Vancomycin-loaded silk fibroin microspheres in an injectable hydrogel for chronic osteomyelitis therapy.

Chronic osteomyelitis remains a clinical challenge in orthopedics. In this study, silk fibroin microspheres (SFMPs) loaded with vancomycin are entrapped in an injectable silk hydrogel to form a vancomycin delivery system for treatment of chronic osteomyelitis. Vancomycin showed continuous release from the hydrogel for up to 25 days.

Preparation and Biocompatibility Characterization of Silk Fibroin 3D Scaffolds.

In this paper, three different mass fractions of sodium carbonate were used for degumming to obtain different degrees of damaged silk fibroin fibers, which were then treated with formic acid to shrink and bond them into 3D scaffolds. The structure and performance of silk fibroin fibers and silk fibroin 3D scaffolds were characterized by scanning electron microscopy, infrared spectroscopy, X-ray diffraction, a differential thermal scanner, a universal materials testing machine, and laser confocal microscopy, and the degradation performance was tested by protease degradation. The results showed that an excessive mass fraction of sodium carbonate would cause partial hydrolysis of fibroin fibers, decrease the mechanical properties of fibroin fiber, increase the surface roughness of fibroin fibers, and make mouse embryonic fibroblasts easier to adhere and grow.

Robust Nanofiber Mats Exfoliated From Tussah Silk for Potential Biomedical Applications.

Nanofibers as elements for bioscaffolds are pushing the development of tissue engineering. In this study, tussah silk was mechanically disintegrated into nanofibers dispersed in aqueous solution which was cast to generate tussah silk fibroin (TSF) nanofiber mats. The effect of treatment time on the morphology, structure, and mechanical properties of nanofiber mats was examined.

Self-Healing, Self-Adhesive Silk Fibroin Conductive Hydrogel as a Flexible Strain Sensor.

Flexible and wearable hydrogel strain sensors have attracted tremendous attention for applications in human motion and physiological signal monitoring. However, it is still a great challenge to develop a hydrogel strain sensor with certain mechanical properties and tensile deformation capabilities, which can be in conformal contact with the target organ and also have self-healing properties, self-adhesive capability, biocompatibility, antibacterial properties, high strain sensitivity, and stable electrical performance. In this paper, an ionic conductive hydrogel (named PBST) is rationally designed by proportionally mixing polyvinyl alcohol (PVA), borax, silk fibroin (SF), and tannic acid (TA).

Silk sericin/fibroin electrospinning dressings: a method for preparing a dressing material with high moisture vapor transmission rate.

The current study focuses on the preparation of sericin and silk fibroin blend electrostatic spinning fiber film dressing. The surface morphology of the fiber films was observed by scanning electron microscope, and the hydrophilicity and swelling property of the fiber membrane dressing were analyzed. The biocompatibility of the four dressings was verified by the CCK-8 method and confocal laser microscopy.

Tough Anisotropic Silk Nanofiber Hydrogels with Osteoinductive Capacity.

Multiple physical cues such as hierarchical microstructures, topography, and stiffness influence cell fate during tissue regeneration. Yet, introducing multiple physical cues to the same biomaterial remains a challenge. Here, a synergistic cross-linking strategy was developed to fabricate protein hydrogels with multiple physical cues based on combinations of two types of silk nanofibers.

Functional silk fibroin hydrogels: preparation, properties and applications.

Over the past decade, the hydrogels prepared from silk fibroin have received immense research attention due to the advantages of safe nature, biocompatibility, controllable degradation and capability to combine with other materials. They have broad application prospects in biomedicine and other fields. However, the traditional silk protein hydrogels have a simple network structure and single functionality, thus, leading to poor adaptability towards complex application environments.

Facile preparation of a strong chitosan-silk biocomposite film.

Chitosan-silk biocomposite films with nanofibrous structures have been prepared by facile solution casting of chitosan and silk co-dissolved in formic acid. The morphology, structure and mechanical properties of the chitosan-silk biocomposite were characterized by SEM, FTIR, TG-DSC, and mechanical testing. The results demonstrate that the prepared biocomposite films with a chitosan-silk ratio of 3:1 shows a high tensile strength of 97.

Injectable Silk Nanofiber Hydrogels for Sustained Release of Small-Molecule Drugs and Vascularization.

Strategies to control neovascularization in damaged tissues remain a key issue in regenerative medicine. Unlike most reported desferrioxamine (DFO)-loaded systems where DFO demonstrates a burst release, here we attain zero-order release behavior above 40 days. This outcome was achieved by blending DFO with silk nanofibers with special hydrophilic-hydrophobic properties.

Gentamicin-loaded silk/nanosilver composite scaffolds for MRSA-induced chronic osteomyelitis.

Methicillin-resistant (MRSA) often induces chronic osteomyelitis and then bone defects. Here, gentamicin-loaded silk/nanosilver composite scaffolds were developed to treat MRSA-induced chronic osteomyelitis. AgNO was reduced with silk as a reducing agent in formic acid, forming silver nanoparticles that were distributed uniformly in the composite scaffolds.

Biological effects different diameters of Tussah silk fibroin nanofibers on olfactory ensheathing cells.

Transplantation of olfactory ensheathing cells (OECs) has potential for treating spinal cord and brain injury. However, they are void of an extracellular matrix to support cell growth and migration. Engineering of tissue to mimic the extracellular matrix is a potential solution for neural repair.

Different angiogenesis modes and endothelial responses in implanted porous biomaterials.

An in vivo experimental model based on implanting porous biomaterials to study angiogenesis was proposed. In the implanted porous polyvinyl alcohol, three major modes of angiogenesis, sprouting, intussusception and splitting, were found. By electron microscopy and three-dimensional simulation of the angiogenic vessels, we investigated the morphological characteristics of the three modes and paid special attention to the initial morphological difference between intussusception and splitting, and it was confirmed that the endothelial abluminal invagination and intraluminal protrusion are pre-representations of intussusception and splitting, respectively.

A novel method to prepare tussah/ silk fibroin-based films.

The possibility of using silk fibroin in biomaterials for tissue engineering is a subject of broad interest. In this study, /tussah silk fibroin (BSF/TSF) blend films were prepared by solution casting using CaCl/formic acid as a co-solvent and water as a rinse solvent. The morphology, crystallinity, thermal resistance, mechanical properties and water contact angle of the blend films as well as the biocompatibility were investigated.

Green process to prepare water-insoluble silk scaffolds with silk I structure.

Silk porous scaffolds have shown promising applications in tissue regenerations as cellular scaffolds to incorporate cells in vitro and in vivo, and facilitate cell proliferation and production of extracellular matrix. It remains strong needs to optimize the microstructures and performances of silk scaffolds for better biocompatibility. Here, a green process was developed to form water-insoluble scaffolds.

Controlled self-assembly of glycoprotein complex in snail mucus from lubricating liquid to elastic fiber.

The pedal mucus secreted by many gastropod mollusks, such as terrestrial snails and slugs, plays crucial roles in locomotion, osmoregulation, reproduction, and repulsing predators. In this report, we presented an intriguing example that terrestrial snail can utilize the self-assembly of glycoprotein complex in secreted mucus at the nanoscale to enhance adhesive force on smooth plates. With increasing crawling angle, the structural transformation of pedal mucus was found to involve at least four distinct stages: assembly of nanoparticles, aggregation into microspheres, formation of gels and solidification into fibers.

A novel silk fibroin nanofibrous membrane for guided bone regeneration: a study in rat calvarial defects.

A novel membrane for guided bone regeneration (GBR), constituting silk fibroin (SF) nanofiber from native silk nanofibril solution, was prepared by electrospinning process. Another barrier membrane, a collagen-type membrane (Bio-Gide®), was used as a comparative sample. Twelve healthy male Sprague-Dawley rats were used in this study.

Novel two-step method to form silk fibroin fibrous hydrogel.

Hydrogels prepared by silk fibroin solution have been studied. However, mimicking the nanofibrous structures of extracellular matrix for fabricating biomaterials remains a challenge. Here, a novel two-step method was applied to prepare fibrous hydrogels using regenerated silk fibroin solution containing nanofibrils in a range of tens to hundreds of nanometers.

Silk fibroin/copolymer composite hydrogels for the controlled and sustained release of hydrophobic/hydrophilic drugs.

In the present study, a composite system for the controlled and sustained release of hydrophobic/hydrophilic drugs is described. Composite hydrogels were prepared by blending silk fibroin (SF) with PLA-PEG-PLA copolymer under mild aqueous condition. Aspirin and indomethacin were incorporated into SF/Copolymer hydrogels as two model drugs with different water-solubility.

Silk fibroin/sodium alginate fibrous hydrogels regulated hydroxyapatite crystal growth.

Use of organic templates for controlling the growth of inorganic crystals is one of the research topics in biomimetic field. In particular, oriented growth of hydroxyapatite (HAp) in organic fibrous matrix is provided a new view angle to study biomineralization of bone and its potential biomedical applications. The crystallization of HAp in fibrous hydrogels could mimic such biomineralization.

Influence factors analysis on the formation of silk I structure.

Regenerated silk fibroin aqueous solution was used to study the crystalline structure of Bombyx mori silk fibroin in vitro. By controlling environmental conditions and concentration of silk fibroin solution, it provided a means for the direct preparing silk I structure and understanding the details of silk fibroin molecules interactions in formation process. In this study, silk fibroin molecules were assembled to form random coil at low concentration of solution and then, as the concentration increases, were converted to silk I at 55% relative humidity (RH).

Facile fabrication of robust silk nanofibril films via direct dissolution of silk in CaCl2-formic acid solution.

In this study, we report for the first time a novel silk fibroin (SF) nanofibrous films with robust mechanical properties that was fabricated by directly dissolving silk in CaCl2-formic acid solution. CaCl2-FA dissolved silk rapidly at room temperature, and more importantly, it disintegrated silk into nanofibrils instead of separate molecules. The morphology of nanofibrils crucially depended on CaCl2 concentrations, which resulted in different aggregation nanostructure in SF films.

[Application of silk fibroin scaffold in bone tissue engineering].

Objective: To review the application of silk fibroin scaffold in bone tissue engineering.

Methods: The related literature about the application of silk fibroin scaffold in bone tissue engineering was reviewed, analyzed, and summarized.

Results: Silk fibroin can be manufactured into many types, such as hydrogel, film, nano-fiber, and three-dimensional scaffold, which have superior biocompatibility, slow biodegradability, nontoxic degradation products, and excellent mechanical strength.

Regeneration of high-quality silk fibroin fiber by wet spinning from CaCl2-formic acid solvent.

Silks spun by silkworms and spiders feature outstanding mechanical properties despite being spun under benign conditions. The superior physical properties of silk are closely related to its complicated hierarchical structures constructed from nanoscale building blocks, such as nanocrystals and nanofibrils. Here, we report a novel silk dissolution behavior, which preserved nanofibrils in CaCl2-formic acid solution, that enables spinning of high-quality fibers with a hierarchical structure.

Silk dissolution and regeneration at the nanofibril scale.

Native silk features strong, extensible and tough properties which originate from its hierarchical nanofibril structure. In the present study, native silk nanofibrils were obtained by dissolving degummed silk in salt-formic acid (FA), such as CaCl-FA. The CaCl-FA dissolved silk by breaking hydrogen bonds in the crystalline region while preserving the nanofibril structures.

Nanoscale Control of Silks for Nanofibrous Scaffold Formation with Improved Porous Structure.

Silk-based porous scaffolds have been used extensively in tissue engineering because of their excellent biocompatibility, tunable biodegradability and robust mechanical properties. Although many silk-based scaffolds have been prepared through freeze-drying, a challenge remains to effectively control porous structures during this process. In the present study silk fibroin with different nanostructures were self-assembled in aqueous solution by repeated drying-dissolving process and then used to improve porous structure formation in lyophilization process.