A lateral flow assay strip based on AND logic gate and DNA self-assembly for dual miRNA detection in breast cancer diagnosis.

A lateral flow analysis (LFA) strip for detecting dual miRNAs (miR155 and miR21) was constructed based on the "AND" logic gate and DNA self-assembly. The ternary synergistic strategy of "logic gating-signal amplification-visual output" enables highly sensitive and visual detection of miR21 and miR155 for breast cancer diagnosis. Only if both miR21 and miR155 are present can the trigger DNA (TDNA) in the sensor specifically dissociate and activate the "AND" logic gate (output signal = "1"); in the absence of either miRNA, the system remains in an inactive state (output signal = "0"). TDNA initiates catalytic hairpin assembly (CHA), and the product of the CHA reaction cascaded triggers the hybridization chain reaction (HCR) to achieve dual signal amplification. Gold nanoparticles (AuNPs) were used to label DNA for the construction of the LFA strip, allowing naked-eye observation of the detection results of miR21 and miR155. Detection results showed that the signal intensity of the test line (T line) had a positive correlation with the concentration of miRNAs (with a miR155:miR21 ratio of 1:1). Within the concentration range of 0.1-10 nM, the average grayscale value of the T line exhibited a good correlation with the logarithm of miRNA concentration (correlation coefficient r = 0.9983), and the limit of detection (LOD) was 30.98 pM. This LFA strip has been preliminarily validated to the detection of human serum samples, and the results indicated that the levels of miR155 and miR21 in the serum of breast cancer patients were significantly higher than those in normal individuals. Free from the limitation of large-scale instruments, this strip holds great commercialization potential.