Sustainable Antibacterial Surgical Suture Based on Recycled Silk Resource by an Internal Combination of Inorganic Nanomaterials.

The current antibacterial treatment methods of silk sutures can only be finished by surface modification, leading to problems of short antibacterial effects, easy slow-release consumption, prominent toxicity, and susceptibility to drug resistance. Speculatively, surgical sutures combining antibacterial material internally will possess a more promising efficacy. Hence, we extracted recycled regenerated silk fibroin (RRSF) from waste silk resources to make RRSF solutions. Internally combining with inorganic titanium dioxide (TiO2) nanoparticles, we fabricated antibacterial RRSF-based surgical sutures. The morphologies, mechanical and antibacterial properties, biocompatibility tests, and in vivo experiments were carried out. The results showed that the surgical sutures with 1.25 wt % TiO2 acquired 2.40 N knot strength (143 µm diameter) and achieved a sustainable antibacterial effect of 93.58%. Surprisingly, the sutures significantly reduced inflammatory reactions and promoted wound healing. Surgical sutures in this paper realize high-value recovery of waste silk fibers and provide a novel approach to preparing multifunctional sutures.

Cooperation between Dual Metal Atoms and Nanoclusters Enhances Activity and Stability for Oxygen Reduction and Evolution.

We have achieved the synthesis of dual-metal single atoms and atomic clusters that co-anchor on a highly graphitic carbon support. The catalyst comprises Ni4 (and Fe4) nanoclusters located adjacent to the corresponding NiN4 (and FeN4) single-atom sites, which is verified by systematic X-ray absorption characterization and density functional theory calculations. A distinct cooperation between Fe4 (Ni4) nanoclusters and the corresponding FeN4 (NiN4) atomic sites optimizes the adsorption energy of reaction intermediates and reduces the energy barrier of the potential-determining steps. This catalyst exhibits enhanced oxygen reduction and evolution activity and long-cycle stability compared to counterparts without nanoclusters and commercial Pt/C. The fabricated Zn-air batteries deliver a high power density and long-term cyclability, demonstrating their prospects in energy storage device applications.

Surface-fill H2S-releasing silk fibroin hydrogel for brain repair through the repression of neuronal pyroptosis.

Traumatic brain injury (TBI) remains the major cause of disability and mortality worldwide due to the persistent neuroinflammation and neuronal death induced by TBI. Among them, pyroptosis, a specific type of programmed cell death (PCD) triggered by inflammatory signals, plays a significant part in the pathological process after TBI. Inhibition of neuroinflammation and pyroptosis is considered a possible strategy for the treatment of TBI. In our previous study, exogenous hydrogen sulfide(H2S) exerted a neuroprotective effect after TBI. Here, we developed a surface-fill H2S-releasing silk fibroin (SF) hydrogel (H2S@SF hydrogel) to achieve small-dose local administration and avoid volatile and toxic side effects. We used a controlled cortical impact (CCI) to establish a mild TBI model in mice to examine the effect of H2S@SF hydrogel on TBI-induced pyroptosis. We found that H2S@SF hydrogel inhibited the expression of H2S synthase in neurons after TBI and significantly inhibited TBI-induced neuronal pyroptosis. In addition, immunofluorescence staining results showed that the necroptosis protein receptor-interacting serine/threonine-protein kinase 1 (RIPK1) partially colocalized with the pyroptosis protein Gasdermin D (GSDMD) in the same cells. H2S@SF hydrogel can also inhibit the expression of the necroptosis protein. Moreover, H2S@SF hydrogel also alleviates brain edema and the degree of neurodegeneration in the acute phase of TBI. The neuroprotective effect of H2S@SF hydrogel was further confirmed by wire-grip test, open field test, Morris water maze, beam balance test, radial arm maze, tail suspension, and forced swimming test. Lastly, we also measured spared tissue volume, reactive astrocytes and activated microglia to demonstrate H2S@SF hydrogel impacts on long-term prognosis in TBI. Our study provides a new theoretical basis for the treatment of H2S after TBI and the clinical application of H2S@SF hydrogel. STATEMENT OF SIGNIFICANCE: Silk fibroin (SF) hydrogel controls the release of hydrogen sulfide (H2S) to inhibit neuronal pyroptosis and neuroinflammation in injured brain tissue. In this study, we synthesized a surface-fill H2S-releasing silk fibroin hydrogel, which could slowly release H2S to reshape the homeostasis of endogenous H2S in injured neurons and inhibit neuronal pyroptosis in a mouse model of traumatic brain injury. Meanwhile, H2S@SF hydrogel could alleviate brain edema and the degree of neurodegeneration, improve motor dysfunction, anxious behavior and memory impairment caused by TBI, reduce tissue loss and ameliorate neuroinflammation. Our study provides a new theoretical basis for the treatment of H2S after TBI and the clinical application of H2S@SF hydrogel.

Implantation of injectable SF hydrogel with sustained hydrogen sulfide delivery reduces neuronal pyroptosis and enhances functional recovery after severe intracerebral hemorrhage.

Hydrogen sulfide (H2S), an important endogenous signaling molecule, plays an important neuroprotective role in the central nervous system. However, there is no ideal delivery material or method involving the sustained and controlled release of H2S for clinical application in brain diseases. Silk fibroin (SF)-based hydrogels have become a potentially promising strategy for local, controlled, sustained drug release in the treatment of various disorders. Here, we show a silk fibroin (SF)-based hydrogel with sustained H2S delivery (H2S@SF hydrogel) is effective in treating brain injury through stereotactic orthotopic injection in a severe intracerebral hemorrhage (ICH) mouse model. In this study, we observed H2S@SF hydrogel sustained H2S release in vitro and in vivo. The physicochemical properties of H2S@SF hydrogel were studied using FE-SEM, Raman spectroscopy and Rheological analysis. Treatment with H2S@SF hydrogel attenuated brain edema, reduced hemorrhage volume and improved the recovery of neurological deficits after severe ICH following stereotactic orthotopic injection. Double immunofluorescent staining also revealed that H2S@SF hydrogel may reduce cell pyroptosis in the striatum, cortex and hippocampus. However, when using endogenous H2S production inhibitor AOAA, H2S@SF hydrogel could not suppress ICH-induced cell pyroptosis. Hence, the therapeutic effect of the H2S@SF hydrogel may be partly the result of the slow-release of H2S and/or the effect of the SF hydrogel on the production of endogenous H2S. Altogether, the results exhibit promising attributes of injectable silk fibroin hydrogel and the utility of H2S-loaded injectable SF hydrogel as an alternative biomaterial toward brain injury treatment for clinical application.