Organic compounds -- part of the class 532-570 series – Organic compounds – Carbohydrates or derivatives
Patent
1991-06-20
1993-04-20
Nutter, Nathan M.
Organic compounds -- part of the class 532-570 series
Organic compounds
Carbohydrates or derivatives
252 6257, 252 6258, 252 6264, 252 6256, 252 6253, C08B 1112
Patent
active
052044572
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a complex of a carboxyalkyl ether of a polysaccharide with a magnetic metal oxide and a process for preparing thereof.
BACKGROUND ART
Usual magnetic fluids are prepared with the addition of a surfactant such as a oleate salt or a dodecylamine in order to make the superfine particles of a magnetic metal oxide or magnetic metal stably existing in a liquid such as water or an oil. Since usual magnetic fluids are poor in chemical stability and have high toxicity, trials to apply them to medical treatment have scarcely been made.
In order to obviate these drawbacks, complexes of dextran with a magnetic iron oxide have been proposed, and for example, Japanese Patent Publication No. 13521/1984 (U.S. Pat. No. 4,10l,435) discloses complexes of dextran or a modified dextran obtained by treating dextran with sodium hydroxide and a magnetic iron oxide having a size of 3 to 20 nm. Further, U.S. Pat. No. 4,452,773 discloses magnetic iron-dextran microspheres of a molecular complex structure such that magnetic iron oxide particles having a colloidal size was coated with dextran molecules. Although these complexes are useful in the form of aqueous sol, they still have problems to be improved particularly for use in medical treatment.
As a result of intensive studies, the present inventors found that complexes of a carboxyalkyl ether of a polysaccharide with a magnetic metal oxide have improved properties in several points, and came to complete the invention.
DISCLOSURE OF INVENTION
Thus, according to the invention, is provided a complex of a carboxyalkyl ether of a polysaccharide with a magnetic metal oxide.
Complexes of the invention are extremely excellent in stability in preservation in the form of aqueous sol and have only low toxicity, and thus are useful for medical treatment, for example, as a nuclear magnetic resonance imaging (hereinafter abbreviated as MRI) contrast medium or a drug-administering carrier or the like.
As for carboxyalkyl ethers of a polysaccharide as one component constituting the complexes of the invention, at least part of them, are known for example, refer to U.S. Pat. Nos. 2,746,906 and 2,876,165, Kogyo Kagakukaishi, 68, 1590 (1965), and such an ether can readily be prepared by adding an alkali to an aqueous solution or suspension of a polysaccharide and then adding a monohaloalkylcarboxylic acid, particularly a monochloroalkylcarboxylic acid to start reaction. A polysaccharide carboxyalkyl ether having a desired limiting viscosity can be obtained by using the polysaccharide having a corresponding intrinsic viscosity as a starting material or by first preparing the polysaccharide carboxyalkyl ether having a high viscosity and then lowering the viscosity. Polysaccharides usable as a starting raw material include neutral polysaccharides and basic polysaccharides, and examples of neutral polysaccharides are glucose polymers such as dextran, starch, glycogen, cellulose, pullulan, curdlan, schizophyllan, lentinan and pestalotian; fructose polymers such as inulin and levan; mannose polymers such as mannan; galactose polymers such as agapose and galactan; xylose polymers such as xylan; L-arabinose polymers such as arabinan; etc, and examples of basic polysaccharides are glucosamine polymers such as chitin.
In the invention, neutral polysaccharides are preferred among them, and particularly preferred are dextran, starch, cellulose and pullulan.
On the other hand, as haloalkylcarboxylic acids usable for the carboxyalkyl etherification of the polysaccharide, halo-lower alkylcarboxylic acids are particularly mentioned, and examples thereof are monochloroacetic acid, monobromoacetic acid, 3-chloropropionic acid, 3-bromopropionic acid, 4-chloro-n-butyric acid, 4-bromo-n-butylic acid, 2-chloropropionic acid, 3-chloro-n-butyric acid, etc.
Preferred carboxyalkyl ethers of the polysaccharide in the invention are at least one selected from carboxymethyl ethers, carboxyethyl ethers and carboxypropyl ethers.
When reacted with a magnetic metal oxide, the polysaccha
REFERENCES:
patent: 4101435 (1978-07-01), Hasegawa et al.
patent: 4452773 (1984-06-01), Molday
CA 84,831b Sep. 5, 1988, Wooding et al. in IEEE Trans. Magn. 1988, 24(2,Pt. 2), 1650-2.
Hasegawa Masakatsu
Maruno Shigeo
Maruno Shigeo
Meito Sangyo Kabushiki Kaisha
Mullis Jeffrey C.
Nutter Nathan M.
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