The early and accurate diagnosis of colorectal cancer is difficult to perform owing to its long incubation period and slow development. MicroRNA (miRNA) in exosomes is a non-coding RNA containing 18?22 nucleotides that participate in transcriptional inhibition and post-transcriptional regulation. Thus, it is closely related to the proliferation and migration of tumor cells. Therefore, colorectal cancer can be diagnosed early by detecting the concentration of miRNA in extracellular vesicles.
We propose a highly sensitive method for detecting miRNA-92a concentrations using terahertz metasurface sensors as detection elements and a mixed-chain reaction (HCR) signal-amplification strategy. In our experiment, we first modified nanogold and a capture probe H0 on a metasurface sensor. Next, we deposited tested miRNAs onto the sensor. Subsequently, we deposited hybrid chains H1 and H2. Finally, we washed uncaptured miRNAs and hybrid chains using PBS buffer.
In this study, a method for detecting the miRNA-92a biomarker in colorectal cancer is devised and verified. This method utilizes the capture probe H0 to bind AuNPs and modify them on a terahertz metasurface sensor. As H0 is designed for miRNA-92a, the modified sensor exhibits good specificity for miRNA-92a. As shown in Figures 7 and 8, the sensor surface is modified using hybrid chains to trigger the HCR reaction, thus forming a DNA long-chain structure and causing a significant shift in the resonant frequency of the sensor.
The experimental results show that the shift in the resonant frequency of the metasurface sensor correlates linearly with the miRNA-92a concentration, and that the maximum detection sensitivity achieved is 6.26 GHz/lgCmiRNA-92a.This method offers the advantages of rapid detection, low detection limit, and high sensitivity, thus rendering it suitable for the rapid detection of cancer-related extracellular vesicle concentrations and the early diagnosis of diseases.