SPRING 2019 SEMINAR SERIES
Dr. Thomas Caltagirone
Synthetic Antibodies- The Emerging Field of “Aptamers” in Diagnostics and Drug Discovery
An aptamer (also known as a synthetic antibody) is a stable DNA, RNA, or peptide ligand that binds with high affinity and specificity to targets such as small molecules, peptides, proteins, biomarkers, cells, and tissues. Typical aptamer affinities are in the nanomolar to picomolar range for several target types. However, unlike the traditional antibody, aptamers have impressive specificities against target antigens, thereby eliminating cross-reactivity with closely related targets and avoiding false-positive results. A classic example is an aptamer that exhibits greater than 10,000-fold binding affinity for theophylline over caffeine, which differ from one another in structure by only a single methyl group. Additional benefits of aptamers include:manufacturing costs and time are all lower compared to that of monoclonal antibody production.Once the aptamer (nucleic acid) sequence is known, the aptamer can be easily synthesized using a DNA (oligo) synthesizer. These aptamer oligos are easy to label with reporters, enzymes, or fluorescent tags. In addition, aptamers can be engineered into molecular switches or apta-switches for signal generation in a drug discovery-based assay or to produce an output in a diagnostic test.