Figure 4.

(a) AuNP–DNAzyme conjugates responsive to the absence and presence of Pb²⁺, leading to assembled (blue) and disassembled (red) nanostructures, respectively. (b) AuNP–aptamer conjugates responding to adenosine. (c) Multiplex detection with assemblies of AuNPs and QDs, with 525 nm emission for adenosine and 585 nm emission for cocaine. (d) Aptazyme responsive to both adenosine and Pb²⁺. (Reproduced with permission from ref (64). Copyright 2007 American Chemical Society.) (e) Two cooperatively triggered disassemblies of NPs in the presence of adenosine and/or cocaine. (f) Time dependent changes of the ratio of extinction at 522 nm over 700 nm for the two designs in (e) in the presence of adenosine (Ade) and/or cocaine (Coc). (Reproduced with permission from ref (69). Copyright 2006 Wiley-VCH.)