Self-assembled nanocomposite film with tunable enhanced fluorescence for the detection of DNA.

In this study, a simple and environmentally friendly, silver nanocomposite film was prepared via the in situ reduction of silver ions in self-assembled chitosan (CS)/sodium alginate film matrixes. Negatively charged DNA containing the fluorescent intercalator acriflavine (Acf) was assembled on the surface of the silver nanocomposite film, to facilitate the detection of DNA. A tunable fluorescence enhancement was achieved for the Acf in the silver nanocomposite film simply by changing the thickness of the interlayer between the DNA and the silver nanocomposite film. Using the interlayer prepared by an assembly of poly(acrylic acid) and CS, a significant enhancement in the fluorescence of Acf was obtained. Owing to the ability of Acf to intercalate into DNA, this hybrid system with an enhanced Acf fluorescence could be used to monitor the template-independent DNA elongation process in a facile, high-efficiency, label-free fashion.