Detection of Small Nucleic Acids Using Electrochemical Devices for Liquid Biopsy
Miyuki Tabata, Member, IEEE and Yuji Miyahara
Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, Tokyo, JAPAN
E-mail: miyahara@tmd.ac.jp
Abstract
Liquid biopsy has got attention by clinicians to diagnose or control disease through minimally-invasive body fluid testing. Circulating small nucleic acids in patient’s blood are known as potential diagnostic biomarkers in liquid biopsy targeting cancers. For example, the concentration of cell-free DNA is higher in diseased than healthy individuals, and the relationship between microRNA (miRNA) expression and type of cancer strictly correlates. These nucleic acids are detected with fluorescence dyes such as intercalating reagents (e.g., SYBR Green) or sequence-specific reporter probes to quantify the amplicons. On the other hand, electrical/electrochemical sensing methods without labeling agents for nucleic acid detection are also attracting attention owing to the advantage in miniaturization of instrument’s size, which is an unnecessary optical detection system such as laser excitation systems and fluorescence detectors.
In this research, we proposed a simplified chip for isothermal nucleic acid amplification and electrochemical detection aiming at application to future liquid biopsy platforms. For the amplification method, three-way junction primer-generation rolling circle amplification (3WJ PG-RCA), was employed and the increase in protons released during the polymerase extension reaction was detected before and after the reaction as pH change using miniaturized Ir/IrOx chip. IrOx is known as an excellent pH-responsive material and the output potentials are converted to a function of the proton concentration (pH) according to the Nernst equation. Our data indicate that miRNAs were successfully amplified with 3WJ PG-RCA and the pH value decreased after the reaction in the presence of target miRNA. Nucleic acid amplification monitoring devices in which combining biology/medical field and electrochemical technology are strongly effective for simplifying of the measurement process, miniaturization of the measurement system, and cost reduction.
Short Bio
Miyuki Tabata received her Ph.D. in Graduate School of Pure and Applied Sciences from University of Tsukuba in 2012. She joined the Tokyo Medical and Dental University in the laboratory of Bioelectronics (Prof. Yuji Miyahara). Her research focuses on developing electrical/electrochemical biosensing devices and the medical applications.