JP2002255518A - Production method for fullerene selectively including isotope atom by ion implantation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method by which a radioactive isotope is included into fullerene by an ion implantation method. SOLUTION: The production method for fullerene including a specific isotope such as a radio active isotope is a method implanting the isotope using fullerene or a fullerene derivative as a target and an ion injector equipped with a mass spectrometry magnet.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to encapsulating radioisotopes and the like in fullerenes,
The method is characterized by using an ion implantation method for producing an isotope-encapsulated fullerene.

[0002]

2. Description of the Related Art As a method for producing an endohedral fullerene using an ion implantation method, an alkali element endohedral fullerene such as Li (Tellgmann R. et al., Nature 382, 407-408 (199)
6), N-encapsulated fullerene (Weidinger A. et al., Appl. P
hys. A 66, 287-292 (1998)) and He and Ne endohedral fullerenes (Shimshi R. et al., J. Am. Chem. Soc. 119, 11).
63-1164 (1997)). These are all production methods related to non-isotope-selective endohedral fullerenes. In addition, the method for producing fullerene containing Xe-127, a radioisotope of xenon, is described as ¹²⁷ I (d, 2n) ¹²⁷ Xe
Using the energy of counter-challenge in the reaction (Ohtsuki
T. et al., Physical Review Letters 81, 967-970 (199
8)) has been reported.

[0003] However, when a nuclear reaction is used, there is a possibility that an undesired radioisotope-encapsulated fullerene is generated. Further, a method has been reported in which a target isotope is contained in a carbon rod electrode and an isotope-encapsulated fullerene is produced by an arc discharge method (Ambe F., J. Radioanal.
ucl. Chem. 243, 21-25 (2000)). However, many kinds of fullerene species of metal-encapsulated fullerenes produced by this method are generated, and it is not possible to produce endohedral fullerenes of any type.

[0004]

As a conventional technique, a method for producing Li, N, He and Ne-encapsulated fullerenes by ion implantation has been reported, but these are all non-isotopic selective. In addition, a method for producing a radioisotope-encapsulated fullerene using a nuclear reaction has been reported. However, a non-target isotope-encapsulated fullerene is generated, and a single isotope-encapsulated fullerene cannot be produced.

Further, a method for producing an isotope-encapsulated fullerene by using an arc discharge method has been reported. However, it has been reported that any of a variety of fullerene species (such as C ₆₀ , C ₇₀ , C _82, etc. (The existence of fullerene species has been clarified.) Thus, the present invention has been devised to solve these problems.

[0006]

According to the present invention, an endohedral fullerene containing no isotope other than the intended one can be produced by using an ion implanter capable of implanting a single isotope. Furthermore, since an arbitrary fullerene species can be selected as a target for ion implantation, an endohedral fullerene of an arbitrary fullerene species can be manufactured.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS For ion implantation by an ion implanter
In the present invention, in order to implant a single isotope,
An ion implanter (FIG. 1) equipped with a mass analysis magnet is used. The outline of the ion implanter is shown below. The target 4 is set in the target chamber 3 of the ion implanter, and ion implantation is performed in a vacuum. At this time, various ions generated by the ion source 1 are carried to the mass analysis magnet 2 as an ion beam. Here, since mass separation of the ion beam is performed, only the target isotope ion beam 5 is ion-implanted into the target 4.

[0008] As the target for ion implantation, any fullerene species including a fullerene derivative is used. In addition, the ion implanter used in the present invention is usually operated at 40 keV for mass separation of a specific isotope, but in producing an isotope-encapsulated fullerene, the incident energy of the isotope ion is too high. It is necessary to slow down the ions.
Therefore, two different methods of deceleration described below are used. (1) Fullerene and a moderator (powder such as CsI) are mixed at an arbitrary ratio to prepare a pellet-shaped target, and isotope ion implantation is performed on the target. (2) Fullerene is deposited on a metal foil to form a thin film target. In front of this thin film target as a reduction gear
A slit to which a voltage of + is applied is installed to perform ion implantation of isotopes. Hereinafter, specific examples of the present invention will be described by taking Xe-133 as a radioisotope as an example.

[0009]

EXAMPLE 200 MBq of ¹³³ Xe gas was transferred to a 3.8 liter sample cylinder by a vacuum line. Approximately 3 cm ³ of ¹²⁹ Xe enriched isotope was also loaded into the same cylinder as an indicator of mass in mass separation. This cylinder was connected to the Nielsen-type ion source of the ion implanter, and was connected to the target fullerene at 40 keV.
¹³³ Xe was ion-implanted. Targets were created in two different ways. The first is with CsCl (0.8g) support, 50m
A mixture of g fullerene (C ₆₀ ) and 18 mg CsI was molded under pressure to produce a pellet (diameter: 18 mm). The second was a target obtained by depositing fullerene (C ₆₀ ) on a Ni foil (25 × 25 mm) with a thickness of about 1.5 μm using a deposition apparatus. When this Ni foil deposition target was used, a slit with a + voltage was installed as a speed reducer in front of the target to reduce ¹³³ Xe ⁺ ions to 0.5 to 3 keV. After ion implantation, these targets were dissolved in o-dichlorobenzene, and fullerene was analyzed by high performance liquid chromatography (HPLC). Further, the eluate was fractionated and the radioactivity of Xe-133 was measured. Since the peak of fullerene by HPLC coincided with the peak of Xe-133 in the eluate, it was confirmed that Xe-133-encapsulated fullerene was generated. Also,
The ratio of the radioactivity of Xe-133 contained in fullerene to the radioactivity of all Xe-133 ion-implanted into the target was calculated as the capture probability.

(Equation 1) The capture probability when the pellets prepared under the above conditions were used showed the maximum value (0.28%) at this stage. The Xe-133-encapsulated fullerene was isolated from the target fullerene by HPLC (DiCamillo BA et a
l., J. Phys. Chem. 100 (22), 9197-9201 (2000)) It is possible in principle. Although an example of ion implantation of Xe-133 has been described here, all the isotope-encapsulated fullerenes can be made by using the present invention in principle, as long as the isotopes are ionizable.

[0010]

According to the present invention, it is possible to produce an isotope-encapsulated fullerene of an arbitrary fullerene type which does not contain an isotope other than the intended one. Furthermore, the prepared isotope-encapsulated fullerenes may be used in nuclear medicine. Of the embodiment
Since Xe-133 is a β ^- ray emitting nuclide, it is considered that Xe-133-encapsulated fullerene can be used as a therapeutic agent for cancer if it is converted into a chemical form that condenses with cancer.

[Brief description of the drawings]

FIG. 1 is a diagram showing an ion implanter for producing an isotope-encapsulated fullerene.

[Explanation of symbols]

 1 ... Ion source 2 ... Magnet analysis magnet 3 ... Target chamber 4 ... Target 5 ... ... Isotope ion beam of interest

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Toshiaki Sekine 1233 Watanukicho, Takasaki City, Gunma Prefecture Inside the Japan Atomic Energy Research Institute Takasaki Research Institute (72) Inventor Nagaaki 1233 Watanukicho, Takasaki City, Gunma Prefecture Japan Atomic Energy Research Institute Takasaki Research Office (72) Inventor Mitsuo Koizumi 1233 Watanuki-cho, Takasaki City, Gunma Prefecture Japan Atomic Energy Research Institute Takasaki Research Institute (72) Inventor Hisakazu Muramatsu Shinano University, 6-figure Nishi-Nagano, Nagano City, Nagano Prefecture (72) Inventor Shimomura Haruhiko Nagano City, Nagano City, Oji Nishi-Nagano 6 Shinshu University (72) Inventor Kosuke Yoshikawa Nagano City, Nagano City, Oji Nishi-Nagano 6 Shinshu University F-term (reference) 4G046 CB01 CC10

Claims (1)

[Claims] 1. A method for producing an atom-encapsulated fullerene, which comprises ion-implanting a specific isotope such as a radioactive isotope using a fullerene and a fullerene derivative as a target by using an ion implanter equipped with a mass spectrometer magnet.