How are thermodynamically stable G-quadruplex-duplex hybrids?

In the last decade, DNA duplex and G-quadruplex motifs have been investigated for their potential applications in nanotechnology. Recently, G-quadruplex-duplex hybrids, generated from the juxtaposition of these two structural elements, have been considered as DNA nanostructures for nanotechnological applications to take advantage of both duplex and G-quadruplex peculiarities. The junction between the two structural motifs can play an important role both for the structure and stability of these hybrids. Here, we analyze the thermodynamics of a number of G-quadruplex-duplex hybrids differing in the bases composition in proximity of the junction. Differential scanning calorimetry, circular dichroism, and gel electrophoresis methodologies were employed to highlight differences in their stability.