Design strategies and advanced applications of primer exchange reactions in biosensing: A review

Early disease diagnosis relies on the sensitive detection and imaging of biomarkers. Signal amplification is one of the most commonly used methods to improve detection sensitivity. Primer exchange reaction (PER) is a novel signal amplification technique that has garnered attention because of its simple and sensitive features. The classical PER involves a single catalytic hairpin, which enables the attachment of custom sequences to the primer chain, generating a long repeat sequence that can bind numerous signaling molecules and achieve powerful signal amplification. Currently, numerous PER-based signal amplification strategies are available that can improve detection sensitivity and promote the development of the signal amplification field. This review focuses on the mechanism of typical PER, the diversification of PER, and PER-based biosensors for various targets. Finally, the challenges and prospects of PER development are discussed.