20745
2006, 110, 20745-20748 Published on Web 10/03/2006
Gold Nanoparticle Based FRET Asssay for the Detection of DNA Cleavage Paresh Chandra Ray,* Angela Fortner, and Gopala Krishna Darbha Department of Chemistry, Jackson State UniVersity, Jackson, Mississippi ReceiVed: August 9, 2006; In Final Form: September 9, 2006
We report gold nanoparticle based FRET assay to monitor the cleavage of DNA by nucleases. Fluorescence signal enhancement is observed by a factor of 120 after the cleavage reaction in the presence of S1 nuclease. The mechanism of distant dependent fluorescence quenching has been discussed. Our experimental results on distance dependent fluorescence quenching match quite well with theoretical findings obtained from the fluorescence quenching model by Gersten and Nitzan (Surf. Sci. 1985, 158, 165). Our experimental observation paradigm for the design of optical based molecular ruler strategies at distances more than double the distances achievable using traditional dipole-dipole Columbic energy transfer based methods.
Damage to DNA in its biological environment has been associated with alterations in DNA sequence, aberrant gene expression, increased mutation rates, cell transformation, and development of cancer.1-7 Interaction of DNA with chemical or physical agents occurring in the environment may result in changes of the genetic information (mutations) and subsequently lead to health disorders.1-5 Ultra-sensitive detection of DNA cleavage species in the environment, water, food, etc. is therefore important for human health protection. To assay the cleavage efficiency, several traditional methods such as gel electrophoresis, filter binding, and high performance liquid chromatography (HPLC) are commonly used.5 All these methods, however, are discontinuous, time-consuming, and laborious. Furthermore, detecting cleavage at low substrate concentration necessitates radio labeling. There have been many recent efforts for the development of fluorescence assays for DNA cleavage.6-7 These assays are based on fluorescence resonance energy transfer (FRET) or non-FRET quenching mechanisms. Usually, a fluorescence signal enhancement is observed after the cleavage reaction. These assays are continuous and convenient. However, the length scale for the detection using the FRET-based method is limited by the nature of the dipole-dipole mechanism, which effectively constrains the length scales to distances on the order of
