Web Release Date: October 19,
Use of the Interparticle i-Motif for the Controlled Assembly of Gold Nanoparticles
and
National Centre for Nanoscience and Technology, No. 2, First North Street, Zhongguancun, Beijing 100080, PR China, Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, U.K., and School of Chemistry and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, U.K.
Received July 27, 2007
In Final Form: September 17, 2007
Abstract:
In this letter, we present a new design that uses single-stranded (ss) DNAs containing two stretches of cytosine (C)-rich domains for the controlled assembly of gold nanoparticles (Au NPs). We show that this assembly is driven by the formation of interparticle i-motif (four-stranded C-quadruplex) structures formed between the C-rich domains of the ssDNAs on neighboring Au NPs. The assembly happens only at slightly acidic pH conditions (pHs below the pKa of the i-motif). The assembly is reversible and can be switched by changing the solution pH. The assembly and disassembly process is accompanied by distinct color changes that are clearly visible to the naked eye. This development may have applications in the controlled assembly of reversible pH-sensitive nanostructures and/or devices.
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