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Objective To construct a two-dimensional (2D) composite membrane and a three-dimensional (3D) biomimetic scaffold by silk fibroin (SF), type I collagen (Col-I) and hydroxyapatite (HA) blends in vitro, so as to study its physicochemical properties, as well as biocompatibility and explore the feasibility of its application in tissue engineering scaffold materials. Methods 2D composite membranes and 3D scaffolds were prepared by blending SF/Col-I/HA at the bottom of cell culture chamber and low temperature 3D printing combined with vacuum freeze drying. The biocompatibility was evaluated by mechanical property testing, scanning electron microscope and Micro-CT to examine the physicochemical properties of the material, and cell proliferation was detected to evaluate its biocompatibility. Results Stable 2D composite membrane and 3D porous structural scaffolds were obtained by blending and low temperature 3D printing. The mechanical properties were consistent. The pore size, water absorption, porosity and elastic modulus were all in accordance with the requirements of constructing tissue engineering bone. The scaffold was a grid-like white cube with good internal pore connectivity; HA was evenly distributed in the composite membrane, and the cells were attached to the composite membrane in a flat shape; the cells were distributed around pore walls of the scaffold. The shape of the shuttle was fusiform, and the growth and proliferation were good. Conclusions The composite membrane and 3D scaffold prepared by SF/Col-I/HA blending system had better pore connectivity and pore structure, which was beneficial to cell and tissue growth and nutrient transport. Its physicochemical properties and biocompatibility could meet the requirements of bone tissue engineering biomaterials.
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Objective: To prepare the molecularly imprinted composite membrane of curcumin by the atom transfer radical polymerization (ATRP) technique and develop a method for the separation and enrichment of curcumin in actual samples. Methods Curcumin MIM were prepared by thermal polymerization method using curcumin as template molecule, methylacrylic acid as functional monmers, cuprous chloride as catalyst, pentamethyldiethylenetriamine as ligand, and polyvinylidene fluoride as base membrane. The microstructure of MIM was investigated by SEM. The maximum adsorption and adsorption equilibrium time of MIM were investigated by static and dynamic adsorption experiment, and the selective penetration capacity was studied. The MIM as membrane material of osmotic device combined with HPLC was used for separation, enrichment and determination of curcumin in samples. Results The results showed that the prepared curcumin MIM had a regular distribution of pores and a uniform size. The maximum adsorption capacity was 3.81 mg/g, and the adsorption equilibrium could be achieved in 15 min. In the selective permeation process of ferulic acid, quercetin and curcumin, MIM had a high selective permeability to curcumin. The average recovery rates of curcumin in ginger, turmeric and curry were (94.100 ± 3.952)%, (98.300 ± 3.637)%, and (97.900 ± 3.133)%, respectively. The RSD was less than 4.2%. The limit of detection was 1.76 μg/kg. Conclusion The prepared MIM is a new material for strong selectivity, separation and enrichment of Chinese medicine curcumin with fast adsorption speed. At the same time, it also provides reference for chemical composition research of other Chinese materia medica.
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Ulocladium atrum inulinase was immobilized on different composite membranes composed of chitosan/nonwoven fabrics. Km values of free and immobilized U. atrum inulinase on different composite membranes were calculated. The enzyme had optimum pH at 5.6 for free and immobilized U. atrum inulinase on polyester nonwoven fabric coated with 3% chitosan solution (PPNWF3), but optimum pH was 5 for immobilized U. atrum inulinase on polyester and polypropylene nonwoven fabrics coated with 1% chitosan solution. The enzyme had optimum temperature at 40°C for immobilized enzyme on each of polyester and polypropylene composite membranes coated with 1% chitosan, while it was 50°C for free and immobilized enzyme on polypropylene nonwoven fabric coated with 3% chitosan solution. Free U. atrum inulinase was stable at 40°C but thermal stability of the immobilized enzyme was detected up to 60°C. Reusability of immobilized enzyme was from 38 to 42 cycles of reuse; after this, the immobilized enzyme lost its activity completely. In conclusion, immobilized U. atrum inulinase was considerably more stable than the free enzyme, and could be stored for extended periods.
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10.3969/j.issn.2095-4344.2013.25.013