Chemistry: analytical and immunological testing – Involving an insoluble carrier for immobilizing immunochemicals – Carrier is inorganic
Patent
1983-11-07
1987-08-18
Warden, Robert J.
Chemistry: analytical and immunological testing
Involving an insoluble carrier for immobilizing immunochemicals
Carrier is inorganic
436529, 436530, 436531, 435 7, 252 6254, G01N 33553, G01N 3353, G01N 33545
Patent
active
046877487
DESCRIPTION:
BRIEF SUMMARY
This invention relates to magnetically responsive crystalline-carbohydrate spheres or particles and to their use together with bioadsorptive materials. This includes coupling, adsorption and/or entrapment of bioadsorptive materials to said spheres or particles in connection with the use of interactions of these bioadsorptive materials with biological substances and cells. Preferably, in this invention use is made of magnetic nano-spheres.
By "magnetic nano-sphere" is meant a sphere or a particle the average diameter of which is 1-999 nm and which is responsive to a magnetic field.
The advantage of using nano-spheres instead of micro-spheres is obvious from a calculation of the ratio of available surface area to volume unit of packed spheres:
A tenfold reduction of the diameter of the sphere gives a tenfold increase of the number of surface units per volume units of packed spheres. When bioadsorptive materials are to be used for covalent coupling or adsorption onto the surface of the spheres, the effort should be to use nano-spheres since the amount of bioadsorptive materials per volume units of packed spheres is maximized. Furthermore, a nano-sphere is desirable in the following examples of separation, since the magnetic force to which for example a cell is exposed is considerably greater than in a case of a magnetic micro-sphere. This is due to the fact that a larger number of interactions is possible between nano-spheres and a cell compared to micro-spheres.
Examples of interactions which can be used in connection with the present magnetic nano-spheres are as follows: combinations of the above interactions.
With the use of said interactions there exists the possibility of separating heterogeneous biological material.
Examples of interactions of the above-mentioned type can be:
cell separation, wherein a combination of interactions is included,
immunochemical analysis, preferably where a pure interaction of any of the types 1-4 is involved depending on the purpose of the analysis,
enzyme reaction, preferably when a protein-low molecular weight substance interacts, but also the types 1-3 are applicable, and,
affinity purifying, when different types of interactions can be used depending on the substance to be purified.
Different types of magnetic spheres or magnetic particles are known since long in the literature for use such as in the above-mentioned interactions. A survey of magnetic spheres as carriers for bioadsorptive material is published in Enz. Microb. Technol. Vol. 2, 1980 by Halling & Dunhill. For example, the desired characteristics which a magnetic sphere or particle should have are mentioned therein: surroundings. way to the surface of the microsphere. magnetic field.
A number of different magnetic materials are described and commercially available, such as Fe.sub.3 O.sub.4, Ni-NiO, Ni-TiO.sub.4, Mn-Zn ferrite, Ni etc. Generally, magnetite (Fe.sub.3 O.sub.4) is used, since it is readily available and is not oxidized in aqueous surroundings.
Useful polymer materials are for example acrylic derivative, agarose, proteins, copolymers of acryl and agarose, starch and cellulose. Among these neither starch nor proteins meet with the requirement of being chemically inert or resistant to degrading.
Known methods for producing magnetic micro-spheres are in general emulsion polymerizations with simultaneous cross-linking of the polymer to obtain stable microspheres. In one case the stabilization is obtained through heat-denaturation of protein (U.S. Pat. No. 4,230,685). As polymer albumin (J. Pharm. Sci (1981) 70, 387-389) or different acrylic derivatives (Nature (1977) 268, 437-438 or Science (1978) 200, 1074-1076) are used. The magnetic material is Fe.sub.3 O.sub.4. Various methods for coupling, adsorption or entrapment of the bioadsorptive material to/in the polymer are described in the literature and reference is made to Methods in Enzymology, vol. 44 (1976) (K. Mosbach).
A method for producing starch micro-spheres in which the magnetic material is entrapped (FEBS Lett. (1979) 102, 112-116) has been
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Halling et al., Biotechnology and Bioengineering, vol. XXI, pp. 393-416, (1979).
Mosbach and Schroder, Magnetic Microspheres for Targeting of Drugs, Enzyme Engineering, vol. 5, Weetall and Royer, Eds., Plenum Publishing Corp., 1980, pp. 239-241.
DeSantis Patricia L.
Gambro Lundia AB
Warden Robert J.
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