Quantitative Analysis of MicroRNA in Blood Serum with Protein-Facilitated Affinity Capillary Electrophoresis

MicroRNAs play an important role in gene regulation and disease etiology and are blood-based biomarkers of diseases. Here, we describe a protein-facilitated affinity capillary electrophoresis (ProFACE) method for ultra-sensitive direct miRNA detection as low as 300,000 molecules in 1 mL of blood serum, using single-stranded DNA binding protein (SSB) and double-stranded RNA binding protein (p19) as separation enhancers. This method utilizes either the selective binding of SSB to a fluorescent single-stranded DNA/RNA probe or the binding of p19 to miRNA–RNA probe duplex.