A light-remote-controllable Core-Shell-Brush nanosystem prepared through a sequential one-pot strategy

Abstract

<p>The development of smart nanosystems that transduce external stimuli to physical changes is an inspiring challenge in current materials chemistry. In this framework, hybrid organic-inorganic nanosystems attract great attention due to the combination of building blocks that respond to specific external stimuli. Poly(<i>N</i>-isopropylacrylamide) –PNIPAm- has been explored in temperature-responsive actuators with applications in drug or gene delivery, biocatalysis, or separation. However, little work has been dedicated to produce nanosystems that couple thermal actuation with other external stimuli that can remote-control the mechanical response. In this work, we present a sequential method for obtaining core-shell-brush nanosystems that can transduce light irradiation into a mechanical response through a thermoplasmonic effect. We synthetize hybrid monodisperse silica colloids covered with controllable PNIPAm brushes, produced through a simple and reproducible radical photopolymerization. This methodology can be applied successfully to Au@SiO<sub>2</sub> nanoparticles, leading to a core-shell-brush architecture. When these systems are irradiated with green LED light, direct light-to-heat conversion leads to shrinkage of the polymer layer. Our results demonstrate that modular hybrid nanosystems composed of a plasmonic heating module, a buffer silica layer, and an external thermo-responsive brush can be designed and produced with photo-thermo-mechanical transduction, which can be applied in smart carriers or soft robotics.</p>