Recent advance of RNA aptamers and DNAzymes for MicroRNA detection

MicroRNAs (miRNAs) are a class of small, single-stranded, and non-coding RNA molecules that act as post-transcriptional regulators of gene expression, participating in the regulation of a variety of important biological activities. Accumulating evidence suggests that miRNAs are closely related to many major human diseases, especially cancer, and they are considered to be highly promising diagnostic biomarkers and therapeutic targets for disease diagnosis and treatment. To this end, the development of highly accurate, selective, and sensitive strategies for miRNA detection is essential for realizing the early diagnosis of diseases and improving the success rate of treatment. Over the past decade, functional nucleic acid nanostructures have emerged as powerful tools for detecting disease-related miRNAs because of their unique advantages, e.g., high stability, specificity, and activity. Particularly, thanks to the rapid advancement of systematic evolution of ligands by exponential enrichment (SELEX) technology, it is now feasible to strictly select and reasonably design functional nucleic acids with high specificity and activity toward targets of interest, and thereby enhance the performance of miRNA detection. In this article, we present a comprehensive review of the application of functional nucleic acids including RNA aptamers and DNAzymes selected by SELEX in the construction of biosensors for miRNA detection in recent years. We also provide insights into the impact of the advantages of RNA aptamers and DNAzymes on the enhancement of the performance of miRNA biosensors. We hope this review will serve as a valuable foundation to inspire more exciting research in this emerging field in near future.