Light-Triggered Formation of Surface Topographies in Azo Polymers

Hendrikx, Matthew; Schenning, Albert P. H. J.; Debije, Michael G.; Broer, Dirk J.

doi:10.3390/cryst7080231

Cited by 34 publications

(27 citation statements)

References 118 publications

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“…By attaching liquid crystal networks (LCNs) as coatings on a support material, different types of deformations can be induced, due to the limiting effect of the attached surface to the lateral stress . Such an approach leads to surfaces whose morphology can be modified and even oscillated by means of light irradiation.…”

Section: Polymeric Photoactuators: Moving Toward Artificial Musclesmentioning

confidence: 99%

“…They can be also attached to a hydrogel or elastomer matrix as crosslinkers in order to stretch polymer chains in the bulk of the material, thereby changing mechanical properties, where the molecular‐level photoswitching transfers energy to the polymer matrix, triggering phase changes and/or structural modifications. The photoisomerization process can affect a variety of material properties allowing for programming material motion at the microscale, or surface mass migration in response to light, leading to formation of micro‐ and nanoscale patterns that are in the relevant range for cell interaction, for the dynamic control of bio‐interfaces, and thus permitting azobenzene‐based materials to be applied as “smart” cell culture supports. The aim of this review is to provide a current survey of the use of these photoreversible azo materials in cell biology and tissue engineering, generally following a “bottom‐up approach”: starting from the control of the molecular motion (orientation, flow) inside the material, leading to how light can be used to produce surface morphological changes, or eventually macroscopically photoactuating surfaces and structures.…”

Section: Introductionmentioning

confidence: 99%

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Photoreversible Soft Azo Dye Materials: Toward Optical Control of Bio‐Interfaces

Chang

Fedele

Priimägi

et al. 2019

Advanced Optical Materials

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systems interact with artificial materials, researchers have now assembled a versatile toolkit of materials and processes that allows one to fine-tune interactions at the interface, tailoring specific biological responses on demand. These strategies for biocontrol can be broadly categorized as chemical (charge, ligand presence, surface groups), material changes (moisture content, stiffness), or morphological changes (molecular orientation, surface topography, or mechanical actuation). Rational design of materials for biological interface applications has a unique set of challenges due to the unique requirements of a wide range of biological systems, since different tissues present specific compositions, with their own elasticity, structural organization, and triggering mechanisms. Even within a single organ or tissue, mechanical properties can vary widely depending on the region. A recent study of viscoelasticity in live mouse brain tissue for example found a tenfold difference within the brain depending on the region and morphological structure studied. [2] However, most biological tissues are far less stiff, and far more viscoelastic than typical artificial materials employed at their interface, especially early artificial cell culture materials, which can be much stiffer than in vivo extracellular matrix by many orders of magnitude. [3] In vivo, cells interface with a surrounding microenvironment consisting of an intricate macromolecular network of proteins and sugars swollen in an aqueous media gel. Therefore, the interaction between cells and the extracellular matrix (ECM) in the body is complex and involves a variety of cues related to topography, chemical markers, protein composition, solubility factors, and mechanical properties such as stiffness and elasticity (Figure 1a). [4] Yet much research over the past decades was focused on studying in vitro the effects of each of these signals on cell behavior, with a particular interest on the chemical factors, whereas only recently more advanced biomaterials with controlled physicomechanical properties have been developed, such as those with tunable and variable stiffness, alignment and orientation of key functional groups, and mechanical actuation. There is a large range of stiffness in human tissue, where bone (≈100 GPa) is nine orders of magnitude harder than brain tissue (≈0.1 kPa). [4] Therefore, biomaterial researchers assume a complex task of providing materials and processing technologies for controlling stiffness and micro-and nanostructures in Photoreversible optically switchable azo dye molecules in polymer-based materials can be harnessed to control a wide range of physical, chemical, and mechanical material properties in response to light, that can be exploited for optical control over the bio-interface. As a stimulus for reversibly influencing adjacent biological cells or tissue, light is an ideal triggering mechanism, since it can be highly localized (in time and space) for precise and dynamic control over a biosystem, and low-power visible light...

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Section: Polymeric Photoactuators: Moving Toward Artificial Musclesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Photoreversible Soft Azo Dye Materials: Toward Optical Control of Bio‐Interfaces

Chang

Fedele

Priimägi

et al. 2019

Advanced Optical Materials

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“…[4][5][6] The azobenzene molecules allow for controlled switching, based on the trans-to-cis and cis-to-trans isomerization. These can be controlled by selectively illuminating the azobenzene's absorption bands, being 365 and 455 nm, respectively.…”

Section: Doi: 101002/admi201800810mentioning

confidence: 99%

Compliance‐Mediated Topographic Oscillation of Polarized Light Triggered Liquid Crystal Coating

Hendrikx

Sırma

Schenning

et al. 2018

Adv Materials Inter

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The ability to induce oscillating surface topographies in light‐responsive liquid crystal networks on‐demand by light is interesting for applications in soft robotics, self‐cleaning surfaces, and haptics. However, the common height of these surface features is in the range of tens of nanometer, which limits their applications. Here a photoresponsive liquid crystal network coating with a patterned director motive exhibiting surface features that oscillate dynamically when addressed by light with modulated polarization is reported. By utilizing a compliant intermediate layer, the surface topographies increase with a factor 10, from roughly 70–100 nm to 1 µm. This increase in topography height is accompanied by a superimposed dynamic oscillation with an amplitude of ≈100 nm. These values can be translated to a 16.7% average static strain with 3.3% oscillations with respect to the coating thickness. Moreover, utilizing the complying support increases the maximum rotation speeds with an in‐phase response from 2.5 up to 25° s−1. However, at this maximized rotation speed the oscillation amplitude decreases to about half of the initial value.

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“…59 Very recently, in 2017, a review of light-triggered topographies in azopolymers including a brief description of the supramolecular work in the field was written by Broer and coworkers. 60 Also in 2017, the use of azobenzene as a building block in molecular machine architectures 61 and in light-powered molecular devices 62 were reviewed. Additionally, in early 2018 light control of nano-objects especially focusing on using noncovalent interactions to couple azobenzene surfactants to these objects was reviewed, thus indicating the timeliness of employing supramolecular interactions in the design of photoresponsive materials.…”

Section: Scope Of This Review and Complementary Readingmentioning

confidence: 99%

Supramolecular design principles for efficient photoresponsive polymer–azobenzene complexes

2018

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a Noncovalent binding of azobenzenes to polymers allows harnessing light-induced molecular-level motions (photoisomerization) for inducing macroscopic effects, including photocontrol over molecular alignment and self-assembly of block copolymer nanostructures, and photoinduced surface patterning of polymeric thin films. In the last 10 years, a growing body of literature has proven the utility of supramolecular materials design for establishing structure-property-function guidelines for photoresponsive azobenzene-based polymeric materials. In general, the bond type and strength, engineered by the choice of the polymer and the azobenzene, influence the photophysical properties and the optical response of the material system. Herein, we review this progress, and critically assess the advantages and disadvantages of the three most commonly used supramolecular design strategies:hydrogen, halogen and ionic bonding. The ease and versatility of the design of these photoresponsive materials makes a compelling case for a paradigm shift from covalently-functionalized side-chain polymers to supramolecular polymer-azobenzene complexes.

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Light-Triggered Formation of Surface Topographies in Azo Polymers

Cited by 34 publications

References 118 publications

Photoreversible Soft Azo Dye Materials: Toward Optical Control of Bio‐Interfaces

Photoreversible Soft Azo Dye Materials: Toward Optical Control of Bio‐Interfaces

Compliance‐Mediated Topographic Oscillation of Polarized Light Triggered Liquid Crystal Coating

Supramolecular design principles for efficient photoresponsive polymer–azobenzene complexes

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