| dc.description.abstract | Early diagnosis of cancer is critical to improving the first 5-year survival rate of patients. However, tissue biopsy, as the gold standard for cancer diagnosis, is invasive and costly, thus not ideal for cancer early screening. Imaging-based methods are noninvasive but lack sensitivity to capture small size tumors at early stages. Liquid biopsies, i.e., circulating tumor DNAs, circulating tumor cells and exosomes in body fluids, are emerging as a promising paradigm for developing sensitive and specific molecular biomarkers for screening and early detection of cancer in a non-invasive manner. Circulating microRNAs (miRNAs) and exosomal messenger RNAs (mRNAs) in the bloodstream have been implicated in tumor initiation, progression, and metastasis. Therefore they have been intensively investigated to develop cancer biomarkers for liquid biopsy tests. Real-time reverse transcription polymerase chain reaction (RT-qPCR), as the gold-standard method for quantitative measurement of miRNA and mRNA, is highly sensitive and robust, but labor-intensive and expensive. Microfluidics is a technology that can manipulate microliters to picoliters of fluids and integrate function modules for multiple laboratory operations in a single device. My research projects took advantage of microfluidic technology to developed methods for the detection of miRNAs and mRNAs that are low cost, robust, sensitive, and automatic. In project 1, we designed a microfluidic device that employed the Duplex-Specific-Nuclease Signal Amplification (DSNSA) for miRNA detection. In Project 2, we developed an exosomal mRNAs quantitation method that combined on-chip exosome enrichment and lysis with droplet digital PCR. In Project 3, we developed a microfluidic alternating-pull-push active digitization method for sample-loss-free digital PCR, which served for Project 4— to develop a microfluidic exosomal mRNA absolute quantitation approach that integrated beads capture, on-chip lysis, and on-chip one-step digital RT-PCR. Our work facilitated the quantitative analysis of miRNA and exosomal mRNA in cancer diagnosis. Moreover, we envision that our work is adaptable in further broader RNA quantitation requests, such as detection of lncRNA, in board biological and clinical applications. | |
