Abstract
MicroRNAs as regulators play an important role in gene expression and subsequently in various diseases. Newly, some studies show that up-regulation of miR-155 has been described in several types of human tumors. Due to the high importance of detecting miRNA with both fast speed and high sensitivity and the fundamental role of miR-155 in the breast cancer, we proposed a new miRNA detection method relying on photocatalytic activity of Cysteine capped gold nanoclusters (Cys-AuNCs). During the experiment, we found an absorbance peak located at around 665 nm. This peak contributed to the redox reaction between TMBred and TMBox, and the adsorption–desorption process of TMB to the positive Cys-AuNCs. When the ssDNA probe was hybridized with the complementary miR-155 sequence, the negative double stranded DNA/miR backbone creates a coating on the positive surface of Cys-AuNCs, thereby inhibiting the cluster oxidation activity. The absorbance peaks were related to the TMBred. The decrease in absorbance caused by decreasing Cys-AuNCs photocatalytic reaction allows the detection of miRNA in the range of 100 fM to 10 μM with a detection limit of 60 fM. Notably, human miRNA from breast cancer cells (SK-BR-3) could also be detected, and the results were compared with the ones obtained using qRT-PCR.
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