse
Affiliation(s)
- Daniel S Mosiman
- Australian Centre for Microscopy and Microanalysis, The University of Sydney, Sydney, New South Wales, 2006, Australia
- Safe Global Water Institute, Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Yi-Sheng Chen
- Australian Centre for Microscopy and Microanalysis, The University of Sydney, Sydney, New South Wales, 2006, Australia
- School of Aerospace Mechanical and Mechatronic Engineering, The University of Sydney, Sydney, New South Wales, 2006, Australia
| | - Limei Yang
- Australian Centre for Microscopy and Microanalysis, The University of Sydney, Sydney, New South Wales, 2006, Australia
| | - Brian Hawkett
- Key Centre for Polymer Colloids School of Chemistry, The University of Sydney, Sydney, New South Wales, 2006, Australia
| | - Simon P Ringer
- Australian Centre for Microscopy and Microanalysis, The University of Sydney, Sydney, New South Wales, 2006, Australia
- School of Aerospace Mechanical and Mechatronic Engineering, The University of Sydney, Sydney, New South Wales, 2006, Australia
| | - Benito J Mariñas
- Safe Global Water Institute, Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Julie M Cairney
- Australian Centre for Microscopy and Microanalysis, The University of Sydney, Sydney, New South Wales, 2006, Australia
- School of Aerospace Mechanical and Mechatronic Engineering, The University of Sydney, Sydney, New South Wales, 2006, Australia
| |
Collapse
|
8
|
Gault B, Chiaramonti A, Cojocaru-Mirédin O, Stender P, Dubosq R, Freysoldt C, Makineni SK, Li T, Moody M, Cairney JM. Atom probe tomography. NATURE REVIEWS. METHODS PRIMERS 2021; 1:10.1038/s43586-021-00047-w. [PMID: 37719173 PMCID: PMC10502706 DOI: 10.1038/s43586-021-00047-w] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 06/01/2021] [Indexed: 09/19/2023]
Abstract
Atom probe tomography (APT) provides three-dimensional compositional mapping with sub-nanometre resolution. The sensitivity of APT is in the range of parts per million for all elements, including light elements such as hydrogen, carbon or lithium, enabling unique insights into the composition of performance-enhancing or lifetime-limiting microstructural features and making APT ideally suited to complement electron-based or X-ray-based microscopies and spectroscopies. Here, we provide an introductory overview of APT ranging from its inception as an evolution of field ion microscopy to the most recent developments in specimen preparation, including for nanomaterials. We touch on data reconstruction, analysis and various applications, including in the geosciences and the burgeoning biological sciences. We review the underpinnings of APT performance and discuss both strengths and limitations of APT, including how the community can improve on current shortcomings. Finally, we look forwards to true atomic-scale tomography with the ability to measure the isotopic identity and spatial coordinates of every atom in an ever wider range of materials through new specimen preparation routes, novel laser pulsing and detector technologies, and full interoperability with complementary microscopy techniques.
Collapse
Affiliation(s)
- Baptiste Gault
- Max-Planck-Institut für Eisenforschung, Düsseldorf, Germany
- Department of Materials, Royal School of Mines, Imperial College, London, UK
| | - Ann Chiaramonti
- National Institute of Standards and Technology, Applied Chemicals and Materials Division, Boulder, CO, USA
| | | | - Patrick Stender
- Institute of Materials Science, University of Stuttgart, Stuttgart, Germany
| | - Renelle Dubosq
- Department of Earth and Environmental Sciences, University of Ottawa, Ottawa, Ontario, Canada
| | | | | | - Tong Li
- Institute for Materials, Ruhr-Universität Bochum, Bochum, Germany
| | - Michael Moody
- Department of Materials, University of Oxford, Oxford, UK
| | - Julie M. Cairney
- Australian Centre for Microscopy and Microanalysis, University of Sydney, Sydney, New South Wales, Australia
- School of Aerospace, Mechanical and Mechatronic Engineering, University of Sydney, Sydney, New South Wales, Australia
| |
Collapse
|
9
|
Schwarz TM, Weikum EM, Meng K, Hadjixenophontos E, Dietrich CA, Kästner J, Stender P, Schmitz G. Field evaporation and atom probe tomography of pure water tips. Sci Rep 2020; 10:20271. [PMID: 33219263 PMCID: PMC7680140 DOI: 10.1038/s41598-020-77130-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Accepted: 11/05/2020] [Indexed: 01/12/2023] Open
Abstract
Measuring biological samples by atom probe tomography (APT) in their natural environment, i.e. aqueous solution, would take this analytical method, which is currently well established for metals, semi-conductive materials and non-metals, to a new level. It would give information about the 3D chemical structure of biological systems, which could enable unprecedented insights into biological systems and processes, such as virus protein interactions. For this future aim, we present as a first essential step the APT analysis of pure water (Milli-Q) which is the main component of biological systems. After Cryo-preparation, nanometric water tips are field evaporated with assistance by short laser pulses. The obtained data sets of several tens of millions of atoms reveal a complex evaporation behavior. Understanding the field evaporation process of water is fundamental for the measurement of more complex biological systems. For the identification of the individual signals in the mass spectrum, DFT calculations were performed to prove the stability of the detected molecules.
Collapse
Affiliation(s)
- T M Schwarz
- Institute for Materials Science, Chair of Materials Physics, University of Stuttgart, Heisenbergstr. 3, 70569, Stuttgart, Germany
| | - E M Weikum
- Institute for Materials Science, Chair of Materials Physics, University of Stuttgart, Heisenbergstr. 3, 70569, Stuttgart, Germany
| | - K Meng
- Institute for Materials Science, Chair of Materials Physics, University of Stuttgart, Heisenbergstr. 3, 70569, Stuttgart, Germany
| | - E Hadjixenophontos
- Institute for Materials Science, Chair of Materials Physics, University of Stuttgart, Heisenbergstr. 3, 70569, Stuttgart, Germany
| | - C A Dietrich
- Institute for Theoretical Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569, Stuttgart, Germany
| | - J Kästner
- Institute for Theoretical Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569, Stuttgart, Germany
| | - P Stender
- Institute for Materials Science, Chair of Materials Physics, University of Stuttgart, Heisenbergstr. 3, 70569, Stuttgart, Germany.
| | - G Schmitz
- Institute for Materials Science, Chair of Materials Physics, University of Stuttgart, Heisenbergstr. 3, 70569, Stuttgart, Germany
| |
Collapse
|
10
|
McCarroll I, Bagot P, Devaraj A, Perea D, Cairney J. New frontiers in atom probe tomography: a review of research enabled by cryo and/or vacuum transfer systems. MATERIALS TODAY. ADVANCES 2020; 7:100090. [PMID: 33103106 PMCID: PMC7581275 DOI: 10.1016/j.mtadv.2020.100090] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
There has been a recent surge in the use of cryo and/or vacuum specimen preparation and transfer systems to broaden the scope of research enabled by the microscopy technique of atom probe tomography. This is driven by the fact that, as for many microscopes, the application of atom probes to air- and temperature-sensitive materials or wet biological specimens has previously been limited by transfer through air at room temperature. Here we provide an overview of areas of research that benefit from these new transfer and analysis protocols, as well as a review of current advances in transfer devices, environmental cells, and glove boxes for controlled specimen manipulation. This includes the study of catalysis and corrosion, biological samples, liquid-solid interfaces, natural aging, and the distribution of hydrogen in materials.
Collapse
Affiliation(s)
- I.E. McCarroll
- Australian Centre for Microscopy and Microanalysis, University of Sydney, Madsen Building F09, NSW 2006, Australia
| | - P.A.J. Bagot
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, United Kingdom
| | - A. Devaraj
- Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA 99352, USA
| | - D.E. Perea
- Environmental Molecular Science Laboratory, Pacific Northwest National Laboratory, P.O. Box 999 Richland, WA 99352, USA
| | - J.M. Cairney
- Australian Centre for Microscopy and Microanalysis, University of Sydney, Madsen Building F09, NSW 2006, Australia
- School of Aerospace, Mechanical and Mechatronic Engineering, University of Sydney, NSW 2006, Australia
- Corresponding author. (J.M. Cairney)
| |
Collapse
|
11
|
Qiu S, Garg V, Zhang S, Chen Y, Li J, Taylor A, Marceau RKW, Fu J. Graphene encapsulation enabled high-throughput atom probe tomography of liquid specimens. Ultramicroscopy 2020; 216:113036. [PMID: 32540722 DOI: 10.1016/j.ultramic.2020.113036] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 05/11/2020] [Accepted: 05/27/2020] [Indexed: 12/22/2022]
Abstract
A new method for imaging liquid specimens with atom probe tomography (APT) is proposed by introducing graphene encapsulation. By tuning the encapsulation speed and the number of encapsulations, controllable volumes of liquid can be encapsulated on a pre-sharpened specimen tip, with the end radius less than 75 nm to allow field ionization and evaporation. Encapsulation of liquid has been confirmed by using various characterization techniques, including electron microscopy and stimulated emission depletion microscopy. The graphene-encapsulated liquid specimen was then directly frozen at the cryogenic stage inside the atom probe instrument, followed by APT imaging in laser-pulsed mode. Using water as a test example, water-related ions have been identified in the acquired mass spectrum, which are spatially correlated to a reconstructed three-dimensional volume of water on top of the base specimen tip, as clearly revealed in the chemical maps. In addition, the proposed method has also been shown to produce multiple liquid specimens simultaneously on a pre-sharpened silicon micro-tip array for high-throughput APT imaging of liquid specimens. It is expected that the proposed lift-out-free method for preparing APT specimens in their hydrated state will open a new avenue for obtaining insights into various materials at atomic resolution.
Collapse
Affiliation(s)
- Shi Qiu
- Department of Mechanical and Aerospace Engineering, Monash University, Clayton, VIC3800, Australia
| | - Vivek Garg
- Department of Mechanical and Aerospace Engineering, Monash University, Clayton, VIC3800, Australia; IITB-Monash Research Academy, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Shuo Zhang
- Department of Mechanical and Aerospace Engineering, Monash University, Clayton, VIC3800, Australia
| | - Yu Chen
- Monash Centre for Electron Microscopy, Monash University, Clayton, VIC3800, Australia
| | - Jian Li
- Biomedicine Discovery Institute, Monash University, Clayton, VIC3800, Australia; Department of Microbiology, Monash University, Clayton, VIC3800, Australia
| | - Adam Taylor
- Deakin University, Institute for Frontier Materials, Geelong, VIC3216, Australia
| | - Ross K W Marceau
- Deakin University, Institute for Frontier Materials, Geelong, VIC3216, Australia.
| | - Jing Fu
- Department of Mechanical and Aerospace Engineering, Monash University, Clayton, VIC3800, Australia; ARC Centre of Excellence for Advanced Molecular Imaging, Monash University, Clayton, VIC3800, Australia.
| |
Collapse
|
12
|
Qiu S, Zheng C, Garg V, Chen Y, Gervinskas G, Li J, Dunstone MA, Marceau RKW, Fu J. Three-Dimensional Chemical Mapping of a Single Protein in the Hydrated State with Atom Probe Tomography. Anal Chem 2020; 92:5168-5177. [DOI: 10.1021/acs.analchem.9b05668] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Shi Qiu
- Department of Mechanical and Aerospace Engineering, Monash University, Clayton, VIC 3800, Australia
| | - Changxi Zheng
- ARC Centre of Excellence for Future Low-Energy Electronics Technologies, Monash University, Clayton, VIC 3800, Australia
- School of Physics and Astronomy, Monash University, Clayton, VIC 3800, Australia
| | - Vivek Garg
- Department of Mechanical and Aerospace Engineering, Monash University, Clayton, VIC 3800, Australia
- IITB-Monash Research Academy, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India
| | - Yu Chen
- Monash Centre for Electron Microscopy, Monash University, Clayton, VIC 3800, Australia
| | - Gediminas Gervinskas
- Monash Ramaciotti Centre for Cryo Electron Microscopy, Monash University, Clayton, VIC 3800, Australia
| | - Jian Li
- Biomedicine Discovery Institute, Monash University, Clayton, VIC 3800, Australia
- Department of Microbiology, Monash University, Clayton, VIC 3800, Australia
| | - Michelle A. Dunstone
- Department of Microbiology, Monash University, Clayton, VIC 3800, Australia
- ARC Centre of Excellence for Advanced Molecular Imaging, Monash University, Clayton, VIC 3800, Australia
| | - Ross K. W. Marceau
- Institute for Frontier Materials, Deakin University, Geelong, VIC 3216, Australia
| | - Jing Fu
- Department of Mechanical and Aerospace Engineering, Monash University, Clayton, VIC 3800, Australia
- ARC Centre of Excellence for Advanced Molecular Imaging, Monash University, Clayton, VIC 3800, Australia
| |
Collapse
|
13
|
Zhang L, Wang Y, Wang C, He M, Wan J, Wei Y, Zhang J, Yang X, Zhao Y, Zhang Y. Light-Activable On-Demand Release of Nano-Antibiotic Platforms for Precise Synergy of Thermochemotherapy on Periodontitis. ACS APPLIED MATERIALS & INTERFACES 2020; 12:3354-3362. [PMID: 31872756 DOI: 10.1021/acsami.9b17335] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The overprescription and improper use of antibiotics have contributed to the evolution of bacterial resistance, making it urgent to develop alternative therapies and agents with better efficacy as well as less toxicity to combat bacterial infections and keep new resistance from developing. In this work, a novel light-activable nano-antibiotic platform (TC-PCM@GNC-PND) was constructed by the incorporation of gold nanocages (GNC) and two thermosensitive gatekeepers, phase-change materials (PCM) and thermosensitive polymer poly(N-isopropylacrylamide-co-diethylaminoethyl methacrylate) (PND), to realize precisely the synergy of photothermal and antimicrobial drugs. GNC exhibits an excellent photothermal effect owing to its strong absorbance in the near-infrared (NIR) region, and hollow interiors make it a favorable vehicle for loading various antibiotics such as tetracycline (TC). The release of the encapsulated drugs could be precisely controlled by NIR light through the dual thermosensitive interaction of liquid-solid transition of PCM and coil-granule transition of PND, improving efficacy and alleviating side effects with on-demand drug release. The thermosensitive hydrogel was formed in situ upon application with body temperature, enhancing retention of the antimicrobial agent in local infectious sites. Highly effective ablation of bacteria is achieved both in vitro and in periodontitis models with little toxicity owing to the synergy of photothermal effects and chemotherapeutic drug release induced by NIR. This study could provide guidance for the design of antibacterial materials and shed substantial light on synergistic treatment.
Collapse
Affiliation(s)
- Lingling Zhang
- State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory of Oral Biomedicine, Ministry of Education, School and Hospital of Stomatology , Wuhan University , Wuhan 430079 , China
- Medical Research Institute, School of Medicine , Wuhan University , Wuhan 430071 , China
| | - Yulan Wang
- State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory of Oral Biomedicine, Ministry of Education, School and Hospital of Stomatology , Wuhan University , Wuhan 430079 , China
- Medical Research Institute, School of Medicine , Wuhan University , Wuhan 430071 , China
| | - Can Wang
- State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory of Oral Biomedicine, Ministry of Education, School and Hospital of Stomatology , Wuhan University , Wuhan 430079 , China
- Medical Research Institute, School of Medicine , Wuhan University , Wuhan 430071 , China
| | - Ming He
- National Engineering Research Center for Nanomedicine, College of Life Science and Technology , Huazhong University of Science and Technology , Wuhan 430074 , China
| | - Jiangshan Wan
- National Engineering Research Center for Nanomedicine, College of Life Science and Technology , Huazhong University of Science and Technology , Wuhan 430074 , China
| | - Yan Wei
- State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory of Oral Biomedicine, Ministry of Education, School and Hospital of Stomatology , Wuhan University , Wuhan 430079 , China
- Medical Research Institute, School of Medicine , Wuhan University , Wuhan 430071 , China
| | - Jinglun Zhang
- State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory of Oral Biomedicine, Ministry of Education, School and Hospital of Stomatology , Wuhan University , Wuhan 430079 , China
- Medical Research Institute, School of Medicine , Wuhan University , Wuhan 430071 , China
| | - Xiangliang Yang
- National Engineering Research Center for Nanomedicine, College of Life Science and Technology , Huazhong University of Science and Technology , Wuhan 430074 , China
| | - Yanbing Zhao
- National Engineering Research Center for Nanomedicine, College of Life Science and Technology , Huazhong University of Science and Technology , Wuhan 430074 , China
| | - Yufeng Zhang
- State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory of Oral Biomedicine, Ministry of Education, School and Hospital of Stomatology , Wuhan University , Wuhan 430079 , China
- Medical Research Institute, School of Medicine , Wuhan University , Wuhan 430071 , China
| |
Collapse
|
14
|
Sundell G, Hulander M, Pihl A, Andersson M. Atom Probe Tomography for 3D Structural and Chemical Analysis of Individual Proteins. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2019; 15:e1900316. [PMID: 31058464 DOI: 10.1002/smll.201900316] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Revised: 04/01/2019] [Indexed: 06/09/2023]
Abstract
Determination of the 3D structure of proteins and other biomolecules is a major goal in structural biology, to provide insights to their biological function. Such structures are historically unveiled experimentally by X-ray crystallography or NMR spectroscopy, and in recent years using cryo-electron microscopy. Here, a method for structural analysis of individual proteins on the sub-nanometer scale using atom probe tomography is described. This technique offers a combination of high-resolution analysis of biomolecules in 3D, and the chemical sensitivity of mass spectrometry. As a model protein, the well-characterized antibody IgG is used. IgG is encapsulated in an amorphous solid silica matrix via a sol-gel process to provide the requisite support for atom probe analysis. The silica synthesis is tuned to resemble physiological conditions. The 3D reconstructions show good agreement with the protein databank IgG crystal structure. This suggests that the silica-embedding strategy can open the field of atom probe tomography to the analysis of biological molecules. In addition to high-resolution structural information, the technique may potentially provide chemical information on the atomic scale using isotopic labeling. It is envisaged that this method may constitute a useful complement to existing tools in structural biology, particularly for the examination of proteins with low propensity for crystallization.
Collapse
Affiliation(s)
- Gustav Sundell
- Department of Chemistry and Chemical Engineering, Chalmers University of Technology, Gothenburg, 41296, Sweden
| | - Mats Hulander
- Department of Chemistry and Chemical Engineering, Chalmers University of Technology, Gothenburg, 41296, Sweden
| | - Astrid Pihl
- Department of Chemistry and Chemical Engineering, Chalmers University of Technology, Gothenburg, 41296, Sweden
| | - Martin Andersson
- Department of Chemistry and Chemical Engineering, Chalmers University of Technology, Gothenburg, 41296, Sweden
| |
Collapse
|
15
|
Stephenson LT, Szczepaniak A, Mouton I, Rusitzka KAK, Breen AJ, Tezins U, Sturm A, Vogel D, Chang Y, Kontis P, Rosenthal A, Shepard JD, Maier U, Kelly TF, Raabe D, Gault B. The Laplace Project: An integrated suite for preparing and transferring atom probe samples under cryogenic and UHV conditions. PLoS One 2018; 13:e0209211. [PMID: 30576351 PMCID: PMC6303089 DOI: 10.1371/journal.pone.0209211] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2018] [Accepted: 11/30/2018] [Indexed: 11/22/2022] Open
Abstract
We present sample transfer instrumentation and integrated protocols for the preparation and atom probe characterization of environmentally-sensitive materials. Ultra-high vacuum cryogenic suitcases allow specimen transfer between preparation, processing and several imaging platforms without exposure to atmospheric contamination. For expedient transfers, we installed a fast-docking station equipped with a cryogenic pump upon three systems; two atom probes, a scanning electron microscope / Xe-plasma focused ion beam and a N2-atmosphere glovebox. We also installed a plasma FIB with a solid-state cooling stage to reduce beam damage and contamination, through reducing chemical activity and with the cryogenic components as passive cryogenic traps. We demonstrate the efficacy of the new laboratory protocols by the successful preparation and transfer of two highly contamination- and temperature-sensitive samples—water and ice. Analysing pure magnesium atom probe data, we show that surface oxidation can be effectively suppressed using an entirely cryogenic protocol (during specimen preparation and during transfer). Starting with the cryogenically-cooled plasma FIB, we also prepared and transferred frozen ice samples while avoiding significant melting or sublimation, suggesting that we may be able to measure the nanostructure of other normally-liquid or soft materials. Isolated cryogenic protocols within the N2 glove box demonstrate the absence of ice condensation suggesting that environmental control can commence from fabrication until atom probe analysis.
Collapse
Affiliation(s)
- Leigh T Stephenson
- Max-Planck-Institut für Eisenforschung GmbH, Max-Planck-Straße 1, 40237 Düsseldorf, Germany
| | - Agnieszka Szczepaniak
- Max-Planck-Institut für Eisenforschung GmbH, Max-Planck-Straße 1, 40237 Düsseldorf, Germany.,Cameca Instruments Inc., 5470 Nobel Dr, Fitchburg, WI 53711, United States of America
| | - Isabelle Mouton
- Max-Planck-Institut für Eisenforschung GmbH, Max-Planck-Straße 1, 40237 Düsseldorf, Germany
| | - Kristiane A K Rusitzka
- Max-Planck-Institut für Eisenforschung GmbH, Max-Planck-Straße 1, 40237 Düsseldorf, Germany
| | - Andrew J Breen
- Max-Planck-Institut für Eisenforschung GmbH, Max-Planck-Straße 1, 40237 Düsseldorf, Germany
| | - Uwe Tezins
- Max-Planck-Institut für Eisenforschung GmbH, Max-Planck-Straße 1, 40237 Düsseldorf, Germany
| | - Andreas Sturm
- Max-Planck-Institut für Eisenforschung GmbH, Max-Planck-Straße 1, 40237 Düsseldorf, Germany
| | - Dirk Vogel
- Max-Planck-Institut für Eisenforschung GmbH, Max-Planck-Straße 1, 40237 Düsseldorf, Germany
| | - Yanhong Chang
- Max-Planck-Institut für Eisenforschung GmbH, Max-Planck-Straße 1, 40237 Düsseldorf, Germany
| | - Paraskevas Kontis
- Max-Planck-Institut für Eisenforschung GmbH, Max-Planck-Straße 1, 40237 Düsseldorf, Germany
| | - Alexander Rosenthal
- Microscopy Improvements e.U., Rudolf von Eichthal str. 66/6, 7000 Eisenstadt, Austria
| | - Jeffrey D Shepard
- Cameca Instruments Inc., 5470 Nobel Dr, Fitchburg, WI 53711, United States of America
| | - Urs Maier
- Ferrovac GmbH, Thurgauerstrasse 72, 8050 Zürich, Switzerland
| | - Thomas F Kelly
- Cameca Instruments Inc., 5470 Nobel Dr, Fitchburg, WI 53711, United States of America
| | - Dierk Raabe
- Max-Planck-Institut für Eisenforschung GmbH, Max-Planck-Straße 1, 40237 Düsseldorf, Germany
| | - Baptiste Gault
- Max-Planck-Institut für Eisenforschung GmbH, Max-Planck-Straße 1, 40237 Düsseldorf, Germany
| |
Collapse
|
16
|
A near atomic-scale view at the composition of amyloid-beta fibrils by atom probe tomography. Sci Rep 2018; 8:17615. [PMID: 30514971 PMCID: PMC6279744 DOI: 10.1038/s41598-018-36110-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Accepted: 11/05/2018] [Indexed: 01/03/2023] Open
Abstract
Amyloid-beta (Ab) proteins play an important role in a number of neurodegenerative diseases. Ab is found in senile plaques in brains of Alzeimer’s disease patients. The 42 residues of the monomer form dimers which stack to fibrils gaining several micrometers in length. Using Ab fibrils with 13C and 15N marker substitution, we developed an innovative approach to obtain insights to structural and chemical information of the protein. We deposited the modified protein fibrils to pre-sharped aluminium needles with >100-nm apex diameters and, using the position-sensitive mass-to-charge spectrometry technique of atom probe tomography, we acquired the chemically-resolved three dimensional information for every detected ion evaporated in small fragments from the protein. We also discuss the influence of experimental parameters such as pulse energy and pulse frequency of the used Laser beam which lead to differences in the size of the gained fragments, developing the capability of localising metal atom within Ab plaques.
Collapse
|
17
|
Li J, Zheng C, Liu B, Chou T, Kim Y, Qiu S, Li J, Yan W, Fu J. Controlled graphene encapsulation: a nanoscale shield for characterising single bacterial cells in liquid. NANOTECHNOLOGY 2018; 29:365705. [PMID: 29889049 DOI: 10.1088/1361-6528/aacba7] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
High-resolution single-cell imaging in their native or near-native state has received considerable interest for decades. In this research, we present an innovative approach that can be employed to study both morphological and nano-mechanical properties of hydrated single bacterial cells. The proposed strategy is to encapsulate wet cells with monolayer graphene with a newly developed water membrane approach, followed by imaging with both electron microscopy (EM) and atomic force microscopy (AFM). A computational framework was developed to provide additional insights, with the detailed nanoindentation process on graphene modelled based on the finite element method. The model was first validated by calibration with polymer materials of known properties, and the contribution of graphene was then studied and corrected to determine the actual moduli of the encapsulated hydrated sample. Application of the proposed approach was performed on hydrated bacterial cells (Klebsiella pneumoniae) to correlate the structural and mechanical information. EM and energy-dispersive x-ray spectroscopy imaging confirmed that the cells in their near-native stage can be studied inside the miniaturised environment enabled with graphene encapsulation. The actual moduli of the encapsulated hydrated cells were determined based on the developed computational model in parallel, with results comparable with those acquired with wet AFM. It is expected that the successful establishment of controlled graphene encapsulation offers a new route for probing liquid/live cells with scanning probe microscopy, as well as correlative imaging of hydrated samples for both biological and material sciences.
Collapse
Affiliation(s)
- Jiayao Li
- Department of Mechanical and Aerospace Engineering, Monash University, Clayton, VIC 3800, Australia
| | | | | | | | | | | | | | | | | |
Collapse
|
18
|
Pulsed-voltage atom probe tomography of low conductivity and insulator materials by application of ultrathin metallic coating on nanoscale specimen geometry. Ultramicroscopy 2017; 181:150-159. [PMID: 28558288 DOI: 10.1016/j.ultramic.2017.05.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Revised: 04/04/2017] [Accepted: 05/09/2017] [Indexed: 11/20/2022]
Abstract
We present a novel approach for analysis of low-conductivity and insulating materials with conventional pulsed-voltage atom probe tomography (APT), by incorporating an ultrathin metallic coating on focused ion beam prepared needle-shaped specimens. Finite element electrostatic simulations of coated atom probe specimens were performed, which suggest remarkable improvement in uniform voltage distribution and subsequent field evaporation of the insulated samples with a metallic coating of approximately 10nm thickness. Using design of experiment technique, an experimental investigation was performed to study physical vapor deposition coating of needle specimens with end tip radii less than 100nm. The final geometries of the coated APT specimens were characterized with high-resolution scanning electron microscopy and transmission electron microscopy, and an empirical model was proposed to determine the optimal coating thickness for a given specimen size. The optimal coating strategy was applied to APT specimens of resin embedded Au nanospheres. Results demonstrate that the optimal coating strategy allows unique pulsed-voltage atom probe analysis and 3D imaging of biological and insulated samples.
Collapse
|