Stimuli-triggered formation of de novo -designed protein biomaterials

SUMMARYProtein-based biomaterials have risen in popularity in recent years owing to their genetic encodability, sequence specificity, monodispersity, and ability to interface with biological systems in comparison with synthetic polymer-based materials. Though naturally derived and minimally engineered proteins have been at the forefront of these efforts, recent advances in computational protein design offer exciting opportunities for next-generation biomaterial development. In this work, we employ de novo protein design methodologies to generate a suite of self-assembling multimeric proteins, whose step-growth heteropolymerization into bulk hydrogels and condensates can be exogenously triggered through small-molecule addition. Our results highlight how changes in programmed multimer valency and their triggered assembly yield materials with varying structures and viscoelasticity. We anticipate that these approaches will prove useful in rapidly generating large libraries of stimuli-responsive biomaterials that are precisely tailored to specific applications in the biosciences and beyond.Graphical AbstractTHE BIGGER PICTUREBiomaterials are revolutionizing how we study biology and treat diseases, offering new platforms for tissue engineering, drug delivery, and cellular modulation. Among these, protein-based materials stand out for their ability to mimic biological environments with unmatched precision. Despite this, most protein hydrogels rely on a narrow set of naturally occurring building blocks, limiting their versatility. This work introduces a new frontier in biomaterials by leveraging de novo protein design, a computational approach that creates entirely new proteins from scratch. By engineering proteins that self-assemble into defined architectures and respond to external stimuli, such as small molecules, we demonstrate the creation of customizable bulk hydrogels and intracellular condensates with tunable mechanical properties and formation dynamics.These materials not only expand the toolkit for bioengineers but also provide a powerful platform for probing fundamental biological processes. For example, the ability to trigger condensate formation inside cells opens new avenues for studying intracellular liquid-liquid phase separation, a phenomenon increasingly linked to aging and disease. Moreover, the modularity of this system, where protein components and triggers can be swapped, suggests broad applicability across biotechnology, synthetic biology, and regenerative medicine. As de novo design continues to evolve, it promises to unlock a vast landscape of protein-based materials with properties and functions beyond what nature has provided, reshaping how we build and interact with biological systems.In briefThis work introduces a modular platform for creating protein-based biomaterials using de novo -designed proteins that self-assemble into hydrogels and condensates upon small-molecule addition. By tuning protein valency and trigger concentration, the material s mechanical properties and formation dynamics are precisely controlled. These materials can be formed both in vitro and in cellulo , offering new tools for studying biomolecular condensates and enabling the development of customizable, responsive biomaterials for biomedical and synthetic biology applications.