Integration of catalytic hairpin assembly probes into microneedles for detection of MicroRNA in plants

MicroRNAs (miRNAs) are crucial in regulating plant growth and their response to abiotic stress. Traditional miRNA detection methods are techniques which are often criticized for being expensive, labor-intensive, and time-consuming. In our research, we present a novel method that combines absorbent microneedles with a catalytic hairpin assembly (CHA) detection system. This integration facilitates swift plant sap extraction and miRNA detection. The CHA system, which consists of two hairpin probes, showcases exceptional sensitivity in identifying target miRNAs, boasting a notable detection limit of 89 pM. By modulating the photo-crosslinking duration, we controlled the swelling attributes of the methacrylic acid-modified hyaluronic acid microneedles. These microneedles proved efficient in rapidly absorbing solutions and maintained sturdy mechanical properties, allowing easy penetration into tobacco leaves for plant sap absorption. Additionally, after absorbing the miRNA solution, the fluorescence intensity of the integrated microneedles correlated linearly with concentration. It's noteworthy that while the microneedles responded to miRNA within plant tissues, it was predominantly at elevated miRNA concentrations. Our findings underscore the potential of hydrophilic microneedle arrays in both extracting and detecting miRNA in plant leaves, emphasizing their promising role in the rapid identification of vital plant compounds. This innovative method paves the way for groundbreaking research and analysis in plant studies.