I prepared modified single DNA bases for their incorporation into solid phase oligonucleotide synthesis, and then used these short alkyne and azide terminated oligonucleotide fragments to prepare either the free axle (via traditional 'click' chemistry) or the interlocked rotaxane-DNA (via AT-CuAAC). Through systematic optimization, I was able to achieve these new materials in good yield with high selectivity (100% conversion to the interlocked structure). These materials were tested as primers for PCR, evaluated for their duplex formation by CD spectroscopy, and initial degradation experiments were performed with exonucleases to further probe the stabilizing effect of the mechanical bond. A significant amount of work went into optimizing the purification, isolation and analysis of these materials, as well as finding mild methods to remove Cu (necessary for the formation of the interlocked structure, though known to be highly cytotoxic). Cleavable linkers were tested for their overall compatibility with macrocycle formation (Ni mediated macrocylization), and there is on-going work in the Goldup lab to generate novel cleavable macrocycles, responsive to selected stimuli (e.g. photolabile), which will help further work begun during this MSCA.
The results of this study formed the basis of a successful application for further funding which will be used to take these new molecules towards applications in chemical biology. The work also formed the basis of a publication in J. Am. Chem. Soc. and several presentations at national meetings in the UK.