Nanoparticle induced conformational change in DNA and chirality of silver nanoclusters

J Nanosci Nanotechnol. 2010 Feb;10(2):819-25. doi: 10.1166/jnn.2010.1903.

Abstract

Nano-clusters formed on macromolecular templates carry the symmetry information of the template. Templates with broken symmetry thus lead to formation of asymmetric clusters. In response, such clusters induce a compensatory stress on the embedded template. Silver nanoparticles grown on a covalently closed negatively supercoiled plasmid DNA (pUC19) exhibit chiral behavior and as a reciprocal response, one observes alteration in DNA conformation. The inference was drawn using gel mobility-shift studies in which a silver nanoparticle (but not ions) induces a mobility shift implying a drift from supercoiled to relaxed state of the plasmid. Supporting evidences for such structural alterations were obtained from circular dichroism (CD) and Fourier transform infrared spectroscopy (FT-IR). Silver ion and silver nanoparticles induce differential FT-IR signals reflected in the fingerprint regions 1720, 1666, 1611, 1529 cm(-1) that respectively corresponds to binding in GT, ATGC, C, and AC (A, T, G, and C representing the four nucleotides). Existence of CD signal in the silver plasmon region (350-550 nm) suggests formation of a chiral clustering of nanoparticles. The reciprocal effect on the covalently closed circular (CCC) pUC19 DNA, namely the transition to a relaxed state, can be regarded as a mimicry of the topological enzyme acting on such CCC DNA.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Circular Dichroism
  • DNA / chemistry*
  • Electrophoresis, Agar Gel
  • Metal Nanoparticles*
  • Nucleic Acid Conformation
  • Silver / chemistry*
  • Spectrophotometry, Ultraviolet
  • Spectroscopy, Fourier Transform Infrared
  • Stereoisomerism

Substances

  • Silver
  • DNA