Fig. 11. (a and b) DNA origami based templates: (a) CD spectra of left- (red lines) and right-handed (blue lines) helices made of nine gold NPs with 16 nm diameter, showing characteristic bisignate signatures in the visible region (the position and intensity of the peaks could be drastically changed by varying the size of the particles). Adapted with permission from ref. 123. Copyright 2012 Nature Publishing Group. (b) CD spectra of plasmonic right-handed (RH – red traces) and left-handed (LH – black traces) helical monomers, dimers, and toroidal metamolecules. Scheme of the stepwise formation of plasmonic toroidal metamolecules and TEM images of LH and RH toroids (inset). Adapted with permission from ref. 125. Copyright 2016 American Chemical Society. (c) Peptide template; CD spectra and TEM tomography image of left-handed (blue trace, top image) and right-handed (red trace, bottom image) gold NP double helices. Adapted with permission from ref. 132. Copyright 2013 American Chemical Society. (d) Organic self-assembled templates; CD spectra of a hydrogel containing one equivalent of molecules and three mol equivalents of Au(i) ions after increasing durations of UV irradiation for reductive growth of gold NPs on the helical nanofibers. Inset: TEM images after UV irradiation for 1 h, 6 h and 24 h show the increase in particle size with time. Adapted with permission from ref. 145. Copyright 2014 American Chemical Society.