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Abstract Extracellular matrices of living tissues exhibit viscoelastic properties, yet how these properties regulate chromatin and the epigenome remains unclear. Here, we show that viscoelastic substrates induce changes in nuclear architecture and epigenome, with more pronounced effects on softer surfaces. Fibroblasts on viscoelastic substrates display larger nuclei, lower chromatin compaction, and differential expression of distinct sets of genes related to the cytoskeleton and nuclear function, compared to those on elastic surfaces. Slow-relaxing viscoelastic substrates reduce lamin A/C expression and enhance nuclear remodeling. These structural changes are accompanied by a global increase in euchromatin marks and local increase in chromatin accessibility atcis-regulatory elements associated with neuronal and pluripotent genes. Consequently, viscoelastic substrates improve the reprogramming efficiency from fibroblasts into neurons and induced pluripotent stem cells. Collectively, our findings unravel the roles of matrix viscoelasticity in epigenetic regulation and cell reprogramming, with implications for designing smart materials for cell fate engineering. 

Abstract We report the electrochemically switchable reactivity of (salfen)Al(OⁱPr) (salfen = 1,1′‐di(2,4‐bis‐tert‐butyl‐salicylimino)ferrocene) toward the ring‐opening polymerization of various cyclic esters, ethers, and carbonates. Using a recently developed electrochemical system comprised of an H‐cell and a glassy carbon working electrode, an applied potential can alternate between the two redox states of the catalyst and alter monomer incorporation during ring‐opening polymerization. We discuss differences in activity and control under electrochemical conditions compared to previously studied chemical redox methods and discuss the necessity of a redox switch during certain copolymerization reactions.