DNase I-assisted 2'-O-methyl molecular beacon for amplified detection of tumor exosomal microRNA-21.

Abstract An end-modified 2′-O-methyl molecular beacon (eMB) with unique nuclease resistance was designed and prepared. The eMB can resist the enzymatic digestion by DNase I, which would otherwise occur upon the hybridization of the eMB with a complementary sequence. As a result, the coupling use of eMBs and DNase I allows highly sensitive detection of miRNA with a limit of detection (LOD) of 2.5 pM. The analytical strategy was further used for detection of tumor exosomal microRNA-21, and down to 0.86 μg mL−1 A375 exosomes were detected. Overall, the present method can effectively quantify tumor-derived exosomes for cancer diagnosis.