Controlling silk fibroin conformation for dynamic, responsive, multifunctional, micropatterned surfaces

Abstract

Protein micro/nanopatterning has long provided sophisticated strategies for a wide range of applications including biointerfaces, tissue engineering, optics/photonics, and bioelectronics. We present here the use of regenerated silk fibroin to explore wrinkle formation by exploiting the structure–function relation of silk. This yields a biopolymer-based reversible, multiresponsive, dynamic wrinkling system based on the protein’s responsiveness to external stimuli that allows on-demand tuning of surface morphologies and properties. The polymorphic transitions of silk fibroin enable modulation of the wrinkle patterns and, consequently, the material’s physical properties. The interplay between silk protein chains and external stimuli enables control over the protein film’s wrinkling dynamics. Thanks to the versatility of regenerated silk fibroin as a technological substrate, a number of demonstrator devices of varying utility are shown ranging from information encoding to modulation of optical transparency and thermal regulation.

Dynamic wrinkling pattern exhibiting tunable fluorescence for anticounterfeiting applications

“…Owing to the randomness, 3D topography, and nondeterministic process and unpredictability of the formation, wrinkling patterns caused by a surface mechanical instability [26][27][28][29][30][31][32] can realize a higher level of security in anticounterfeiting. Combining both responsive fluorescent behavior and the dynamic wrinkling pattern [33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48] into the same anticounterfeiting tag will undoubtedly enhance the information capacity and security. Owing to the complexity of the involved chemistry and material, however, it is still very challenging to fabricate surface patterns offering dynamic fluorescence and topography.…”

Photodynamic Pattern Memory Surfaces with Responsive Wrinkled and Fluorescent Patterns

“…Accordingly, as a naturally mechanical phenomenon, wrinkled patterning on film–substrate bilayer systems [ 8 ] resulting from compressive stress provides an intriguing avenue for overcoming the abovementioned obstacles and has attracted considerable research interest owing to the distinguished optical, [ 9 ] electrical, [ 10 ] biological, [ 11 ] and mechanical [ 9b,12 ] performances of the developed patterns. To date, manipulating the progress of stress relaxation and modulus within the wrinkled topologies based on indirect or direct actuation (e.g., light, temperature, pH, and solvents) has enabled the realization of dynamically tunable smart surfaces.…”

“…To date, manipulating the progress of stress relaxation and modulus within the wrinkled topologies based on indirect or direct actuation (e.g., light, temperature, pH, and solvents) has enabled the realization of dynamically tunable smart surfaces. [ 8a ] Nevertheless, most of the PMSs reported to date face problems due to single morphology memory and require invasive stimuli because of the sophisticated preparation methodologies and molecular‐level material chemistries. [ 13 ] Moreover, an ideal photodynamic strategy, especially near‐infrared (NIR)‐induced stimulation capable of noninvasive and remote regulation, which is previously seldom established, is indeed anticipated to enable the temporal alternative tuning of memory appearances and properties.…”

“…The wrinkling of thin supramolecular networks above elastic bases is a significant alternative to various technologies due to natural generation, versatility, and sensitivity of the patterns. [ 8b ] In this respect, adjusting the multi‐responsive chemical bonds for controlling the modulus and cross‐linking density of the supramolecular network is the key point in forming wrinkling patterns. [ 16 ] To synergistically realize controlled fluorescence intensity, the strategical integration of one kind of unique luminophores, whose emission can be observably transformed by tuning the intermolecular interactions within the supramolecular network, is urgently required.…”

Active optics with silk

“…Dynamic, tunable optical functions can also be obtained through the combination of two independent stimuli-responsive behaviors. As a demonstration, the polymorphic transition of silk fibroin has been combined with its thermal responsiveness to develop reversible and dynamic wrinkling micropatterns [51]. These wrinkling systems consist of a bilayer structure composed of a stiff silk thin layer and a soft PDMS substrate.…”