Colorimetric Detection of microRNA-378 Based on Y-Shaped Structure Formed by Gold Nanoparticles and Catalytic Hairpin Self-Assembly

The timely and accurate detection of cancer is crucial for preventing disease progression and for the early treatment of confirmed cases. MiRNAs are cancer markers. In this study, a simple miRNA detection method is proposed. Three hairpins were designed based on gold nanoparticles combined with catalytic hairpin assembly nucleic acid amplification technology. The low-pH method was used for rapid coupling, and hairpin H1 was opened by miR-378, triggering the cycle reaction and signal amplification and finally forming a Y-shaped structure, thereby narrowing the distance between gold nanoparticles and achieving colorimetric detection. The absorbance change (A₆₂₀/A₅₂₀) was proportional to the concentration of miR-378 (0.05-5 nM), with a detection limit of 0.05 nM. This method also has an evident detection effect on real samples. HeLa and L-02 cell extracts were analyzed using this method. The former showed no obvious color change, whereas the maximum absorption peak of the latter showed a red shift, and the color changed from red to purple. The minimum number of cells that could be detected using HeLa cells was 500 cells/mL.