Colorimetric Detection of miRNA with DNA-Functionalized Gold Nanoparticles

Abstract

Early detection of cancer is important for improving patient prognosis. miRNAs are good biomarkers for cancer screening because they are found in peripheral blood and their dysregulation is associated with cancer development. However, current miRNA detection assays, like RT-PCR, require expensive equipment. We are developing an assay that can be heated and quantified in a portable sensor. The assay involves a rolling circle transcription reaction that activates a Cas12a enzyme in the presence of a miRNA target, resulting in the cleavage of DNA-conjugated gold nanoparticles. This produces a colorimetric output that is quantified using a 3D printed portable detector. The presence of miRNA successfully initiates ligation, rolling circle transcription, and the activation of Cas12a. Successful aggregation of AuNPs occurs in the presence of the linker sequence, while absence of a linker prevents aggregation. However, the Cas12a activation assay must be combined with the AuNP complex to ensure proper aggregation when linker is intact, and lack of aggregation when Cas12a cleaves the linker.