Diagnostic potential of PhotoSELEX-evolved ssDNA aptamers

High sensitivity and specificity of two modified ssDNA aptamers capable of photocross-linking recombinant human basic fibroblast growth factor (bFGF(( 115))) were demonstrated. The aptamers were identified through a novel, cov alent, in vitro selection methodology called photochemical systematic evolu tion of ligands by exponential enrichment (PhotoSELEX). The aptamers exhibi ted high sensitivity for bFGF((115)) comparable with commercially available ELISA monoclonal antibodies with an absolute sensitivity of at least 0.058 ppt bFGF((115)) under prevailing test conditions. The aptamers exquisitely distinguished bFGF((115)) from consanguine proteins, vascular endothelial growth factor (VEGF) and platelet derived growth factor (PDGF). A commercia lly viable diagnostic system incorporating PhotoSELEX-evolved aptamers capa ble of simultaneous quantification of a large number of analyte molecules i s also described. Such a system benefits from covalent bonding of aptamer t o target protein allowing vigorous washing with denaturants to improve sign al to noise. (C) 2000 Elsevier Science B.V. All rights reserved.