In vitro biocompatibility of electrospun silk fibroin mats with Schwann cells

Silk fibroin-derived electrospun materials for biomedical applications: A review

Electrospinning is a versatile technique for fabricating polymeric fibers with diameters ranging from micro- to nanoscale, exhibiting multiple morphologies and arrangements. By combining silk fibroin (SF) with synthetic and/or natural polymers, electrospun materials with outstanding biological, chemical, electrical, physical, mechanical, and optical properties can be achieved, fulfilling the evolving biomedical demands. This review highlights the remarkable versatility of SF-derived electrospun materials, specifically focusing on their application in tissue regeneration (including cartilage, cornea, nerves, blood vessels, bones, and skin), disease treatment (such as cancer and diabetes), and the development of controlled drug delivery systems. Additionally, we explore the potential future trends in utilizing these nanofibrous materials for creating intelligent biomaterials, incorporating biosensors and wearable sensors for monitoring human health, and also discuss the bottlenecks for its widespread use. This comprehensive overview illuminates the significant impact and exciting prospects of SF-derived electrospun materials in advancing biomedical research and applications.

Electrospun Poly(ethylene Terephthalate)/Silk Fibroin Composite for Filtration Application

In this study, fibrous membranes from recycled-poly(ethylene terephthalate)/silk fibroin (r-PSF) were prepared by electrospinning for filtration applications. The effect of silk fibroin on morphology, fibers diameters, pores size, wettability, chemical structure, thermo-mechanical properties, filtration efficiency, filtration performance, and comfort properties such as air and water vapor permeability was investigated. The filtration efficiency (FE) and quality factor (Qf), which represents filtration performance, were calculated from penetration through the membranes using aerosol particles ranging from 120 nm to 2.46 μm. The fiber diameter influenced both FE and Qf. However, the basis weight of the membranes has an effect, especially on the FE. The prepared membranes were classified according to EN149, and the most effective was assigned to the class FFP1 and according to EN1822 to the class H13. The impact of silk fibroin on the air permeability was assessed. Furthermore, the antibacterial activity against bacteria S. aureus and E. coli and biocompatibility were evaluated. It is discussed that antibacterial activity depends not only on the type of used materials but also on fibrous membranes' surface wettability. In vitro biocompatibility of the selected samples was studied, and it was proven to be of the non-cytotoxic effect of the keratinocytes (HaCaT) after 48 h of incubation.

Biofunctionalized silk fibroin nanofibers for directional and long neurite outgrowth

Engineered scaffolds simultaneously exhibiting multiple cues are highly desirable for neural tissue regeneration. Silk fibroin is a promising natural protein material for nerve repair. However, the lack of specific bioactive cues significantly hinders its application. In this study, the electrospun silk fibroin nanofibers with both biochemical and topographical cues were prepared. The alignment of electrospun nanofibers was optimized by controlling the surface linear velocity of a rotating drum. The silk fibroin nanofibers were further functionalized with laminin through covalent binding, confirmed by immunostaining observation. Cell proliferation and neurite outgrowth assays confirmed that the functionalized aligned nanofibers significantly enhanced directional axonal extensions, providing physical and bioactive cues for neurite outgrowth. Furthermore, the tubular scaffolds with longitudinally aligned microchannels were designed by rolling the functionalized silk fibroin nanofibers. The neurite extension across the lumen of the conduit along the direction of the aligned fibers is apparent. These results highlight the ability of laminin-immobilized silk fibroin nanofibers to enhance neurite outgrowth and to control directional neurite extension, providing a useful approach to construct a regenerative microenvironment for nerve repair materials.

A Comparison of Tissue Engineering Scaffolds Incorporated with Manuka Honey of Varying UMF

Purpose. Manuka honey (MH) is an antibacterial agent specific to the islands of New Zealand containing both hydrogen peroxide and a Unique Manuka Factor (UMF). Although the antibacterial properties of MH have been studied, the effect of varying UMF of MH incorporated into tissue engineered scaffolds have not. Therefore, this study was designed to compare silk fibroin cryogels and electrospun scaffolds incorporated with a 5% MH concentration of various UMF. Methods. Characteristics such as porosity, bacterial clearance and adhesion, and cytotoxicity were compared. Results. Pore diameters for all cryogels were between 51 and 60 µm, while electrospun scaffolds were 10 µm. Cryogels of varying UMF displayed clearance of approximately 0.16 cm for E. coli and S. aureus. In comparison, the electrospun scaffolds clearance ranged between 0.5 and 1 cm. A glucose release of 0.5 mg/mL was observed for the first 24 hours by all scaffolds, regardless of UMF. With respect to cytotoxicity, neither scaffold caused the cell number to drop below 20,000. Conclusions. Overall, when comparing the effects of the various UMF within the two scaffolds, no significant differences were observed. This suggests that the fabricated scaffolds in this study displayed similar bacterial effects regardless of the UMF value.

Silk-based biomaterials in biomedical textiles and fiber-based implants

Biomedical textiles and fiber-based implants (BTFIs) have been in routine clinical use to facilitate healing for nearly five decades. Amongst the variety of biomaterials used, silk-based biomaterials (SBBs) have been widely used clinically viz. sutures for centuries and are being increasingly recognized as a prospective material for biomedical textiles. The ease of processing, controllable degradability, remarkable mechanical properties and biocompatibility have prompted the use of SBBs for various BTFIs for extracorporeal implants, soft tissue repair, healthcare/hygiene products and related needs. The present Review focuses on BTFIs from the perspective of types and physical and biological properties, and this discussion is followed with an examination of the advantages and limitations of BTFIs from SBBs. The Review covers progress in surface coatings, physical and chemical modifications of SBBs for BTFIs and identifies future needs and opportunities for the further development for BTFIs using SBBs.

Significantly reinforced composite fibers electrospun from silk fibroin/carbon nanotube aqueous solutions

Microcomposite fibers of regenerated silk fibroin (RSF) and multiwalled carbon nanotubes (MWNTs) were successfully prepared by an electrospinning process from aqueous solutions. A quiescent blended solution and a three-dimensional Raman image of the composite fibers showed that functionalized MWNTs (F-MWNTs) were well dispersed in the solutions and the RSF fibers, respectively. Raman spectra and wide-angle X-ray diffraction (WAXD) patterns of RSF/F-MWNT electrospun fibers indicated that the composite fibers had higher β-sheet content and crystallinity than the pure RSF electrospun fibers, respectively. The mechanical properties of the RSF electrospun fibers were improved drastically by incorporating F-MWNTs. Compared with the pure RSF electrospun fibers, the composite fibers with 1.0 wt % F-MWNTs exhibited a 2.8-fold increase in breaking strength, a 4.4-fold increase in Young's modulus, and a 2.1-fold increase in breaking energy. Cytotoxicity test preliminarily demonstrated that the electrospun fiber mats have good biocompatibility for tissue engineering scaffolds.

Silk fibroin in tissue engineering

Tissue engineering (TE) is a multidisciplinary field that aims at the in vitro engineering of tissues and organs by integrating science and technology of cells, materials and biochemical factors. Mimicking the natural extracellular matrix is one of the critical and challenging technological barriers, for which scaffold engineering has become a prime focus of research within the field of TE. Amongst the variety of materials tested, silk fibroin (SF) is increasingly being recognized as a promising material for scaffold fabrication. Ease of processing, excellent biocompatibility, remarkable mechanical properties and tailorable degradability of SF has been explored for fabrication of various articles such as films, porous matrices, hydrogels, nonwoven mats, etc., and has been investigated for use in various TE applications, including bone, tendon, ligament, cartilage, skin, liver, trachea, nerve, cornea, eardrum, dental, bladder, etc. The current review extensively covers the progress made in the SF-based in vitro engineering and regeneration of various human tissues and identifies opportunities for further development of this field.