Fabrication of a Dual Stimuli-Responsive Assorted Film Comprising Magnetic- and Gold-Nanoparticles with a Self-Assembly Protein of α-Synuclein

Abstract

Development of sensing elements for controllable soft materials is crucial to improve their responsiveness toward remotely provided external stimuli. Magnetic nanoparticles (MNPs) and gold nanoparticles (AuNPs) have been coassembled into a flexible free-floating 2D film to produce a shape deformable mobile structure in the presence of magnetic field and light irradiation by employing a self-assembly protein of α-synuclein (αS). αS was demonstrated to be essential for the preparation of a multisensory system because the intrinsically disordered protein led to a complete dispersion of MNPs to an average size of 10 nm in aqueous solution, pH-dependent closely packed single layer adsorption of αS-MNPs, and α-helix-mediated free-floating MNP monolayer film formation upon dissolving the underlying polycarbonate substrate with chloroform. As AuNPs were incorporated into the assorted hybrid film in the presence of MNPs, however, the β-sheet component became prominent. By placing the assorted film between a spin-coated thin layer of thermoresponsive P(AAc-co-NIPAAm) hydrogel comprising acrylic acid and N-isopropylacrylamide and a passive layer of silicone elastomer, the resulting triply structure exhibited not only magnet-induced locomotion but also shape deformation due to asymmetric contraction of the sandwiching two layers caused by the heat generated by AuNPs upon near IR irradiation. In fact, two adjoining planar layers of another triply structure were shown to form a three-dimensional lotus flower with the light. This multisensory system is suggested to be further functionalized by modifying the αS molecules and incorporating additional nanoparticles to react to diverse stimuli, which would make the system be utilized in the areas of not only soft robotics but also foldable electronics, high-performance sensors/ actuators, and medical/wearable applications.

3D shape morphing of stimuli-responsive composite hydrogels

“…There are two common fabrication techniques utilized for developing thin films for stimuli-responsive composite hydrogels: coating and casting. Coating gives the ability to deposit ultra-thin coatings by either spraying, 268 spinning, 269 or dipping 270 a hydrogel precursor solution onto an existing surface. Whereas casting allows for the fabrication of both thin and thicker hydrogel films alike, with the added benefit of casting hydrogels into customizable 2-dimensional structures.…”

“…8b. 269 When placing a thin film of AuNP on P(AAc- co -NIPAAm)/Ecoflex, the actuator has the capability bending when exposed both magnetic and light stimuli. 269…”

“…8b. 269 When placing a thin film of Fig. 8 Fabrication of composite bilayer hydrogel structures using different coating techniques: (a) spray coating of liquid crystal elastomer (LCN) onto the surface of polyamide 6 (PA6) using a spray gun.…”

Wearable Electrochemical Sensors Based on Nanomaterials for Healthcare Applications

“…Gold nanoparticles [96][97][98][99][100][101][102][103][104] are widely used in the preparation of various sensors. The Ayoung Choe group [105] described that raspberry-like plasma microgels that could reversively change color under temperature change were prepared by modifying gold nanoparticles (AuNPs) on poly (N-isopropylacrylamide)(PNIPAM) microgels.…”

Nanoparticle–Hydrogel Based Sensors: Synthesis and Applications

“…The collagenbased hydrogel prepared by Zhang et al [69] also showed strong adhesion to the skin and exhibited excellent hemostatic properties in animal experiments. In addition, studies have been conducted on adding AuNPs to composite materials for strain sensors [70][71][72]. The photothermal effect of AuNPs enables the hydrogel to respond to a variety of stimuli, such as light, heat, motion, and diverse movements, and has a wider range of applications.…”