Self-assembly of DNA G-quadruplex nanowires: a study of the mechanism towards micrometer length

The G-quadruplex (GQ) formed by guanine-rich DNA strands exhibits superior thermal stability and electric properties, which have generated substantial interest in applying GQ DNA to bioelectric interfaces. However, single G-wires formed by GQs have not yet surpassed the μm length due to the lack of an optimal assembly protocol and understanding of assembly mechanisms that limit application. Herein, we optimized a self-assembly protocol for a short 4-nt oligonucleotide (dG4) to achieve micrometer lengths of G-wires, including the buffer composition, incubation process and surface assembly. Furthermore, both theoretical modeling and chemical modifications were applied to unveil the atomic-level detail of GQ monomer interfaces and indicated that the assembly process follows a stepwise mechanism from nucleation to grow into oligomers and nanowires.