| Tussah silk fibroin is a good natural biological material containing the RGD sequence to promote cell adhesion and growth.Currentlly,the preparation process of silkworm protein solution is basically mature,however,the preparation of soluble tussah silk fibroin is complex and immature due to the special structure between tussah silk and silkworm.Sodium alginate has good biocompatibility and gel activity,while it is prone to cause a sudden drug release owing to its higher hydrophilicity.The introduction of tussah silk fibroin protein can regulate and improve the properties of sodium alginagte to reduce the sudden drug release.The reported methords in the previous literatures can make the alpha helix of fibroin Ⅰtype change into the beta folding structure of fibroin Ⅱ,which is difficult to obtain soluble protein powder.Fistly,to solve this problem,a large number of process conditions were explored in this study.The results showed that the water-soluble regeneration of tussah silk fibroin protein powder could be obtained as the tussah silk was degummed with 5 g/L Na2CO3 solution,and then dissolved with Ca(NO3)2·4H2O at 105℃,followed by dialysis at 4℃,and freeze-dried at 80℃.Secondly,the composite membrane was prepared by mixture of the regenerated tussah silk fibroin(SF)and sodium alginate(SA).The structure,morphology and thermal stability of the composite membranes were characterized by SEM,XRD,FTIR and TGA.SF in the composite membrane existed in a conformationally stable β-sheet structure,and presents good compatibility with SA.Porous structure could be found in the membranes with good surface wettability.Furthermore,the molecular chain in the membrane became more stable as there were a large number of hydrogen bonds,the electrostatic interaction and the complexation of Ca2+.In this study,the effect ratio of SF to SA,PEG dosage,Ca2+concentration,basic conditions of filming and the temperature on the mechanical properties,swelling properties and dissolution rate of the composite film was discussed.The carrier materials based on composite membrane with the best mechanical properties,a great swelling degree of and dissolution rate could prepared at the following conditions:the ration of SF to SA,was 40%:60%,PEG content was 3%,Ca2+concentration was 1.4%,pH was 9 and the temperature was 70℃.At last,the drug carrier was prepared from the cross-linked composite membrane.SF/SA composite films loaded Rhodamine B or Artemisinin were prepared by embedding method.The drug release behavior was investigated using phosphate buffer solution as medium to simulate the body fluid.The effect of SF/SA ratio,Ca2+ concentration,cross-linking time and pH on the drug release performance was invesitgated.The results showed that drug on the surface of membrane dissolved quickly at first 6-8 h with a dissolution rate of 30%,due to the concentration difference of surface drug.The final cumulative release of experimental drug could reach 60-90%.This result indicated that the SF/SA membrane could meet the requirements of the carrier material for drug release.In terms of Rhodamine B and Artemisinin,the increase of Ca2+ concentration,cross-linking time and pH could inhibit the drug release rate,which could achieve the aim of drug controlled release.The SF content showed different effect on the release bavior between Rhodamine B and Artemisinin,the release rate of rhodamine B decreased,while the release rate of artemisinin decreased firstlt and then increased as the SF conent increased in the memberane.And the sustained release time of Rhodamine B and Artemisinin could reach more than 96 h and 192 h,respectively.Therefore,the drug release rate of the composite membrane carrier could be controlled by tailoring the ratio of the raw materials ratio,Ca2+ concentration,cross-linking time and the environment pH.This study will lay a certain foundation for the application of tussah silk fibroin in drug delivery and tissue engineering. |
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