Silver cluster-assembled materials for label-free DNA detection.

Herein, we report two newly synthesized silver cluster-assembled materials (SCAMs), [Ag14(StBu)10(CF3COO)4(bpa)2]n (bpa = 1,2-bis(4-pyridyl)acetylene) and [Ag12(StBu)6(CF3COO)6(bpeb)3]n (bpeb = 1,4-bis(pyridin-4-ylethynyl)benzene) composed of Ag14 and Ag12 chalcogenolate cluster cores, respectively, bridged by acetylenic bispyridine linkers. The linker structures and electrostatic interaction between positively charged SCAMs and negatively charged DNA confer the SCAMs with the ability to suppress the high background fluorescence of single-stranded (ss) DNA probes with SYBR Green I nucleic acid stain, leading to high signal-to-noise ratio for label-free target DNA detection.