Organic compounds -- part of the class 532-570 series – Organic compounds – Carbohydrates or derivatives
Patent
1994-09-16
1998-03-03
Truong, Duc
Organic compounds -- part of the class 532-570 series
Organic compounds
Carbohydrates or derivatives
536112, 536114, 5361231, 536124, 55 67, 73 192, C08B 3716
Patent
active
057236011
DESCRIPTION:
BRIEF SUMMARY
This application is a 371 of PCT/8E/93/00226 filed Mar. 16, 1993.
The present invention is related to polysaccharide gels containing, besides pores of a molecular dimension, for instance 20-500 .ANG., also interconnected macroscopic pores, typically with a pore diameter about 0.5-500 micrometers. These new materials have been found to considerably broaden the application areas for polysaccharide gels which have many advantageous characteristics for use in biotechniques, like chromatographic separations, membrane separation technology and support for solid phase chemistry, especially in biologically sensitive systems.
These superporous polysaccharide gels are produced by mixing a water-containing solution of the polysaccharide with an essentially water immiscible organic phase under vigorous stirring whereafter the finely dispersed mixture is allowed to solidify and the organic phase finally is washed away. The above organic phase is the superpore-forming phase. It must therefore be composed in such a way that it can exist as a continuous phase in the presence of a continuous agarose phase.
The new polysaccharide gels may be produced in various shapes, for instance more or less regular beads like spheres, membranes, etc, and can be used as a base matrix for the manufacture of chromatographic media, and as a carrier matrix in general for various biomolecules like cells, enzymes, antibodies etc.
Polysaccharide gels are known to play an important role for the manufacture of materials for separation of mixtures of biomolecules. Among the characteristics making these gels especially interesting can be mentioned their inertness in contact with proteins and other biomolecules and their porous structure. A further important property is their resistance against alkaline conditions, which is of great importance in large scale separation processes requiring frequent regeneration/sterilization of the gel. Polysaccharide gels unlike many other separation materials allow such in situ regeneration with, for instance 1M NaOH, which is an effective agent, frequently used for purification and sterilization.
Polysaccharide gels are used for various types of chromatography. One such example is gel filtration, whereby the sample constituents are size fractionated. This is an application where the inertness is of crucial importance since any interaction between the gel material as such and the sample molecules makes the separation less effective and might even completely destroy the result. Commercially very important materials for this type of separation have, for many years, been produced from crosslinked dextran and native or optionally crosslinked agarose (for instance Sephadex and Sepharose from Pharmacia LKB Biotechnology AB, Uppsala, Sweden).
Another example of a commercially important chromatographic technique is ion exchange chromatography. Several materials for ion exchange chromatography are derived from dextran, agarose or cellulose. The choice of polysaccharide gels as the carrier matrix is based, as above, on their inertness and a well established derivatization chemistry for the introduction of ion exchange groups.
A further example is affinity chromatography. Again, polysaccharide gels are preferred in many applications due to the number of convenient techniques available for introducing the affinity ligands and the minimum of unspecific binding of biomolecules.
The polysaccharide gels accordingly have several important characteristics making them an obvious choice as a base matrix for the preparation of materials for chromatographic separation. The gels exhibit, however, also certain drawbacks, like the limited mechanical stability. This is not a real problem when comparatively large gel beads (around 0.1 mm) are used as in traditional chromatography with the low flow rates through the gel bed required for diffusion reasons. The situation is, however, quite different when attempts are made to increase the separation efficacy by the use of smaller gel beads (around 5-20 micrometers). At flow rates optimal for dif
REFERENCES:
patent: 4741872 (1988-05-01), De Luca et al.
patent: 4935365 (1990-06-01), Nilsson et al.
patent: 5019270 (1991-05-01), Afeyan et al.
Pharmacia Biotech AB
Truong Duc
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