Silk-based porous scaffolds have been used extensively in tissue engineering because of their excellent biocompatibility, tunable biodegradability and robust mechanical properties. Although many silk-based scaffolds have been prepared through freeze-drying, a challenge remains to effectively control porous structures during this process. In the present study silk fibroin with different nanostructures were self-assembled in aqueous solution by repeated drying-dissolving process and then used to improve porous structure formation in lyophilization process. Viscosity, secondary structures and water interactions were also studied to exclude their influence on the formation and control of porous structures. Following nanofiber formation in aqueous solution, silk scaffolds with improved porous structure were directly formed after lyophilization and then stabilized with water or methanol annealing treatments. Compared to silk scaffolds derived from fresh solution, the nanofibrous scaffolds showed significantly better cell compatibility in vitro. Therefore, this nanoscale control of silk offers feasible way to regulate the matrix features including porous structure and nanostructure, which are important in regulating cell and tissue outcomes in tissue engineering and regeneration, and then achieve silk-based scaffolds with improved properties.
This work presents a novel approach for preparing TiO 2 nanotube arrays loaded with highly dispersed Co nanoparticles through an ultrasound aided photochemical route. The Co content doped on the arrays was controlled by changing the concentration of Co(NO 3 ) 2 and the ultrasound time. The Co doped TiO 2 nanotube arrays were characterized by SEM, XRD, EDS and UV-Vis spectrum. The photocatalytic activities of TiO 2 nanotube arrays electrode were studied. The results showed that Co doping significantly enhanced the photocatalytic degradation rate of TiO 2 nanotube arrays under UV-light irradiation. The main factors affected photocatalytic degradation of sugar wastewater such as the illumination time, pH, different concentrations of H 2 O 2 and wastewater with undoped TiO 2 nanotube arrays were compared. The results showed that the longer the exposure time, the higher the initial pH of wastewater is more favorable for the CoTiO 2 nanotube arrays, The concentration of H 2 O 2 is 60mmol/L, and compared to undoped TiO 2 nanotube arrays Co doped TiO 2 nanotube arrays have better photocatalytic properties.
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