Browsing by Author "Chen, Chien-Hsu"

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Fe Doped Magnetic Nanodiamonds Made by Ion Implantation as Contrast Agent for MRI
(2018-05-04)
Lin, Bo-Rong
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Chen, Chien-Hsu
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Kunuku, Srinivasu
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Chen, Tzung-Yuang
;
Hsiao, Tung-Yuan
We report in this paper a new MRI contrast agent based on magnetic nanodiamonds fabricated by Fe ion implantation. The Fe atoms that are implanted into the nanodiamonds are not in direct contact with the outside world, enabling this new contrast agent to be free from cell toxicity. The image enhancement was shown clearly through T2 weighted images. The concentration dependence of the T2 relaxation time gives a relaxivity value that is about seven times that of the regular non-magnetic nanodiamonds. Cell viability study has also been performed. It was shown that they were nearly free from cytotoxicity independent of the particle concentration used. The imaging capability demonstrated here adds a new dimension to the medical application of nanodiamonds. In the future one will be able to combine this capability of magnetic nanodiamonds with other functions through surface modifications to perform drug delivery, targeted therapy, localized thermal treatment and diagnostic imaging at the same time.
Fluorescent B-10 embedded nanodiamonds as B-10 delivery agent for boron neutron capture therapy
(2019-06-26)
Lin, Bo-Rong
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Kunuku, Srinivasu
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Chen, Tzung-Yuang
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Chang, Yu-Jen
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Liao, Li-Chuan
Boron neutron capture therapy is a potentially powerful anti-cancer treatment, the success of which depends heavily on the boron delivery agent. Enabling the real-time tracing of delivery agents as they move through the body is crucial to the further development of boron neutron capture therapy. In this study, we fabricate fluorescent B-10 embedded nanodiamonds using physical ion implantation in conjunction with a two-step annealing process. Fluorescent B-10 embedded nanodiamonds perform well in cell viability test. The red fluorescence of the B-10 embedded nanodiamonds allows their use in fluorescence microscopy and in vivo imaging systems, thereby making it possible to conduct tracking in real time. The proposed fluorescent B-10 embedded nanodiamonds, combining optical visibility and B-10 transport capability, might be a promising boron delivery agent suitable for a wide range of biomedical applications.
Fluorescent Fe Embedded Magnetic Nanodiamonds Made by Ion Implantation
(2019-02-04)
Lin, Bo-Rong
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Kunuku, Srinivasu
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Chen, Chien-Hsu
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Chen, Tzung-Yuang
;
Hsiao, Tung-Yuan
We demonstrate fluorescent Fe embedded magnetic nanodiamonds by ion implantation and two-step annealing. The diamond characteristics with a highly ordered core and a graphite surface layer are maintained after the implantation process. After the two-step annealing process, a bright red fluorescence associated with nitrogen-vacancy centers is observed. These new fluorescent magnetic nanodiamonds can be used as a dual-function in vivo tracer with both optical visibility and magnetic resonance imaging capabilities. They are potentially useful for the more advanced in vivo biological and medical applications.
Investigation of the spectral characteristics of silicon-vacancy centers in ultrananocrystalline diamond nanostructures and single crystalline diamond
(2020-01-21)
Kunuku, Srinivasu
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Chen, Yen-Chun
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Chen, Chien-Hsu
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Kandasami, Asokan
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Chang, Wen-Hao
Silicon-vacancy (SiV) centers were produced in single crystalline diamond (SCD) and ultrananocrystalline diamond (UNCD) nanostructures via Si ion implantation or in situ Si doping. SiV-embedded UNCD (SiV-UNCD) was fabricated by both top-down and bottom-up methods. The spectral properties of the SiV centers, including the zero phonon line (ZPL) width and decay time, were investigated in the SCD and UNCD nanostructures. All the SiV-UNCD nanostructures showed bright emission regardless of the preparation method. However, the decay time of the SiV centers was affected by the synthesis procedure. A SiV decay time of tau similar to 0.19 ns was observed for UNCD nanostructures formed by in situ doping, whereas the SiV decay time was similar to 0.43 ns for SiV-UNCD clusters prepared by Si ion implantation into UNCD deposited on Ti/sapphire substrates. The ultrasonication of UNCD clusters on Ti/sapphire pyramids produced bright SiV-UNCD nanoclusters with sizes of similar to 50 nm, a ZPL width of 13.5 nm, and a decay time of 0.35 ns, suggesting promising potential in bioimaging applications. SiV-containing SCD (type Ia or type IIa) showed enhanced SiV spectral properties with a ZPL width of 6.08 nm and longer decay time of 1.3 ns. Published under license by AIP Publishing.
Iron embedded magnetic nanodiamonds for in vivo MRI contrast enhancement
(2019-12-11)
Lin, Bo-Rong
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Chen, Chien-Hsu
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Chang, Chun-Hsiang
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Kunuku, Srinivasu
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Chen, Tzung-Yuang
Although nanodiamonds have long being considered as a potential tool for biomedical research, the practical in vivo magnetic resonance imaging (MRI) application of nanodiamonds remains relatively unexplored. In this paper, we present the first application of in vivo MRI contrast enhancement using only iron embedded magnetic nanodiamonds. An MR image enhancement was clearly demonstrated in the rendering of T2-weighted images of mice obtained using an unmodified commercial MRI scanner. The excellent contrast obtained using these nanodiamonds opens the door to the non-invasive in vivo tracking of nanodiamonds and image enhancement. In the future, one can apply these magnetic nanodiamonds together with surface modifications to facilitate drug delivery, targeted therapy, localized thermal treatment, and diagnostic imaging.
Manganese ion implanted ultrananocrystalline diamond films: Optical and electrical characterization
(2019-04-01)
Kunuku, Srinivasu
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Chen, Chien-Hsu
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Hsieh, Ping-Yen
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Lin, Bo-Rong
;
Tai, Nyan-Hwa
We report the optical and electrical properties of high-dose (10(15)-10(17) ions/cm(2)) Mn-ion implanted ultrananocrystalline diamond (Mn-UNCD) films. Mn-ion implantation and post-annealing of UNCD films lead to the formation of Mn-related color centers, characterized in Mn-UNCD films by their zero phonon line emissions at 621.2 nm and phonon sidebands at 611.2 nm and 630.3 nm. Raman spectra of Mn-UNCD films indicated amorphization via high-dose Mn-ion implantation and that the annealing process results in graphitization of the films. The Mn-UNCD film implanted with the Mn-ion dose of 1017 ions/cm(2) exhibits a conductivity of 122.25 (Omega cm)(-1), as well as enhanced field electron emission (FEE) properties such as a turn-on field of 10.67 V/mu m and a FEE current density of 0.85 mA/cm(2).
Secondary ion mass spectrometry to verify the implantation of magnetic ions in nanodiamonds
(2019-11-07)
Lin, Bo-Rong
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Wang, Chiung-Chi
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Chen, Chien-Hsu
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Kunuku, Srinivasu
;
Hsiao, Tung-Yuan
Ion implantation is used to create nanodiamonds (NDs) with embedded magnetic ions for use in a wide range of biological and medical applications; however, the effectiveness of this process depends heavily on separating magnetic NDs from nonmagnetic ones. In this study, we use secondary ion mass spectrometry to verify the implantation of magnetic ions in NDs and the success of separation. When applied to a series of NDs with embedded iron or manganese ions, the sorting tool used in this study proved highly effective in selecting magnetic NDs. Besides, multienergy ion implantation and precise thickness control of NDs coating on the silicon wafer were suggested to improve this technology. Published under license by AIP Publishing.
Strain and optical characteristics study of ferromagnetic GaMnAs fabricated by ion beam induced epitaxial crystallization
(2016-11-25)
Chen, Nai-Hui
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Chen, Chien-Hsu
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Lee, Chien-Ping
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
In this study, we use a semi-insulating GaAs wafer to prepare a GaMnAs thin film by Mn ion implantation and subsequent helium ion beam induced epitaxial crystallization. In addition, we use different helium energies to anneal the GaMnAs thin films. The regrown GaMnAs thin films are measured using high-resolution X-Ray diffraction, Raman scattering and spectrophotometry to analyze the crystal structures and optical properties. It is found that the GaMnAs thin films remain fully strained. All experimental results indicate that the GaMnAs thin film is formed after the ion beam induced epitaxial crystallization annealing. (C) 2016 Elsevier B.V. All rights reserved.
Strain and optical characteristics study of ferromagnetic GaMnAs fabricated by ion beam induced epitaxial crystallization
(2016-11-25)
Chen, Nai-Hui
;
Chen, Chien-Hsu
;
Lee, Chien-Ping
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
In this study, we use a semi-insulating GaAs wafer to prepare a GaMnAs thin film by Mn ion implantation and subsequent helium ion beam induced epitaxial crystallization. In addition, we use different helium energies to anneal the GaMnAs thin films. The regrown GaMnAs thin films are measured using high-resolution X-Ray diffraction, Raman scattering and spectrophotometry to analyze the crystal structures and optical properties. It is found that the GaMnAs thin films remain fully strained. All experimental results indicate that the GaMnAs thin film is formed after the ion beam induced epitaxial crystallization annealing. (C) 2016 Elsevier B.V. All rights reserved.