Preparation and surface characterization of DNA encapsulated by silica nanoparticles

The encapsulation of the anionic dye Reactive Green-19 by silica nanoparticles was explored and optimized. Starting from commercially available 100 nm silica nanoparticles, the surface was modified by the treatment with N-[3-(trimethoxysilyl)propyl]-N,N,N-trimethylammonium chloride in the presence of ammonia. Subsequent deposition of Reactive Green-19 followed by outer shell-formation gave silica nanoparticle-encapsulated Reactive Green-19. The process was applied to the encapsulation of DNA on a 100 ml scale. The release of Reactive Green-19 and DNA from encapsulation was effected by the treatment with concentrated aqueous ammonium hydroxide. The released DNA was amplified by polymerase chain reactions and identified by agarose gel electrophoresis. The surface properties of modified silica nanoparticles throughout DNA encapsulation were characterized by scanning electron microscopy and X-ray photoelectron spectroscopy.