Methods for multiplexed selection of functional ligands

A method of selecting aptamers from a library of oligonucleotides comprising:

• contacting a plurality of identifiers each of which comprising an oligonucleotide comprising a unique identity sequence denoting a predetermined position on a substrate with a corresponding plurality of target spots disposed at predetermined positions on said substrate, each of said target spots comprising least one target molecule contacted with members of a library of oligonucleotides and washed to remove non-binders;
• and
• attaching any of said plurality of identifiers to any of said members of said library of oligonucleotides bound at one of said target spots by hybridizing, each of said identifiers comprising a first constant region which hybridizes to a second constant region on each of said members of said library of oligonucleotides;
• wherein each of said unique identity sequences of said plurality of identifiers correlate to one of said predetermined positions on said substrate.

A method of selecting aptamers comprising:

• contacting an identifier comprising an oligonucleotide comprising a unique identity sequence denoting a predetermined position on a substrate with a corresponding target spot disposed at said predetermined position on said substrate, said target spot comprising an aptamer bound to a target molecule;
• attaching said identifier to said aptamer bound at said target spot by hybridizing, said oligonucleotide comprising a first constant region which hybridizes to a second constant region on said aptamer;
• and
• performing a nucleic acid extension reaction on said hybridized identifier and said aptamer to produce an extension product comprising said identity sequence and a complementary sequence to said aptamer, or their complements;
• wherein each of said unique identity sequence correlates to said predetermined position on said substrate.