Do you still use Northern Blot to quantitate microRNAs expression? Here I recommend Splinted Ligation Assay[1,2], though this method is an old story (published in 2007).
Detection of miRNAs using splinted ligation. Schematic depiction of the assay process. As described in the text, the assay involves: (1) Labeling of the ligation oligonucleotide; (2) concurrent annealing of the ligation oligonucleotide and miRNA to a bridge oligonucleotide; (3) linking of the ligation oligonucleotide to the miRNA by DNA ligase; (4) removal of labeled phosphate from unligated oligonucleotide; and (5) fractionation on a denaturing gel.
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[1] Maroney, P. a, Chamnongpol, S., Souret, F., & Nilsen, T. W. (2007). A rapid, quantitative assay for direct detection of microRNAs and other small RNAs using splinted ligation. RNA (New York, N.Y.), 13(6), 930-6. doi:10.1261/rna.518107
[2] Maroney, P. A., Chamnongpol, S., Souret, F., & Nilsen, T. W. (2008). Direct detection of small RNAs using splinted ligation. Nat. Protocols, 3(2), 279-287. Nature Publishing Group. Retrieved from http://dx.doi.org/10.1038/nprot.2007.530