Investigate the Effect of Thawing Process on the Self-Assembly of Silk Protein for Tissue Applications

Abstract

Biological self-assembly is a process in which building blocks autonomously organize to form stable supermolecules of higher order and complexity through domination of weak, noncovalent interactions. For silk protein, the effect of high incubating temperature on the induction of secondary structure and self-assembly was well investigated. However, the effect of freezing and thawing on silk solution has not been studied. The present work aimed to investigate a new all-aqueous process to form 3D porous silk fibroin matrices using a freezing-assisted self-assembly method. This study proposes an experimental investigation and optimization of environmental parameters for the self-assembly process such as freezing temperature, thawing process, and concentration of silk solution. The optical images demonstrated the possibility and potential of −80ST48 treatment to initialize the self-assembly of silk fibroin as well as controllably fabricate a porous scaffold. Moreover, the micrograph images illustrate the assembly of silk protein chain in 7 days under the treatment of −80ST48 process. The surface morphology characterization proved that this method could control the pore size of porous scaffolds by control of the concentration of silk solution. The animal test showed the support of silk scaffold for cell adhesion and proliferation, as well as the cell migration process in the 3D implantable scaffold.

Evaluation of the Morphology and Biocompatibility of Natural Silk Fibers/Agar Blend Scaffolds for Tissue Regeneration

“…To weaken these interactions, medium bases as Na 2 CO 3 are used under thermal condition. According to SEM results, there were no sericin as well as other impurities and the fact that there is no sign of destruction or damage on the surface of silk fibers implies that the degumming process was appropriative [4].…”

“…In its natural form, silk is composed of fibroin as an inner layer and a sericin coating as an outer layer [1]. Silk fibroin protein can be used as a potential biomaterial in biomedical applications due to its unique mechanical and biochemical properties, such as high tensile strength, good degree of toughness and elasticity, high permeability to oxygen and water, relatively low thrombogenicity, morphologic flexibility, and the support for cell adhesion and growth [2][3][4]. In contrast, there are several reports concerning immune responses which relate to macrophage activation, in vivo inflammation or skin irritation, and skin allergies of sericin proteins [2,5].…”

“…In contrast, there are several reports concerning immune responses which relate to macrophage activation, in vivo inflammation or skin irritation, and skin allergies of sericin proteins [2,5]. This is the reason why, for biomedical and clinical application, sericin protein should be eliminated completely from the silk fibers via degumming process before any further application [3,4].…”

Seeking Solvation: Exploring the Role of Protein Hydration in Silk Gelation

“…Similarly, freezing the protein solution [9,16,[20][21][22] produces a lower energy state for the water (i.e., as ice), thereby enticing it to leave the hydration shell. This example is particularly instructive, as it is the increased entropy of liquid water overcoming the stronger enthalpic component of ice crystals that defines its melting point.…”