Bacterial Analysis Using an Electrochemical DNA Biosensor with Poly-Adenine-Mediated DNA Self-Assembly

摘要

The spatial arrangement of DNA probes on the electrode surface is of critical significance for the performance probe surface remains challenging. In this work, we develop a of electrochemical biosensors. However, rational control of the capture probe carrying a poly-adenine anchoring block to construct a programmable self-assembled monolayer for a "sandwich-type" electrochemical biosensor. We show that with a co-assembling strategy using a polyA capture probe and 6-mercapto-l-hexanol, the density of the probes on the gold electrode can be simply adjusted by the length of polyA. The electron-transfer effect and thus the hybridization efficiency can as well be optimized by tuning the polyA length. As a result, we obtained an excellent biosensor performance with a limit of detection as low as 5 fM for a synthetic DNA target. We demonstrate the practicability of this system by analyzing a PCR product from Escherichia coli genomic DNA (0.2 pg/mu L). On the basis of the ideal electrochemical interface, our polyA-based biosensor exhibited excellent reusability and stability, which is important for potential applications in the onsite analysis for a wide range of targets.