Papers by Author: Dai Di Fan

Abstract: In this investigation, the N, O-carboxymethyl chitosan (NOCC) was synthesized. A novel pH-sensitive hydrogel system composed of a water-soluble chitosan derivative (N,O-carboxymethyl chitosan, NOCC)and Human-like collagen (HLC) blended with phosphate was developed for controlling drug delivery and NOCC–HLC microspheres were prepared by the technology of electrostatic droplet generation technique. The release profiles of a model protein drug (bovine serum albumin, BSA) from test hydrogels were studied in simulated gastric and intestinal media.

Abstract: Amino acids, the basic unit of protein molecules, are closely related to some important biological activities and they affect cell growth and metabolism directly or indirectly. Previous studies showed that adding amino acids can improve the productivity of human-like collagen (HLC). Thus, we analyzed the amino acids metabolism during the fermentation process. The results of metabolic flux analysis of amino acids implied that the cell growth and production of HLC were active as long as the free amino acids in the medium were adequate. This suggested control the concentration of amino acids could improve cell growth and human-like collagen production.

Abstract: In this paper, the cross-linking injection hydrogel were synthesized by EDC crosslinker and Carboxymethyl chitosan (CMCS)/Human-like collagen (HLC). Cytotoxicity was assessed by Methylthiazolydiphenyl-tetrazolium bromide (MTT) assay which indicated that the hydrogels was non-toxic to the BHK21 cell .Chondrocyct-encapsulation of this hydrogel were studied in order to asses the cells compatibility of the injection gel. The result showed that the material has no cytotoxicity to the cells and promoted cell adhesion and proliferation. Injected those hydrogels into mice subcutaneous , the following parameters were evaluated: inflammatory response, vascularization, new hypoderm generation. After 2,4,12,and 24 weeks of healing, the rats were sacrilifced suggested that gels in animals did not induce inflammation obvious, vessel bestrid the material after 4 weeks injection, new hypoderm generated in 12 weeks and packaged the hydrogels after 24 weeks. Consequently the gels are promised for the application in the biomaterials area.

Abstract: An efficient agar plate mutagenesis and screening technique for improving mutation frequency was established by using dielectric barrier discharge (DBD) plasma. And very few studies have reported strains of A. calcoaceticus as phosphate solubilizing plant-associated bacteria. In this study, A.calcoaceticus showed a good ability in phosphate solubilizing. DBD plasma was conducted to A. calcoaceticus mutation for improving the phosphate-soubilizing activity. The results showed that the phosphate-soubilizing activity of mutants increased compared with original strain, and the phosphate-soubilizing activity of the best mutants up to 584.3mg/L, is 1.23-fold of original strain. It demonstrated that DBD plasma treatment has a high-efficient quality, and it will be a useful method of mutation.

Abstract: Two control models, manual way and automatic way, have been compared during the fermentation process in this study. The automatic way is achieved by a fermentation controller developed by ourselves. Compared to manual way, biomass (OD₆₀₀) and the production of human-like collagen (HLC) could be increases significantly, reaching to 144 and 7.12g/L respectively. Acetic acid, a key byproduct, is also lowered very obviously. Beside the production controlled by automation model was very stable, the automatic controller can regulate the feeding rate in real time and save labor force.

Abstract: A new hydrophobic method of regenerated silk fibroin was introduced here, in which glycerol was used as the inducer. As a consequence, the soluble form of silk was transformed into hydrophobic form, which hence suggests glycerol has a significant effect of hydrophobic induction. Then the morphology and mechanical properties of the hydrophobic silk fibroin was respectively shown by scanning electron microscope (SEM) and strain test. The results showed induced silk fibroin had a compact surface and good mechanical property. Finally, the induction mechanism of glycerol was discussed that glycerol could soften the fibroin’s structure during dry process ,which was the main reason leading to β-sheets of fibroin partly being rebuilt and then the hydrophobic transformation being achieved.

Abstract: This paper focuses on the properties of the transdermal absorption of Human-like collagen (HLC). In present study, fluorescent marker (isothiocyanates were fluorescent element) was used to detect the absorptivity of HLC and gelatin was considered as a control. 2% HLC solution, 2% gelatin solution, a mixture of 2% HLC and azone, a mixture of 2% gelatin and azone were prepared, respectively. And then this solution was smeared on skin of mice. After 4h and 8h, the skin were collected and observed under a fluorescence microscope. In conclusion, pure human-like collagen has certain transdermal absorption and azone promote the transdermal absorption property of Human like collagen in comparison with gelatin.