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Dykas MM, Poddar K, Yoong SL, Viswanathan V, Mathew S, Patra A, Saha S, Pastorin G, Venkatesan T. Enhancing image contrast of carbon nanotubes on cellular background using helium ion microscope by varying helium ion fluence. J Microsc 2017; 269:14-22. [PMID: 28703381 DOI: 10.1111/jmi.12604] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [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: 02/16/2017] [Revised: 06/08/2017] [Accepted: 06/22/2017] [Indexed: 01/28/2023]
Abstract
Carbon nanotubes (CNTs) have become an important nano entity for biomedical applications. Conventional methods of their imaging, often cannot be applied in biological samples due to an inadequate spatial resolution or poor contrast between the CNTs and the biological sample. Here we report a unique and effective detection method, which uses differences in conductivities of carbon nanotubes and HeLa cells. The technique involves the use of a helium ion microscope to image the sample with the surface charging artefacts created by the He+ and neutralised by electron flood gun. This enables us to obtain a few nanometre resolution images of CNTs in HeLa Cells with high contrast, which was achieved by tailoring the He+ fluence. Charging artefacts can be efficiently removed for conductive CNTs by a low amount of electrons, the fluence of which is not adequate to discharge the cell surface, resulting in high image contrast. Thus, this technique enables rapid detection of any conducting nano structures on insulating cellular background even in large fields of view and fine spatial resolution. The technique demonstrated has wider applications for researchers seeking enhanced contrast and high-resolution imaging of any conducting entity in a biological matrix - a commonly encountered issue of importance in drug delivery, tissue engineering and toxicological studies.
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Affiliation(s)
- M M Dykas
- Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore.,Nanoscience & Nanotechnology Initiative, National University of Singapore, Singapore
| | - K Poddar
- Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore.,Nanoscience & Nanotechnology Initiative, National University of Singapore, Singapore.,Department of Orthopedic Surgery, National University of Singapore, Singapore
| | - S L Yoong
- Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore.,Department of Pharmacy, National University of Singapore, Singapore
| | - V Viswanathan
- Nanoscience & Nanotechnology Initiative, National University of Singapore, Singapore.,Department of Electrical and Computer Engineering, National University of Singapore, Singapore
| | - S Mathew
- Nanoscience & Nanotechnology Initiative, National University of Singapore, Singapore
| | - A Patra
- Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore.,Nanoscience & Nanotechnology Initiative, National University of Singapore, Singapore
| | - S Saha
- Nanoscience & Nanotechnology Initiative, National University of Singapore, Singapore
| | - G Pastorin
- Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore.,Nanoscience & Nanotechnology Initiative, National University of Singapore, Singapore.,Department of Pharmacy, National University of Singapore, Singapore
| | - T Venkatesan
- Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore.,Nanoscience & Nanotechnology Initiative, National University of Singapore, Singapore.,Department of Electrical and Computer Engineering, National University of Singapore, Singapore.,Department of Materials Science and Engineering, National University of Singapore, Singapore.,Department of Physics, National University of Singapore, Singapore
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