Assembly of Nanoscale Scaffolds from Peptide Nucleic Acids (PNA)

Current models of G-quadruplex (multiple stacking G-tetrads) formation based on DNA are large structures containing at least four consecutive guanine bases. PNAs containing one to four guanines were synthesized using standard Fmoc peptide coupling conditions. Monitoring the assembly of short PNA quadruplexes with variable cation concentrations as well as with various cations shows an independence of PNA G-quadruplexes on cation concentration with short sequences. The strategy for synthesis allows modification of both ends of a PNA sequence. This in theory would allow one to synthesize multivalent nanoparticles containing up to eight additional substituents. A quadruplex containing four strands with four guanine residues in each strand occupies a volume of only about 8 nm(3). Consequently, depending on the modifications, this approach should allow directed-assembly of nanomaterials with volumes in the 10 to 100 nm range.