ABSTRACT
BACKGROUND:A pure chitosan (CS) scaffold has poor mechanical properties,and cannot play a load-bearing role in the bone defect region.Therefore,many scholars attempt to develop multi-walled carbon nanotube (MWCNT)/chitosan (MWCNT/CS) bone tissue scaffolds.OBJECTIVE:To develop the functionalized MWCNT/CS composite scaffolds carrying zinc (f-MWCNT/CS-Zn) and to test its mechanical properties,antibacterial activity and biocompatibility.METHODS:(1) F-MWCNT composite scaffolds were prepared by the acid mixture method,and f-MWCNT/CS-Zn composite scaffolds were prepared through mixing CS,f-MWCNT (0.5％) with different concentrations of ZnSO4·7H2O (the concentrations of Zn in the composite scaffolds were 0.2％,1％,2％,respectively).The surface hardness and tensile strength of the pure CS scaffold and the f-MWCNT/CS-Zn composite scaffolds were measured.(2) The inhibitory effect on Staphylococcus aureus or Escherichia coii of the pure CS scaffold and f-MWCNT/CS-Zn scaffolds was tested by inhibition zone test.(3) The osteoblasts MC3T3-El were cultured with the leaching solution of f-MWCNT/CS-Zn composite scaffolds.The cell proliferation was detected by MTT assay at 1,2,3 days after culture,then the relative proliferation rate was calculated and the cytotoxicity was evaluated.RESULTS AND CONCLUSION:(1) The surface hardness and tensile strength of the f-MWCNT/CS-Zn composite scaffolds were higher than those of the pure CS scaffold (P ＜ 0.05),and there was no significant difference in the surface hardness and tensile strength between the different zinc-containing composite scaffolds.(2) The antibacterial properties of the three f-MWCNT/CS-Zn composite scaffolds against Staphylococcus aureus and Escherichia coii were higher than those of the pure CS scaffold (P ＜ 0.05),and the antibacterial activity was enhanced with the increase of zinc mass fraction.(3) The f-MWCNT/CS-0.2％Zn and f-MWCNT/CS-1％Zn composite scaffolds had no cytotoxicity.To conclude,the f-MWCNT/CS-1％Zn composite scaffold has good mechanical properties,antibacterial activity and biocompatibility.
ABSTRACT
Carbon monoxide has been proved to be an important signal molecule in body. Transition metal carbonyl compounds are solidified form of carbon monoxide. Numerous studies have shown that Ruthenium carbonyl carbon monoxide releasing molecules have a strong pharmacological activity. In this paper, five Ruthenium (II) carbonyl CORMs 1-5 were synthesized and their toxicology, tissue distribution and interaction with blood endogenous substances were investigated. The results showed CORMs' IC50 to fibroblasts are ranged from 212.9 to 2089.2 micromol x L(-1). Their oral LD50 to mouse is between 800 to 1600 mg x kg(-1). After repeated administration, CORMs 1 and CORMs 5 haven't shown an obvious influence to rats' liver and kidney function, but caused the injury to liver and kidney cells. The in vivo distribution result revealed the majority of CORMs were distributed in blood, liver and kidney, only a small part of CORMs distributed in lung, heart and spleen. They could scarcely cross the blood-brain barrier and distribute to brain. The non-CO ligands in structure have an obvious relevance to their in vivo absorption and distribution. Interestingly, CORMs could enhance the fluorescence of bovine serum albumin, and this enhancement was in direct proportion with the concentration of CORMs. Under different conditions, interaction of CORMs with glutathione got different type of products, one is Ruthenium (II) tricarbonyl complexes, and Ruthenium (II) dicarbonyl complexes.