A Practical Guide of Choosing and Validating Aptamers for Biosensors

Aptamers have been reported for hundreds of targets, and for many important analytes, multiple independent selections have yielded distinct sequences. Subsequent truncation, mutation, and chemical modification have further generated numerous variants of the original aptamers. This rapidly expanding sequence space, however, has created a growing reproducibility challenge. Many reported aptamers remain insufficiently characterized or inadequately validated, and sequence modifications are often adopted without rigorous confirmation of target binding. Consequently, identifying a reliable aptamer for biosensor development has become increasingly difficult, particularly for researchers new to the field. In this Perspective, we present a practical, step-by-step framework for evaluating aptamers, beginning with critical assessment of the original aptamer selection experiment, including the extent of sequence enrichment and alignment, family assignment, secondary structural plausibility, and the quality of binding data. Candidates that pass this initial assessment should then undergo independent, in-house validation using rigorous binding assays and appropriate controls. Although our discussion focuses on small-molecule-binding aptamers, the same principles of sequence evaluation and independent binding validation are broadly applicable to protein-binding aptamers. Looking forward, we advocate for greater transparency, standardized validation practices, and community-driven benchmarks to improve the reliability of aptamer research. Adoption of these practices will strengthen the foundation of aptamer-based biosensing.