Detection of MicroRNA with a Reusable Silicon Nanowire Field-Effect Transistor
Date Issued
2012
Date
2012
Author(s)
Tseng, Ling-Wei
Abstract
MicroRNAs (miRNA) of around 22 nucleotides and long non-protein-coding RNAs can play an important regulatory role in animals and plants by targeting mRNA for cleavage or translational repression. Recent research finding shows that miRNAs, which had already existed in a cell before viruses invaded, help to serve as an advanced preparation to counteract infection. Viral mRNA might be regulated by the cleavage directed by miRNA-programmed RNA-induced silencing complex (RISC). Since plant virus infections resulted in a dramatic increase in miRNA, we detected specific miRNA with a sensitive silicon nanowire field-effect transistor (SiNW-FET) biosensor to confirm if the plant was infected. In addition, recent studies have evidenced that miRNA mutation or mis-expression is responsible for various human cancers. The reduction or deletion of some significant miRNAs, acting as tumor suppressors, might lead to the tumor formation during miRNA biogenesis. The amplification or overexpression of the specific miRNA at inappropriate time or in wrong tissues would also result in tumor formation. Therefore, different amounts of specific miRNA from cancer cells and normal cells could make miRNA act as a biomarker for cancer diagnosis. In this study, SiNW-FETs were utilized to detect a specific miRNA biomarker for early cancer diagnosis. Based on its high sensitivity and selectivity, real-time response, and label-free detection capabilities, SiNW-FET has been widely used in a variety of detections, including protein, nucleic acid, small molecules, and virus. Here, we immobilized DNA probes on the SiNW-FET surface via a disulfide linker, which was then applied to detect target RNAs through DNA-RNA hybridization. After detection, dithiothreitol (DTT) was employed to cleave the disulfide linker, concurrently removing the DNA-RNA complex and allowing for the SiNW-FET device reusable. Our experiments show that a DNA-modified SiNW-FET is able to probe target miRNAs from a cocktail solution, such as the detection of miR159 in total RNA extracted from leaves. Moreover, the reusable SiNW-FET has made it possible to fast screen various target RNAs by easily replacing different DNA probes. Finally, miR21, a biomarker of breast cancer, was selected as the target sequence to diagnose cancer and normal cells. However, it was difficult to distinguish cancer cells from normal ones at high sample concentrations, because of the binding saturation on the SiNW-FET sensing device. Fortunately, distinction became apparent as the concentration decreased, where the amount of miR21 from cancer cells was measured to be more than that from normal cells. As a conclusion, a SiNW-FET modified with specific DNA probes not only provides an excellent platform for miRNA biomarker detections, but also exhibits the potential in biomedical applications for early cancer diagnosis.
Subjects
silicon nanowire field-effect transistor
biosensor
microRNA
cancer biomarker
SDGs
Type
thesis
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