Enhancing image contrast of carbon nanotubes on cellular background using helium ion microscope by varying helium ion fluence

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.

Helium-ion-beam nanofabrication: extreme processes and applications

“…HIM technology has also been used to show the detailed characteristics of conducting nanostructures on insulating cells. The above results highlight the potential of HIM technology to further understand the organic-inorganic interfaces of nanomaterials used in the biological field [39].…”

Applications of Filled Single-Walled Carbon Nanotubes: Progress, Challenges, and Perspectives

“…The cellular uptake of SWCNTs can also be tuned by the surface functionalization of SWC-NTs, which can be utilized to enhance the therapeutic effect on the targeted cells [110]. All these can improve the suitability of functionalized SWCNTs for applications [111][112][113][114][115][116][117][118][119][120][121][122][123][124][125][126].…”

Clinical Applications of Carbon Nanomaterials in Diagnostics and Therapy

“…As with NDs, carbon nanotubes (CNTs) can be functionalized by a diverse array of surface modifications. This property, in combination with inherent advantages of CNTs, such as high tensile strength, flexibility, and electrical conductivity, makes CNTs an attractive platform for a wide range of biomedical applications . Among these applications, CNTs have been most extensively explored in drug delivery and tissue engineering ( Figure ).…”