Fabrication And Characterization Of Vitamin C Functionalized Silk Fibroin Nanofibers

As an excellent biocompatible and biodegradable protein polymer, silk fibroin (SF) have found wide applications, particularly serving as therapeutic agents for tissue engineering applications, on which both post-spin treatment and sterilization processing are crucial to drug-loaded matrices. To find a safe, effective and appropriate post-spin treatment and sterilization approach for drug-loaded biomaterial matrices is one of the major problems in the field of tissue engineering at present. In this work, a simple, safe and effective approach skillfully integrating post-spin treatment with sterilization processing was developed to drug-loaded SF nanofibrous matrices. Electrospun SF nanofibrous matrices from its aqueous solution were post-treated with 75% ethanol vapor. The 13C-NMR and WAXD analysis demonstrated that such post-spin treatment rendered the structure of SF nanofibrous matrices transform from silkâ… form to silkâ…¡form. Furthermore, biological assays suggested that as-treated SF nanofibrous matrices significantly promoted the development of murine connective tissue fibroblasts. Skillfully integrated with novel sterilization processing,75% ethanol vapor treatment could be a potential approach to designing and fabricating diverse drug-loaded SF nanofibrous matrices serving as therapeutic agents for tissue engineering applications in that it can effectively protect the drug from losing compared with traditional post-spin treatment and sterilization processing.A novel Vitamin C (VC) loaded silk fibroin (SF) nanofibers was fabricated by electrospinning with blend aqueous solution of the materials. The morphology of electrospun VC loaded SF (VC/SF) nanofibers was observed by scanning electronic microscope (SEM) and the compositions of the composite nanofibers were inspected by X-ray photoelectron spectroscopy (XPS). The nanofibrous membrane was post-treated by methanol vapor, which rendered the nanofibers a good water-insoluble characterization. After soaked into phosphate buffered saline (PBS) for 4 days, the water-insoluble nanofibers have swelled due to the absorbing of water. The electrospun SF nanofiber membrane could be a more effective vehicle to delivery the VC into skin tissue and this novel product of VC/SF composite nanofiber is expected to have a good prospect of application on skin care, wound dressing and skin tissue engineering.Vitamin C (VC) is a pivotal biologically active agent involved in many physiologic functions. Almost all species of animals can synthesize VC, however, the human can not. At present, VC has hunted the attention of people as a bioactive agent in a variety of skin-care products. Studies have well documented that VC plays a robust role in the antioxidations by scavenging quenching free radicals. As an antioxidant agent, VC can also protect skin from damaging caused by UV radiation and sunburn, photosensitivity reactions, photoaging, skin cancer and so on. However, VC is instable in the presence of light, moisture, oxygen, and so on. In addition, it is very difficult for many active agents including Vitamins (including VC) to penetrate the stratum corneum. Therefore, appropriate derivatives and advanced vehicle should be developed so as to effectively deliver vitamins to the skin and play their potentials to the full to meet the need for use topically.As a main component of silkworm silk, Silk fibroin (SF) is a naturally occurring protein polymer. SF has recently captured great attention of researchers, due to its distinguishing properties including remarkable biocompatibility, good oxygen and water vapor permeability, and biodegradability, low inflammatory response, and mechanical properties. In addition, SF has the ability to help skin maintain moisture. Furthermore, SF can be used as sunscreen, which can not only absorb ultraviolet radiation and protect the skin from damage of radiation, but also function to decrease melanocyte pigment production. In practice, SF has been currently a popular additive to a variety of fields, such as medical materials for human health, food additives and skin-care products, especially cosmetics.Electrospinning is an effective and versatile method to produce the nanofibers of different materials in variety of fibrous assemblies and electrospun nanofibers have been applied into many fields due to their unique performances, especially the high porosity and their large surface-to-volume ratio. In resent years, much more attention was paid to electrospinning of SF for mimicking the extracellular matrix (ECM), due to the similarity of electrospun SF nanofibers to ECM in composition and structure.In this work, a simple, safe and effective approach skillfully integrating post-spin treatment with sterilization processing was developed to drug-loaded SF nanofibrous matrices. Electrospun SF nanofibrous matrices from its aqueous solution were post-treated with 75% ethanol vapor. The 13C-NMR and WAXD analysis demonstrated that such post-spin treatment rendered the structure of SF nanofibrous matrices transform from silk I form to silk II form. Furthermore, biological assays suggested that as-treated SF nanofibrous matrices significantly promoted the development of murine connective tissue fibroblasts. Skillfully integrated with novel sterilization processing, 75% ethanol vapor treatment could be a potential approach to designing and fabricating diverse drug-loaded SF nanofibrous matrices serving as therapeutic agents for tissue engineering applications in that it can effectively protect the drug from losing compared with traditional post-spin treatment and sterilization processing.By the green processing above, VC/SF composite nanofibrous matrices were successfully fabricated. SEM analysis showed that VC was beneficial to obtain uniform SF nanofibers with smooth surface at a low concentration (25 wt.%).13C-nuclear magnetic resonance (13C-NMR) and Wide-angle X-ray diffraction (WAXD) analysis demonstrated structure of SF nanofibrous matrices had not been significantly changed with VC. The structure of composite nanofibrous matrices was induced from silk I into silk II form with 75% ethanol vapor treatment. Vitamin-C-loaded as-spun composite nanofibrous matrices exhibited a rapid release, which could be beneficial to composite nanofibrous matrices serving as novel skin-care products and therapeutic agents. The results of real time PCR showed that SF nanofibrous matrices can support SOD gene expression and VC/SF composite nanofibrous matrices significantly promoted GSH-px gene expression, which was significant to composite nanofibrous matrices for tissue engineering applications.Therefore, VC loaded as spun SF (VC/SF) nanofibers be more effective on delivering vitamins to the skin so as to meet the need for use topically, as the composite nanofibers not only integrate the advantages of both SF and VC but provide larger surface area for the attachment of skin cells.