Construction For Sustained-Releasing System Of Silk Fibroin/Sodium Alginate Blend Membrane And Its Performance Analysis

Silk Fibroin is a natural macromolecule protein,which is degummed by cocoon,and it is popular for the fileds of the cosmetics,food and biomedical materials,because of its excellent biocompatibility,physical and chemical properties and wound healing.At present,the basis and application study of biomedical materials based on silk fibroin are numerous,but their clinical application has not yet made a breakthrough.The bottleneck of clinical application is mainly due to: 1)silk fibroin is a natural protein and its acquisition and process used is difficult to control,resulting in poor reproducibility of the preparation results,and then it is difficult to provide reliable data for the medical industry;2)Because of the structure composited of hydrophilic amino acids,such as alanine,etc.,silk fibroin-based medical materials have a certain water-soluble properties,and the method to eliminate the criticism is single,and its safety need to be further studied;3)silk fibroin itself Performance is not yet fully meet the multi-standards of biomedical materials,such as: mechanical,shape,breathable and so on.The silk fibroin-based wound dressing is one of the silk fibroin biomedical materials.Although silk fibroin-based dressing has good mechanical properties and drug slow-release function,it still need to address the following drawbacks: water soluble,Poor and poor comfort t o meet the requirements of the ideal type of wound dressing.Therefore,in this paper,silk fibroin(SF)is uesd for the raw material,whose drug slow-release effect is regared as the main line;Sodium alginate(SA)is an absorbent polysaccharide fiber,and its solution is chosed to mixed with SF solution to enhance the water mataining and retaining of dressing;Next,glycerol(Gly)was added into the composition,increasing the comfort of dressing,and the volatile crosslinking agent glutaraldehyde(GA)is added into the composition,reducing the water solubility of the dressing,and thus silk fibroin-based controlled-releasing wound dressings has bee prepared with superior performance.Namely,the content range of SA,GA and Gly has been selected by that silk fibroin-based dressing was not soluble in PBS and could slowly release drug from it,at the same time,pharmacokinetics of drug releasing from dressing has been analyzed.Next,the content values of SA,GA and Gly have been optimized from membrane's mechanical properties.At last,the secondary structure and thermal stability of optimized silk fibroin dressing were analyzed,and then its biological activity and safety were evaluated.What above has a great practical significance for explaining the treatment of silk fibroin-based wound dressing and promoting the substantial breakthrough of modern wound dressing containing silk fibroin-based dressing.1.Construction for sustained-releasing system of silk fibroin/sodium alginate blend membrane and its drug release kinetics analysisSilk fibroin and alginic acid polysaccharide,which are both natural fiber,are good raw material for biomedical materials.The silk II content of silk fibroin and the degree of crosslinking of sodium alginate are the key factors of drug sustained-release from membrane,which has attracted much attention from domestic and foreign scholars.In this study,we established the sustained-release system of silk fibroin/sodium alginate/model drug membrane to detect the drug release rate and cumulative release rate in PBS,and then the release rate,cumulative release rate and drug release kinetics model of the sustained release carrier were analyzed.The results showed that SA group and Gly group had a certain degree of promoting effect on drug release from membranes,while GA was opposite.Compared to other concentration carriers,the 0.8% SA,low concentration of Gly and low concentration of GA has weakened the release rateo,and showed stable release rate.In addition,All drug release curves of SF/SA sustained-release film dressings were less than 0.5,which belonged to the Fickian model diffusion mechanism,but it is different from typical planar,spherical and columnar materials.In conclusion,the concentration range of SF/SA membrane dressing was successfully defined.The effects of the variables on the release of carrier drugs were analyzed.And the mechanism of drug release was classified,which supported for the clinical application of SF/SA drug sustained-release membrane as the theoretical reference.2.Preparation of silk fibroin/alginate blend membrane as sustained-releasing carrier by response surface methodologyMechanical propertiy is a important indicators of ideal membrane wound dressings.In order to optimize the preparation parameters of SF/SA-GA-Gly membrane with the best mechanical properties,the response surface method has been introducted.Results showed that when the content of SA was 0.7 %,content of GA was 1.06 %,and content of Gly was 1.2 %,the SF/SA-GA-Gly film can meet the requirements of comfort dressing(when E is 20%,Ts<14N),and the tensile strength is 16.602 % here.The results are conducive to the preparation of comfort dressings,and has a certain practical significance.3.Physical properties evaluation of silk fibroin/alginate blend membranes as sustained-releasing carrierIn this study,pure SF,SF-Gly and SF-GA were used as reference.SF/SA,SF/SA-Gly and SF/SA-GA were used for control group.SF/SA-Gly-GA membranes were evaluated.The results show that GA has a positive and significant effect on the hot water stability of membrane;Gly also has a positive effect on the swelling degree of membrane.At the same time,both GA and Gly weaken the water absorption performance of SF/SA film and enhance the water retention performance.SF/SA-Gly-GA membrane can slowly release drug,and its release kinetic mechanism belongs to the Fickan model.The results provide a reliable data reference for the further study of SF/SA wound dressing membranes.4.Characterization of silk fibroin/alginate blend membranes as sustained-releasing carrierDrug sustained release effect of membrane carrier are closely related with its morphology and structure.At present,drug release mechanism has yet been analyzed by carrier structure test,except the drug release rate and kinetic analysis.In this experiment,the apparent morphology of SF/SA-Gly-GA membrane carrier was observed by scanning electron microscopy(SEM).In addition,X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FT-IR)and differential scanning calorimetry(DSC)was used to test the membrane carrier structure.The results of SEM show that there are many gel balls with diameters about 20 ?m,and it is integrated with the membrane.XRD,FT-IR and DSC showed that in the presence of GA and Gly,The secondary structure of the SF/SA-GA-Gly membrane is changed from random coil to ? structure,and the structure of the membrane crystal region is increased.The results provide a theoretical basis for the physical properties of membrane drug carriers.5.Biosafety and antibacterial efficacy of silk fibroin/alginate blend membranesBiological safety and biological activity are the necessary criteria to consider the clinical feasibility of biomaterials.SF and SA component of the SF/SA-GA-Gly membrane have good biocompatibility,and Gly and GA are common medical agents,but the content of GA can cause cytotoxicity,once the value more than 0.2%.To assess the biosafety and biological activity of the SF/SA-GA-Gly membrane after washed,cytotoxicity(MTT)detection and antimicrobial activity(bacteriostatic assay)were experimented to evaluate the primary and secondary washed membranes.The results showed that there is no cytotoxicity of the material washed twice(RGR>75 %);While both the one washed twice and the one washed once can inhibit bacterial,and the activity between them was not significant.In summary,the SF/SA-GA-Gly membrane,which has been washed several times,has anti-Gram-negative and positive bacteria and has the potential to clinically cure wounds.