Biosensors & Bioelectronics

Biography

Biography: Ying Wan

Abstract

Electrochemical DNA (E-DNA) sensors have great potential in point-of-care diagnosis because of their ability to produce a simple, accurate and inexpensive platform for DNA sensing. However, it is difficult to detect extremely low abundance of DNA biomarkers in clinical samples. Thus different signal amplification methods have been developed to improve the sensitivity of E-DNA sensors. In this paper, we developed an ultrasensitive E-DNA sensor based on the signal amplification efficiency of nanoprobe and surface-initiated enzymatic polymerization (SIEP). In this method, nanoprobe was fabricated by gold nanoparticles (AuNPs) modified with reporter probe DNA. Coupling with the nanoprobe, capture probe, which was immobilized on gold electrode, would form a “sandwich” with target DNA. Upon hybridization, nanoprobe could be bound to the electrode and then subjected to terminal deoxynucleotidyl transferase (TdT) catalyzed elongation of DNA strand at its 3′ terminal. During the terminal extension reaction, biotin labels are incorporated into the SIEP-generated long single-stranded DNA (ssDNA). Then specific binding of avidin modified – horseradish peroxidase (HRP) to the biotin label would lead to an enzyme turnover-based signal transduction. As there are hundreds of DNA probes on the nanoprobe, one hybridization event would generate hundreds of long ssDNA, resulting in tens of thousands of HRP catalyzed reduction of hydrogen peroxide. By employing nanoprobe and TdT, we demonstrated that our E-DNA sensor has a detection limit of 10 fM and excellent differentiation ability for even single mismatches.