Reversible Shrinkage of DNA‐Functionalized Gold Nanoparticle Assemblies Revealed by Surface Plasmon Resonance

A technique for tuning interparticle distance in plasmonic gold nanoparticle (AuNP) assemblies has shown great potential for the development of optoelectronic nanodevices. However, it still remains a challenge to reversibly alter the distance in a facile manner. DNA-templated AuNP assemblies are among the mostly investigated plasmonic nanomaterials. In previous work, salt-induced structural shrinkage of DNA-templated AuNP (5 nm in diameter) dimers/trimers is demonstrated only by electron microscopic analyses. In the present study, interparticle distance is modulated in larger AuNP (15 nm or 20 nm in diameter) dimers that exhibit strong surface plasmon resonance (SPR). The reversible SPR shift is achieved by using the temperature-dependent shrinkage/extension of the DNA-templated AuNP dimers. The present proof-of-concept study suggests a potential application of the reversible structural change to optical switching.