Search citation statements
Paper Sections
Citation Types
Year Published
Publication Types
Relationship
Authors
Journals
Silk fibroin is increasingly emerging as an important biomaterial for tissue engineering applications. The ability to fluorescently image silk matrices under a microscope would be helpful in differentiating embedded labeled cells from background signal, critical for the study of silk-based engineered tissues. In this study, we fabricated a scaffold using freeze drying and confirmed its structure by X-ray diffraction and Fourier transform infrared spectroscopy. We then examined the fluorescence of the silk fibroin scaffold using confocal microscopy, both before and after cell seeding and fluorescent labeling. We subsequently investigated the fluorescent signature of the silk fibroin scaffold chemically. Fluorophore-labeled cells seeded into the scaffold showed the same fluorescent color as the scaffold itself when excited by the same wavelength of light. UV-Vis and fluorescence spectroscopy of a silk fibroin solution indicated absorption and emission maxima at 277 and 345 nm, respectively, which is a typical protein-derived signal. HPLC and GC-MS were used to detect quercetin and quercetin derivatives, without success. We therefore conclude that unlike silk cocoons, the fluorescent behavior of silk fibroin scaffolds does not derive from quercetin and its derivatives but from the intrinsic fluorescence of fibroin protein. We also find that the fluorescent signals deriving from a scaffold and from labeled cells embedded in it can be distinguished when the different optical channels are merged.
Silk fibroin is increasingly emerging as an important biomaterial for tissue engineering applications. The ability to fluorescently image silk matrices under a microscope would be helpful in differentiating embedded labeled cells from background signal, critical for the study of silk-based engineered tissues. In this study, we fabricated a scaffold using freeze drying and confirmed its structure by X-ray diffraction and Fourier transform infrared spectroscopy. We then examined the fluorescence of the silk fibroin scaffold using confocal microscopy, both before and after cell seeding and fluorescent labeling. We subsequently investigated the fluorescent signature of the silk fibroin scaffold chemically. Fluorophore-labeled cells seeded into the scaffold showed the same fluorescent color as the scaffold itself when excited by the same wavelength of light. UV-Vis and fluorescence spectroscopy of a silk fibroin solution indicated absorption and emission maxima at 277 and 345 nm, respectively, which is a typical protein-derived signal. HPLC and GC-MS were used to detect quercetin and quercetin derivatives, without success. We therefore conclude that unlike silk cocoons, the fluorescent behavior of silk fibroin scaffolds does not derive from quercetin and its derivatives but from the intrinsic fluorescence of fibroin protein. We also find that the fluorescent signals deriving from a scaffold and from labeled cells embedded in it can be distinguished when the different optical channels are merged.
To understand mechanisms for the difference of uptaking and transporting the pigments between the male and female in the silkworm, Bombyx mori strain of sex-related fluorescent cocoon, the fluorescent pigments in the midgut lumen, midgut, blood, silk glands and cocoon were analyzed with thin-layer chromatography, and showed that fluorescent colors of cocoons consisted with that of blood and silk glands. The different fluorescent colors of cocoons between the male and female may be mainly caused by the difference of accumulation and transportation for fluorescent pigments in the midgut and in the silk glands. Furthermore the midgut proteins were separated with Native-PAGE, and the proteins respectively recovered from three fluorescent regions presenting on a Native-PAGE gel for the female silkworms were determined using shotgun proteomics and mass spectrometry sequencing, of which 60, 40 and 18 proteins respectively from the region 1, 2 and 3 were identified. It was found that the several kinds of low molecular mass 30 kDa lipoproteins and the actins could be detected in all three regions, troponin, 30 kDa lipoprotein and 27 kDa glycoprotein precursor could be detected in the region 2 and 3, suggesting these proteins may be fluorescent pigments binding candidates proteins. Analysis of gene ontology indicated that the identified proteins in the three regions linked to the cellular component, molecular function, and biological process categories. These results provide a new clew to understand the formation mechanism of sex-related fluorescent cocoon of silkworm.
By using silkworms, Bombyx mori, fluorescent cocoon sex identification (FCSI) as an experimental material, direct fluorescence spectrometry of the cocoon surface indicates that the fluorescent color of silkworm cocoons is made up of two peaks of yellow and blue-purple fluorescence emission. The fluorescent difference between male and female cocoons is attributed to the differential absorption of yellow fluorescent substances by the midgut tissue of 5th instar female silkworms. Thin layer chromatography (TLC) and fluorescent spectra indicate that blue-purple fluorescent substances are composed of at least five blue-purple fluorescent pigments, and yellow fluorescent substances are made up of at least three. UV spectra and AlCl₃ color reaction show that the three fluorescent yellow pigments are flavonoids or their glycosides. Silkworm FCSI is due to selective absorption or accumulation of the yellow fluorescent pigments by the posterior midgut cells of female 5th instar larvae. The cells of the FCSI silkworm midgut, especially the cylinder intestinal cells of the posterior midgut have a component which is a yellow fluorescent pigment-specific binding protein that may be vigorously expressed in the 5th instar larvae.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.