Photodegradable Polyacrylamide Gels for Dynamic Control of Cell Functions

Abstract

Cross-linked polyacrylamide hydrogels are commonly used in biotechnology and cell culture applications due to advantageous properties, such as the precise control of material stiffness and the attachment of cell adhesive ligands. However, the chemical and physical properties of polyacrylamide gels cannot be altered once fabricated. Here, we develop a photodegradable polyacrylamide gel system that allows for a dynamic control of polyacrylamide gel stiffness with exposure to light. Photodegradable polyacrylamide hydrogel networks are produced by copolymerizing acrylamide and a photocleavable ortho-nitrobenzyl (o-NB) bis-acrylate cross-linker. When the hydrogels are exposed to light, the o-NB cross-links cleave and the stiffness of the photodegradable polyacrylamide gels decreases. Further examination of the effect of dynamic stiffness changes on cell behavior reveals that in situ softening of the culture substrate leads to changes in cell behavior that are not observed when cells are cultured on presoftened gels, indicating that both dynamic and static mechanical environments influence cell fate. Notably, we observe significant changes in nuclear localization of YAP and cytoskeletal organization after in situ softening; these changes further depend on the type and concentration of cell adhesive proteins attached to the gel surface. By incorporating the simplicity and well-established protocols of standard polyacrylamide gel fabrication with the dynamic control of photodegradable systems, we can enhance the capability of polyacrylamide gels, thereby enabling cell biologists and engineers to study more complex cellular behaviors that were previously inaccessible using regular polyacrylamide gels.

Hydrogel from Chrome Shavings as a Sustainable, Highly Sensitive Ionic Skin for Pressure Sensing

“…Construction of a Fiber Hybrid Hydrogel Based on Chrome Shavings. The most traditional hydrogels are synthesized involving polymerization of monomers through initiators; this usually requires precise control of the monomer reaction process, which means complicated conditions, such as an oxygen-free environment, 37 light irradiation, 24 and so forth. Even so, the fragile mechanical properties caused by the insufficient crosslinking and the lack of support skeleton still hinder the application of hydrogel in CPSs.…”

Design of a UCST Polymer with Strong Hydrogen Bonds and Reactive Moieties for Facile Polymer–Protein Hybridization

“…Polyacrylamide (PAAm) is a biocompatible polymer and has been widely used in bio-related areas, such as the control of cell functions, stem cell transplantation, cell culture, cell adhesion, and drug delivery systems. , PAAm has a H-acceptor (−CO) and H-donor (−N H 2 ). However, it cannot form interpolymer hydrogen bonds and show a UCST behavior in water due to the weak activity of its H-donor (−N H 2 ).…”

Current strategies for ligand bioconjugation to poly(acrylamide) gels for 2D cell culture: Balancing chemo-selectivity, biofunctionality, and user-friendliness

“…Several methodologies allow ligand patterning using various chemical strategies as shown in previous sections. ( Daliri et al, 2021 ) Noteworthy, the introduction of photolabile comonomers into PAM has recently been exploited to dynamically and locally tune the mechanical ( Norris et al, 2021 ) and cell-adhesive ( Missirlis et al, 2022 ) properties of light-responsive PAM gels. In contrast, the realization of truly high throughput PAM systems is still in its infancy.…”

“…( Prouvé et al, 2021 ) A possible way to control excessive swelling is the use of longer-chain carboxylic acid-functionalized comonomers. ( Heras-Bautista et al, 2019 ; Norris et al, 2021 )…”