Xin Chen

Protein nanofibrils assemble hierarchically, yet directing the mesoscale topology that connects fibrillar growth to network mechanics remains challenging. Here, we show that crystalline seed identity redirects regenerated silk fibroin assembly while retaining a common silk II packing motif. Top‐down silk nanocrystals promote core‐arm units with dense cores and radiating fibrillar arms, whereas seed‐free assembly and length‐matched bottom‐up nanofibril seeds yield predominantly linear structures. Cryogenic transmission electron microscopy and spectroscopy reveal preorganized, β‐sheet‐rich fibrillar bundles within the seeds. Time‐resolved imaging supports a mechanism in which these scaffolds accommodate multiple local growth regions, followed mainly by arm elongation. Composition‐dependent morphologies are consistent with precursor allocation among these regions, linking seed abundance to arm length and assembly‐unit density. At matched solids content, core‐arm gels enter the flow regime at lower strains than linear gels while retaining substantial modulus recovery after repeated high‐strain deformation. Idealized network simulations suggest that multivalent cores preserve global connectivity while shorter reconstruction pathways facilitate reversible bridge exchange. These findings establish crystalline seed interfaces as topology‐selecting elements in protein assembly and provide a strategy for constructing thixotropic and injectable protein materials without additional chemical cross‐linking.

Spatial organization underpins efficient multistep catalysis in nature, yet recreating such organization on living cell surfaces using mild, enzyme-compatible and catalytically functional materials remains challenging. Here we report an l-cysteine-triggered silk fibroin/lysozyme ultrathin film (SLF) that assembles directly on living microbial cells as a catalytic surface layer. SLF forms continuous nanoscale coatings on Saccharomyces cerevisiae, Gluconobacter oxydans and Escherichia coli Nissle 1917. Spectroscopic and structural analyses show that film formation proceeds through electrostatic complexation, restricted conformational rearrangement, increased hydrophobic exposure, β-sheet-rich ordering and network formation, rather than simple deposition. The coating maintains cell viability, enhances stress tolerance and provides size-selective permeability for small-molecule transport. SLF also incorporates exogenous enzymes efficiently during assembly. As a proof of concept, ω-transaminase-integrated SLF on G. oxydans couples host glycerol oxidation with surface transamination, enabling one-pot conversion of glycerol to serinol with a titer of 2.7 g L–1 within 12 h, up to 37-fold higher than a stepwise process. This work establishes ultrathin protein films as living catalytic interfaces for single-cell biocatalyst design and cascade biomanufacturing.

The mechanical response of silk fibers is commonly associated with β-sheet crystallinity and molecular orientation, yet how these molecular descriptors are transmitted across the fibrillar hierarchy remains less clear. Here, we compare Hyphantria cunea silk with Bombyx mori silk to examine how nanofibril-level load-transfer descriptors are associated with deformation when β-sheet fraction and axial orientation are comparable. Peptide profiling and single-fiber synchrotron infrared microspectroscopy show that H. cunea silk contains β-sheet-compatible sequence motifs and reaches β-sheet content and axial orientation comparable to those of B. mori silk. Despite this similarity, H. cunea silk exhibits a high-strength, near-linear tensile response, whereas B. mori silk follows a yielding−extension−hardening pathway. AFM-based fibrillar analysis and topology-constrained load-transfer modeling identify systematic differences in ex situ contour characteristics, effective coupling, and characteristic load-transfer descriptors that are consistent with the observed mechanical divergence. These results identify nanofibril coupling topology as a structural descriptor for programming silk fiber deformation beyond β-sheet order.

AFM-derived molecular dynamics and graph analysis reveal that strain-stiffening in semiflexible fibrous networks arises from the formation of a rigidity-percolating load-bearing backbone.

Rigid biogenic nanofibrils are generally understood through their backbone structure, crystallinity, and molecular alignment, whereas the role of sparse geometric defects in governing whole-fibril mechanics remains less clear. Here, we show that highly rigid Hyphantria cunea silk nanofibrils contain intrinsic kink defects that dominate contour-level orientational decorrelation and govern the defect-mediated bending response of the fibril. These localized angular discontinuities interrupt otherwise straight rigid segments and produce contour statistics that cannot be captured by uniform thermal bending alone. Interfacial assembly of regenerated Bombyx mori silk fibroin on the nanofibril surface progressively suppresses kink expression, smooths contour curvature, and shifts the bending mode from kink-dominated segmented reorientation toward distributed bending. Selective removal of the assembled interfacial layer partially restores the original high-curvature features and defect-mediated bending state, demonstrating that the effect is largely reversible and arises from contour statistical redistribution rather than permanent modification of the rigid backbone. Our results establish interfacial assembly as a route to reprogram defect expression in rigid biogenic nanofibrils and thereby tune single-fibril bending mechanics. This framework may provide broader insight into interface-controlled mechanics in other high-aspect ratio biogenic fibrillar systems.

Greener epoxide-α-amino acid N -carboxyanhydride (NCA) synthesis yields biodegradable host defense peptide (HDP) mimics that clear biofilms with reduced material and energy use.

Multifunctional membranes integrating pollutant separation, treatment, and detection are highly desirable but challenging to create. Here, we report a coordination-adsorption-reduction strategy to fabricate ultrathin, flexible, self-supporting silk fibroin-Ag (SAFE) membranes at the air-water interface. Mechanistic studies reveal that silver(Ι) center coordination guides silk fibroin aggregation, which templates uniform AgNP growth. The resulting membranes achieve exceptional electrical conductivity (up to 1.9 × 10⁷ S m^-1) and mechanical robustness. Functionally, they provide high-flux separation and superior pollutant adsorption, while the embedded AgNPs offer multifaceted treatment via antimicrobial, catalytic, and electrochemical activities and enable sensitive SERS detection of trace contaminants. This integrated "separation-treatment-detection" approach establishes SAFE membranes as a promising platform for intelligent and sustainable water purification.

With the global aging population and the rising incidence of cardiovascular diseases, the demand for long‐term anticoagulant medication is increasing, leading to a higher risk of bleeding in medical fields such as oral surgery, particularly during tooth extractions. To address this clinical need, a convenient one‐step method is developed to fabricate expandable silk fibroin/montmorillonite (SF/MMT) porous scaffolds by leveraging the procoagulant and osteogenic differentiation‐promoting effects of montmorillonite (MMT), along with the biocompatibility of silk fibroin. The resulting SF/MMT porous scaffolds exhibit excellent shape recovery, with a volume expansion ratio of up to 400%. Furthermore, through the rapid blood absorption facilitated by the porous structure and the procoagulant effect of MMT, these scaffolds demonstrate superior hemostatic ability in both in vitro coagulation tests and in vivo rat tail amputation/liver laceration models. Finally, this expandable SF/MMT porous scaffolds used as hemostatic fillers showed significantly enhancement on bone regeneration in the tooth extraction socket of rat with coagulation disorders, outperforming commonly used gelatin sponges. In summary, this simple method for preparing expandable SF/MMT porous scaffolds addresses the challenge of managing post‐extraction bleeding in patients on anticoagulant therapy and effectively promotes bone regeneration in extraction sockets, demonstrating considerable potential for application in stomatological clinic field.

Silk fibroin hydrogels offer attractive biocompatibility and optical clarity but suffer from water-induced fragility, freezing, and biofouling. Here, regenerated silk networks are enzymatically cross-linked and subsequently exchanged with choline-chloride deep eutectic solvents (DESs) containing glycerol and ethylene glycol to create transparent, ionically conductive SF-DES gels. DES infusion preserves the protein's β-sheet framework while generating a more homogeneous nanonetwork and denser microstructure, increasing compressive modulus by up to 70% without altering protein concentration. The low volatility and depressed freezing points of DESs impart exceptional durability: the glycerol-based gel loses −1 at −40 °C. Choline-based electrolytes inhibit growth of Escherichia coli and Staphylococcus aureus, mitigating microbial degradation. Leveraging this combination of mechanical resilience, environmental stability, ionic conductivity, and antimicrobial activity, bendable indium-free capacitive touch sensors are fabricated that achieve centimeter-scale position resolution and rapid gesture tracking. The study establishes DES infiltration as a general, aqueous-compatible route to robust, multifunctional protein gels, opening opportunities for sustainable wearable electronics, biomedical interfaces, and extreme-environment sensing.

We introduce amorphous calcium polyphosphate (CaPP) with tunable degrees of polymerization (DP) as a bioactive component into regenerated silk fibroin (RSF) hydrogels to address the bone regeneration challenge.