Analytical perspectives on RNA aptamer switch-based biosensors

RNA aptamer switches are programmable tools that enable ligand-responsive control of gene expression, making them valuable as genetically encoded biosensors in synthetic biology, diagnostics, and therapeutic applications. RNA aptamer switch functionality is often evaluated through changes in reporter gene expression following ligand recognition; however, analytical methods used to characterize RNA aptamer switch activity vary across studies, making it difficult to compare between platforms. This review examines analytical approaches to evaluate RNA aptamer switch-based biosensors, highlighting how each method captures different aspects of switch performance and how molecular, cellular, and experimental factors shape output. We also discuss considerations for experimental design, including normalization, controls, assay context, and sensitivity. By comparing the strengths and limitations of different analytical readouts, we provide suggestions for selecting appropriate measurement methods. Finally, we discuss current challenges in standardization, with the goal of improving quantitative and predictive evaluation of RNA aptamer switch-based biosensors.