Rigidity-tuneable stable 2T7 tensegrity triangles: template for fluorescent silver nanoclusters

Tensegrity triangles are a unique creation of semantomorphic science. Triangle motifs are composed of three double stranded DNAs (dsDNA) assembled from as many different sequences of ssDNA with programmed complementarity. The 3D arrangements of these tessellated motifs generate different sized pores and channels suitable for cluster growth. DNA-templated silver nanocluster (AgNC) is an interesting class of fluorophore. Although the spectroscopic properties of these NCs are mostly investigated in the regime of ssDNA as a template, dsDNA can also play the part. In this study, we developed fluorescent AgNCs with 6.63 ns excited state lifetime in the curated pockets of 2T7 tensegrity triangles. pH changes neither affected the 2T7 template nor the grown AgNCs. Two small oligonucleotides, TFO1, TFO2 and a 13 nt triplex forming oligonucleotide TFO3, having anti-parallel and parallel complementarity to different areas of the triangle, are introduced, which interact with the tensegrity triangles by triad formation at different pH and provide more stability and rigidity to the template. The 2T7-TFO, as a template, enhances the excited state lifetime of the AgNCs to 8.38 ns at pH 8, and the 2T7-TFO3 increases it to 8.85 ns at pH 5. Such tensegrity triangles can act as vessels for nanomaterials and molecules and help mediate various photophysical processes.