Controlled Monofunctionalization of Molecular Spherical Nucleic Acids on a Buckminster Fullerene Core

An azide-functionalized 12-armed Buckminster fullerene has been monosubstituted in organic media with a substoichiometric amount of cyclooctyne-modified oligonucleo-tides. Exposing the intermediate products then to the same reaction (i. e., strain-promoted alkyne-azide cycloaddition, SPAAC) with an excess of slightly different oligonucleotide constituents in an aqueous medium yields molecularly defined monofunctionalized spherical nucleic acids (SNAs). This procedure offers a controlled synthesis scheme in which one oligonucleotide arm can be functionalized with labels or other conjugate groups (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid, DOTA, and Alexa-488 demonstrated), whereas the rest of the 11 arms can be left unmodified or modified by other conjugate groups in order to decorate the SNAs' outer sphere. Extra attention has been paid to the homogeneity and authenticity of the C60-azide scaffold used for the assembly of full-armed SNAs.

Automated summary

A 12-armed Buckminster fullerene with azide functional groups was monosubstituted in organic media with cyclooctyne-modified oligonucleotides, leading to the production of molecularly defined monofunctionalized spherical nucleic acids (SNAs). This controlled synthesis scheme allows for one oligonucleotide arm to be functionalized with labels or conjugate groups, while the other arms can remain unmodified or be decorated with different conjugate groups on the outer sphere of the SNAs. Attention was given to the homogeneity and authenticity of the C60-azide scaffold used for assembling the full-armed SNAs.