Copolymer‐induced silk‐based hydrogel with porous and nanofibrous structure

Abstract

A novel physical blend method was developed to accelerate the self-assembly process of silk fibroin (SF) solution into porous and nanofibrous hydrogel by temperature-sensitive copolymer. Silk-based hydrogel was firstly achieved through blending SF solution with copolymer aqueous solution and then removed the copolymer from blend solution by heat treatment (50 C) after 24 h hydrogelation. Copolymer molecules would interact with SF molecules resulting in reduction of copolymer micelles, which further affect the hydrogelation of SF solutions. Copolymers could be separated from blend solution by heat treatment under an acceptable temperature (50 C), especially the copolymer 2 . Fourier transform infrared (FTIR) and X-ray diffraction showed the blending of copolymer significantly accelerated the self-assembly of SF into physically crosslinked b-sheet crystals at room temperature which led to the sol-gel transition. Results from DTA and X-ray diffraction showed that the effect of copolymer on crystalline structure of SF in silk-based hydrogel was very weak. SF molecules transformed from distributed globular nanoparticles to nanofilaments clustered during hydrogelation, resulting in the porous and nanofibrous structure of silk-based hydrogel. Furthermore, silk-based hydrogel was prepared in aqueous solution avoiding organic solvents and harsh processing conditions, suggesting that this silkbased hydrogel could be a potential candidate scaffold for biomedical applications.

Cooperative Assembly of a Peptide Gelator and Silk Fibroin Afford an Injectable Hydrogel for Tissue Engineering

“…Recent studies revealed that the slow dynamics of gelation for a pure SF solution is mainly relevant with conformational transition from random coil to β-sheet structure, which then gradually self-assembles into close-packed β-sheet crystals, acting as a physical cross-link to stabilize SF hydrogel. ,, Although many physical treatment methods (e.g., pH, vortexing, sonication, and electrical field), − or the addition of certain organic molecules (e.g., ethanol, surfactants, or hydrophilic polymers), are able to increase the gelation rate of SF by adjusting protein chain–chain interactions, − the gelation process induced by instrumental parameters may not be compatible with certain clinical environments, and potential toxicity of certain organic molecules can raise a significant concern for biomedical applications. Thus, searching for a simple and biocompatible way to trigger the gelation of SF is highly desirable.…”

Chitosan/silk fibroin composite scaffolds for wound dressing

“…SF scaffolds have been prepared in various methods, e.g., freeze‐drying, salt leaching, gas foaming, electrospinning, and nonwoven techniques . Based on the above methods, SF scaffolds can be fabricated into various forms, including film, hydrogels, nonwoven fabrics, and 3D porous scaffolds . However, SF does not have antimicrobial properties, which often result in wound infection.…”

Cationic Surfactant-Induced Instantaneous Gelation of Silk Fibroin Solution

“…However, the clinical appli-cation of silk fibroin is limited because of its time consuming nature; it often takes too long to form a hydrogel unless nonphysiological treatments are used (e.g., low pH and high temperature) 8 . In an attempt to combat this disadvantage, some studies have reportedly added polyethylene oxide (PEO) and polymeric surfactants to accelerate the hydrogelation, but they only shortened the hydrogelation time for a limited range 9 . Furthermore, Wu et al 10 found that adding sodium dodecyl sulphate (SDS) as the gelling agent under mild conditions (37 ºC and pH 7.0 ± 0.2) could reduce the silk fibroin gelation time.…”