Method for the manufacture of agarose gels

1. A method for the manufacture of an agarose separation gel, comprising the steps of:

i) providing agar material comprising a solution of agar or partially desulphated agar,

ii) two or more substeps (ii.A, ii.B, ii.C etc) that comprise removing natively occurring sulphate groups, thereby transforming the agar material to agarose having a degree of substitution of sulphate groups that is less than the degree of substitution of sulphate groups in the starting agar material, and

iii) gelling the solution of agar material prior to step (ii) by cooling the solution to a temperature below the gelling temperature of the starting agar material and securing the desulphated agar material in gel form during the complete process of the substeps of step (ii),

wherein step (ii), in addition to the desulphating substeps (ii.A, ii.B, ii.C etc), further comprises a sequence (S 1 ) which comprises one or more substeps (ii.1 1 , ii.2 1 etc) and introduces a cross-linking structure into the gel under alkaline desulphating conditions, and wherein one or more of the desulphating substeps (ii.A, ii.B, ii.S etc) coincides with a substep (ii.1, ii.2 etc) of sequence (S 1 ).

2. The method of claim 1 , wherein the removing comprises replacing sulphate groups with hydroxyl groups.

3. The method of claim 1 , wherein the gel form is in the form of beads.

4. The method of claim 1 , wherein said desulphating in at least one of said substeps comprises alkaline hydrolysis performed in aqueous solution at a pH≧10, in the presence of a soluble metal hydroxide at a concentration of hydroxide≧0.1 M.

5. The method of claim 1 , wherein step (ii), in addition to the desulphating substep (ii.A, ii.B, ii.C etc) and the sequence (S 1 ), comprises one or more sequences (S 2 etc), each of which comprises one or more substeps (ii.1 2 , ii.2 2 etc; etc) and introduces a chemical structure which is different between the respective sequences (S 1 , S 2 etc) and is present in the gel product.

6. The method claim 5 , wherein at least one of the sequences (S 2 etc) introduces a chemical structure that is a functional group.

7. The method of claim 5 , wherein one or more of the substeps (ii.A, ii.B, ii.C etc) coincides at least partly with a substep (ii.1, ii.2 etc) in at least one of the sequences (S 2 etc).

8. The method of claim 5 , wherein at least one of the sequences (S 1 , S 2 etc) comprises the substeps of:

ii.1) transforming a first structure to a second structure where the first structure is present in the agar material at the start of said at least one sequence or has been introduced as an intermediary structure in a previous substep,

ii.2) transforming the second structure to a third structure that is an intermediary structure,

ii.3) transforming the third structure to a fourth structure that is present in the agar material wherein the fourth structure is equal to a chemical structure that is present in the end product, or is an intermediary structure in substep (ii),

ii.4) performing substeps (ii.1-ii.3) a predetermined number of times until the desired chemical structure has been accomplished on the gel.

9. The method of claim 8 , wherein

substep (ii.1) comprises transformation of hydroxyl to a structure comprising unsaturation,

substep (ii.2) comprises transformation of the unsaturation to a structure that comprises halohydrin or vicinal halide by addition of hypohalite or halogen under moderate pH-conditions,

substep (iii.3) comprises transformation of the halohydrin or vicinal halide to a vicinal dialcohol under alkaline conditions, and

substep (ii.4) comprises performing substeps (ii.1-ii.3) a second time, a third time etc, until a cross-linking giving the gel a predetermined rigidity or as an alternative stopping the final repetition after a halohydrin/vicinal dihalide or epoxide has been introduced in substep ii.2.

10. The method of claim 9 , wherein the transformation of hydroxyl to a structure comprising unsaturation is achieved by reacting hydroxyl with an unsaturated alkyl halide under alkaline conditions.

11. The method of claim 8 , wherein the chemical structure is selected from the group consisting of a) a cross-linking structure, b) a reactive structure that is to be used for further derivatization of the gel, and c) an affinity structure.

12. The method of claim 5 , wherein the chemical structure is an affinity group, or a group that can be used for further functionalization.

13. The method of claim 1 , wherein the gel provided in step (iii) is in the form of particles having a mean size selected within the interval 1-1000 μm, with the particles saturated with water.

14. The method of claim 1 , wherein the gel provided in step (iii) is in the form of beads with ≧40 of the particles having sizes within the interval of the mean size±1000% of the mean bead size with the beads saturated with water.

15. The method of claim 1 , wherein the concentration of agar in the solution provided in step (i) is ≦25% (w/w).

16. The method of claim 1 , wherein the number of desulphating steps is two or more.

17. The method of claim 1 , wherein excess of reactants and/or byproducts formed during a substep are removed after the substep.

18. The method of claim 1 , wherein the agar material is transformed to agarose having a degree of substitution of sulphate groups that is ≦75% of the degree of substitution of sulphate groups in the starting agar material.

19. The method of claim 1 , wherein the number of desulphating steps is three or more.

20. The method of claim 1 , wherein the number of desulphating steps is three or more.