Sensing Thermally Denatured DNA by Inhibiting the Growth of Au Nanoparticles: Spectral and Electrochemical Studies

• Published in: Journal of physical chemistry. C 2011-08, Vol.115 (30), p.14461-14468
• Main Authors: Pan, Hongcheng, Li, Dunnan, Liu, Jiangtao, Li, Jianping, Zhu, Wenyuan, Zhao, Yixin
• Format: Article
• Language: English
• Subjects: C: Nanops and Nanostructures
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/jp201396j

The inhibition effect of DNA bases, guanine (G), adenine (A), cytosine (C), or thymine (T), on the growth of Au nanoparticles (NPs) was clarified by UV–vis absorption spectra, resonance light scattering (RLS) spectra, transmission electron microscopy (TEM), differential pulse voltammetry (DPV), and theoretical calculations. It is found that the inhibition efficiency of the bases in the growth of Au NPs follows the order G > A > C > T, confirmed by the nucleobase concentration-dependent absorbance and RLS study. The DPV analysis reveals that observed base-dependent differences could be attributed to the varying ability of the bases to coordinate to the Au(III). The conditional stability constants of the complexes of Au(III)–G, Au(III)–A, Au(III)–C, and Au(III)–T are also in the order of G > A > C > T and were determined to be 5.66 × 105, 3.55 × 104, 1.15 × 104, and 4.61 × 103, respectively. Further theoretical calculations support that the DNA bases bind to Au(III) with relative affinity G > A > C > T. The thermally denatured salmon sperm DNA has the same inhibition effect on the growth of Au NPs as the individual DNA bases, while native salmon sperm DNA shows no significant effect on the growth of Au NPs. The observed difference results from the fact that the binding sites of bases are freely accessible for interaction with Au(III) species in the thermally denatured DNA, but double-helix structure of DNA in the native salmon sperm sterically inhibits the bases from adopting their most strongly bound orientation, resulting in a weak interaction with Au(III). The presented method could be a potential indirect monitoring method for DNA damage and DNA base-pair mismatch.