Assembly of DNA-Functionalized Nanoparticles in Alcoholic Solvents Reveals Opposite Thermodynamic and Kinetic Trends for DNA Hybridization

DNA has been a key molecule in biotechnology and nanotechnology. To date, the majority of the experiments involving DNA have been performed in aqueous solutions, which may be related to the perception that DNA hybridization is slower and less stable in organic solvents. All studies on the effect of organic solvents have focused on thermodynamic properties such as DNA melting temperature and the B-to-A form transition for very long DNAs, but not on the hybridization kinetics of short synthetic DNAs. We employed DNA-functionalized gold nanoparticles (AuNPs) as a model system and found that if the alcohol content is less than similar to 30%, more alcohol leads to a faster DNA hybridization, although with a decreased melting temperature. The generality of this observation was independently verified with two molecular beacon systems (in the absence of AuNPs) using fluorophore and quencher-labeled DNAs. With 25% ethanol, the hybridization rates are three to four times faster than in the case with water. This discovery will extend the application of DNA bio- and nanotechnology to organic solvents with improved performance.