A chiral switch based on dye-intercalated layer-by-layer assembled DNA film

Induced chirality of achiral TMPyP (tetrakis (N-methylpyridinium-4-yl) porphine) is observed in a DNA/PAH (poly (allylamine hydrochloride)) multilayer film due to intercalation. The induced chirality can be canceled when the film is exposed to HCl gas and recovers after exposing the film to NH3 gas and water vapor. Such reversible changes in the chirality can be repeated many times.