Silk fibroin film from golden‐yellow Bombyx mori is a biocomposite that contains lutein and promotes axonal growth of primary neurons

Abstract

The use of doped silk fibroin (SF) films and substrates from Bombyx mori cocoons for green nanotechnology and biomedical applications has been recently highlighted. Cocoons from coloured strains of B. mori, such as Golden-Yellow, contain high levels of pigments that could have a huge potential for the fabrication of SF based biomaterials targeted to photonics, optoelectronics and neuroregenerative medicine. However, the features of extracted and regenerated SF from cocoons of B. mori Golden-Yellow strain have never been reported. Here we provide a chemophysical characterization of regenerated silk fibroin (RSF) fibers, solution, and films obtained from cocoons of a Golden-Yellow strain of B. mori, by SEM, (1) H-NMR, HPLC, FT-IR, Raman and UV-Vis spectroscopy. We found that the extracted solution and films from B. mori Golden-Yellow fibroin displayed typical Raman spectroscopic and optical features of carotenoids. HPLC-analyses revealed that lutein was the carotenoid contained in the fiber and RSF biopolymer from yellow cocoons. Notably, primary neurons cultured on yellow SF displayed a threefold higher neurite length than those grown of white SF films. The results we report pave the way to expand the potential use of yellow SF in the field of neuroregenerative medicine and provide green chemistry approaches in biomedicine.

Silk Fibroin‐Based Films Enhance Rhodamine 6G Emission in the Solid State: A Chemical–Physical Analysis of their Interactions for the Design of Highly Emissive Biomaterials

“…The total β‐sheet content is higher in films (48.4%) with respect to solution (38.8%), while, as mentioned, 70% methanol treatment induces additional β‐sheet formation (57.4%) (Table ), in line with previously published data . FTIR data indicate that the conformational properties of SF films display a dominance of Silk I (random coil and alpha‐helices secondary structures) with respect to the Silk II conformation (β‐sheet secondary structures), consistent with reported data, while the addition of RHD (at all tested ratios) slightly decreases the total β‐sheet structure in SF films. The component at 1615 cm −1 represents intermolecular β‐sheet aggregate due to stacked β‐sheets from different molecules, stabilized by side chain interactions, as observed in β‐amyloids .…”

“…Protein materials are characterized by the position and intensity of the amide I, amide II, and amide III bands occurring at 1630–1655, 1540–1520, and 1270–1235 cm −1 , respectively. FTIR spectra of silk fibroin films in the amide regions (1800–1200 cm −1 ) are correlated with Silk I (1655, 1540, and 1235 cm −1 ) and Silk II (1630, 1520, and 1270 cm −1 ) content, an indicator of the conformational properties of the self‐assembled proteins . In addition to the commonly reported β‐sheet and turn structures, it is also possible to identify a β‐aggregated structure, which enhances the amide I band at 1615 cm −1 , due to the presence of intermolecularly hydrogen bonded β‐sheets .…”

The Effect of Strain and Rearing Medium on the Chemical Composition, Fatty Acid Profile and Carotenoid Content in Silkworm (Bombyx mori) Pupae

“…Combined supernatants were centrifuged at 14,000 rpm for 5 min and 20 µL of this solution was injected in a HPLC system equipped with a dual piston solvent delivery pump LC-10ADvp (Shimadzu, Kyoto, Japan), a low pressure quaternary gradient mixer FCV-10ALvp (Shimadzu, Kyoto, Japan), a thermostated column compartment CTO-10ASvp (Shimadzu, Kyoto, Japan), a vacuum solvent delivery degassers Gastorr 154 (Flom; San Diego, CA, USA), a photodiode array detector UV6000LP (Thermoquest; Waltham, MA, USA), and a chromatographic column Adsorbosphere UHS C18, 150 × 4.6 mm, particle size 5 µm (Alltech; Lokeren, Belgium). According to [32], samples were eluted at a flow rate of 1.4 mL/min by 2 mobile phases: Solution A tris buffer 0.01M pH 7.5—acetonitrile (60-40, v-v), solution B acetonitrile—dioxane (65–35, v-v). For elution, a linear gradient was used: T0 min 35% sol.…”

Silk Fibroin Based Technology for Industrial Biomanufacturing

“…Studies to integrate optofluidic component in one LOC for diagnosis of brain pathologies such brain tumours are under investigation. Moreover, we are exploring the possibility of exploitation of a direct application in biomaterials and biomedical field of coloured silk fibroin extracted from coloured cocoons [31,32]. The results reported here were the basis for application for national, private sector supported projects, for the development of silk-based anti-counterfeiting technologies and for European initiatives regarding biomedical use of silk fibroin.…”