Method of isolating nucleic acid using material positively charged at first pH and containing amino group and carboxyl group

A method of isolating nucleic acid from a sample containing nucleic acid, the method comprising:

• contacting the sample with a bifunctional material that contains an amino group and a carboxyl group and is positively charged at a first pH to allow binding of nucleic acid to the bifunctional material to form a nucleic acid-bifunctional material complex;
• and
• extracting the bound nucleic acid at a second pH which is higher than the first pH from the complex,
• wherein the bifunctional material is represented by the following Formula 1 or Formula 2:
• where n is an integer from 1 to 10;
• and A is
• or a combination, from 1,2,4,5-benzenetetracarboxylic dianhydride;
• from 3,3′,4,4′-biphenyltetracarboxylic dianhydride, 2,2′,3,3′-biphenyltetracarboxylic dianhydride, or 2,3,3′,4′-biphenyltetracarboxylic dianhydride;
• or a combination, from bis(3,4-dicarboxyphenyl)sulfone dianhydride;
• or a combination, from 2,2-bis(3,4-dicarboxyphenyl)-hexafluoropropane dianhydride;
• or a combination, from bis(3,4-dicarboxyphenyl) ether dianhydride;
• from 3,3′,4,4′-benzophenonetetracarboxylic dianhydride, 2,2′,3,3′-benzophenonetetracarboxylic dianhydride or 2,3,3′,4′-benzophenonetetracarboxylic dianhydride;
• from 1,4,5,8-naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, or 2,3,6,7-naphthalenetetracarboxylic dianhydride, wherein the naphthalene is further unsubstituted or a carbonyl group and a carboxyl group is substituted on any carbon position except for a linking portion of the rings;
• from cyclobutanetetracarboxylic dianhydride;
• from methylcyclobutanetetracarboxylic dianhydride;
• or
• from 1,2,3,4-tetracarboxybutane dianhydride, wherein moiety A is a group generated from a reaction between the corresponding tetracarboxylic dianhydride, and an amino group of an NH2(CH2)nNH2 where n is an integer from 1 to 10;
• and
• where R1 and R2 are each independently selected from the group consisting of an —OH group and an —NH(CH2)nNH2 group, where n is an integer from 1 to 10;
• R3 is an alkyl group having 1 to 10 carbon atoms;
• and 1 is an integer from 1 to 30,000.