Detection of Trace Hg~(2+) via Induced Circular Dichroism of DNA Wrapped Around Single-Walled Carbon Nanotubes

摘要

The conductivity and fluorescent properties of singled-wall carbon nanotubes (SWCNTs) have been well developed to detect trace molecules in solution. However, the chiral properties of SWCNTs have not been well studied and applied. In theory, induced circular dichroism (ICD) will occur for DNA wrapped around SWCNTs (DNA-SWCNTs) when the transition dipole moments of the optically active chiral SWCNTs couple to the transition dipole moments of DNA, thereby producing a strong ICD signal. The ICD of DNA-SWCNTs could be used to detect chemicals which can disturb the coupling effect of the transition dipole moments between DNA and SWCNTs and thus change the ICD signals significantly. Here, evidence to support this principle is disclosed.rnWe have found that Hg ions have a strong and specific binding affinity for the nucleic bases of single-strand DNA (T bases) wrapped around SWCNTs via a pseudo-first-order kinetic interaction. When the Hg~(2+) ions bind to the DNA bases, the tightness of the DNA wrapping around the SWCNTs is loose; in addition a repulsive electrostatic force will be introduced along the DNA strand causing the DNA to stretch.