The Effect of Ultrasonication on the Gelation Velocity and Structure of Silk Fibroin

Abstract

Silk fibroin hydrogels is an important morphous of biomaterial. As a natural protein collosol, purified native silk fibroin solution can be gelatinized under certain conditions. The main mechanism of the gelation is that the fibroin molecules turn into the β-sheet conformation from the random coils. This transformation of silk fibroin molecules would be influenced by various parameters such as the temperature, pH value, ion concentration and so on. In this paper, the effect of ultrasonication on the gelation velocity and structure of silk fibroin were discussed. It is believed that the cavitations caused by sonication could accelerate the process of gelation of silk fibroin. Our experiments demonstrated that the ultrasonic treatment could greatly reduce the silk fibroin gelation time, especially at a high sonication power exceeding 400W. The results of XRD, FTIR, and Raman spectra indicated that the ultrasonication had no significant effect on the final structure and composition of the silk fibroin gels except the acceleration for the molecular transition from random coil and α-structure to β-sheet conformation of silk fibroin. The SEM images showed freeze-dried fibroin gels close to the ultrasonication source had compact structure, while the structure was more loosening far away to the source.

Ultrasound regulated flexible protein materials: Fabrication, structure and physical-biological properties

“… [40] also confirmed that the conformation of silk fibroin would undergo transformation with the increase of ultrasonic power. Besides, some studies [41] , [42] , [43] also proved that the long-time sonication could make the random coils converted to stable β -sheet structures and accelerate the formation of silk fibroin gels. Therefore, ultrasound time and power can precisely regulate the secondary structures and the crystallinities of silk fibroin materials.…”

Silk Fibroin Aqueous-Based Adhesives Inspired by Mussel Adhesive Proteins

“…Silk fibroin , has an amino acid sequence consisting of repeats of glycine-alanine-glycine-alanine-glycine-serine (GAGAGS) that self-assemble to form beta sheets. Formation of beta sheets may be triggered by various processing techniques that involve energy input (e.g., sonication − or vortexing), lowering the solution pH, or through dehydration of the protein by removal of water (e.g., by methanol treatment). Beta sheets are highly crystalline and serve to physically cross-link the protein through intra- and intermolecular hydrogen bonding and van der Waals interactions.…”

Ultrasound-assisted air-jet spinning of silk fibroin-soy protein nanofiber composite biomaterials

“…The decrease of Δ C p suggests that the β -sheet crystalline content of the system increases with increasing sonication time. Other studies [13] , [14] , [36] , [8] have also determined that long-term ultrasonic treatment can transform the random coil protein structure into a stable β -sheet structure. These findings are consistent with our findings that ultrasonic time influences the transformation of the secondary structures in SPI/SF materials.…”

“…Silk fibroin protein chains exist as aggregates and micelles in the silkworm's glandular, forming a β -sheet structure when the silkworm spits out, with a crystallinity of about 75% [12] , [13] . Previous studies [1] , [2] , [14] , [15] , [16] found that the molecular chain of silk fibroin consist of an H-chain and an L-chain as well as a P25 protein. This factor plays a crucial role in the thermal and mechanical properties of silk.…”

“… •SDG-7: Affordable, reliable, and sustainable access to modern energy for everyone. Target 7.1 China [14] The ultrasonic parameters, including the output power and time, and the concentration of silk fibroin were controlled to control the gelation of silk fibroin. •Ultrasonic treatment can control the gelation of silk fibroin protein within minutes to hours.…”