Development of ratiometric DNA biosensors with improved accuracy, precision, and signal-to-noise ratio

Ratiometric DNA biosensors, which utilize DNA as the recognition element and integrate dual signals from diverse sensing platforms including fluorescence, electrochemistry, and surface-enhanced Raman scattering (SERS), have demonstrated remarkable proficiency in detecting a wide range of targets. In this review, we showcase the significant progress achieved by ratiometric biosensors. Firstly, ratiometric biosensors have made notable advancements in analyzing real samples. These include the analysis of pH values near cancer cells, quantification of miRNA in human cell lysates, detection of human telomerase RNA in cell extracts, and performing DNA logic-gated in situ bioimaging on cell membranes. Secondly, excellent sensitivity has been attained through the utilization of effective amplification methods such as RCA, HCR, and CHA, among others. Thirdly, the construction of stable reference signals has resulted in significantly improved precision for ratiometric biosensors. This breakthrough has overcome matrix effects, enabling reliable detection in real samples with high selectivity. This review provides a comprehensive overview of recent advancements in strategies employed by ratiometric DNA biosensors. We present three types of biosensors based on distinct sensing platforms: fluorescent, electrochemical, and SERS biosensors. Additionally, we discuss future directions and primary challenges in the development of ratiometric DNA biosensors.