Preparing Silk Fibroin Nanofibers through Electrospinning: Further Heparin Immobilization toward Hemocompatibility Improvement

Abstract

Sodium heparin (HS) was immobilized on the surface of the silk fibroin nanofibers (FS) prepared by electrospinning with the objective of improving the hemocompatibility of the fibers for application as scaffolds in tissue engineering. The nanofiber mats of silk fibroin without (MF-FS) and with (MF-FS/HS) immobilized heparin were characterized through scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy with attenuated total reflectance (FTIR-ATR), thermogravimetric analyses (TGA), energy dispersive spectroscopy (EDS), contact angle, chemical analysis, and biological tests. The formation of hydrogen bonds between the silk fibroin and heparin was discussed based on FTIR-ATR spectra. The amount of immobilized heparin was quantified through papain/N-acetyl-l-cysteine digestion followed by dimethylmethylene blue complexation. Furthermore, the samples with immobilized HS showed higher hydrophilic capability compared to samples without HS due to lower contact angles. It was possible to verify that the capillary end-to-collector distance of 8.5 cm and flow rate of 0.35 mL h(-1) used in the electrospinning process at 20 kV are good conditions for obtaining a small average fiber diameter maintaining the amount of immobilized heparin on MF-FS/HS in ca. 4% w/w. Biological analysis showed that no hemolysis is provoked by MF-FS and MF-FS/HS mat fragments and those such mats are not toxic to Vero cells. However, the MF-FS/HS showed higher cell growth and proliferation than MF-FS, indicating an improvement in the hemocompatibility of the material due to heparin immobilization.

Silk fibroin nanofibers: a promising ink additive for extrusion three-dimensional bioprinting

“…For clinical use, removal of sericin from silk by degumming is essential because sericin has traditionally been linked to the inflammatory response reported for virgin silk [ 20 , 21 ]. SFNFs have often been prepared based on the electrospinning of silk fibroin solutions obtained by dissolution through the decomposition of the β-sheet structure of silk fibroin that contributes to the mechanical robustness of native silk fibers [ [22] , [23] , [24] ]. However, obtaining SFNFs by mechanical disintegration of degummed silk fibers is simpler and less energy- and time-consuming than preparation of SFNFs by electrospinning [ 25 ].…”

Silk fibroin nanofibers electrospun on glass fiber as a potential device for solid phase microextraction

“…The voltage for the electrospinning process was set at 20 kV; three different flow rates (0.20 mL h −1 , 0.50 mL h −1 , 0.35 mL h −1 ) and three capillary tip‐to‐collector distances (7.0 cm, 9.5 cm, and 12.0 cm) were used . After the electrospinning process, fused silica fibers coated with RFS nanofibers were immersed for 24 h in a solution containing methanol to remove any remaining non‐adherent nanofibers, after which the final material was dried at room temperature …”

Application of blocking and immobilization of electrospun fiber in the biomedical field

“…Biodegradable polymer materials are much widely used in the eld of biomedicine (e.g., tissue engineering and drug delivery) including variety of natural materials (e.g., collagen, gelatin, hyaluronic acid, alginate, silk broin) and synthetic materials (e.g., polyolen, polyamides, polyester, aramide, acrylic). [23][24][25] The solution or melting solution of one or more polymer materials mentioned above can obtain ultra-ne nanobers by electrospinning, which plays an important role in all branches of the biomedical eld, especially the blocking effect and immobilization effect caused by the particularity of the structure. First of all, it can load the drug as a carrier for drug delivery 26 and become a potential drug repository.…”