Modified L-nucleic acid

1. A modified L-nucleic acid, comprising an L-nucleic acid part and a non-L-nucleic acid part, wherein the L-nucleic acid part is conjugated with the non-L-nucleic acid part, wherein the conjugate of the L-nucleic acid part with the non-L-nucleic acid part has an increased retention time in an organism compared to an L-nucleic acid comprising only the L-nucleic acid part, wherein said L-nucleic acid part is a spiegelmer, and wherein said L-nucleic acid part comprises SEQ ID NO:1.

2. The modified L-nucleic acid of claim 1 , wherein the non-L-nucleic acid part has a molecular weight of more than about 300 Da.

3. The modified L-nucleic acid of claim 1 , wherein the modified L-nucleic acid has a molecular weight to 500,000 Da.

4. The modified L-nucleic acid of claim 1 , wherein the L-nucleic acid part has a molecular weight to 50,000 Da.

5. The modified L-nucleic acid of claim 1 , wherein the non-L-nucleic acid part is Linked to the L-nucleic acid part via a functional group of the L-nucleic acid part, wherein the functional group is selected from the group consisting of terminal and non-terminal phosphates, terminal and non-terminal sugar portions, natural and non-natural purine bases, and natural and non-natural pyrimidine bases.

6. The modified L-nucleic acid of claim 5 , wherein the linkage of the non L-nucleic acid part with the L-nucleic acid part is via the 2′-OH—, 3′-OH—, 5′-OH-group or a derivative therefrom, or one or more sugars of the L-nucleic acid part.

7. The modified L-nucleic acid of claim 5 , wherein the linkage is via at least one of the positions 5 or 6 of a pyrimidine base.

8. The modified L-nucleic acid of claim 5 , wherein the linkage is via a purine base.

9. The modified L-nucleic acid of claim 5 , wherein the linkage is at one or more of the exocyclic amine groups, endocyclic amine groups or keto groups of a purine or pyrirnidine base or a basic position.

10. The modified L-nucleic acid of claim 1 , wherein the non-L-nucleic acid part is selected from the group consisting of linear poly (ethylene) glycol, branched poly (ethylene) glycol, hydroxyethyl starch, a peptide, a protein, a polysaccharide, a sterol, polyoxypropylene, polyoxyamidate, poly (2-hydroxyethyl)-L-glutamine and polyethylene glycol.

11. The modified L-nucleic acid of claim 1 , wherein a linker is arranged between the L-nucleic acid part and the non-L-nucleic acid part.

12. The modified L-nucleic acid of claim 11 , wherein said linker is a 6-aminohexylphosphate at the 5′-OH end.

13. The modified L-nucleic acid of claim 12 , wherein polyethylene glycol is coupled to the free amine of the aminohexyiphosphate linker.

14. A pharmaceutical composition comprising the modified L-nucleic acid of claim 1 and a pharmaceutically acceptable carrier, excipient or diluent.

15. A method for preparing the modified L-nucleic acid of claim 1 , comprising the steps:

(a) providing an L-nucleic acid comprising SEQ ID NO: 1;

(b) providing a non-L-nucleic acid;

(c) reacting the L-nucleic acid from (a) and the non-L-nucleic acid from (b); and

(d) optionally isolating the modified L-nucleic acid obtained in step (c) wherein the L-nucleic acid part is a Spiegelmer.

16. The method of claim 15 , wherein the L-nucleic acid in step (a) comprises a linker.

17. The method of claim 15 , wherein after providing the L-nucleic acid instep (a), a linker is provided.

18. The modified L-nucleic acid of claim 2 , wherein the molecular weight is more than about 20,000 Da.

19. The modified L-nucleic acid of claim 18 , wherein the molecular weight is more than 40,000 Da.

20. The modified L-nucleic acid of claim 8 , wherein said linkage occurs at the 8 position.