pH dependent ion exchange matrix and method of use in the isolation of nucleic acids

A multimodal pH dependent ion exchange matrix, comprising:

• a solid support;
• a plurality of first ion exchange ligands, each first ion exchange ligand comprising:
• a cap comprising an amine with a pK of less than about 9;
• a spacer covalently attached to the cap, the spacer comprising a spacer alkyl chain with an amine terminus;
• and
• a linker comprising a linker alkyl chain covalently attached to the solid support at a first end of the linker alkyl chain and covalently attached to the amine terminus of the spacer at a second end of the linker alkyl chain;
• a plurality of second ion exchange ligands, each second ion exchange ligand comprising:
• a second alkyl chain covalently attached to the solid support at a first end of the second alkyl chain;
• and
• a second acidic moiety covalently attached to a second end of the second alkyl chain,
• wherein the matrix has a capacity to adsorb to a target nucleic acid at a first pH, and to release the target nucleic acid at a desorption pH which is higher than the first pH.

A method of isolating a target nucleic acid using a multimodal pH dependent ion exchange matrix, comprising the steps of:

• (a) providing a multimodal pH dependent ion exchange matrix comprising:
• a solid support;
• a plurality of first ion exchange ligands, each first ion exchange ligand comprising:
• a cap comprising an amine with a pK of less than 9, wherein the amine is selected from the group consisting of a primary, a secondary, and a tertiary amine;
• a spacer covalently attached to the cap, the spacer comprising a spacer alkyl chain with an amine terminus;
• and
• a linker comprising a linker alkyl chain covalently attached to the solid support at a first end of the linker alkyl chain and covalently attached to the amine terminus of the spacer at a second end of the linker alkyl chain;
• a plurality of second ion exchange ligands comprising:
• a second alkyl chain covalently attached to the solid support at a first end of the second alkyl chain;
• and
• a second acidic moiety covalently attached to a second end of the second alkyl chain,
• wherein the matrix has a capacity to adsorb to a target nucleic acid at a first pH, and to release the target nucleic acid at a desorption pH which is higher than the first pH,
• (b) providing a mixture comprising the target nucleic acid;
• (c) combining the mixture and the matrix and incubate at the first pH until the nucleic acid adsorbs to the matrix, forming a complex;
• (d) separating the complex from the mixture;
• and
• (e) combining the complex with an elution solution at the desorption pH.

A method of making a pH dependent ion exchange matrix, comprising the steps of:

• (a) providing a solid phase;
• (b) providing a linker comprising an alkyl chain having a first end and a second end;
• (c) combining the silica based solid phase and the linker under conditions where a covalent bond is formed between the solid phase and the first end of the linker alkyl chain, thereby producing a linker-modified solid phase;
• (d) providing an acidic aromatic amine comprising:
• an aromatic hydrocarbon ring, wherein at least one member of the ring is an amine;
• a spacer which is covalently attached to the aromatic hydrocarbon, wherein the spacer comprises a spacer alkyl chain with an amino terminus;
• and an acidic substituent which is covalently attached to the spacer alkyl chain;
• and
• (e) combining the linker-modified solid phase with the acidic aromatic amine under conditions where a covalent bond is formed between the amino terminus of the spacer alkyl chain of the acidic aromatic amine and the second end of the linker.

A method of making a bimodal pH dependent ion exchange matrix, comprising the steps of:

• (a) providing a solid support;
• (b) providing a first ion exchange ligand comprising:
• a cap comprising an amine with a pK of less than about 9, wherein the amine is selected from the group consisting of a primary, a secondary, or a teritary amine;
• a spacer covalently attached to the cap, the spacer comprising a spacer alkyl chain and with an amine terminus;
• and
• a linker comprising a linker alkyl chain having a first end and a second end, wherein the second end is covalently attached to the amine terminus of the spacer;
• (c) combining the solid phase and the first ion exchange ligand under conditions where a covalent bond is formed between solid phase and the first end of the linker alkyl chain;
• (d) providing a second ion exchange ligand, comprising a second alkyl chain and an acidic residue covalently attached thereto, wherein the acidic residue has a protective group covalently attached thereto;
• (e) combining the solid phase with the first ion exchange ligand attached thereto with a second ligand under conditions which promote formation of a covalent bond between the protected second ion exchange ligand and the solid phase;
• and
• (f) deprotecting the acidic residue of the second anion exchange ligand by removing the protective group therefrom.