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As an excellent hosting matrices for enzyme immobilization, metal-organic framework (MOFs) provides superior physical and chemical protection for biocatalytic reactions. In recent years, the hierarchical porous metal-organic frameworks (HP-MOFs) have shown great potential in enzyme immobilization due to their flexible structural advantages. To date, a variety of HP-MOFs with intrinsic or defective porous have been developed for the immobilization of enzymes. The catalytic activity, stability and reusability of enzyme@HP-MOFs composites are significantly enhanced. This review systematically summarized the strategies for developing enzyme@HP-MOFs composites. In addition, the latest applications of enzyme@HP-MOFs composites in catalytic synthesis, biosensing and biomedicine were described. Moreover, the challenges and opportunities in this field were discussed and envisioned.
Assuntos
Estruturas Metalorgânicas/química , Porosidade , Enzimas Imobilizadas/química , Biocatálise , CatáliseRESUMO
The joint is an important athletic organ,and has special structure,i.e.no blood supply in the mature articular cartilage.Hence,once articular cartilage is damaged and is difficult to self-repair.Nowadays,there are several clinical methods for articular cartilage injury,such as micro-fracture,transplant of articular cartilage,replacement of articular cartilage and cartilage tissue engineering.But the repairing effects of these methods are unsatisfactory.Growth factors are biologically active substances that are synthesized by cells in vivo and can accelerate cell growth,promote cell proliferation and induce cell migration etc.There are many growth factors participate in the development of cartilage,such as fibroblast growth factor (FGF),bone morphogenetic protein(BMP),insulin-like growth factor (IGF) and so on.Some research showed that the addition of exogenous growth factor in articular cartilage repair can effectively promote the repair of articular cartilage injury.In this paper,the main growth factors used for articular cartilage injury repair were reviewed,and the functions of these factors in the development and the repair of articular cartilage were discussed.The problems of growth factors in the application of articular cartilage repair were analyzed.
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The joint is an important athletic organ,and has special structure,i.e.no blood supply in the mature articular cartilage.Hence,once articular cartilage is damaged and is difficult to self-repair.Nowadays,there are several clinical methods for articular cartilage injury,such as micro-fracture,transplant of articular cartilage,replacement of articular cartilage and cartilage tissue engineering.But the repairing effects of these methods are unsatisfactory.Growth factors are biologically active substances that are synthesized by cells in vivo and can accelerate cell growth,promote cell proliferation and induce cell migration etc.There are many growth factors participate in the development of cartilage,such as fibroblast growth factor (FGF),bone morphogenetic protein(BMP),insulin-like growth factor (IGF) and so on.Some research showed that the addition of exogenous growth factor in articular cartilage repair can effectively promote the repair of articular cartilage injury.In this paper,the main growth factors used for articular cartilage injury repair were reviewed,and the functions of these factors in the development and the repair of articular cartilage were discussed.The problems of growth factors in the application of articular cartilage repair were analyzed.
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Objective To study the effects of fibroblast growth factor 2 (FGF2) on the proliferation and gene expression profiles of rabbit articular chondrocytes in vitro after different time periods of stimulation.Methods The chondrocytes were isolated and cultured in vitro,and the 3rd generation cells were harvested.Cells were divided into three groups.In the group 1 (FGF2 short-time action group),chondrocytes were cultured in medium with FGF2 for one day,and then transferred to fresh culture medium without FGF2 and cultured for another 6 days.In the group 2 (FGF2 long-time action group),chondrocytes were cultured in medium with FGF2 for 7 days.In the Group 3 (control group),chondrocytes were cultured in culture medium without FGF2 for 7 days.After culture for 1,3,and 7 days,the proliferation of chondrocytes in the all groups was detected respectively.Following extraction of mRNA,the gene expressions of BMP2,BMP4,SOX9 and COL2A1 of the chondrocytes in the all groups were determined by quantitative real-time polymerase chain reaction (qRT-PCR).The content of type Ⅱ collagen was measured via immunofluorescence staining.Results Compared with the control group,FGF2 promoted the proliferation of chondrocytes in the short-and long-time action groups and there was no significant difference between the two FGF2-treated groups.The results of qRT-PCR indicated that different treatment induced different gene expression profile.Particularly,compared with the control group and the FGF2 long-time action group,the expression of BMP2,BMP4,SOX9 and COL2A1 in the short-time action group were significantly upregulated at the 7th day.Immunofluorescence intensity of type Ⅱ collagen in the group 1 was stronger than that in the control group and group 2.Conclusions Different administration of FGF2 for different time periods induced different responses of chondrocytes.Short-term FGF2 stimulation was more beneficial to maintain the phenotype of chondrocytes and the synthesis of extracellular matrix.