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Disulfide hydrogels, derived from cysteine‐based redox systems, exhibit active self‐assembly properties driven by reversible disulfide bond formation, making them a versatile platform for dynamic material design. Detailed cryogenic electron microscopy (cryo‐EM) analysis reveals a consistent fiber diameter of 5.4 nm for individual fibers. Using cryo‐EM‐informed radial positional restraints, all‐atom molecular dynamics (MD) simulations are employed to reproduce fibers with dimensions closely matching experimental observations, validated further through simulated cryo‐EM images. The MD simulations reveal that the disulfide gelator (CSSC) predominantly adopts an open conformation, with hydrogen bonds emerging as the key intermolecular force stabilizing the fibers. Notably, intermolecular interactions are found to be higher at 70% conversion to the disulfide gelator compared with 100%, comparable with past unrestrained simulations. Water molecules and solute‐water hydrogen bonds are present throughout the fiber, indicating that the fiber remains hydrated. These findings underscore the potential role of the thiol precursor CSH in stabilizing the transient phase and highlight the importance of CSH‐CSSC interplay. Herein, it provides novel insights into molecular mechanisms governing active self‐assembly and offers strategies for designing tunable materials through controlled assembly conditions. 

Abstract Electron tomography holds great promise as a tool for investigating the 3D morphologies and internal structures of metal‐organic framework‐based protein biocomposites (protein@MOFs). Understanding the 3D spatial arrangement of proteins within protein@MOFs is paramount for developing synthetic methods to control their spatial localization and distribution patterns within the biocomposite crystals. In this study, the naturally occurring iron oxide mineral core of the protein horse spleen ferritin (Fn) is leveraged as a contrast agent to directly observe individual proteins once encapsulated into MOFs by electron microscopy techniques. This methodology couples scanning electron microscopy, transmission electron microscopy, and electron tomography to garner detailed 2D and 3D structural interpretations of where proteins spatially lie in Fn@MOF crystals, addressing the significant gaps in understanding how synthetic conditions relate to overall protein spatial localization and aggregation. These findings collectively reveal that adjusting the ligand‐to‐metal ratios, protein concentration, and the use of denaturing agents alters how proteins are arranged, localized, and aggregated within MOF crystals. 

We elucidate the mechanisms of chemically driven self-assembly processes, demonstrating how synchronous assembly–disassembly reactions can stabilize transient structures and create morphologies that differ from conventional assemblies.