Accelerated Discovery of Aptamer Beacons via Massively Parallel Screening

Aptamer beacons are unimolecular probes that undergo a reversible conformational change upon target binding, making them a promising tool for the real-time detection and monitoring of molecular analytes. However, the development of such sensors has been impeded by the lack of generalizable tools for the efficient discovery and optimization of aptamer beacons for diverse molhhtmlecular targets. Here, we present a scalable approach for converting existing strand-displacement aptamer switches into aptamer beacons by introducing targeted mismatches within their non-target-binding stem domain, destabilizing the aptamer structure to an extent that it can only refold upon binding its target. In order to perform this screening in a high-throughput fashion, we have developed the Massively-parallel Aptamer Performance Analyzer (MAPA), an automated, fluorescence-based screening platform based on a reconfigured sequencing instrument that can functionally evaluate millions of aptamer variants in parallel. Using MAPA, we identified multiple aptamer beacons for glucose, serotonin, and dopamine, and demonstrated that these beacons retain their sensing performance when translated from the on-chip surface-based MAPA format to a solution-based assay. We performed all three aptamer beacon experiments on a single MAPA chip, and even greater multiplexing should be possible, greatly accelerating the discovery of aptamer-based sensors for real-time molecular detection.