Abstract: Methods to obtain nucleic acid ligands that photocrosslink to target molecules associated with a disease state are provided. The methods presented are variations on the photoSELEX methods for obtaining nucleic acid ligands. In one method, a candidate mixture of photocrosslinkable nucleic acids is contacted with a biological substance obtained from a source associated with a disease state suspected of containing a target molecule to form nucleic acid-target molecule complexes, the complexes are irradiated to form crosslinked complexes, the photocrosslinked complexes are partitioned from the remainder of the candidate mixture; and the nucleic acid ligands that photocrosslink to molecule are retained. These nucleic acids are then contacted with a second biological substance of the same type as the first, but obtained from a source not associated with a disease state. This removes nucleic acids with affinity to molecules that are not associated with the disease state.

Abstract: Methods are described for the identification and preparation of high-affinity nucleic acid ligands to bFGF. Included in the invention are specific DNA ligands to bFGF identified by the photoSELEX method. Also included is a method for determining the position of a nucleic acid ligand-protein photoadduct.

Abstract: A method for identifying nucleic acid ligands to target molecules using the SELEX procedure. Nucleic acid candidate sequences contain photoreactive groups. After exposure of the nucleic acid sequences to the target molecule, nucleic acid-target molecule complexes are formed between nucleic acids having increased affinity to the target molecule and the target molecule. The complexes are irradiated such that photocrosslinks form between the photoreactive groups of the bound nucleic acids and the target molecule. The photocrosslinked complexes are separated from unbound nucleic acids, and the nucleic acids amplified to yield a ligand-enriched mixture of nucleic acids.

Abstract: This invention is directed towards a method for obtaining nucleic acid ligands against target proteins without directly purifying the target proteins. The method used in the invention is called SELEX, which is an acronym for Systematic Evolution of Ligands by EXponential enrichment. The nucleic acid ligands of the invention are useful as diagnostic and therapeutic agents for diseases in which the targets proteins play a causative role.

Abstract: A method for identifying nucleic acid ligands to target molecules using the SELEX procedure wherein the candidate nucleic acids contain photoreactive groups and nucleic acid ligands identified thereby are claimed. The complexes of increased affinity nucleic acids and target molecules formed in the procedure are crosslinked by irradiation to facilitate separation from unbound nucleic acids. In other methods partitioning of high and low affinity nucleic acids is facilitated by primer extension steps as shown in the figure in which chain termination nucleotides, digestion resistant nucleotides or nucleotides that allow retention of the cDNA product on an affinity matrix are differentially incorporated into the cDNA products of either the high or low affinity nucleic acids and the cDNA products are treated accordingly to amplification, enzymatic or chemical digestion or by contact with an affinity matrix.

Abstract: A Nucleic acid ligand “Biochip” is disclosed, consisting of a solid support to which one or more specific Nucleic acid ligands is attached in a spatially defined manner. Each Nucleic acid ligand binds specifically and avidly to a particular Target molecule contained within a Test mixture, such as a Bodily fluid The Target molecules include, but are not limited to, proteins (cellular, viral, bacterial, etc.) hormones, sugars, metabolic byproducts, cofactor, and intermediates, drugs, and toxins. Contacting the Test mixture with the Biochip leads to the binding of a Target molecule to its cognate Nucleic acid ligand. Binding of Target to the Nucleic acid ligand results in a detectable change at each specific location on the Biochip. The detectable change can include, but is not limited to, a change in fluorescence, or a change in a physical parameter, such as electrical conductance or refractive index, at each location on the Biochip.