The influence of the hydrophilic–lipophilic environment on the structure of silk fibroin protein

Abstract

The present study examines the influence of the hydrophilic-lipophilic environment, mediated by small molecules, on the structural changes in silk protein fibroin. Small molecules mediate the various hydrophilic-lipophilic balances (HLBs) that impact the organisation of silk protein chains. Changes in the silk fibroin structure due to additives are related to the HLB value. At HLB > 10, silk fibroin primarily forms Silk I crystalline structures. Small molecules with HLB < 8.9 primarily induce the formation of Silk II crystalline structures. When 8.9 < HLB < 10, the crystalline structure of silk is related to the content of small molecules. The Silk I structure is primarily formed when the content of small molecules is low, whereas the Silk II structure is formed when the small molecule content is high. The structure of silk fibroin is maintained by regulating the HLB in the fibroin environment. This type of control for the functional design of materials may play a role in fine-tuning the biomaterial properties of silk fibroin protein.

Silk Fibroin/Orange Peel Foam: An Efficient Biocomposite for Water Remediation

“…The peak at 24.2° is attributed to the less ordered crystalline form of β‐sheet structures, with crystalline spacing of 3.7 Å . The diffraction profile of the SFOP foam also shows weak peaks at angles 12.2° and 19.7° (crystalline spacing of 7.4 and 4.5 Å), which are also associated to the less ordered β‐sheet crystalline form . This can be attributed to the presence of the OP filler, which influences the self‐assembly into β‐sheet crystallites during the protein gelation, causing an increase of the less ordered content.…”

“…As shown in Figure c, both samples exhibit a prevalent highly ordered structure. The most intense peak at 20.6° is typical of the highly ordered crystalline form characterized by the intra‐hydrogen‐bonded β‐sheet structure, which corresponds to a crystalline spacing of 4.3 Å . The peak at 24.2° is attributed to the less ordered crystalline form of β‐sheet structures, with crystalline spacing of 3.7 Å .…”

“…The most intense peak at 20.6° is typical of the highly ordered crystalline form characterized by the intra‐hydrogen‐bonded β‐sheet structure, which corresponds to a crystalline spacing of 4.3 Å . The peak at 24.2° is attributed to the less ordered crystalline form of β‐sheet structures, with crystalline spacing of 3.7 Å . The diffraction profile of the SFOP foam also shows weak peaks at angles 12.2° and 19.7° (crystalline spacing of 7.4 and 4.5 Å), which are also associated to the less ordered β‐sheet crystalline form .…”

Smart Windows Prepared from Bombyx mori Silk

“…Additives such as polyalcohols impact the SF structure to a variable extent depending on their hydrophilic–lipophilic balance (HLB) value. Lu et al . recently demonstrated that upon addition of polyalcohols with HLB>10, SF primarily exists as silk I.…”

Finely dispersed palladium on silk‐fibroin as an efficient and ligand‐free catalyst for Heck cross‐coupling reaction

“…Pure SF (Figure a) presented absorption bands at 1647 cm −1 and 1545 cm −1 that corresponded to amide ‐ I (C = O stretching) and amide ‐ II (N‐H bending) of silk II structural conformation (β‐sheet). Another absorption band observed at 1247 cm −1 corresponded to amide ‐ III (C‐N stretching), which is typically silk I conformation (α‐helix or random coil structure) . Peaks were observed at 1411 cm −1 (due to symmetric stretching vibrations of carboxylate group) and 1339 cm −1 (indicating the presence of methylic groups of alanine in the silk chain).…”