Preparation,Modification Of Bacterial Celllulose And Its Application In Mask

Bacterial cellulose is a kind of natural high polymer.Compared with plant cellulose,it has ultra-fine mesh structure,high purity,good water retention and biocompatibility,which makes it widely used in biomedical,food,paper,cosmetics and other fields.This research mainly focused on the mutation and screening of bacterial cellulose producing strains,the identification and characterization of products,the optimization of fermentation conditions for high yield strains,the preparation,characterization and application of bacterial cellulose composite membranes,to get a good performance of bacterial cellulose mask and broaden its application in the field of cosmetics category.The specific experimental results are as follows:(1)The purchased Komagataeibacter xylinus was screened by Atmospheric and room temperature plasma technology,and finally the mutant G31 with a yield higher than 38.3%of the original strain was obtained.The product was initially identified as cellulose by enthrone colorimetric method and enzymatic hydrolysis method.The product was characterized by Fourier transform infrared spectroscopy,scanning electron microscopy,X-ray diffraction and solid-state NMR and it was proved to be bacterial cellulose and belonged to crystalline cellulose type I with crystallinity of 92.42%,with hyperfine three-dimensional network structure.Bacterial cellulose has good thermal stability by differential thermal scanning and thermogravimetric analysis.The tensile properties,water holding capacity,water vapor transmission rate and oxygen transmission rate of bacterial cellulose were tested.The results showed that bacterial cellulose can be used as a mask matrix,which laid a foundation for the application of bacterial cellulose in the mask field.(2)Based on the yield of bacterial cellulose,through the single factor test and the response surface test,the fitted regression equation was obtained by analyzing the response surface data:Y=8.61+0.23*A+0.62*B+0.39*C+0.0025*AB+0.29*AC-0.040*BC-0.24*A~2-0.44*B~2-0.56*C~2,the regression coefficient deterministic coefficient R~2=0.9884,indicating that the data fitting effect is better,and finally the optimal conditions for preparing bacterial cellulose are screened out.The optimal process parameters obtained by combining various factors are:glucose 20 g/L,mannitol 20 g/L,yeast extract 10g/L,peptone 10 g/L,glacial acetic acid 2.5 mL/L,potassium hydrogen phosphate 2.5 g/L,MgSO4·7H2O 1.3 g/L,pH 5.5,temperature 30°C,liquid volume 150 mL.The yield of bacterial cellulose prepared under optimal conditions was 8.49 g/L,which was 2.53 times that before optimization.(3)Two kinds of bacterial cellulose-silk sericin/hyaluronic acid composite membranes were prepared,one is in-situ modified bacterial cellulose-silk sericin/hyaluronic acid composite membrane,and the other is post-modified bacterial cellulose-silk sericin/Hyaluronic acid composite membrane.The two composite membranes were characterized by Fourier transform infrared spectroscopy,scanning electron microscopy,X-ray diffraction,atomic force microscopy and X-ray photoelectron spectroscopy.The results showed that silk sericin and hyaluronic acid were successfully modified onto bacterial cellulose,and the post-modified bacterial cellulose-silk sericin/hyaluronic acid composite film has a lower surface roughness.Thermal stability analysis of the two composite masks was carried out by differential calorimetry and thermogravimetric analysis.The results showed that the addition of silk sericin and hyaluronic acid could improve water retention,thermal stability and biodegradability.The effect of two kinds of composite membrane extracts on the survival rate of mouse L929 cells was examined by MTT assay,so the cytotoxicity of the two composite membranes can be evaluated.The experimental results showed that the cells cultured in the post-modified bacterial cellulose-silk sericin/hyaluronic acid composite extract have a higher survival rate and it can promote the proliferation of the cells to some extent.The tensile properties,water holding capacity,water vapor transmission rate and oxygen transmission rate of the two composite membranes were tested.The results showed that the performance of the post-modified bacterial cellulose-silk sericin/hyaluronic acid composite membrane was Higher than the original bacterial cellulose in all aspects.(4)Commercially available non-woven mask,silk mask,bio-fiber mask,self-made BC mask and BC-SS/HA composite mask were compared and analyzed in terms of morphology,mechanical properties,dryness resistance,moisture retention,moisture permeability,cytotoxicity.The self-made BC mask and BC-SS/HA composite mask have better retiform structure than the commercially available non-woven mask,silk mask and bio-fiber mask,and can be perfectly combined with the skin,so that it allows each nutrient to penetrate deep into the skin for better skin care.Compared with the commercially available non-woven mask,silk mask and biological fiber mask,the self-made BC mask and BC-SS/HA composite mask have good tensile strength.They are not easy to deform under certain tension,have good water holding capacity and moisture retention ability,strong water locking ability,no toxicity to cells,and to a certain extent,promote cell proliferation,and their morphology has remained unchanged.It shows that BC mask and BC-SS/HA composite mask can be applied to cosmetics mask area.