Methods and compositions of nucleic acid ligands for detection of clinical analytes related to human health

Specific DNA sequences for binding various clinically relevant analytes from the human body are described. Each of these sequences or their linear, two- and three-dimensional linked sequences can function in varying assay and sensor formats with varying degrees of success. Linkage of the whole or partial DNA sequences (putative binding sites) can be used to enhance specificity and affinity towards complex targets, thereby improving assay selectivity and sensitivity in many instances. In addition, a FRET-based quantitative method is described for normalizing analyte data by assessing urine creatinine and urea levels. Finally, a method is described for removing creatinine or urea by size-exclusion chromatography prior to a FRET-based aptamer assay to avoid the denaturing effects of these compounds.