Recognition, Signal Transduction, and Amplification of Nucleic Acids Under Isothermal Condition.

Isothermal nucleic acid detection has become a compelling alternative to PCR, enabling rapid analysis with minimal instrumentation and strong potential for point-of-care use. Central to assay performance are three interconnected processes: recognition, signal transduction, and amplification. Recognition strategies now extend beyond base pairing to include engineered proteins, catalytic nucleic acids, and synthetic modules. Signal transduction has advanced through orthogonal chemistries and functional nanomaterials, converting molecular events into optical, electrical, or colorimetric outputs. Amplification encompasses not only nucleic acid replication but also catalytic cycles and cascade reactions that magnify signals across molecular and material scales. These innovations are converging toward integrated, programmable platforms that support multiplexing and digital readouts. In this Perspective, we highlight emerging mechanisms and design principles that define isothermal detection, and outline future opportunities to achieve accurate, scalable, and accessible diagnostics for clinical, environmental, and translational applications.