Detection of Alzheimer’s associated microRNAs using a DNA-based smart reagent

Alzheimer’s disease (AD) is the most common neurodegenerative disorder, with significant research efforts devoted to identifying new biomarkers for clinical diagnosis and treatment. MicroRNAs have emerged as likely disease regulators and biomarkers for AD, now implicated as having roles in several biological processes related to progression of the disease. In this work, we use the miRacles assay ( mi cro R NA a ctivated c onditional l ooping of e ngineered s witches) for single-step detection of AD-related microRNAs. The technology is based on conformationally responsive DNA nanoswitches that loop upon recognition of a target microRNA and report their on/off status through an electrophoretic readout. Unlike many other methods, our approach directly detects native microRNAs without amplification or labeling, eliminating the need for expensive enzymes, reagents, and equipment. We used this assay to screen for AD-related microRNAs, demonstrate specificity within a microRNA family, sensitivity of ∼ 8 fM, and multiplexing capability to simultaneously detect four microRNA targets. Toward clinical use, we provide proof-of-concept detection and quantifiable dysregulation of specific microRNAs from total RNA extracts derived from healthy and AD brain samples. In the context of AD, this “smart reagent” could facilitate biomarker discovery, accelerate efforts to understand the role of microRNAs in AD, and have clinical potential as a diagnostic or monitoring tool for validated biomarkers.