High-affinity nucleic acid ligands that discriminate between theophylline and caffeine

Nucleic acid ligands to theophylline identified according to a method for identifying nucleic acid ligands from a candidate mixture comprised of nucleic acids, said method comprising:

• a) preparing a candidate mixture of nucleic acids;
• b) contacting said candidate mixture with theophylline, wherein nucleic acids having an increased affinity to theophylline relative to the candidate mixture may be partitioned from the remainder of the candidate mixture;
• c) partitioning the increased affinity nucleic acid ligands from the remainder of the candidate mixture;
• and
• d) amplifying the increased affinity nucleic acids to yield a ligand-enriched mixture of nucleic acid, whereby nucleic acid ligands of theophylline may be identified.

Nucleic acid ligands to caffeine identified according to a method for identifying nucleic acid ligands from a candidate mixture comprised of nucleic acids, said method comprising:

• a) preparing a candidate mixture of nucleic acids;
• b) contacting said candidate mixture with caffeine, wherein nucleic acids having an increased affinity to caffeine relative to the candidate mixture may be partitioned from the remainder of the candidate mixture;
• c) partitioning the increased affinity nucleic acid ligands from the remainder of the candidate mixture;
• and
• d) amplifying the increased affinity nucleic acids to yield a ligand-enriched mixture of nucleic acid, whereby nucleic acid ligands of caffeine may be identified.

A method for identifying nucleic acid ligands to a target molecule comprising:

• (a) preparing a candidate mixture of nucleic acids;
• (b) contacting the candidate mixture with one or more non-target molecules, wherein nucleic acids with affinity to the non-target molecule(s) are removed;
• (c) contacting the candidate mixture from (b) with the target molecule, wherein nucleic acids having an increased affinity to the target relative to the candidate mixture may be partitioned from the remainder of the candidate mixture;
• (d) partitioning the increased affinity nucleic acids from the remainder of the candidate mixture;
• (e) amplifying the nucleic acids with specific affinity to the target molecule to yield a mixture of nucleic acids enriched for nucleic acid sequences with relatively higher affinity and specificity for binding to the target molecule, whereby nucleic acid ligands of the target molecule may be identified.