A pico-HPLC-LIF system for the amplification-free determination of multiple miRNAs in cells

MicroRNAs are a class of important biomarkers, and the simultaneous detection of multiple miRNAs can provide valuable information about many diseases and biological processes. Amplification-free determination has been developed for the analysis of multiple miRNAs because of its characteristic low cost and high fidelity. Herein, a method for the amplification-free analysis and simultaneous detection of multiple miRNAs based on a so-called pico-HPLC-LIF system is described. In this process, a bare open capillary with an inner diameter of 680 nm is used as a separation column for a sample volume of several hundreds of femtoliters (300 fL), followed by separation and detection. The technique has a zeptomolar limit of detection. The method was applied to detect cellular miRNA from adenocarcinomic human alveolar basal epithelial (A549) cell extracts, and the simultaneous detection of the mir-182, miR-155, and let-7a was achieved. The results showed that the expression of mir-182 and miR-155 was up-regulated and that of let-7a was down-regulated in A549 cells. This method for multiple miRNAs detection is expected to have broad applications in miRNA-based disease diagnosis, prognosis, treatment, and monitoring.