JPS6253036B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a sensitizer for autoradiography. In tracer experiments using radioisotopes, autoradiography, in which a sample is developed using paper chromatography, thin layer chromatography, or electrophoresis, and the radioactivity of each component is captured as a photographic image, is the most commonly used method. This is one of the methods of measuring radioactivity. However, weak beta emitters, especially tritium, have low emission energy and therefore have poor film sensitivity, often making it impossible to obtain sufficient images. In order to improve this sensitivity, research has been conducted on a method (fluorography) in which a liquid with a sensitizing effect is poured onto paper or a plate, dried, and then exposed to film, and this method has become an important technology for tritium autoradiography. Literatures 1) to 14) are listed as the main reports. 1 U. Luthi, et al., Noture, 205 , 1190
(1969) 2 K.Randerath, Anal.Chem., 41 , 991
(1969) 3 K.Randerath, Anal.Biochem., 34 . 188
(1970) 4 K.Randerath, et al., J.Chromatogr., 82 ,
59 (1973) 5 K.Randerath, et al., Anal.Biochem., 48 ,
172 (1973) 6 K.Randerath, et al., Anal.Biochem., 59 ,
263 (1974) 7 J.Shine, et al., Anal.Biochem., 59 , 360
(1974) 8 SR Burzynski, Anal.Biochem., 65 , 93
(1975) 9 M. Faust, et al., Anal.Biochem., 79 , 16
(1977) 10 Keiichi Kusama, Biochemistry Experiment Course 6. Tracer Experiment Method (1) P265 Tokyo Kagaku Dojin (1977) 11 E. Grunstein, et al., Anal.Biochem., 61 ,
429 (1974) 12 B, G, M. Durie, et al., Science, 190 ,
1093 (1975) 13 WMBonner, et al., Eur.J.Biochem.,
46 , 83 (1974) 14 EI, Grunstein, et al., Anal.Biochem.,
76 , 452 (1976) These series of attempts attempted to improve the transmittance of low-energy beta rays, which have poor permeability through materials, by converting them into light on the sample, thereby effectively transmitting energy to the photographic film. It is something. Furthermore, sensitizers are now commercially available for this purpose.
For example, New England New Clear
There is EN ³ HANCE (trade name (import and sales agency ^: Daiichi Chemical Co., Ltd.)) manufactured by England Nuclear. In these studies or in fluorography using commercially available products, 2,5-diphenyloxazole (PPO) or PPO・
By precipitating organic scintillators such as naphthalene as microcrystals, radiation is converted into light. For this reason, the sample and the organic scintillator come into solid-solid contact, resulting in different local concentrations, resulting in poor reproducibility, and also poor photoconversion efficiency due to self-quenching due to the high local concentration of the organic scintillator. It has drawbacks such as: As a result of various studies, the present inventors have developed a new autoradiography method in which an organic scintillator is dissolved in a non-volatile liquid, aromatic silicone oil or a polyether derivative, and if necessary, this is diluted with a volatile organic solvent. discovered a sensitizer for use in Since this sensitizer contains the above-mentioned non-volatile liquid, when the sample is impregnated with the solution and dried, the non-volatile liquid and organic scintillator remain on the sample as a solution, so the sample and the organic scintillator come into liquid-solid contact. This not only improves the reproducibility of results, but also makes the concentration of the scintillator uniform, which increases the efficiency of light conversion. This improves film sensitivity, significantly shortens exposure time, and improves image quality. It is now possible to obtain sufficient results even for samples for which it was previously impossible to obtain. As used herein, "aromatic silicone oil" refers to a compound having at least one phenyl group in general polysiloxane, and has the general formula (In the formula, R ¹ to ^{R n+2} are each a methyl group or a phenyl group, and at least one of R ¹ to ^{R n+2} is a phenyl group.) This product is HIVAC manufactured by Shin-Etsu Chemical Co., Ltd.
Examples include F4 and HIVAC-F5.
In addition, polyether derivatives have the general formula (In the formula, R ¹ to ^{R 5} are a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or a cyclohexyl group, R ⁶
and R ⁷ are a hydrogen atom or a methyl group, and cannot be a methyl group at the same time. m is 0 or 1,
n is a value of 2-15. ), and Triton X ₁₀₀ (trade name) manufactured by Rohm & Haas, which contains these compounds as main ingredients, can also be used. The organic scintillators used in the present invention include p-terphenyl, 2,5-diphenyloxazole, 2-phenyl-5-(4-biphenyl)-
1,3,4-oxadiazole, 2-(4-t-
butylphenyl)-5-(4-biphenylyl)-
1,3,4-oxadiazole, 4,4'-bis-
(2-Butyloctyloxy)-p-coaterphenyl, 2,5-bis-2-(5-t-butylbenzoxazolyl)-thiophene, 1,4-bis-
2-(5-phenyloxazolyl)-benzene,
Examples include 2-(1-naphthyl)-5-phenyloxazole, p-bis-(o-methylstyryl)-benzene, 2-(4'-biphenylyl)-6-phenylbenzoxazole, etc. . Mixing ratio (weight ratio) of aromatic silicone oil or polyether derivative to organic scintillator
is preferably in the range of 1000:1 to 50; if the ratio of organic scintillator is less than 1, the luminous efficiency will be poor;
% or more is not preferable because solubility may deteriorate. The sensitizer of the present invention can also be used after being further diluted with a volatile organic solvent. As the volatile organic solvent, ethers such as dimethyl ether and diethyl ether, alcohols such as methanol and ethanol, carboxylic acids such as formic acid and acetic acid, and sulfoxides such as dimethyl sulfoxide can be used. It is necessary to select and use a volatile organic solvent that does not dissolve the labeled compound. If the sample is a paper chromatograph or thin layer chromatograph, where the sensitizer can be easily and uniformly impregnated over the entire surface, the diluent should be one with good volatility. For example, ether, ethyl acetate, ethanol, etc. are often suitable. Furthermore, if the sample is a polyacrylamide plate gel used for electrophoresis, sufficient uniform impregnation cannot be achieved by spraying the sensitizer on the surface. In such a case, use dimethyl sulfoxide (DMSO) or acetic acid as the dilution solvent, impregnate the gel plate with the sensitizer by immersing it in this solution, and after a predetermined period of time, After removing unnecessary parts by washing with water and drying, it is preferable to contact and expose the film to an X-ray photographic film. Alternatively, if a flat gel is directly immersed without using any volatile organic solvent and water is removed under reduced pressure, drying and impregnation can be performed in parallel and measurements can be made. The volatile organic solvent can be used in any amount relative to the mixture of aromatic silicone oil or polyether derivative and organic scintillator, but it is preferably used in an amount less than 10 times (volume). If the volatile organic solvent is present in an amount exceeding the above range, the sensitizing effect will be weakened. Hereinafter, the present invention will be further explained in detail with reference to Examples. [Example 1] Sensitizers 1 and 2 according to the present invention and conventional methods 3 and 4
Comparison of relative darkening degree. A filter paper was immersed in a benzene solution of ³ H-labeled polymethyl methacrylate and dried to prepare a surface radiation source of (5×20)×10 ⁵ dpm/cm ² .
This was impregnated with various sensitizers and dried. These samples were then placed on a plate, covered with a thin polyethylene sheet, tightly attached to an X-ray film, and incubated at approximately -70°C (dry ice temperature) for 2 hours.
After being left for a period of time, it was developed by a prescribed method, and its degree of blackening was measured using a densitometer. The radioactivity of the surface source was determined by liquid scintillation counting. Sensitizers 1 and 2 have been shown to have good film sensitivity, excellent linearity, and excellent performance. (Sensitizer 1) PPO 7g, 1,4-bis[2-(4-methyl-5-phenyloxazole)]benzene (DMPOPOP) 0.2g, aromatic silicone oil
HIVAC-F4 (Shin-Etsu Chemical) 1, ethanol 2 (sensitizer 2) ppo 30gr, CH ₃ C ₆ H ₄ O (CH ₂ CH ₂ O) _2~5 H1, ethanol 1 (sensitizer 3) ppo 30g , ethyl ether 1 (sensitizer 4) EN ³ HANCE (manufactured by New England Nuclear)
was dropped into water, and 50g of the precipitate (main component: naphthalene, PPO) was taken and dissolved in 1 part ethanol.

[Table] Standardized and displayed.
[Example 2] Sensitizers 1 and 2 according to the present invention and conventional methods 3 and 4
Comparison of photoconductivity. A surface radiation source (12×
10 ⁵ dpm/cm ² ) converted into light by sensitizer 1 is used as the sample light source, covered with a filter paper impregnated with sensitizers 1 to 4, and an X-ray film is tightly attached to this.
The decrease in photosensitivity was measured as in Example 1.

[Table] As a result, sensitizers 1 and 2 according to the present invention had a smaller rate of decrease in photosensitivity than conventional methods 3 and 4, and exhibited extremely high photoconductivity. This shows that the present invention is particularly effective in measuring thick samples.

Claims (1)

[Claims] 1. General formula (In the formula, R ¹ to ^{R n+2} are each a methyl group or a phenyl group, at least one of R ¹ to ^{R n+2} is a phenyl group, and n is an integer from 10 to 1000.) Aromatic silicone oil or (In the formula, R ¹ to ^{R 5} are a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or a cyclohexyl group, R ⁶
Alternatively, R ⁷ is a hydrogen atom or a methyl group, and cannot be a methyl group at the same time. m is 0 or 1,
n is a value of 2-15. ) An autoradiographic sensitizer consisting of a polyether derivative represented by () and an organic scintillator. 2. The sensitizer according to claim 1, which contains a volatile organic solvent. 3. Claim 1, wherein the mixing ratio (weight ratio) of aromatic silicone oil or polyether derivative to organic scintillator is 100:1 to 50.
sensitizer. 4. The sensitizer according to claim 2, wherein the amount of the volatile organic solvent used is 10 times or less (by volume) relative to the amount of the aromatic silicone oil or the mixture of the polyether derivative and the organic scintillator.