Effects of sterilization methods on the physical, chemical, and biological properties of silk fibroin membranes

Silk fibroin has been widely explored for many biomedical applications, due to its biocompatibility and biodegradability. Sterilization is a fundamental step in biomaterials processing and it must not jeopardize the functionality of medical devices. The aim of this study was to analyze the influence of different sterilization methods in the physical, chemical, and biological characteristics of dense and porous silk fibroin membranes. Silk fibroin membranes were treated by several procedures: immersion in 70% ethanol solution, ultraviolet radiation, autoclave, ethylene oxide, and gamma radiation, and were analyzed by scanning electron microscopy, Fourier‐transformed infrared spectroscopy (FTIR), X‐ray diffraction, tensile strength and in vitro cytotoxicity to Chinese hamster ovary cells. The results indicated that the sterilization methods did not cause perceivable morphological changes in the membranes and the membranes were not toxic to cells. The sterilization methods that used organic solvent or an increased humidity and/or temperature (70% ethanol, autoclave, and ethylene oxide) increased the silk II content in the membranes: the dense membranes became more brittle, while the porous membranes showed increased strength at break. Membranes that underwent sterilization by UV and gamma radiation presented properties similar to the nonsterilized membranes, mainly for tensile strength and FTIR results1024869876CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPsem informaçã

Blendas E Compàsitos Compreendendo FibroÍna E Alginato, Processos De ProduÇço E Produtos Obtidos Dos Mesmos

ELENDAS E COMPÓSITOS COMPREENDENDO FIBROÍNA E ALGINATO, PROCESSOS DE PRODUÇÃO E PRODUTOS OBTIDOS DOS MESMOS. A presente invenção se refere à biendas compreendendo uma mistura solidificada e homogênea de polimeros naturais compreendendo fibroina e alginato, bem como a compósitos compreendendo fibras de fibroina dispersas em uma matriz polimérica de origem natural. Em virtude de suas propriedades físicas e mecânicas, as blendas e compósitos da presente invenção podem ser utilizados na produção de diversos biomateriais. Processos para a produção das blendas e dos compósitos são também descritos.BRPI1101774 (A2)C08L89/00A61K9/52C08H1/00BR2011PI01774C08L89/00A61K9/52C08H1/0

Preparation and Characterization of Insoluble Silk Fibroin/Chitosan Blend Films

The aim of this study was to prepare and characterize membranes of silk fibroin (SF) and chitosan (CHI) blends. Moreover, a conformation transition of SF to a more stable form induced by the addition of CHI was verified. Blend membranes were prepared, after pH adjustment, in different ratios, and physical integrity, crystallinity, structural conformation and thermal stability were characterized. The results of crystallographic analysis (XRD) indicated the tendency to higher structural organization caused by the addition of CHI. Fourier transformed infrared spectroscopy (FTIR) showed that SF is present in a more stable form in the presence of a CHI content of only 25 wt%. Thermal analysis indicated that SF is thermally stable and that when its proportion in the blend increases, the temperature at which degradation is initiated also increases

Silk fibroin and sodium alginate blend: Miscibility and physical characteristics

Films of silk fibroin (SF) and sodium alginate (SA) blends were prepared by solution casting technique. The miscibility of SF and SA in those blends was evaluated and scanning electron microscopy (SEM) revealed that SF/SA 25/75 wt.% blends underwent microscopic phase separation, resulting in globular structures composed mainly of SF. X-ray diffraction indicated the amorphous nature of these blends, even after a treatment with ethanol that turned them insoluble in water. Thermal analyses of blends showed the peaks of degradation of pristine SF and SA shifted to intermediate temperatures. Water vapor permeability, swelling capacity and tensile strength of SF films could be enhanced by blending with SA. Cell viability remained between 90 and 100%, as indicated by in vitro cytotoxicity test. The SF/SA blend with self-assembled SF globules can be used to modulate structural and mechanical properties of the final material and may be used in designing high performance wound dressing408591CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPsem informaçã

Silk Fibroin And Sodium Alginate Blend: Miscibility And Physical Characteristics.

Films of silk fibroin (SF) and sodium alginate (SA) blends were prepared by solution casting technique. The miscibility of SF and SA in those blends was evaluated and scanning electron microscopy (SEM) revealed that SF/SA 25/75 wt.% blends underwent microscopic phase separation, resulting in globular structures composed mainly of SF. X-ray diffraction indicated the amorphous nature of these blends, even after a treatment with ethanol that turned them insoluble in water. Thermal analyses of blends showed the peaks of degradation of pristine SF and SA shifted to intermediate temperatures. Water vapor permeability, swelling capacity and tensile strength of SF films could be enhanced by blending with SA. Cell viability remained between 90 and 100%, as indicated by in vitro cytotoxicity test. The SF/SA blend with self-assembled SF globules can be used to modulate structural and mechanical properties of the final material and may be used in designing high performance wound dressing.4085-9

Effect of freezing methods on the properties of lyophilized porous silk fibroin membranes

Silk fibroin is a fibrous protein that has been extensively studied for application in the biomedical field, and has been used as a scaffold for bone tissue engineering. Biomaterials made of proteins are prone to physical and chemical degradation during storage; lyophilization, a drying method that consists of freezing and drying steps, is known to promote minimal changes in structure and biological activity of biomaterials. This study evaluates the effect of freezing methods on the properties of lyophilized porous silk fibroin membranes. The membranes were obtained from silk fibroin solution, frozen in liquid nitrogen or ultrafreezer, lyophilized, and then characterized by XRD, FTIR, TGA, DSC and SEM. Although the membranes presented similar physical, chemical and microstructural characteristics, quench freezing with liquid nitrogen, followed by lyophilization, promoted collapse of the membranes, while slow cooling performed by ultrafreezer preserved membrane integrity