Light-Induced Polymer Response through Thermoplasmonics Transduction in Highly Monodisperse Core-Shell-Brush Nanosystems

Abstract

Smart nanosystems that transduce external stimuli to physical changes are an inspiring challenge in current materials chemistry. Hybrid organic−inorganic materials attract great attention due to the combination of building blocks responsive to specific external solicitations. In this work, we present a sequential method for obtaining an integrated core-shell-brush nanosystem that transduces light irradiation into a particle size change through a thermoplasmonic effect. We first synthesize hybrid monodisperse systems made up of functionalized silica colloids covered with controllable thermoresponsive poly(Nisopropylacrylamide), PNIPAm, brushes, produced through radical photopolymerization. This methodology was successfully transferred to Au@SiO 2 nanoparticles, leading to a core-shell-brush architecture, in which the Au core acts as a nanosource of heat; the silica layer, in turn, adapts the metal and polymer interfacial chemistries and can also host a fluorescent dye for bioimaging. Upon green LED irradiation, a light-to-heat conversion process leads to the shrinkage of the external polymer layer, as proven by in situ DLS. Our results demonstrate that modular hybrid nanosystems can be designed and produced with photothermo-physical transduction. These remote-controlled nanosystems present prospective applications in smart carriers, responsive bioscaffolds, or soft robotics.

Plasmonic Properties of Colloidal Assemblies

“…When poly( N ‐isopropylacrylamide) (PNiPAAM) brushes are grafted onto gold NPs, shell collapse can be induced by plasmonic (local) heating of the gold core environment. [ 15 ] Because the heating occurs only locally, the shell may rehydrate (expand) fast (≈100 ns) after stopping the illumination. [ 16 ] A PNiPAAM coating of gold NPs thereby offers the possibility to thermally induce local refractive index changes leading to the described optical response.…”

“…If only the size of an isolated particle is changed, the properties illustrated in Figure 1a can be obtained: With increasing size, the plasmonic resonance shifts to higher wavelengths (lower energy). Determined by the dielectric constant of the metal, the [15][16][17][18][19][20] polystyrene; [21,22] star block copolymers of poly(N-isopropylacrylamide) and poly(N,N-dimethylacrylamide); [23] poly(N-isopropylamide-co-allylacetic acid); [24] poly[(di(ethylene glycol) ethyl ether acrylate-co-oligoethylene glycol acrylate)-block-(N-(3-(dimethylamino)propyl) methacrylamide)]; [25] poly(ethylene glycol) [26] pH Poly(aniline); [27][28][29] poly(allylamine); [30] poly(dimethylaminoethyl methacrylate); [31] poly(N-isopropylamide-co-allylacetic acid) [24] Redox reaction Poly(aniline) [32,33,28] Solvent environment Polystyrene; [34][35][36][37] poly(styrene-block-(4-vinylbenzoic acid)); [38] poly(methyl methacrylate) [39] Light Spiropyran-containing poly(methacrylate); [40] azobenzene-containing poly(methacrylate); [41] block-copolymers with coumarin-containing poly(methacrylate) blocks [42] Figure 1. a) Simulation of gold monomers, dimers, and trimers with a diameter of the individual nanoparticles between 15 and 60 nm.…”

Adaptive Nanoparticle‐Polymer Complexes as Optical Elements: Design and Application in Nanophotonics and Nanomedicine

“…[86] In the recent study, hybrid core-shell-brush nanosystem (Au core, SiO 2 shell and PNIPAM brush) were synthesized as adaptive complex nanosystem responsible to green light. [87] As mentioned above, NIR light-responsive NP-polymer complexes are mostly used in nanomedicine due to the increased penetration depth of light into biological tissues. [30] Therefore, NIR light-sensitive core-shell NPs are often used as drug delivery carriers and in bioimaging applications.…”

“…[ 86 ] In the recent study, hybrid core–shell‐brush nanosystem (Au core, SiO 2 shell and PNIPAM brush) were synthesized as adaptive complex nanosystem responsible to green light. [ 87 ]…”

100th Anniversary of Macromolecular Science Viewpoint: Poly(N-isopropylacrylamide)-Based Thermally Responsive Micelles

“…In turn, many PNIPAAm contained copolymers were well designed and studied, which were extensively utilized to prepare thermosensitive brushes, − hydrogels, − vesicles, , and micelles. − Five decades-long developments in the area of such polymers and their applications were reviewed in many comprehensive articles. − However, it remains difficult for PNIPAAm to attain its full potential as stimuli-responsive materials. For example, its possible depolymerization and chronic bioaccumulation in the body may greatly limit its application in the biomedical area. − Thus, continuous efforts have to be made to improve the property and explore the potential of PNIPAAm-containing polymers, leading to a renaissance of research in the field of polymer chemistry.…”