  DNA-driven self-assembly enables precise positioning of the colloidal
nanoparticles owing to specific Watson-Crick interactions. Another important
feature of this self-assembly method is its reversibility by controlling the
temperature of the medium. In this work, we study the potential of another
mechanism to control binding/unbinding process of the DNA-functionalized gold
nanoparticles. We employ the laser radiation that can be absorbed by the gold
nanoparticles to heat their network and disassociate it. Here, we show that we
can actively control the optical properties of the nanoparticle network by an
external optical excitation. We find out that by irradiating the structure with
a green hand-held laser the total transmittance can increase by ~30% compared
to the transmittance of the sample not irradiated by the laser. Similarly, the
optical microscopy images indicate the transformation of the nanoparticle
network from opaque to transparent while the nanoparticles formed a network
again after the laser irradiation stopped. Our results prove that the optical
excitation can be used to tailor the structure and thus the optical properties
of the DNA-self-assembled nanoparticle networks.
