A fluorescence/colorimetric dual-mode sensing strategy for miRNA based on graphene oxide

MicroRNAs (miRNAs) are small non-coding RNAs, which are involved in RNA silencing and post-transcriptional regulation of gene expression. Numerous studies have determined the expression of certain miRNAs in specific tissues and cell types, and their aberrant expression is associated with a variety of serious diseases such as cancers, immune-related diseases, and many infectious diseases. This suggests that miRNAs may be attractive and promising non-invasive biomarkers of diseases. In this study, we established a graphene oxide (GO)-based fluorescence/colorimetric dual sensing platform for miRNA by using a newly designed probe. The probe was designed to form a hairpin-like configuration with a fluorescent dye-labeled long tail, possessing a guanine (G)-rich DNAzyme domain in the loop region and target binding domain over the stem region and tail. By introducing this new hairpin-like probe in a conventional GO-based fluorescence platform, we observed both the miRNA-responsive color change by direct observation and sensitive fluorescence increase even below the nanomolar levels in a single solution without an additional separation step.