Caffeine-induced release of small molecules from DNA nanostructures

Several planar aromatic molecules are known to intercalate between base pairs of double-stranded DNA. This mode of interaction has been used to stain DNA as well as to load drug molecules onto DNA-based nanostructures. Some small molecules are also known to induce deintercalation in double-stranded DNA, one such molecule being caffeine. Here, we compared the ability of caffeine to cause deintercalation of ethidium bromide, a representative DNA intercalator, from duplex DNA and three DNA motifs of increasing structural complexity (four-way junction, double crossover motif, and DNA tensegrity triangle). We found that caffeine impedes the binding of ethidium bromide in all these structures to the same extent, with some differences in deintercalation profiles. Our results can be useful in the design of DNA nanocarriers for intercalating drugs, where drug release can be chemically stimulated by other small molecules.