A new all‐aqueous and green process is described to form three‐dimensional porous silk fibroin matrices with control of structural and morphological features. Silk‐based scaffolds are prepared using lyophilization. Gelatin is added to the aqueous silk fibroin solution to change the silk fibroin conformation and silk fibroin–water interactions through adjusting the hydrophilic interactions in silk fibroin–gelatin–water systems to restrain the formation of separate sheet like structures in the material, resulting in a more homogenous structure. Water annealing is used to generate insolubility in the silk fibroin–gelatin scaffold system, thereby avoiding the use of organic solvents such as methanol to lock in the β‐sheet structure. The adjusting of the concentration of gelatin, as well as the concentration of silk fibroin, leads to control of morphological and functional properties of the scaffolds. The scaffolds were homogeneous in terms of interconnected pores, with pore sizes ranging from 100 to 600 µm, depending on the concentration of silk fibroin used in the process. At the same time, the morphology of the scaffolds changed from lamellar sheets to porous structures based on the increase in gelatin content. Compared with salt‐leaching aqueous‐derived scaffolds and hexafluoroisopropanol (HFIP)‐derived scaffolds, these freeze‐dried scaffolds had a lower content of β‐sheet, resulting in more hydrophilic features. Most of gelatin was entrapped in the silk fibroin–gelatin scaffolds, without the burst release in PBS solution. During in vitro cell culture, these silk fibroin–gelatin scaffolds had improved cell‐compatibility than salt‐leaching silk fibroin scaffolds. This new process provides useful silk fibroin‐based scaffold systems for use in tissue engineering. Furthermore, the whole process is green, including all‐aqueous, room temperature and pressure, and without the use of toxic chemicals or solvents, offering new ways to load bioactive drugs or growth factors into the process.
Near-infrared spectroscopy (NIR) and differential scanning calorimetry (DSC) were used to investigate temperature-induced changes in the secondary structure and hydration of reconstituted Bombyx mori silk fibroin, with and without freezing water, by looking at regenerated silk fibroin films with a range of water content. We suggest that freezing water facilitates the movement of peptide chains and thus contributes to the conformational transition at 60 °C. The structural changes during heat treatment were analyzed by the two-dimensional correlation method. It was found that the band at 4600 cm−1 consists of complex overlapping components due to different secondary structure elements which compose the protein architecture. Thus, this band could be used as a sensitive probe to estimate the conformations of silk fibroin. By monitoring the variations of the spectral components dynamically, an NIR procedure for tracking the conformational transition of silk fibroin was established. 相似文献
The utilization of implantable devices beseeches highly invasive surgeries considering the adversaries in the insertion of large, impliable devices through the body channels, which necessitate the development of implantable devices using biocompatible shape memory polymers. Silk displays prodigious heterogeneity in its genetic structure and physical properties in accordance with the spinning and storage process, where proteins undergo folding and unfolding. The stimuli-responsive nature of silk can be explained with the help of the structural morphology and composition of the material, where the hydrogen bonds in β-sheet domains and amorphous region act as switch points and net points, respectively. This review provides a primary attempt to enswathe all the literature available to date on the stimuli-responsive nature of silk and silk-based materials as a natural and biodegradable alternative for commercially used synthetic shape memory materials taking their elastomeric nature and reduction in glass transition temperature into account. Further constitutive model using the continuum approach has been utilized to explain the anisotropic elasticity damping effect and plastic deformation based on the α-helix chains, β-sheets, and β-spiral structures. The practicability to develop biomedical devices such as patient-specific-injectable scaffolds, drug carriers, and artificial muscles has been encompassed in this article. 相似文献
