Effect of polypyridine copper complex [Cu(dppz)(l-Ser)]NO3·H2O on the stabilization of triplex DNA based on gold-nanoparticles

Abstract

A localized surface plasmon resonance (LSPR) light-scattering strategy to study the effect of [Cu(dppz)(L-Ser)]NO₃·H₂O on the stabilization of triplex DNA based on unmodified gold-nanoparticles (AuNPs) has been described in this work. Polypyridine copper complex, [Cu(dppz)(L-Ser)]NO₃·H₂O, acted as an intercalator to improve the stability of the triplex structure in a weak alkaline environment. The LSPR light-scattering signal was enhanced dramatically by the existence of [Cu(dppz)(L-Ser)]NO₃·H₂O, which illustrated the copper complex stabilized the triplex structure formed by single strand and duplex DNA parallel to the single strand DNA. The state of the AuNPs, protected by single-stranded DNA, changed from a dispersion state to an aggregation state in the presence of [Cu(dppz)(L-Ser)]NO₃·H₂O. Electronic spectra and transmission electron microscopy were also used to explain the reason for the enhancement of the LSPR light-scattering. Furthermore, ethidium bromide (EB) was employed for comparison with the copper complex, and the results showed that [Cu(dppz)(L-Ser)]NO₃·H₂O had a stronger effect on the enhancement of the stability of triplex than EB. The strategy was simple and had low toxicity. It may offer a new pathway for enhancing the stability of triplex DNA.