Feng Zhang

Silk fibroin (SF) cryogels are promising biomaterials for tissue engineering owing to their hierarchical porous architecture, tunable mechanical properties, and favorable hydrogel characteristics, yet conventional fabrication relying on chemical crosslinkers compromises biocompatibility and limits translational potential. Herein, we developed an ethanol-assisted physical crosslinking strategy to fabricate SF cryogels via ice-templating under -20 °C, eliminating toxic chemical crosslinkers entirely. The formation of SF cryogels was driven by the synergistic effects of ice-templating-induced molecular self-assembly and ethanol-mediated conformational transition of SF from random coils to a dominant β-sheet structure. The effect of parameters (freezing temperature, ethanol concentration, and SF concentration) on the formation of SF hydrogels and their physicochemical properties were characterized, including microstructure, mechanical strength, degradation kinetics, porosity, and swelling capacity. Notably, Macroporous SF cryogels were successfully prepared from 1–7.5 wt% SF solutions containing 0.5 or 1 wt% ethanol at −20 °C, exhibiting shape recoverability, cyclic compression stability (60% strain for 10 cycles), and controlled degradability dependent on ethanol/SF concentrations. In vitro cell culture studies with NIH3T3 fibroblasts demonstrated excellent cell adhesion and proliferation on the SF cryogels, confirming superior cytocompatibility. Given their physically crosslinked nature, tunable multi-scale properties, hierarchical porosity, and favorable cytocompatibility, these SF cryogels hold significant potential as 3D scaffolds for tissue regeneration.

Wound healing remains a critical clinical challenge due to uncontrolled bleeding, bacterial infections, poor vascularization, and cell migration at damaged tissue sites. To address this challenge, we developed a radially structured, multifunctional biomimetic scaffold. Tussah silk was subjected to physical shearing and alkaline hydrolysis treatment to obtain tussah silk nanofibers (TSn). The TSn, chitosan (CS), and graphene oxide (GO) were then processed into radially aligned TSn/CS/GO scaffolds. These anisotropic composite scaffolds demonstrated not only antibacterial activity and rapid hemostatic properties but also effectively guided cell migration from the wound periphery toward the center. To achieve multifunctionality, including antioxidant activity, enhanced cell migration, and vascularization, the central void of the TSn/CS/GO scaffold was filled with a silk fibroin hydrogel integrated with Puerarin (PUE). In vivo studies using rat models confirmed that the TSn/CS/GO@PUE3 scaffold significantly accelerated wound healing (99.98 ± 0.02%), angiogenesis (the positive expression rates of CD31 and α‐SMA were 21.66 ± 0.74% and 41.28 ± 1.09%, respectively), and collagen deposition (75.26 ± 2.10%). This study thus provides a valuable strategy for developing multifunctional biomimetic scaffolds to accelerate wound repair.

Scaffolds with anisotropic structures are attractive for wound repair due to their enhanced ability to promote cell adhesion, migration, and tissue growth. In this study, anisotropic tussah silk nanofiber (TSn) scaffolds were developed through physical shearing, NaOH hydrolysis, and ice templating to accelerate wound healing. The anisotropic TSn scaffolds demonstrated radial and aligned structures, which would influence cell behavior and tissue regeneration. In vitro cellular studies have demonstrated that radial and aligned structures promoted fibroblast proliferation and directional migration. Furthermore, the disordered scaffolds (DS), aligned scaffolds (AS), and radial scaffolds (RS) were investigated to elucidate the effect of the different structures on wound healing. In vivo results demonstrated that the RS (99.8 ± 0.1%) exhibited the fastest healing rate, which may be attributed to the enhanced peripheral to central growth of blood vessels (the positive expression rates of CD31 and α-SMA were 13.0 ± 1.1% and 18.8 ± 0.8%, respectively) and tissues (the collagen deposition rate was 71.2 ± 3.5%) 14 days post implantation under the guidance of its radial structure. Taken together, biomimetic TSn scaffolds with radial structures performed the best in wound healing, offering promising applications in skin wound healing.

Nerve guide conduits (NGCs) offer promise for peripheral nerve regeneration, yet their performance remains inferior to autologous nerve grafts. To address this limitation, we developed novel aligned silk fibroin nerve conduits (ASNC) and evaluated their performance in enhancing nerve regeneration. ASNCs were fabricated and their biocompatibility and regenerative potential were assessed in vitro and in vivo. Random silk fibroin nerve conduits (RSNCs) served as control materials. In vitro experiments evaluated ASNC effects on cell adhesion, proliferation, and morphological elongation. For in vivo studies, a 10-mm-long sciatic nerve defect rat model was established, followed by ASNCs treatment. Post-implantation evaluations included axonal regeneration (sciatic function index, myelinated fiber density, muscle weight preservation) and functional recovery (walking track analysis, electrophysiology, histological evaluations). Compared to RSNCs, ASNCs significantly promoted cell adhesion and directional growth along the aligned fibers, whereas RSNCs exhibited slower growth and random orientation. In vivo results showed ASNCs achieved axonal regeneration and functional recovery comparable to autografts. This was demonstrated by improvements in the number and area of myelinated nerve fibers and enhanced muscle wet weight ratios. The newly developed ASNCs demonstrated comparable effectiveness to autografts in guiding axonal growth and promoting nerve regeneration. These findings position ASNCs as a promising alternative to autologous nerve grafts, offering a viable therapeutic approach for peripheral nerve repair. This study demonstrates that aligned silk fibroin nerve conduits (ASNCs) significantly enhance peripheral nerve regeneration, achieving functional recovery comparable to autologous nerve grafts. By leveraging the directional guidance of aligned fibers, ASNCs promote axonal growth and mitigate the limitations of current treatments, such as donor site morbidity and insufficient donor tissue availability. These findings advance the field of neural tissue engineering by providing a scalable, biomaterial-based alternative for peripheral nerve repair. The potential clinical translation of ASNCs offers a promising therapeutic strategy for addressing long-gap nerve defects, with implications for improving patient outcomes and expanding treatment options.