Aptamers: An emerging class of molecules that rival antibodies in diagnostics

Antibodies, the most popular class of molecules providing molecular recogni tion needs for a wide range of applications, have been around for more than three decades. As a result, antibodies have made substantial contributions toward the advancement of diagnostic assays and have become indispensable in most diagnostic tests that are used routinely in clinics today. The deve lopment of the systematic evolution of ligands by exponential enrichment (S ELEX) process, however, made possible the isolation of oligonucleotide sequ ences with the capacity to recognize virtually any class of target molecule s with high affinity and specificity. These oligonucleotide sequences, refe rred to as "aptamers", are beginning to emerge as a class of molecules that rival antibodies in both therapeutic and diagnostic applications. Aptamers are different from antibodies, yet they mimic properties of antibodies in a variety of diagnostic formats. The demand for diagnostic assays to assist in the management of existing and emerging diseases is increasing, and apt amers could potentially fulfill molecular recognition needs in those assays . Compared with the bellwether antibody technology, aptamer research is sti ll in its infancy, but it is progressing at a fast pace. The potential of a ptamers may be realized in the near future in the form of aptamer-based dia gnostic products in the market. In such products, aptamers may play a key r ole either in conjunction with, or in place of, antibodies. It is also like ly that existing diagnostic formats may change according to the need to bet ter harness the unique properties of aptamers. (C) 1999 American Associatio n for Clinical Chemistry.