Copper-free click chemistry as an emerging tool for the programmed ligation of DNA-functionalised gold nanoparticles.

We demonstrate a new method to program the ligation of single stranded DNA-modified gold nanoparticles using copper-free click chemistry. Gold nanoparticles functionalized with a discrete number of 3'-azide or 5'-alkyne modified oligonucleotides, can be brought together via a splint strand and covalently 'clicked', in a simple one-pot reaction. This new approach to the assembly of gold nanoparticles is inherently advantageous in comparison to the traditional enzymatic ligation. The chemical ligation is specific and takes place at room temperature by simply mixing the particles without the need for special enzymatic conditions. The yield of 'clicked' nanoparticles can be as high as 92%. The ease of the copper-free, 'click-ligation' method allows for its universal applicability and opens up new avenues in programmed nanoparticle organization.